Journal of Neuroscience Research

Rapid, effective, and long-lasting behavioral recovery produced by microsutures, methylene blue, and polyethylene glycol after completely cutting rat sciatic nerves.

Publication Date: 2012 Feb 3 PMID: 22302646
Authors: Bittner, G. D. - Keating, C. P. - Kane, J. R. - Britt, J. M. - Spaeth, C. S. - Fan, J. D. - Zuzek, A. - Wilcott, R. W. - Thayer, W. P. - Winograd, J. M. - Gonzalez-Lima, F. - Schallert, T.
Journal: J Neurosci Res

Behavioral function lost in mammals (including humans) after peripheral nerve severance is slowly (weeks to years) and often poorly restored by 1-2-mm/day, nonspecifically directed outgrowths from proximal axonal stumps. To survive, proximal stumps must quickly repair (seal) plasmalemmal damage. We report that, after complete cut- or crush-severance of rat sciatic nerves, morphological continuity, action potential conduction, and behavioral functions can be consistently (>98% of trials), rapidly (minutes to days), dramatically (70-85% recovery), and chronically restored and some Wallerian degeneration prevented. We assess axoplasmic and axolemmal continuity by intra-axonal dye diffusion and action potential conduction across the lesion site and amount of behavioral recovery by Sciatic Functional Index and Foot Fault tests. We apply well-specified sequences of solutions containing FDA-approved chemicals. First, severed axonal ends are opened and resealing is prevented by hypotonic Ca(2+) -free saline containing antioxidants (especially methylene blue) that inhibit plasmalemmal sealing in sciatic nerves in vivo, ex vivo, and in rat B104 hippocampal cells in vitro. Second, a hypotonic solution of polyethylene glycol (PEG) is applied to open closely apposed (by microsutures, if cut) axonal ends to induce their membranes to flow rapidly into each other (PEG-fusion), consistent with data showing that PEG rapidly seals (PEG-seals) transected neurites of B104 cells, independently of any known endogenous sealing mechanism. Third, Ca(2+) -containing isotonic saline is applied to induce sealing of any remaining plasmalemmal holes by Ca(2+) -induced accumulation and fusion of vesicles. These and other data suggest that PEG-sealing is neuroprotective, and our PEG-fusion protocols that repair cut- and crush-severed rat nerves might rapidly translate to clinical procedures. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Cellular mechanisms of plasmalemmal sealing and axonal repair by polyethylene glycol and methylene blue.

Publication Date: 2012 Feb 3 PMID: 22302626
Authors: Spaeth, C. S. - Robison, T. - Fan, J. D. - Bittner, G. D.
Journal: J Neurosci Res

Mammalian neurons and all other eukaryotic cells endogenously repair traumatic injury within minutes by a Ca(2+) -induced accumulation of vesicles that interact and fuse with each other and the plasmalemma to seal any openings. We have used uptake or exclusion of extracellular fluorescent dye to measure the ability of rat hippocampal B104 cells or rat sciatic nerves to repair (seal) transected neurites in vitro or transected axons ex vivo. We report that endogenous sealing in both preparations is enhanced by Ca(2+) -containing solutions and is decreased by Ca(2+) -free solutions containing antioxidants such as dithiothreitol (DTT), melatonin (MEL), methylene blue (MB), and various toxins that decrease vesicular interactions. In contrast, the fusogen polyethylene glycol (PEG) at 10-50 mM artificially seals the cut ends of B104 cells and rat sciatic axons within seconds and is not affected by Ca(2+) or any of the substances that affect endogenous sealing. At higher concentrations, PEG decreases sealing of transected axons and disrupts the plasmalemma of intact cells. These PEG-sealing data are consistent with the hypothesis that lower concentrations of PEG directly seal a damaged plasmalemma. We have considered these and other data to devise a protocol using a well-specified series of solutions that vary in tonicity, Ca(2+) , MB, and PEG content. These protocols rapidly and consistently repair (PEG-fuse) rat sciatic axons in completely cut sciatic nerves in vivo rapidly and dramatically to restore long-lasting morphological continuity, action potential conduction, and behavioral functions. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Ischemic tolerance in the brain: Endogenous adaptive machinery against ischemic stress.

Publication Date: 2012 Feb 3 PMID: 22302606
Authors: Kitagawa, K.
Journal: J Neurosci Res

Although more than 100 drugs have been examined clinically, tissue plasminogen activator remains the only drug approved for the treatment of acute ischemic stroke. Since the discovery of ischemic tolerance, it has been widely recognized that the brain possesses an endogenous protective machinery to protect against ischemic stress. Recent studies have clarified that both the upregulation of neuroprotective signaling and the downregulation of inflammatory or apoptotic pathways are involved equally in the acquisition of ischemic tolerance. The triggering stimuli for ischemic stresses are divided into hypoxic, oxidant/inflammatory, and glutamate stress. Glutamate stress, particularly the synaptic stimulation of the N-methyl-D-aspartate receptor, leads to activation of the cAMP response element-binding protein, which could subsequently induce gene expression of several neuroprotective molecules. Gene reprogramming and metabolic downregulation are intimately involved in ischemic tolerance as well as in hibernation and hypothermia. Micro-RNAs may be a key player for tuning the level of gene expression in ischemic tolerance. Future research should be performed to investigate the most effective combination for brain protection, enhancement of cell survival signaling, and inhibition of the inflammatory or apoptotic pathways. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Increased [(3) H]D-aspartate release and changes in glutamate receptor expression in the hippocampus of the mnd mouse.

Publication Date: 2012 Feb 3 PMID: 22302580
Authors: Bigini, P. - Milanese, M. - Gardoni, F. - Longhi, A. - Bonifacino, T. - Barbera, S. - Fumagalli, E. - Di Luca, M. - Mennini, T. - Bonanno, G.
Journal: J Neurosci Res

Neuronal ceroid lipofuscinoses (NCLs) are a group of hereditary childhood diseases characterized mainly by lipopigment accumulation and a multisystemic pattern of symptoms including mental retardation, seizures, motor impairment, and blindness. The mnd mouse, carrying a mutation in the Cln8 gene, has been proposed as a model of epilepsy with mental retardation (EPMR, ornorthern epilepsy). We recently showed neuronal hyperexcitability and seizure hypersusceptibility in mnd mice. To elucidate the cellular mechanisms related to hippocampal hyperexcitability, the glutamatergic transmission and the expression of postsynaptic glutamate receptors were investigated in hippocampus. A significant increase in either spontaneous or KCl-stimulated overflow of [(3) H]D-aspartate was found in mnd mice compared with controls. This increase was maintained after DL-threo-beta-benzyloxyaspartic acid (TBOA) treatment, suggesting a nonrelevant role for transporter-mediated release and supporting the involvement of exocytotic [(3) H]D-aspartate release. Accordingly, Ca(2+) -dependent overflow induced by ionomycin was also increased in mnd mice. Levels of glutamate 1-3 AMPA receptor subunits were increased, and levels of the NR2A NMDA receptor subunit were decreased in the hippocampus of mnd mice, suggesting an adaptive response to glutamate overstimulation. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Neddylation positively regulates the ubiquitin E3 ligase activity of parkin.

Publication Date: 2012 Jan 24 PMID: 22271254
Authors: Um, J. W. - Han, K. A. - Im, E. - Oh, Y. - Lee, K. - Chung, K. C.
Journal: J Neurosci Res

Mutations in the parkin gene underlie a familial form of Parkinson's disease known as autosomal recessive juvenile Parkinsonism (AR-JP). Dysfunction of parkin, a ubiquitin E3 ligase, has been implicated in the accumulation of ubiquitin proteasome system-destined substrates and eventually leads to cell death. However, regulation of parkin enzymatic activity is incompletely understood. Here we investigated whether the ubiquitin E3 ligase activity of parkin could be regulated by neddylation. We found that parkin could be a target of covalent modification with NEDD8, a ubiquitin-like posttranslational modifier. In addition, NEDD8 attachment caused an increase of parkin activity through the increased binding affinity for ubiquitin-conjugating E2 enzyme as well as the enhanced formation of the complex containing parkin and substrates. These findings point to the functional importance of NEDD8 and suggest that neddylation is one to the diverse modes of parkin regulation, potentially linking it to the pathogenesis of AR-JP. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

ID2: A negative transcription factor regulating oligodendroglia differentiation.

Publication Date: 2012 Jan 18 PMID: 22253220
Authors: Chen, X. S. - Zhang, Y. H. - Cai, Q. Y. - Yao, Z. X.
Journal: J Neurosci Res

Remyelination of the central nervous system in multiple sclerosis patients is often incomplete. Remyelination depends on normal oligodendrogenesis and the differentiation of oligodendrocyte precursor cells (OPC) into mature oligodendrocytes (OL). Inhibitor of DNA binding (ID), a transcription factor, is thought to inhibit oligodendrogenesis and the differentiation of OPC. This Mini-Review aims to reveal the roles of and mechanisms used by IDs (mainly ID2) in this process. An interaction between ID2 and retinoblastoma tumor suppressor is responsible for the cell cycle transition from G1 to S. The translocation of ID2 between the nucleus and cytoplasm is regulated by E47 and OLIG. An interaction between ID2 and OLIG mediates the inhibitory effects of bone morphogenic proteins and G protein-coupled receptor 17 on oligodendroglia differentiation. ID2 expression is regulated by Wnt and histone deacetylases during the differentiation of OPC. ID4, another member of the ID family, functions similarly to ID2 in regulating the differentiation of OPC. The main difference is that ID4 is essential for oligodendrogenesis, whereas ID2 is nonessential. This could have important implications for demyelinating diseases, and interfering with these pathways might represent a viable therapeutic approach for these diseases. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Motor performance of young dystrophic mdx mice treated with long-circulating prednisolone liposomes.

Publication Date: 2012 Jan 18 PMID: 22253213
Authors: Weller, C. - Zschuntzsch, J. - Makosch, G. - Metselaar, J. M. - Klinker, F. - Klinge, L. - Liebetanz, D. - Schmidt, J.
Journal: J Neurosci Res

For Duchenne muscular dystrophy (DMD), a common myopathy that leads to severe disability, no causal therapy is available. Glucocorticosteroids improve patients' muscle strength, but their long-term use is limited by negative side effects. Thus, pharmacological modifications of glucocorticosteroids are required to increase the efficacy by drug targeting. Liposomal encapsulation augments systemic half-life and local tissue concentrations of glucocorticosteroids and, at the same time, reduces systemic side effects. In this study, the efficacy of novel, long-circulating, polyethylene-glycol-coated liposomes encapsulating prednisolone was compared with free prednisolone in the treatment of mdx mice, a well-established animal model for DMD. Using an objective and sensitive computerized 24-hr detection system of voluntary wheel-running in single cages, we demonstrate a significant impairment of the running performance in mdx compared with black/10 control mice aged 3-6 weeks. Treatment with liposomal or free prednisolone did not improve running performance compared with saline control or empty liposomes. Histopathological parameters, including the rate of internalized nuclei and fiber size variation, and mRNA and protein expression levels of transforming growth factor (TGF)-beta and monocytes chemotactic protein (MCP)-1 also remained unchanged. Bioactivity in skeletal muscle of liposomal and free prednisolone was demonstrated by elevated mRNA expression of muscle ring finger protein 1 (MuRF1), a mediator of muscle atrophy, and its forkhead box transcription factors (Foxo1/3). Our data support the assessment of voluntary running to be a robust and reproducible outcome measure of skeletal muscle performance during the early disease course of mdx mice and suggest that liposomal encapsulation is not superior in treatment efficacy compared with conventional prednisolone. Our study helps to improve the future design of experimental treatment in animal models of neuromuscular diseases. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Minocycline protects oligodendroglial precursor cells against injury caused by oxygen-glucose deprivation.

Publication Date: 2012 Jan 18 PMID: 22253205
Authors: Schmitz, T. - Endesfelder, S. - Chew, L. J. - Zaak, I. - Buhrer, C.
Journal: J Neurosci Res

Ischemic brain injury is widely modeled in vitro with paradigms of oxygen-glucose deprivation (OGD), which leads to cell death. The prevention and attenuation of brain injury by the tetracycline antibiotic minocycline has been attributed largely to suppression of microglial activation, but its benefits in oligodendrocyte cells have not been well characterized. Using primary cultures of rat oligodendroglial precursor cells (OPC) exposed to OGD, we investigated the direct effects of minocycline on the survival, proliferation, and maturation of oligodendroglial lineage cells. OGD for 2 hr caused a decrease in the total number of OPC and the amount of proliferating progenitors by 50%, which was attenuated by inclusion of minocycline. The reduced numbers of immature oligodendroglial cells at 72 hr and of mature oligodendrocytes at 120 hr after OGD were partially restored by minocycline. In OPC, OGD caused an increase of reactive oxygen species (ROS) and production of TUNEL-positive cell numbers, which was abolished by minocycline. Minocycline preferentially increased the expression of superoxide dismutase under OGD but not in control OPC. Minocycline also prevented the OGD-induced downregulation of the transcription factors Sox10 and Olig2 and of myelin-specific genes 2'3' cyclic nucleotide phosphodiesterase (CNP) and myelin basic protein (MBP) in response to OGD. These studies demonstrate direct protective actions of minocycline on oligodendroglial-lineage cells, suggesting potential benefit in white matter injury involving OGD. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Expression of antioxidant molecules after peripheral nerve injury and regeneration.

Publication Date: 2012 Jan 18 PMID: 22253198
Authors: Lanza, C. - Raimondo, S. - Vergani, L. - Catena, N. - Senes, F. - Tos, P. - Geuna, S.
Journal: J Neurosci Res

Oxidative stress is considered to be one of the main causes of neural damage after injury. However, little is known about the changes in mRNA expression of antioxidant molecules that occur after injury and regeneration of the peripheral nerve. In the present study, the rat median nerve was transected, and transcriptional changes were studied at day 6 and day 12 after injury in both the proximal and the distal stumps, in the absence or presence of microsurgical repair. The expression profiles of the following genes were investigated: three metallothionein isoforms (MT-1, MT-2, and MT-3), the main antioxidant enzymes (catalase, superoxide dismutase, and glutathione-S-transferase), and the marker of cellular damage poly(ADP-ribose) polymerase-1 (PARP-1). The results showed that, in the proximal nerve stump, MT-3 mRNA expression was significantly and markedly up-regulated in the absence of surgical repair, whereas MT-1 and MT-2 showed significant down-regulation. In the distal nerve portion, mRNA expression of all MT isoforms decreased significantly in the absence of microsurgical reconstruction, whereas, after repair, MT-3 mRNA expression alone was up-regulated. Expression of all the antioxidant enzymes decreased significantly after repair in the proximal nerve portion, but a significant general increase in their mRNA expression was revealed in the distal nerve stump. PARP-1 expression was significantly up-regulated in the proximal nerve portion without repair but dramatically reduced after reconstruction. In contrast, PARP-1 expression increased markedly in the distal stump after surgical repair. Taken together, these findings indicate that antioxidant molecules are differentially modulated and might, therefore, play an important role in peripheral nerve injury and regeneration. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Effect of dyrk1a activity inhibition on development of neuronal progenitors isolated from Ts65Dn mice.

Publication Date: 2012 Jan 18 PMID: 22252917
Authors: Mazur-Kolecka, B. - Golabek, A. - Kida, E. - Rabe, A. - Hwang, Y. W. - Adayev, T. - Wegiel, J. - Flory, M. - Kaczmarski, W. - Marchi, E. - Frackowiak, J.
Journal: J Neurosci Res

Overexpression of dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A (DYRK1A), encoded by a gene located in the Down syndrome (DS) critical region, is considered a major contributor to developmental abnormalities in DS. DYRK1A regulates numerous genes involved in neuronal commitment, differentiation, maturation, and apoptosis. Because alterations of neurogenesis could lead to impaired brain development and mental retardation in individuals with DS, pharmacological normalization of DYRK1A activity has been postulated as DS therapy. We tested the effect of harmine, a specific DYRK1A inhibitor, on the development of neuronal progenitor cells (NPCs) isolated from the periventricular zone of newborn mice with segmental trisomy 16 (Ts65Dn mice), a mouse model for DS that overexpresses Dyrk1A by 1.5-fold. Trisomy did not affect the ability of NPCs to expand in culture. Twenty-four hours after stimulation of migration and neuronal differentiation, NPCs showed increased expression of Dyrk1A, particularly in the trisomic cultures. After 7 days, NPCs developed into a heterogeneous population of differentiating neurons and astrocytes that expressed Dyrk1A in the nuclei. In comparison with disomic cells, NPCs with trisomy showed premature neuronal differentiation and enhanced gamma-aminobutyric acid (GABA)-ergic differentiation, but astrocyte development was unchanged. Harmine prevented premature neuronal maturation of trisomic NPCs but not acceleration of GABA-ergic development. In control NPCs, harmine treatment caused altered neuronal development of NPCs, similar to that in trisomic NPCs with Dyrk1A overexpression. This study suggests that pharmacological normalization of DYRK1A activity may have a potential role in DS therapy. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Activation of group III metabotropic glutamate receptors by endogenous glutamate protects against glutamate-mediated excitotoxicity in the hippocampus in vivo.

Publication Date: 2012 Jan 18 PMID: 22252898
Authors: Vera, G. - Tapia, R.
Journal: J Neurosci Res

Perfusion of 4-aminopyridine (4-AP) by microdialysis in the hippocampus produces intense epileptiform behavioral and electrical activity and neurodegeneration, resulting from a stimulated release of glutamate from nerve endings. In contrast, accumulation of extracellular glutamate by blockade of its transport in vivo in anesthetized rats is innocuous, and studies in vitro in brain slices suggest that under these conditions glutamate may activate presynaptic group III metabotropic glutamate receptors (mGluRs) and inhibit its own release. Therefore, using microdialysis, EEG recording, and histological evaluation, we studied the effect of increased endogenous extracellular glutamate by blockade of its transport with pyrrolidine dicarboxylic acid (PDC) on the excitotoxic action of 4-AP in the hippocampus of awake rats. We found that up to a 20-fold increase in extracellular glutamate during >90 min with PDC does not induce any sign of excitotoxicity. On the contrary, this glutamate increase notably protected against the 4-AP-induced seizures and neurodegeneration, and, remarkably, this protection was dependent on the time of perfusion with PDC and thus on the duration of extracellular glutamate accumulation. To test whether this protective action was mediated by the activation of group III mGluRs, we used specific antagonists of these receptors and found that they clearly prevented the protective effect of PDC, without affecting the accumulation of extracellular glutamate. We conclude that the spillover of the excess extracellular glutamate activates presynaptic group III mGluRs and inhibits the stimulatory effect of 4-AP on its release, thus preventing the activation of postsynaptic N-methyl-D-aspartate receptors and its deleterious consequences. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Herpes simplex virus type 1 induces nuclear accumulation of hyperphosphorylated tau in neuronal cells.

Publication Date: 2012 Jan 18 PMID: 22252837
Authors: Alvarez, G. - Aldudo, J. - Alonso, M. - Santana, S. - Valdivieso, F.
Journal: J Neurosci Res

Herpes simplex virus type 1 (HSV-1) is a neurotropic virus that remains latent in host neurons. Viral DNA replication is a highly structured process in which the redistribution of nuclear proteins plays an important role. Although tau is most widely known as a microtubule-associated protein found in a hyperphosphorylated state in the brains of patients with Alzheimer's disease (AD), this protein has also been detected at other sites such as the nucleolus. Here, we establish that HSV-1 infection gives rise to an increase in tau phosphorylation and that hyperphosphorylated tau accumulates in the nucleus, forming defined structures in HSV-1-infected neuronal cells reminiscent of the common sites of viral DNA replication. When tau expression in human neuroblastoma cells was specifically inhibited using an adenoviral vector expressing a short hairpin RNA to tau, viral DNA replication was not affected, indicating that tau is not required for HSV-1 growth in neuronal cells. Given that HSV-1 is considered a risk factor for AD, our results suggest a new way in which to understand the relationships between HSV-1 infection and the pathogenic mechanisms leading to AD. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Altered microtubule dynamics in Mecp2-deficient astrocytes.

Publication Date: 2012 Jan 18 PMID: 22252744
Authors: Nectoux, J. - Florian, C. - Delepine, C. - Bahi-Buisson, N. - Khelfaoui, M. - Reibel, S. - Chelly, J. - Bienvenu, T.
Journal: J Neurosci Res

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in the gene MECP2 encoding the methyl-CpG binding protein 2. This genetic disease affects predominantly girls and is characterized by a period of normal development that lasts for 8-18 months, followed by neurologic regression affecting both motor and mental abilities. Previous studies performed on brains from RTT subjects and Mecp2-deficient mice showed striking changes in neuronal maturation and dendritic arborization. Recently, we showed that expression of stathmin-like 2 (STMN2) was significantly reduced in fibroblasts from RTT patients, and similar results were obtained in the cerebellum of Mecp2-deficient mice. Because assembly and dynamics of microtubules are known to be modulated by STMN2, we studied microtubule dynamics in brain cells from Mecp2-deficient mice. We observed that Mecp2 deficiency affects microtubule dynamics in astrocytes from Mecp2-deficient mice. Our data reinforce the fact that the loss of Mecp2 in astrocytes may influence the onset and progression of RTT. These results imply that Mecp2 has a stabilizing role in microtubule dynamics and that Mecp2 deficiency, which is associated with STMN2 down-regulation, could lead to impaired microtubule stability, hence explaining the dendritic abnormalities observed in RTT brains. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Sendai virus vector-mediated brain-derived neurotrophic factor expression ameliorates memory deficits and synaptic degeneration in a transgenic mouse model of Alzheimer's disease.

Publication Date: 2012 Jan 18 PMID: 22252710
Authors: Iwasaki, Y. - Negishi, T. - Inoue, M. - Tashiro, T. - Tabira, T. - Kimura, N.
Journal: J Neurosci Res

Growing evidence suggests that decreased brain-derived neurotrophic factor (BDNF) levels are associated with Alzheimer's disease (AD) pathogenesis. Therefore, BDNF gene therapy is considered to be a promising therapeutic strategy for treating AD. Sendai virus (SeV) is a type I parainfluenza virus that does not interact with host chromosomes because of its strict cytoplasmic life cycle. Although SeV is nonpathogenic in primates, including humans, its infectivity for neurons is strong. Here we demonstrate that SeV vectors effectively infected neurons, even though they were injected into subcortical white matter. Moreover, SeV vectors significantly induced BDNF expression, ameliorating synaptic degeneration and memory deficits in a transgenic mouse model of AD (Tg2576). This is the first study to demonstrate that viral vector administration in white matter is sufficient to restore cognitive function in vivo. These results also support the feasibility of using SeV vectors for gene therapy targeting the brain. (c) 2012 Wiley Periodicals, Inc.

post to: CiteULike

Epigenetic regulation of self-renewal and fate determination in neural stem cells.

Publication Date: 2012 Mar PMID: 22183977
Authors: Mohamed Ariff, I. - Mitra, A. - Basu, A.
Journal: J Neurosci Res

Differentiation and self-renewal are two primary properties that characterize stem cells. Differentiation of neural stem/precursor cells (NSPCs) gives rise to multiple neural lineages, including neurons, astrocytes, and oligodendrocytes. Self-renewal, by definition, signifies the progressive growth of cells, while preserving an undifferentiated state. A large number of interdependent factors, including transcription factors, epigenetic control, and micro-RNA regulators, modulate these opposing processes without disrupting the regular neural network. The epigenetic modification of developmental genes, including alterations in DNA methylation, histone modifications, polycomb gene group and noncoding RNA expression, which are passed on through successive cell divisions, has proved to be one of the major mechanisms determining the fate of neural stem cells. Here, we review the diverse epigenetic pathways that decide whether NSPCs undergo proliferation or differentiation into different neuronal cell lineages. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Experimental evidence that pristanic acid disrupts mitochondrial homeostasis in brain of young rats.

Publication Date: 2012 Mar PMID: 22183871
Authors: Busanello, E. N. - Amaral, A. U. - Tonin, A. M. - Grings, M. - Moura, A. P. - Eichler, P. - Vargas, C. R. - Wajner, M.
Journal: J Neurosci Res

Patients affected by peroxisomal disorders commonly present neurologic dysfunction and brain abnormalities, whose neuropathology is poorly understood. Given that high sustained concentrations of pristanic acid (Prist) are found in the brain of these patients, it is conceivable that this complex branched-chain fatty acid is neurotoxic. Therefore, the present work investigated the in vitro effects of Prist at similar concentrations found in plasma of affected patients with some peroxisomal disorders on important parameters of energy homeostasis, including respiratory parameters determined by oxygen consumption, membrane potential (DeltaPsim), NAD(P)H content, and swelling in mitochondrial preparations obtained from brain of young rats using glutamate plus malate or succinate as respiratory substrates. Prist markedly increased state 4 respiration and decreased state 3 respiration, the respiratory control ratio (RCR), and the ADP/O ratio with both substrates. The mitochondrial DeltaPsim and the matrix NAD(P)H content were also decreased by Prist, which was also able to provoke mitochondrial swelling. Furthermore, Prist-induced mitochondrial swelling was dependent on oxidative damage to the permeability transition pore (PTP), because cyclosporine A and the thiol-reducing agent N-acetylcysteine totally prevented mitochondrial swelling. These data suggest that Prist impairs mitochondrial homeostasis, acting as an uncoupler of oxidative phosphorylation and as a metabolic inhibitor, besides causing mitochondrial swelling probably mediated by the permeability transition pore. It is proposed that these pathomechanisms may potentially be involved in the neurological abnormalities characteristic of the peroxisomal diseases in which Prist accumulates. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Treatment with sodium orthovanadate reduces blood-brain barrier disruption via phosphatase and tensin homolog deleted on chromosome 10 (PTEN) phosphorylation in experimental subarachnoid hemorrhage.

Publication Date: 2012 Mar PMID: 22183833
Authors: Hasegawa, Y. - Suzuki, H. - Altay, O. - Chen, H. - Zhang, J. H.
Journal: J Neurosci Res

Attenuation of blood-brain barrier (BBB) disruption is one of the therapeutic candidates for treatment of subarachnoid hemorrhage (SAH). In this study, the protective effect of sodium orthovanadate (SOV) on BBB disruption was investigated in SAH using the endovascular perforation model. Fifty-five rats were randomly assigned to sham-operated, SAH treated with saline (as a vehicle), or 10 mg/kg SOV groups and were evaluated for neurofunction and Evans blue dye extravasation. The phosphorylation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and mitogen-activated protein kinase (MAPK) and the expression of matrix metalloproteinase-9 (MMP-9), occludin, and collagen-IV were examined by Western blot analyses. Cell death among endothelial cells was revealed by immunofluorescence and terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end-labeling staining. SOV significantly improved neurofunction and reduced Evans blue dye extravasation in brains after SAH. SOV phosphorylated PTEN, decreased phospho-JNK and MMP-9, and preserved occludin expression. SOV also attenuated SAH-induced capillary endothelial cell death. The current study showed that SOV was protective against BBB disruption after SAH, possibly via PTEN phosphorylation. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Wallerian degeneration slow mouse neurons are protected against cell death caused by mechanisms involving mitochondrial electron transport dysfunction.

Publication Date: 2012 Mar PMID: 22183770
Authors: Tokunaga, S. - Araki, T.
Journal: J Neurosci Res

Ischemia elicits a variety of stress responses in neuronal cells, which result in cell death. wld(S) Mice bear a mutation that significantly delays Wallerian degeneration. This mutation also protects all neuronal cells against other types of stresses resulting in cell death, including ischemia. To clarify the types of stresses that neuronal cell bodies derived from wld(S) mice are protected from, we exposed primary cultured neurons derived from wld(S) mice to various components of hypoxic stress. We found that wld(S) mouse neurons are protected against cellular injury induced by reoxygenation following hypoxic stress. Furthermore, we found that wld(S) mouse neurons are protected against functional impairment of the mitochondrial electron transport chain. These data suggest that Wld(S) protein expression may provide protection against neuronal cell death caused by mechanisms involving mitochondrial electron transport dysfunction. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Expressions of hypoxic stress sensor proteins after transient cerebral ischemia in mice.

Publication Date: 2012 Mar PMID: 22183753
Authors: Shang, J. - Liu, N. - Tanaka, N. - Abe, K.
Journal: J Neurosci Res

The role of hypoxia sensor proteins is important in responding and protecting cells against hypoxic/ischemic injury in brain. Seven in absentia homolog 1 (Siah1) regulates primarily the downstream sensor proteins factor inhibiting alpha subunit of hypoxia-inducible factor-1 (FIH) under normoxic conditions and prolyl hydroxylases domain 3 (PHD3) under hypoxic conditions. In the present study, we investigated the temporal and spatial changes of these hypoxia sensor proteins, Siah1, FIH, and PHD3, after 60 min of transient middle cerebral artery occlusion (tMCAO) up to 72 hr after reperfusion in ICR mice. Immunohistochemistry and Western blot analyses showed that Siah1 was quickly and strongly induced in neuronal cells of the ischemic penumbra, with a peak at 2 hr, and gradually returned toward the sham control (SC) level until 72 hr. In contrast, the expressions of FIH and PHD3 were strongly visualized in the SC brains, and significantly reduced in a time-dependent manner with reperfusion until 72 hr. In the ischemic core region, Siah1, FIH, and PHD3 showed a similar change of strong and progressive decrease until 72 hr. Double-immunofluorescence analyses showed a cytoplasmic localization of Siah1 and both cytoplasmic and nuclear localizations of FIH and PHD3 and that Siah1 plus FIH or PHD3 were well colocalized in same neuron at 2 hr after tMCAO. The present study suggests that hypoxia sensor proteins (Siah1, FIH, and PHD3) showed temporally and spatially different expressions after tMCAO, which could provide an effective neuroprotective reaction through their further downstream proteins after cerebral ischemia. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Minocycline protects SH-SY5Y cells from 6-hydroxydopamine by inhibiting both caspase-dependent and -independent programmed cell death.

Publication Date: 2012 Mar PMID: 22108958
Authors: Ossola, B. - Lantto, T. A. - Puttonen, K. A. - Tuominen, R. K. - Raasmaja, A. - Mannisto, P. T.
Journal: J Neurosci Res

Minocycline, a tetracyclic antibiotic, exerts both antiinflammation by acting on microglia and a direct protection on neurons by inhibiting the apoptotic machinery at various levels. However, we are not aware of any study investigating the effects of minocycline on caspase-independent programmed cell death (PCD) pathways. This study investigated these alternative pathways in SH-SY5Y cells, a human dopaminergic cell line, challenged with 6-hydroxydopamine (6-OHDA). Minocycline exhibited neuroprotection and inhibition of the toxin-induced caspase-3-like activity, DNA fragmentation, and chromatin condensation, hallmarks of apoptosis. Moreover, we revealed that 6-OHDA also activated caspase-independent PCDs (such as paraptosis), which required de novo protein synthesis. Additionally, by separately monitoring caspase-dependent and caspase-independent pathways, we showed that inhibition of apoptosis only partially explained the protective effect of minocycline. Moreover, we observed that minocycline reduced the protein content of cells but, unexpectedly, increased the protein synthesis. These findings suggest that minocycline may actually increase protein degradation, so it may also accelerate the clearance of aberrant proteins. In conclusion, we report for the first time evidence indicating that minocycline may inhibit PCD pathways that are additional to conventional apoptosis. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Regulatory role of zinc during aluminium-induced altered carbohydrate metabolism in rat brain.

Publication Date: 2012 Mar PMID: 22108899
Authors: Singla, N. - Dhawan, D. K.
Journal: J Neurosci Res

Aluminium is considered an environmental neurotoxicant and causes many neurological disorders, whereas zinc is vital for many biological functions. The present study was carried out to investigate the role of Zn, if any, in mitigating the adverse effects inflicted by Al on carbohydrate metabolism in rat brain. Male Sprague-Dawley rats weighing 140-160 g were divided into four different groups: normal control, Al-treated (100 mg/kg b.w./day in drinking water via oral gavage), Zn-treated (227mg/liter in drinking water), and combined Al- and Zn-treated rats. All the treatments were continued for 2 months, and their effects on carbohydrate-metabolizing enzymes were studied. Additionally, expressions of the proteins glycogen synthase kinase-3 (GSK3) and protein phosphatase (PP1), which help in regulating carbohydrate energy metabolism, were also studied. Al treatment resulted in increased activities of the glucose-6-phosphatase (G6P), glucose-6-isomerase (G6I), and lactate dehydrogenase (LDH), whereas the activities of hexokinase and succinate dehydrogenase (SDH) and glycogen content were decreased. Moreover, no significant change was observed in the biochemical parameters upon Zn supplementation alone. However, Zn supplementation to Al-treated rats was able to reduce significantly the Al-induced increased activities of G6P, G6I, and LDH, but it elevated the levels of hexokinase, SDH, and glycogen. Furthermore, Al treatment increased the protein expression of GSK3 and decreased the PP1 expression, which were found to be reversed upon Zn administration. Hence, Zn is effective in regulating theAl-induced alterations in carbohydrate metabolism. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Transgenic mice with SCA10 pentanucleotide repeats show motor phenotype and susceptibility to seizure: A toxic RNA gain-of-function model.

Publication Date: 2012 Mar PMID: 22065565
Authors: White, M. - Xia, G. - Gao, R. - Wakamiya, M. - Sarkar, P. S. - McFarland, K. - Ashizawa, T.
Journal: J Neurosci Res

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant neurodegenerative disorder manifested by ataxia and seizure. SCA10 is caused by a large expansion of an intronic ATTCT pentanucleotide repeat in the ATXN10 gene. We have recently postulated a toxic RNA-mediated gain of function in the pathogenesis of spinal cerebellar ataxia type 10 (SCA10). The spliced intron-9 RNA containing the expanded AUUCU repeat aggregates in SCA10 cells and sequesters hnRNP K. hnRNP K sequestration triggers the translocation of protein kinase Cdelta (PKCdelta) to mitochondria, leading to activation of caspase-3 and apoptosis. To confirm the toxic RNA-mediated gain of function, we generated a new transgenic mouse model in which the expanded pentanucleotide repeats are constructed in the 3'-untranslated region (3'UTR) to ensure transcription without translation of the repeat. We constructed an artificial transgene containing the SCA10 (ATTCT)(500) track within the 3'UTR of the LacZ gene driven by the rat prion promoter (PrP) and used this to generate a new transgenic mouse model for SCA10. We then examined these mice for neurological phenotypes and histopathological, molecular, and cellular changes. The transgenic mice showed irregular gait and increased seizure susceptibility at the age of 6 months, resembling the clinical phenotype of SCA10. The cerebral cortex, hippocampus, and pontine nuclei showed neuronal loss. The brains of these animals also showed molecular and cellular changes similar to those previously found in an SCA10 cell model. Expression of the expanded SCA10 AUUCU repeat within the 3'UTR of a gene results in neuronal loss with associated gait abnormalities and increased seizure susceptibility phenotypes, which resemble those seen in SCA10 patients. Moreover, these results bolster the idea that the SCA10 disease mechanism is mediated by a toxic RNA gain-of-function mutation of the expanded AUUCU repeat. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Transplant-mediated repair properties of rat olfactory mucosal OM-I and OM-II sphere-forming cells.

Publication Date: 2012 Mar PMID: 22057888
Authors: Toft, A. - Tome, M. - Lindsay, S. L. - Barnett, S. C. - Riddell, J. S.
Journal: J Neurosci Res

Olfactory mucosa is a source of cells for transplant-mediated repair of spinal cord injury (SCI) and is currently being assessed in clinical trials. We previously reported that olfactory mucosa can generate two types of sphere-forming cells with stem cell-like properties. Here we have assessed the repair potential of these cells in a rodent SCI model. Sphere-forming cells transplanted into a dorsal column injury integrated with the host spinal cord, filling the injury cavity, but showed no evidence of differentiation in vivo. Moreover, transplants supported robust axonal regeneration, particularly when suspensions of smaller spheres, rather than large aggregates, were transplanted. However, tract-tracing of dorsal column fibers showed that regenerating axons did not extend beyond the transplant. These observations show that undifferentiated olfactory spheres, though capable of supporting axonal regeneration, do not show any advantage over olfactory ensheathing cells isolated from adult olfactory tissue. In addition, olfactory spheres induced a greater astrocytic hypertrophy at the injury site than previously observed for purified olfactory ensheathing cells. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Minocycline-induced reduction of brain-derived neurotrophic factor expression in relation to cancer-induced bone pain in rats.

Publication Date: 2012 Mar PMID: 22057846
Authors: Wang, L. N. - Yang, J. P. - Zhan, Y. - Ji, F. H. - Wang, X. Y. - Zuo, J. L. - Xu, Q. N.
Journal: J Neurosci Res

Previous studies have suggested that the release of brain-derived neurotrophic factor (BDNF) from microglia in spinal cord is necessary for maintaining pain hypersensitivity after nerve injury. However, little is known about its role in cancer-induced bone pain (CIBP), which is in some ways unique. This study demonstrates a critical role of minocycline (a potent inhibitor of microglial activation)-modulated BDNF in the induction and maintenance of behavioral hypersensitivity in a rat model of CIBP. We assessed mechanical threshold and spontaneous pain of CIBP rats. Moreover, minocycline was administered intrathecally from day 4 to day 6 (early stage) or from day 10 to day 12 (later stage), after carcinoma cell inoculation. Real-time PCR, Western blots, and double immunofluorescence were used to detect the expression of OX-42 (marker of activated microglia), phosphorylated p38-MAPK (p-p38), and BDNF. We found that intrathecal minocycline could prevent CIBP at an early stage of tumor growth (from day 4 to day 6). However, at the late stage (from day 10 to day 12), intrathecal minocycline had no effect. Moreover, the expression of OX-42 and BDNF under CIBP, peaking on day 6, were all reduced after minocycline injection from day 4 to day 6. The ability of minocycline-induced reduction of BDNF in the induction of behavioral hypersensitivity could provide an opportunity for alleviating CIBP. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Involvement of N-methyl-D-aspartate receptor subunits in zinc-mediated modification of CA1 long-term potentiation in the developing hippocampus.

Publication Date: 2012 Mar PMID: 22057830
Authors: Takeda, A. - Itagaki, K. - Ando, M. - Oku, N.
Journal: J Neurosci Res

Zinc is an endogenous N-methyl-D-aspartate (NMDA) receptor blocker. It is possible that zinc-mediated modification of hippocampal CA1 long-term potentiation (LTP) is linked to the expression of NMDA receptor subunits, which varies with postnatal development. In the present study, the effect of ZnCl(2) and CaEDTA, a membrane-impermeable zinc chelator, on CA1 LTP induction was examined in hippocampal slices from immature (3-week-old) and young (6-week-old) rats. Tetanus (10-100 Hz, 1 sec)-induced CA1 LTP was more greatly enhanced in 3-week-old rats. CA1 LTP was inhibited in the presence of 2-amino-5-phosphonovalerate (APV), an NMDA receptor antagonist, and CaEDTA in 3-week-old rats, as in the case of 6-week-old rats reported previously. In 3-week-old rats, on the other hand, 5 muM ZnCl(2) attenuated NMDA receptor-mediated EPSPs more than in 6-week-old rats and significantly attenuated CA1 LTP. Moreover, 5 muM ZnCl(2) significantly attenuated CA1 LTP in the presence of (2R,4S)-4-(3-phosphonopropyl)-2-piperidinecarboxylic acid (PPPA), an NR2A antagonist, in 3-week-old rats, but not that in the presence of ifenprodil, an NR2B antagonist, suggesting that zinc-mediated attenuation of CA1 LTP is associated with the preferential expression of NR2B subunit in 3-week-old rats. In 6-week-old rats, however, 5 muM ZnCl(2) significantly potentiated CA1 LTP and also CA1 LTP in the presence of PPPA. The present study demonstrates that endogenous zinc may participate in the induction of CA1 LTP. It is likely that the changes in expression of NMDA receptor subunits are involved in the zinc-mediated modification of CA1 LTP in the developing hippocampus. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Docosahexaenoic acid modulates inflammatory and antineurogenic functions of activated microglial cells.

Publication Date: 2012 Mar PMID: 22057807
Authors: Antonietta Ajmone-Cat, M. - Lavinia Salvatori, M. - De Simone, R. - Mancini, M. - Biagioni, S. - Bernardo, A. - Cacci, E. - Minghetti, L.
Journal: J Neurosci Res

The complex process of microglial activation encompasses several functional activation states associated either with neurotoxic/antineurogenic or with neurotrophic/proneurogenic properties, depending mainly on the extent of activation and the nature of the activating stimuli. Several studies have demonstrated that acute exposure to the prototypical activating agent lipopolysaccharide (LPS) confers antineurogenic properties upon microglial cells. Acutely activated microglia ortheir conditioned media (CM) reduce neural stem progenitor cell (NPC) survival and prevent NPC differentiation into neurons. The present study tested the hypothesis that docosahexaenoic acid (DHA), a long-chain polyunsatured fatty acid (L-PUFA) with potent immunomodulatory properties, could dampen microglial proinflammatory functions and modulate their antineurogenic effect. We demonstrate that DHA dose dependently inhibits the synthesis of inflammatory products in activated microglia without inducing an alternative antiinflammatory phenotype. Among the possible DHA mechanisms of action, we propose the inhibition of p38 MAPK phosphorylation and the activation of the nuclear receptor peroxisome proliferator activated receptor (PPAR)-gamma. The attenuation of M1 proinflammatory phenotype has relevant consequences for the survival and differentiation of NPC, because DHA reverses the antineurogenic activities of conditioned media from LPS-activated microglia. Our study identifies new relevant potentially protective and proneurogenic functions of DHA, exerted through the modulation of microglial functions, that could be exploited to sustain or promote neuroregenerative processes in damaged/aged brain. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

DNA polymerase-beta mediates the neurogenic effect of beta-amyloid protein in cultured subventricular zone neurospheres.

Publication Date: 2012 Mar PMID: 22057776
Authors: Calafiore, M. - Copani, A. - Deng, W.
Journal: J Neurosci Res

beta-Amyloid protein (Abeta) is thought to be responsible for neuronal apoptosis in Alzheimer's disease (AD). Paradoxically, Abeta can also promote neurogenesis, both in vitro and in vivo, by inducing neural progenitor cells (NPCs) to differentiate into neurons. However, the mechanisms of Abeta-induced neurogenesis are unknown. Here we examined the role of DNA polymerase-beta (DNA pol-beta), a DNA repair enzyme that is required for proper neurogenesis during brain development and is also responsible for Abeta-induced neuronal apoptosis. In neurospheres obtained from the adult mouse subventricular zone (SVZ), the knockdown of DNA pol-beta or its pharmacological blockade showed that the enzyme functioned both to repress proliferation of early nestin(+) progenitor cells and to promote the maturation of TuJ-1(+) neuronal cells. In neurospheres challenged with oligomers of synthetic Abeta(42) , the expression levels of DNA pol-beta were rapidly increased. DNA pol-beta knockdown prevented the Abeta(42) -promoted differentiation of nestin(+) progenitor cells into nestin(+) /Dlx-2(+) neuroblasts. Moreover, when neurospheres were seeded to allow full differentiation of their elements, blockade of DNA pol-beta prevented Abeta(42) -induced differentiation of progenitors into MAP-2(+) neurons. Thus, our data demonstrate that Abeta(42) arrests the proliferation of a subpopulation of nestin(+) cells via the induction of DNA pol-beta, thereby allowing for their differentiation toward the neuronal lineage. Our findings reveal a novel role of DNA pol-beta in Abeta(42) -induced neurogenesis and identify DNA pol-beta as a key mechanistic link between the neurogenic effect of Abeta(42) on NPCs and the proapoptotic effect of Abeta(42) on mature neurons. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

TDP-43 toxicity is mediated by the unfolded protein response-unrelated induction of C/EBP homologous protein expression.

Publication Date: 2012 Mar PMID: 22057717
Authors: Suzuki, H. - Matsuoka, M.
Journal: J Neurosci Res

Transactive response DNA-binding protein-43 (TDP-43) neuronal toxicity plays an essential role in the pathogenesis of amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitin-positive inclusions. In our previous study, we showed that low-grade overexpression of TDP-43, which is thought to mimic the gain-of-function of TDP-43, caused neuronal death, mediated by the upregulation of Bim and the downregulation of Bcl-xL in vitro. In this study, we show that TDP-43 overexpression caused the upregulation of C/EBP-homologous protein (CHOP) and that disruption of the CHOP gene markedly attenuated TDP-43-induced cell death. These results indicate that increases in CHOP expression contribute to TDP-43-induced cell death. We also show that the TDP-43-induced upregulation of CHOP expression is mediated by both the upregulation of the mRNA level of CHOP and the attenuation of thedegradation of CHOP, which is independent on the PERK/eIF2alpha/ATF4 or other pathway related to the unfolded protein response (UPR) to endoplasmic reticulum stress. This study provides the first example of the CHOP-mediated cell death that is independent of the UPR. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Induction of interferon-lambda contributes to toll-like receptor 3-mediated herpes simplex virus type 1 inhibition in astrocytes.

Publication Date: 2012 Feb PMID: 22057682
Authors: Li, J. - Ye, L. - Wang, X. - Hu, S. - Ho, W.
Journal: J Neurosci Res

Toll-like receptor 3 (TLR3) recognizes double-stranded RNA and induces type I interferon (IFN)-mediated antiviral immunity against a number of viral infections. Type III IFN (IFN-lambda) is a newly identified antiviral cytokine that has biological functions similar to those of type I IFNs. We thus investigated the role of IFN-lambda in TLR3 activation-mediated inhibition of herpes simplex virus type 1 (HSV-1) in human primary astrocytes. Human astrocytes express endogenous IFN-lambda1 and IFN-lambda receptor complex, interleukin-28 receptor alpha subunit (IL-28Ralpha), and IL-10Rbeta. The activation of TLR3 by poly-I:C treatment significantly induced the expression of IFN-lambda1 and IFN-lambda2/3 in astrocytes. The induction of IFN-lambda contributed to TLR3 activation-mediated HSV-1 inhibition in astrocytes. Investigation of the mechanisms showed that treatment of astrocytes with specific antibody against IFN-lambda receptor attenuated the anti-HSV-1 activity of poly-I:C, indicating that endogenous IFN-lambda contributes to the anti-HSV-1 effect of TLR3 activation. The anti-HSV-1 effect of endogenous IFN-lambda was also confirmed by the finding that recombinant IFN-lambda treatment inhibited HSV-1 infection of astrocytes. These results provide direct and compelling evidence that endogenous IFN-lambda participates in TLR3-mediated antiviral activity, which may have important implications in host cell innate immunity against HSV-1 infection in the CNS.

post to: CiteULike

Intracranial transplantation of monocyte-derived multipotential cells enhances recovery after ischemic stroke in rats.

Publication Date: 2012 Feb PMID: 22057655
Authors: Hattori, H. - Suzuki, S. - Okazaki, Y. - Suzuki, N. - Kuwana, M.
Journal: J Neurosci Res

Cell transplantation has emerged as a potential therapy to reduce the neurological deficits caused by ischemic stroke. We previously reported a primitive cell population, monocyte-derived multipotential cells (MOMCs), which can differentiate into mesenchymal, neuronal, and endothelial lineages. In this study, MOMCs and macrophages were prepared from rat peripheral blood and transplanted intracranially into the ischemic core of syngeneic rats that had undergone a left middle cerebral artery occlusion procedure. Neurological deficits, as evaluated by the corner test, were less severe in the MOMC-transplanted rats than in macrophage-transplanted or mock-treated rats. Histological evaluations revealed that the number of microvessels that had formed in the ischemic boundary area by 4 weeks after transplantation was significantly greater in the MOMC-transplanted rats than in the control groups. The blood vessel formation was preceded by the appearance of round CD31(+) cells, which we confirmed were derived from the transplanted MOMCs. Small numbers of bloodvessels incorporating MOMC-derived endothelial cells expressing a mature endothelial marker RECA-1 were detected at 4 weeks after transplantation. In addition, MOMCs expressed a series of angiogenic factors, including vascular endothelial growth factor, angiopoetin-1, and placenta growth factor (PlGF). These findings provide evidence that the intracranial delivery of MOMCs enhances functional recovery by promoting neovascularization in a rat model for ischemic stroke.

post to: CiteULike

Effects of berberine on hippocampal neuronal damage and matrix metalloproteinase-9 activity following transient global cerebral ischemia.

Publication Date: 2012 Feb PMID: 22052603
Authors: Hong, J. S. - Chu, Y. K. - Lee, H. - Ahn, B. H. - Park, J. H. - Kim, M. J. - Lee, S. - Ryoo, H. S. - Jang, J. H. - Lee, S. R. - Park, J. W.
Journal: J Neurosci Res

Berberine, an isoquinoline alkaloid with a long history of use in Chinese medicine, has several important pharmacological effects. Several studies have revealed that berberine has neuroprotective and neuropsychiatric effects. However, there are few reports regarding the protective effect of berberine against neuronal damage following transient global cerebral ischemia. In this study, mice were subjected to 20 min of global brain ischemia and sacrificed 72 hr later. Berberine was administered for 7 days prior to ischemia and daily until sacrifice. Mice treated with berberine showed reduced matrix metalloproteinase-9 (MMP-9) activity. Berberine inhibited gelatinase activity directly in in situ zymography and reduced neuronal damage following global ischemia. Laminin expression and NeuN expression were markedly reduced in CA1 and CA2 areas after ischemia, and berberine reduced the laminin degradation and neuronal loss. In the TUNEL assay, damaged neurons were also apparent in the CA1 and CA2 areas, and berberine reduced TUNEL-positive cells. These data demonstrate that berberine, a plant alkaloid, may protect from hippocampal neuronal damage following transient global ischemia by reducing MMP-9 activity.

post to: CiteULike

Regulation by lipocalin-2 of neuronal cell death, migration, and morphology.

Publication Date: 2012 Mar PMID: 22038922
Authors: Lee, S. - Lee, W. H. - Lee, M. S. - Mori, K. - Suk, K.
Journal: J Neurosci Res

A secreted protein, lipocalin-2 (LCN2), has been previously shown to regulate a variety of cellular phenotypes such as cell death, migration, and morphology. The role of LCN2, however, appears to be different depending on the cellular context. Here, we investigated how LCN2 influences neuronal phenotypes by using primary cortical neuronal cell cultures and neuroblastoma cell lines as a model. When exposed to LCN2 protein, neurons and neuroblastoma cells were sensitized to cell death evoked by nitric oxide, oxidative stress, and tumor necrosis factor-alpha (TNF-alpha). A forced expression of lcn2 in glia enhanced neuronal cell death in cocultures of glia and neurons, indicating that both exogenous protein addition and endogenous expression of lcn2 give rise to similar results. Iron and BCL2-interacting mediator of cell death (BIM) protein were involved in LCN2-induced cell death sensitization, based on the studies using iron donor, chelator, siderophore, and short hairpin RNA (shRNA)-mediated knockdown of bim expression. Furthermore, cell migration assay and immunofluorescence microscopic observation revealed that LCN2 accelerated neuronal motility and process extension, suggesting multiple roles for LCN2 in the regulation of neuronal cell death, migration, and morphology. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Early in vivo changes in calcium ions, oxidative stress markers, and ion channel immunoreactivity following partial injury to the optic nerve.

Publication Date: 2012 Mar PMID: 22038561
Authors: Wells, J. - Kilburn, M. R. - Shaw, J. A. - Bartlett, C. A. - Harvey, A. R. - Dunlop, S. A. - Fitzgerald, M.
Journal: J Neurosci Res

CNS injury is often localized but can be followed by more widespread secondary degenerative events that usually result in greater functional loss. Using a partial transection model in rat optic nerve (ON). we recently demonstrated in vivo increases in the oxidative stress-associated enzyme MnSOD 5 min after injury. However, mechanisms by which early oxidative stress spreads remain unclear. In the present study, we assessed ion distributions, additional oxidative stress indicators, and ion channel immunoreactivity in ON in the first 24 hr after partial transection. Using nanoscale secondary ion mass spectroscopy (NanoSIMS), we demonstrate changes in the distribution pattern of Ca ions following partial ON transection. Regions of elevated Ca ions in normal ON in vivo rapidly decrease following partial ON transection, but there is an increasingly punctate distribution at 5 min and 24 hr after injury. We also show rapid decreases in catalase activity and later increases in immunoreactivity of the advanced glycation end product carboxymethyl lysine in astrocytes. Increased oxidative stress in astrocytes is accompanied by significantly increased immunoreactivity of the AMPA receptor subunit GluR1 and aquaporin 4 (AQP4). Taken together, the results indicate that Ca ion changes and oxidative stress are early events following partial ON injury that are associated with changes in GluR1 AMPA receptor subunits and altered ionic balance resulting from increased AQP4. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Modulation of neurotransmitter release in orexin/hypocretin-2 receptor knockout mice: A microdialysis study.

Publication Date: 2012 Mar PMID: 22038504
Authors: Ortega, J. E. - Katner, J. - Davis, R. - Wade, M. - Nisenbaum, L. - Nomikos, G. G. - Svensson, K. A. - Perry, K. W.
Journal: J Neurosci Res

Orexinergic neurons are discretely localized within the lateral hypothalamus and have widespread projections to the whole brain. Here, the role of orexin/hypocretin-2 receptors (OX2) in modulating extracellular concentrations of neurotransmitters was evaluated in the hypothalamus and the prefrontal cortex (PFC) of OX2 knockout (KO) mice by using a microdialysis technique. In the hypothalamus, basal concentrations of norephinephrine (NE), acetylcholine (ACh), and histamine (Hist) were significantly higher in KO mice, whereas KCl perfusion (147 mM) resulted in significantly lesser increases in NE, ACh, and Hist release in KO compared with wild-type (WT) mice. No differences in basal concentrations or evoked release of serotonin (5-HT) or dopamine (DA) were found in the hypothalamus between genotypes. In the PFC, no differences in the basal concentrations of the studied neurotransmitters were found between genotypes. After KCl perfusion, significantly higher increases in NE, 5-HT, and DA release were found in KO compared with WT mice. No differences in the evoked release of ACh and Hist in the PFC were found between genotypes. The present results demonstrate that genetic deletion of OX2 receptors differentially modulates extracellular concentrations of distinct neurotransmitters in the somatodendritic region vs. a nerve terminal region of the orexinergic neurons. In the hypothalamus, an inhibitory role of the OX2 receptors in modulating basal concentrations of NE, ACh, and Hist was revealed, which probably accounts for the reduced responsiveness to KCl as well. In the PFC, the evoked release of the monoamines NE, 5-HT, and DA seems to be controlled negatively by OX2 receptors. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

mGluR5 is involved in proliferation of rat neural progenitor cells exposed to hypoxia with activation of mitogen-activated protein kinase signaling pathway.

Publication Date: 2012 Feb PMID: 22034224
Authors: Zhao, L. - Jiao, Q. - Chen, X. - Yang, P. - Zhao, B. - Zheng, P. - Liu, Y.
Journal: J Neurosci Res

Hypoxia/ischemia induces proliferation of neural progenitor cells (NPCs) in rodent and human brain; however, the mechanisms remain unknown. We investigated the effects of metabotropic glutamate receptor 5 (mGluR5) on NPC proliferation under hypoxia, the expression of cyclin D1, and the activation of the mitogen-activated protein kinases (MAPKs) signaling pathway in cell culture. The results showed that hypoxia induced mGluR5 expression on NPCs in vitro. Under hypoxia, the mGluR5 agonists DHPG and CHPG significantly increased NPC proliferation in cell activity, diameter of neurospheres, bromodeoxyuridine (BrdU) incorporation and cell division, and expression of cyclin D1, with decreasing cell death. The mGluR5 siRNA and antagonist MPEP decreased the NPC proliferation and expression of cyclin D1, with increasing cell death. Phosphorylated JNK and ERK increased with the proliferation of NPCs after DHPG and CHPG treatment under hypoxia, while p-p38 level decreased. These results demonstrate that the expression of mGluR5 was upregulated during the proliferation of rat NPCs stimulated by hypoxia in vitro. The activation of the ERK and JNK signaling pathway and the expression of cyclin D1 were increased in this process. These finding suggest the involvement of mGluR5 in rat NPC proliferation and provide a target molecule in neural repair after ischemia/hypoxia injury of CNS.

post to: CiteULike

Functional interaction between the dorsal hippocampus and the striatum in visual discrimination learning.

Publication Date: 2012 Mar PMID: 22012685
Authors: Fidalgo, C. - Conejo, N. M. - Gonzalez-Pardo, H. - Arias, J. L.
Journal: J Neurosci Res

The hippocampus and the striatum have traditionally been considered as part of different and independent memory systems. However, there is evidence that supports a functional interaction between the hippocampus and the dorsal striatum at least in particular learning tasks. Here, we evaluated the functional contribution of both brain regions in a visual discrimination learning task using cytochrome c oxidase (CO) quantitative histochemistry. Compared with other brain metabolic mapping techniques, CO activity reflects steady-state neuronal energy demand. Rats were trained for 6 days in a water T-maze to find a hidden escape platform associated with an intramaze visual cue. A control group of animals swam for an equivalent amount of time compared as the trained group but without any escape platform available. After finishing the behavioral task, CO activity was measured in subdivisions of the dorsal hippocampus and the dorsal striatum in both groups. Results show significantly higher CO activity in the CA1 area and the dentate gyrus of the dorsal hippocampus in the trained rats compared with the control group. In addition, a significant negative functional cross-correlation between area CA1 of the dorsal hippocampus and the anterodorsal striatum was found. Our results support current theories on competitive interaction of different memory systems during visual discrimination learning. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

High expression of disease-related Cln6 in the cerebral cortex, purkinje cells, dentate gyrus, and hippocampal ca1 neurons.

Publication Date: 2012 Mar PMID: 22012656
Authors: Thelen, M. - Fehr, S. - Schweizer, M. - Braulke, T. - Galliciotti, G.
Journal: J Neurosci Res

Mutations in the CLN6 gene cause a variant form of late infantile neuronal ceroid lipofuscinosis, a relentless neurodegenerative disease that is inherited as an autosomal recessive trait in humans and in the naturally occurring nclf mouse strain. The CLN6 protein is localized in the endoplasmic reticulum, but it has an unknown function. To develop a molecular understanding of neurodegeneration induced by mutations in CLN6, we examined the spatial and temporal distribution of Cln6 mRNA expression in murine brain. By using Northern blot and tissue qPCR array techniques, a single Cln6 transcript was detected throughout the adult brain, with greatest expression in the cerebellum and hypothalamus. Real-time qPCR showed 2.4-4-fold increases in Cln6 mRNA levels in the cortex and cerebellum during the first 28 days of life, with less prominent enhancement of expression in the hippocampus. In situ hybridization analyses demonstrated Cln6 expression in brainstem, dentate gyrus, and hippocampal neurons of newborn P0 mice. From P14 onward, Cln6 expression is widely distributed throughout the brain and is most prominent in cells of cortical layers II-VI, the Purkinje cell layer, dentate gyrus, and hippocampal CA1 region of adult mice. In different regions of the brain in P0 and P28 nclf mice, the Cln6 mRNA abundance was reduced by 30-40% compared with control mice. These findings implicate Cln6 in the survival and maturation of specific neuronal populations during development and make it possible to compare regional Cln6 expression with the distribution of subsequent pathology. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Eag1, Eag2, and SK3 potassium channel expression in the rat hippocampus after global transient brain ischemia.

Publication Date: 2012 Mar PMID: 22006722
Authors: de Oliveira, R. M. - Martin, S. - de Oliveira, C. L. - Milani, H. - Schiavon, A. P. - Joca, S. - Pardo, L. A. - Stuhmer, W. - Del Bel, E. A.
Journal: J Neurosci Res

Transient global brain ischemia causes delayed neuronal death in the hippocampus that has been associated with impairments in hippocampus-dependent brain function, such as mood, learning, and memory. We investigated the expression of voltage-dependent Kcnh1 and Kcnh5, ether a go-go-related Eag1 and Eag2 (K(V) 10.1 and K(V) 10.2), and small-conductance calcium-activated SK3 (K(Ca) 2.3, Kcnn3) K(+) channels in the hippocampus in rats after transient global brain ischemia. We tested whether the expression of these channels is associated with behavioral changes by evaluating the animals in the elevated plus maze and step-down inhibitory avoidance task. Seven or tweny-eight days after transient global brain ischemia, one group of rats had the hippocampus bilaterally dissected, and mRNA levels were determined. Seven days after transient global brain ischemia, the rats exhibited a decrease in anxiety-like behavior and memory impairments. An increase in anxiety levels was detected 28 days after ischemia. Eag2 mRNA downregulation was observed in the hippocampus 7 days after transient global brain ischemia, whereas Eag1 and SK3 mRNA expression remained unaltered. This is the first experimental evidence that transient global brain ischemia temporarily alters Eag2. The number of intact-appearing pyramidal neurons was substantially decreased in CA1 and statistically measurable in CA2, CA3, and CA4 hippocampal subfields compared with sham control animals 7 or 28 days after ischemia. mRNA expression in the rat hippocampus. The present results provide further information for the characterization of the physiological role of Eag2 channels in the central nervous system. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Huperzine A alleviates synaptic deficits and modulates amyloidogenic and nonamyloidogenic pathways in APPswe/PS1dE9 transgenic mice.

Publication Date: 2012 Feb PMID: 22002568
Authors: Wang, Y. - Tang, X. C. - Zhang, H. Y.
Journal: J Neurosci Res

Huperzine A (HupA) is a potent acetylcholinesterase inhibitor (AChEI) used in the treatment of Alzheimer's disease (AD). Recently, HupA was shown to be active in modulating the nonamyloidogenic metabolism of beta-amyloid precursor protein (APP) in APP-transfected human embryonic kidney cell line (HEK293swe). However, in vivo research concerning the mechanism of HupA in APP transgenic mice has not yet been fully elucidated. The present study indicates that the loss of dendritic spine density and synaptotagmin levels in the brain of APPswe/presenilin-1 (PS1) transgenic mice was significantly ameliorated by chronic HupA treatment and provides evidence that this neuroprotection was associated with reduced amyloid plaque burden and oligomeric beta-amyloid (Abeta) levels in the cortex and hippocampus of APPswe/PS1dE9 transgenic mice. Our findings further demonstrate that the amelioration effect of HupA on Abeta deposits may be mediated, at least in part, by regulation of the compromised expression of a disintegrin and metalloprotease 10 (ADAM10) and excessive membrane trafficking of beta-site APP cleavage enzyme 1 (BACE1) in these transgenic mice. In addition, extracellular signal-regulated kinases 1/2 (Erk1/2) phosphorylation may also be partially involved in the effect of HupA on APP processing. In conclusion, our work for the first time demonstrates the neuroprotective effect of HupA on synaptic deficits in APPswe/PS1dE9 transgenic mice and further clarifies the potential pharmacological targets for this protective effect, in which modulation of nonamyloidogenic and amyloidogenic APP processing pathways may be both involved. These findings may provide adequate evidence for the clinical and experimental benefits gained from HupA treatment.

post to: CiteULike

Immunization with A91 peptide or copolymer-1 reduces the production of nitric oxide and inducible nitric oxide synthase gene expression after spinal cord injury.

Publication Date: 2012 Mar PMID: 22002544
Authors: Garcia, E. - Silva-Garcia, R. - Mestre, H. - Flores, N. - Martinon, S. - Calderon-Aranda, E. S. - Ibarra, A.
Journal: J Neurosci Res

Immunization with neurally derived peptides (INDP) boosts the action of an autoreactive immune response that has been shown to induce neuroprotection in several neurodegenerative diseases, especially after spinal cord (SC) injury. This strategy provides an environment that promotes neuronal survival and tissue preservation. The mechanisms by which this autoreactive response exerts its protective effects is not totally understood at the moment. A recent study showed that INDP reduces lipid peroxidation. Lipid peroxidation is a neurodegenerative phenomenon caused by the increased production of reactive nitrogen species such as nitric oxide (NO). It is possible that INDP could be interfering with NO production. To test this hypothesis, we examined the effect of INDP on the amount of NO produced by glial cells when cocultured with autoreactive T cells. We also evaluated the amount of NO and the expression of the inducible form of nitric oxide synthase (iNOS) at the injury site of SC-injured animals. The neural-derived peptides A91 and Cop-1 were used to immunize mice and rats with SC injury. In vitro studies showed that INDP significantly reduces the production of NO by glial cells. This observation was substantiated by in vivo experiments demonstrating that INDP decreases the amount of NO and iNOS gene expression at the site of injury. The present study provides substantial evidence on the inhibitory effect of INDP on NO production, helpingour understanding of the mechanisms through which protective autoimmunity promotes neuroprotection. (c) 2011 Wiley Periodicals, Inc.

post to: CiteULike

Physiological oxygen level is critical for modeling neuronal metabolism in vitro.

Publication Date: 2012 Feb PMID: 22002503
Authors: Zhu, J. - Aja, S. - Kim, E. K. - Park, M. J. - Ramamurthy, S. - Jia, J. - Hu, X. - Geng, P. - Ronnett, G. V.
Journal: J Neurosci Res

In vitro models are important tools for studying the mechanisms that govern neuronal responses to injury. Most neuronal culture methods employ nonphysiological conditions with regard to metabolic parameters. Standard neuronal cell culture is performed at ambient (21%) oxygen levels, whereas actual tissue oxygen levels in the mammalian brain range from 1% to 5%. In this study, we examined the consequences of oxygen level on the viability and metabolism of primary cultures of cortical neurons. Our results indicate that physiological oxygen level (5% O(2)) has a beneficial effect on cortical neuronal survival and mitochondrial function in vitro. Moreover, oxygen level affects metabolic fluxes: glucose uptake and glycolysis was enhanced at physiological oxygen level, whereas glucose oxidation and fatty acid oxidation were reduced. Adenosine monophosphate-activated protein kinase (AMPK) was more activated in 5% O(2) and appears to play a role in these metabolic effects. Inhibiting AMPK activity with compound C decreased glucose uptake, intracellular ATP level, and viability in neurons cultured in 5% O(2). These data indicate that oxygen level is an important parameter to consider when modeling neuronal responses to stress in vitro.

post to: CiteULike

Muller glial cells induce stem cell properties in retinal progenitors in vitro and promote their further differentiation into photoreceptors.

Publication Date: 2012 Feb PMID: 21972118
Authors: Simon, M. V. - De Genaro, P. - Abrahan, C. E. - de los Santos, B. - Rotstein, N. P. - Politi, L. E.
Journal: J Neurosci Res

Using stem cells to replace lost neurons is a promising strategy for treating retinal neurodegenerative diseases. Among their multiple functions, Muller glial cells are retina stem cells, with a robust regenerative potential in lower vertebrates, which is much more restricted in mammals. In rodents, most retina progenitors exit the cell cycle immediately after birth, differentiate as neurons, and then cannot reenter the cell cycle. Here we demonstrate that, in mixed cultures with Muller glial cells, rat retina progenitor cells expressed stem cell properties, maintained their proliferative potential, and were able to preserve these properties and remain mitotically active after several consecutive passages. Notably, these progenitors retained the capacity to differentiate as photoreceptors, even after successive reseedings. Muller glial cells markedly stimulated differentiation of retina progenitors; these cells initially expressed Crx and then developed as mature photoreceptors that expressed characteristic markers, such as opsin and peripherin. Moreover, they were light responsive, insofar as they decreased their cGMP levels when exposed to light, and they also showed high-affinity glutamate uptake, a characteristic of mature photoreceptors. Our present findings indicate that, in addition to giving rise to new photoreceptors, Muller glial cells might instruct a pool of undifferentiated cells to develop and preserve stem cell characteristics, even after successive reseedings, and then stimulate their differentiation as functional photoreceptors. This complementary mechanism might contribute to enlarge the limited regenerative capacity of mammalian Muller cells.

post to: CiteULike

Neuropeptide Y Y1 receptor hippocampal overexpression via viral vectors is associated with modest anxiolytic-like and proconvulsant effects in mice.

Publication Date: 2012 Feb PMID: 21971867
Authors: Olesen, M. V. - Christiansen, S. H. - Gotzsche, C. R. - Nikitidou, L. - Kokaia, M. - Woldbye, D. P.
Journal: J Neurosci Res

Neuropeptide Y (NPY) exerts anxiolytic- and antidepressant-like effects in rodents that appear to be mediated via Y1 receptors. Gene therapy using recombinant viral vectors to induce overexpression of NPY in the hippocampus or amygdala has previously been shown to confer anxiolytic-like effect in rodents. The present study explored an alternative and more specific approach: overexpression of Y1 receptors. Using a recombinant adeno-associated viral vector (rAAV) encoding the Y1 gene (rAAV-Y1), we, for the first time, induced overexpression of functional transgene Y1 receptors in the hippocampus of adult mice and tested the animals in anxiety- and depression-like behavior. Hippocampal Y1 receptors have been suggested to mediate seizure-promoting effect, so the effects of rAAV-induced Y1 receptor overexpression were also tested in kainate-induced seizures. Y1 receptor transgene overexpression was found to be associated with modest anxiolytic-like effect in the open field and elevated plus maze tests, but no effect was seen on depression-like behavior using the tail suspension and forced swim tests. However, the rAAV-Y1 vector modestly aggravated kainate-induced seizures. These data indicate that rAAV-induced overexpression of Y1 receptors in the hippocampus could confer anxiolytic-like effect accompanied by a moderate proconvulsant adverse effect. Further studies are clearly needed to determine whether Y1 gene therapy might have a future role in the treatment of anxiety disorders.

post to: CiteULike

Toll-like receptors 2 and 3 agonists differentially affect oligodendrocyte survival, differentiation, and myelin membrane formation.

Publication Date: 2012 Feb PMID: 21971760
Authors: Bsibsi, M. - Nomden, A. - van Noort, J. M. - Baron, W.
Journal: J Neurosci Res

Toll-like receptors (TLRs) play a key role in controlling innate immune responses to a wide variety of pathogen-associated molecules as well as endogenous signals. In addition, TLR expression within nonimmune cells has been recognized as as modulator of cell behavior. In this study we have addressed the question of whether functional TLRs are expressed on oligodendrocytes, the myelinating cells of the central nervous system. Primary cultures of rat oligodendrocytes at different maturation stages were found to express TLR2 and, to lesser extent, TLR3. Immunocytochemical analysis revealed that both TLRs were localized at the cell body and primary processes and were excluded from myelin-like membranes. Interestingly, innate immune receptor ligands were able to modulate oligodendrocyte survival, differentiation, and myelin-like membrane formation, indicating that TLRs on oligodendrocytes are functional. In highly purified oligodendrocytes cultures, the TLR2 agonist zymosan promoted survival, differentiation, and myelin-like membrane formation, whereas poly-I:C, a TLR3 ligand, was a potent inducer of apoptosis. Together, these data indicate that, in addition to other neural cell types, also oligodendrocytes express functional TLRs, which play a role in regulating various aspects of oligodendrocyte behavior.

post to: CiteULike

Role of gap junctions in chronic pain.

Publication Date: 2012 Feb PMID: 21971745
Authors: Wu, A. - Green, C. R. - Rupenthal, I. D. - Moalem-Taylor, G.
Journal: J Neurosci Res

Gap junctions are specialized transmembrane channels that allow rapid electrical signalling and direct intercellular communication for maintenance and coordination of normal cellular activities and homeostasis. Although gap junction channels in the nervous system mediate intercellular coupling between glial cells and between neurons, they also contribute to the spread of secondary damage and inflammation under pathological conditions. There is now evidence of the involvement of gap junctions in chronic pain caused by nervous system damage or tissue inflammation. In this Mini-Review, we highlight recent studies demonstrating the dynamic plasticity of gap junctions in response to nervous system injury and the effects of gap junction blockade on neuronal survival and modulation of pain in animal models of neuropathic and inflammatory pain. The involvement of dorsal root ganglia and spinal cord gap junctions in mediating chronic pain and the potential for targeting connexins as a novel modality for the treatment of intractable pain syndromes arising from nervous system injury and disorders are discussed.

post to: CiteULike

Altered glutamate receptor function in the cerebellum of the Ppt1(-/-) mouse, a murine model of infantile neuronal ceroid lipofuscinosis.

Publication Date: 2012 Feb PMID: 21971706
Authors: Finn, R. - Kovacs, A. D. - Pearce, D. A.
Journal: J Neurosci Res

The neuronal ceroid lipofuscinoses (NCLs) are a family of devastating pediatric neurodegenerative disorders and currently represent the most common form of pediatric-onset neurodegeneration. Infantile NCL (INCL), the most aggressive of these disorders, is caused by mutations in the CLN1 gene that encodes the enzyme palmitoyl protein thioesterase 1 (PPT1). Previous studies have suggested that glutamatergic neurotransmission may be disrupted in INCL, so the present study investigates glutamate receptor function in the Ppt1(-/-) mouse model of INCL by comparing the sensitivity of cultured wild-type (WT) and Ppt1(-/-) cerebellar granule cells to glutamate receptor-mediated toxicity. Ppt1(-/-) neurons were significantly less sensitive to AMPA receptor-mediated toxicity but markedly more vulnerable to NMDA receptor-mediated cell death. Because glutamate receptor function is regulated primarily by the surface expression level of the receptor, the surface level of AMPA and NMDA receptor subunits in the cerebella of WT and Ppt1(-/-) mice was also examined. Western blotting of surface cross-linked cerebellar samples showed a significantly lower surface level of the GluR4 AMPA receptor subunit in Ppt1(-/-) mice, providing a plausible explanation for the decreased vulnerability of Ppt1(-/-) cerebellar neurons to AMPA receptor-mediated cell death. The surface expression of the NR1, NR2A, and NR2B NMDA receptor subunits was similar in the cerebella of WT and Ppt1(-/-) mice, indicating that there is another mechanism behind the increased sensitivity of Ppt1(-/-) cerebellar granule cells to NMDA toxicity. Our results indicate an AMPA receptor hypofunction and NMDA receptor hyperfunction phenotype in Ppt1(-/-) neurons and provide new therapeutic targets for INCL.

post to: CiteULike

Perisynaptic aggrecan-based extracellular matrix coats in the human lateral geniculate body devoid of perineuronal nets.

Publication Date: 2012 Feb PMID: 21959900
Authors: Lendvai, D. - Morawski, M. - Bruckner, G. - Negyessy, L. - Baksa, G. - Glasz, T. - Patonay, L. - Matthews, R. T. - Arendt, T. - Alpar, A.
Journal: J Neurosci Res

The extracellular matrix surrounds different neuronal compartments in the mature nervous system. In a variety of vertebrates, most brain regions are loaded with a distinct type of extracellular matrix around the somatodendritic part of neurons, termed perineuronal nets. The present study reports that chondrotin sulfate proteoglycan-based matrix is structured differently in the human lateral geniculate body. Using various chondrotin sulfate proteoglycan-based extracellular matrix antibodies, we show that perisomatic matrix labeling is rather weak or absent, whereas dendrites are contacted by axonal coats appearing as small, oval structures. Confocal laser scanning microscopy and electron microscopy demonstrated that these typical structures are associated with synaptic loci on dendrites. Using multiple labelings, we show that different chondrotin sulfate proteoglycan components of the extracellular matrix do not associate exclusively with neuronal structures but possibly associate with glial structures as well. Finally, we confirm and extend previous findings in primates that intensity differences of various extracellular matrix markers between magno- and parvocellular layers reflect functional segregation between these layers in the human lateral geniculate body.

post to: CiteULike

Neuroprotection by hypoxic preconditioning involves upregulation of hypoxia-inducible factor-1 in a prenatal model of acute hypoxia.

Publication Date: 2012 Feb PMID: 21953610
Authors: Giusti, S. - Fiszer de Plazas, S.
Journal: J Neurosci Res

The molecular pathways underlying the neuroprotective effects of preconditioning are promising, potentially drugable targets to promote cell survival. However, these pathways are complex and are not yet fully understood. In this study we have established a paradigm of hypoxic preconditioning based on a chick embryo model of normobaric acute hypoxia previously developed by our group. With this model, we analyzed the role of hypoxia-inducible factor-1alpha (HIF-1alpha) stabilization during preconditioning in HIF-1 signaling after the hypoxic injury and in the development of a neuroprotective effect against the insult. To this end, we used a pharmacological approach, based on the in vivo administration of positive (Fe(2+), ascorbate) and negative (CoCl(2)) modulators of the activity of HIF-prolyl hydroxylases (PHDs), the main regulators of HIF-1. We have found that preconditioning has a reinforcing effect on HIF-1 accumulation during the subsequent hypoxic injury. In addition, we have also demonstrated that HIF-1 induction during hypoxic preconditioning is necessary to obtain an enhancement in HIF-1 accumulation and to develop a tolerance against a subsequent hypoxic injury. We provide in vivo evidence that administration of Fe(2+) and ascorbate modulates HIF accumulation, suggesting that PHDs might be targets for neuroprotection in the CNS.

post to: CiteULike

Decrease in the expression of N-methyl-D-aspartate receptors in the nucleus tractus solitarii induces antinociception and increases blood pressure.

Publication Date: 2012 Feb PMID: 21948527
Authors: Marques-Lopes, J. - Martins, I. - Pinho, D. - Morato, M. - Wilson, S. P. - Albino-Teixeira, A. - Tavares, I.
Journal: J Neurosci Res

N-methyl-D-aspartate receptors (NMDAR) have a role in cardiovascular control at the nucleus tractus solitarii (NTS), eliciting increases or decreases in blood pressure (BP), depending on the area injected with the agonists. In spite of the association between cardiovascular control and pain modulation, the effects of manipulating NMDAR in pain responses have never been evaluated. In this study, we decreased the expression of NMDAR in the NTS using gene transfer to target receptor subunits and evaluate long-term effects. Seven days after the injection of lentiviral vectors containing the NR1a subunit cDNA of NMDAR, in antisense orientation, into the intermediate NTS of Wistar rats, BP was measured, and the formalin test of nociception was performed. The antisense vector induced a decrease of NR1 expression in the NTS and elicited BP rises and hypoalgesia. Antisense vectors inhibited formalin-evoked c-Fos expression in the spinal cord, indicating decreased nociceptive activity of spinal neurons. Using a time-course approach, we verified that the onset of both the increases in BP and the hypoalgesia was at 4 days after vector injection into the NTS. The injection of NMDA into the NTS reversed the effects of antisense vectors in pain behavioral responses and spinal neuronal activation and decreased BP and heart rate. The present study shows that the NR1 subunit of the NMDAR at the NTS is critical in the regulation of tonic cardiovascular and nociceptive control and shows an involvement of the nucleus in the modulation of sustained pain.

post to: CiteULike

Long-lasting neuroprotective effect of sildenafil against 3,4-methylenedioxymethamphetamine- induced 5-hydroxytryptamine deficits in the rat brain.

Publication Date: 2012 Feb PMID: 21948520
Authors: Puerta, E. - Barros-Minones, L. - Hervias, I. - Gomez-Rodriguez, V. - Orejana, L. - Pizarro, N. - de la Torre, R. - Jordan, J. - Aguirre, N.
Journal: J Neurosci Res

Sildenafil, given shortly before 3,4-methylenedioxymethamphetamine (MDMA), affords protection against 5-hydroxytryptamine (5-HT) depletions caused by this amphetamine derivative by an acute preconditioning-like mechanism. Because acute and delayed preconditionings do not share the same mechanisms, we investigated whether sildenafil would also protect the 5-HT system of the rat if given 24 hr before MDMA. For this, MDMA (3 x 5 mg/kg i.p., every 2 hr) was administered to rats previously treated with sildenafil (8 mg/kg p.o.). One week later, 5-HT content and 5-HT transporter density were measured in the striatum, frontal cortex, and hippocampus of the rats. Our findings indicate that sildenafil afforded significant protection against MDMA-induced 5-HT deficits without altering the acute hyperthermic response to MDMA or its metabolic disposition. Sildenafil promoted ERK1/2 activation an effect that was paralleled by an increase in MnSOD expression that persisted 24 hr later. In addition, superoxide and superoxide-derived oxidants, shown by ethidium fluorescence, increased after the last MDMA injection, an effect that was prevented by sildenafil pretreatment. Similarly, MDMA increased nitrotyrosine concentration in the hippocampus, an effect not shown by sildenafil-pretreated rats. In conclusion, our data demonstrate that sildenafil produces a significant, long-lasting neuroprotective effect against MDMA-induced 5-HT deficits. This effect is apparently mediated by an increased expression of MnSOD and a subsequent reduced susceptibility to the oxidative stress caused by MDMA.

post to: CiteULike

Microtubule-associated protein 2, an early blood marker of ischemic brain injury.

Publication Date: 2012 Feb PMID: 21948028
Authors: Park, D. - Joo, S. S. - Lee, H. J. - Choi, K. C. - Kim, S. U. - Kim, Y. B.
Journal: J Neurosci Res

The aim of this study was to develop a sensitive and rapid blood marker to detect ischemic brain injury, because imaging techniques have a limited capacity to identify lesions during the first crucial hours without massive tissue destruction. Rats were subjected to middle cerebral artery occlusion for various durations (0.5-3 hr), followed by reperfusion. At different time points after ischemia and/or ischemia-reperfusion, the amounts of glial fibrillary acidic protein (GFAP) and microtubule-associated protein 2 (MAP2) in the cerebrospinal fluid (CSF) and serum were analyzed by Western blotting. Brain infarction was observed in an ischemia-duration-dependent manner. GFAP was drastically increased in the CSF 24 and 48 hr after reperfusion, without change in the serum level. Serum levels of MAP2 remarkably increased as early as 0.5 hr of ischemia, much earlier than the observation of minimal tissue injury 3 hr following occlusion. The serum MAP2 level was further increased by a short period (2 hr) of reperfusion, even in 0.5- and 1-hr ischemic rats, despite not observing any typical tissue injuries 24 hr after reperfusion. These results indicate that the MAP2 protein may be able to detect early neuronal injuries, because the level of this protein in the blood spikes before the appearance of visible macrolesions. Therefore, MAP2 could potentially be used as a novel early marker for the detection of a neurotoxic insult.

post to: CiteULike

Creatine affects in vitro electrophysiological maturation of neuroblasts and protects them from oxidative stress.

Publication Date: 2012 Feb PMID: 21948019
Authors: Sartini, S. - Sestili, P. - Colombo, E. - Martinelli, C. - Bartolini, F. - Ciuffoli, S. - Lattanzi, D. - Sisti, D. - Cuppini, R.
Journal: J Neurosci Res

Creatine (Cr) is a very popular ergogenic molecule that has recently been shown to have antioxidant properties. The effectiveness of Cr supplementation in treating neurological diseases and Cr deficiency syndromes has been demonstrated, and experimental reports suggest that it plays an important role in CNS development. In spite of this body of evidence, the role of Cr in functional and structural neuronal differentiation is still poorly understood. Here we used electrophysiological, morphological, and biochemical approaches to study the effects of Cr supplementation on in vitro differentiation of spinal neuroblasts under standard conditions or subjected to oxidative stress, a status closely related to perinatal hypoxia-ischemia, a severe condition for developing brain. Cr supplementation (10 and 20 mM) completely prevented the viability decrease and neurite development impairment induced by radical attack, as well as nonprotein sulphydryl antioxidant pool depletion. Similar results were obtained using the antioxidant trolox. Furthermore, Cr supplementation induced a significant and dose-dependent anticipation of Na(+) and K(+) current expression during the period of in vitro network building. Consistently with the latter finding, higher excitability, expressed as number of spikes following depolarization, was found in supplemented neuroblasts. All effects were dependent on the cytosolic fraction of Cr, as shown using a membrane Cr-transporter blocker. Our results indicate that Cr protects differentiating neuroblasts against oxidative insults and, moreover, affects their in vitro electrophysiological maturation, suggesting possibly relevant effects of dietary Cr supplementation on developing CNS.

post to: CiteULike

Regional brain axial and radial diffusivity changes during development.

Publication Date: 2012 Feb PMID: 21938736
Authors: Kumar, R. - Nguyen, H. D. - Macey, P. M. - Woo, M. A. - Harper, R. M.
Journal: J Neurosci Res

The developing human brain shows rapid myelination and axonal changes during childhood, adolescence, and early adulthood, requiring successive evaluations to determine normative values for potential pathological assessment. Fiber characteristics can be examined by axial and radial diffusivity procedures, which measure water diffusion parallel and perpendicular to axons and show primarily axonal status and myelin changes, respectively. Such measures are lacking from widespread sites for the developing brain. Diffusion tensor imaging data were acquired from 30 healthy subjects (age 17.7 +/- 4.6 years, range 8-24 years, body mass index 21.5 +/- 4.5 kg/m(2), 18 males) using a 3.0-Tesla MRI scanner. Diffusion tensors were calculated, principal eigenvalues determined, and axial and radial diffusivity maps calculated and normalized to a common space. A set of regions of interest was outlined from widespread brain areas within rostral, thalamic, hypothalamic, cerebellar, and pontine regions, and average diffusivity values were calculated using normalized diffusivity maps and these regions of interest masks. Age-related changes were assessed with Pearson's correlations, and gender differences evaluated with Student's t-tests. Axial and radial diffusivity values declined with age in the majority of brain areas, except for midhippocampus, where axial diffusivity values correlated positively with age. Gender differences emerged within putamen, thalamic, hypothalamic, cerebellar, limbic, temporal, and other cortical sites. Documentation of normal axial and radial diffusivity values will help assess disease-related tissue changes. Axial and radial diffusivities change with age,with fiber structure and organization differing between sexes in several brain areas. The findings may underlie gender-based functional characteristics, and mandate partitioning age- and gender-related changes during developmental brain pathology evaluation.

post to: CiteULike