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Reactive Astrocytes (reactive + astrocyte)
Selected AbstractsInactivation of astroglial NF-,B promotes survival of retinal neurons following ischemic injuryEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2009Galina Dvoriantchikova Abstract Reactive astrocytes have been implicated in neuronal loss following ischemic stroke. However, the molecular mechanisms associated with this process are yet to be fully elucidated. In this work, we tested the hypothesis that astroglial NF-,B, a key regulator of inflammatory responses, is a contributor to neuronal death following ischemic injury. We compared neuronal survival in the ganglion cell layer (GCL) after retinal ischemia-reperfusion in wild-type (WT) and in GFAP-I,B,-dn transgenic mice, where the NF-,B classical pathway is suppressed specifically in astrocytes. The GFAP-I,B,-dn mice showed significantly increased survival of neurons in the GCL following ischemic injury as compared with WT littermates. Neuroprotection was associated with significantly reduced expression of pro-inflammatory genes, encoding Tnf-,, Ccl2 (Mcp1), Cxcl10 (IP10), Icam1, Vcam1, several subunits of NADPH oxidase and NO-synthase in the retinas of GFAP-I,B,-dn mice. These data suggest that certain NF-,B-regulated pro-inflammatory and redox-active pathways are central to glial neurotoxicity induced by ischemic injury. The inhibition of these pathways in astrocytes may represent a feasible neuroprotective strategy for retinal ischemia and stroke. [source] Glial reactions in Parkinson's diseaseMOVEMENT DISORDERS, Issue 4 2008Patrick L. McGeer MD Abstract Dopaminergic neurons of the substantia nigra are particularly vulnerable to oxidative and inflammatory attack. Such processes may play a crucial role in the etiology of Parkinson disease (PD). Since glia are the main generators of these processes, the possibility that PD may be caused by glial dysfunction needs to be considered. This review concentrates on glial reactions in PD. Reactive astrocytes and reactive microglia are abundant in the substantia nigra (SN) of PD cases indicating a robust inflammatory state. Glia normally serve neuroprotective roles but, given adverse stimulation, they may contribute to damaging chronic inflammation. Microglia, the phagocytes of brain, may be the main contributors since they can produce large numbers of superoxide anions and other neurotoxins. Their toxicity towards dopaminergic neurons has been demonstrated in tissue culture and various animal models of PD. The MPTP and ,-synuclein models are of particular interest. Years after exposure to MPTP, inflammation has been observed in the SN. This has established that an acute insult to the SN can result in a sustained local inflammation. The ,-synuclein model indicates that an endogenous protein can induce inflammation, and, when overexpressed, can lead to autosomal dominant PD. Less is known about the role of astrocytes than microglia, but they are known to secrete both inflammatory and anti-inflammatory molecules and may play a role in modulating microglial activity. Oligodendrocytes do not seem to play a role in promoting inflammation although, like neurons, they may be damaged by inflammatory processes. Further research concerning glial reactions in PD may lead to disease-modifying therapeutic approaches. © 2007 Movement Disorder Society [source] Chlorotoxin-sensitive Ca2+ -activated Cl, channel in type R2 reactive astrocytes from adult rat brainGLIA, Issue 4 2003Stanislava Dalton Abstract Astrocytes express four types of Cl, or anion channels, but Ca2+ -activated Cl, (ClCa) channels have not been described. We studied Cl, channels in a morphologically distinct subpopulation (, 5% of cells) of small (10,12 ,m, 11.8 ± 0.6 pF), phase-dark, GFAP-positive native reactive astrocytes (NRAs) freshly isolated from injured adult rat brains. Their resting potential, ,57.1 ± 4.0 mV, polarized to ,72.7 ± 4.5 mV with BAPTA-AM, an intracellular Ca2+ chelator, and depolarized to ,30.7 ± 6.1 mV with thapsigargin, which mobilizes Ca2+ from intracellular stores. With nystatin-perforated patch clamp, thapsigargin activated a current that reversed near the Cl, reversal potential, which was blocked by Cl, channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and Zn2+, by I, (10 mM), and by chlorotoxin (EC50 = 47 nM). With conventional whole-cell clamp, NPPB- and Zn2+ -sensitive currents became larger with increasing [Ca2+]i (10, 150, 300 nM). Single-channel recordings of inside-out patches confirmed Ca2+ sensitivity of the channel and showed open-state conductances of 40, 80, 130, and 180 pS, and outside-out patches confirmed sensitivity to chlorotoxin. In primary culture, small phase-dark NRAs developed into small GFAP-positive bipolar cells with chlorotoxin-sensitive ClCa channels. Imaging with biotinylated chlorotoxin confirmed the presence of label in GFAP-positive cells from regions of brain injury, but not from uninjured brain. Chlorotoxin-tagged cells isolated by flow cytometry and cultured up to two passages exhibit positive labeling for GFAP and vimentin, but not for prolyl 4-hydroxylase (fibroblast), A2B5 (O2A progenitor), or OX-42 (microglia). Expression of a novel chlorotoxin-sensitive ClCa channel in a morphologically distinct subpopulation of NRAs distinguishes these cells as a new subtype of reactive astrocyte. GLIA 42:325,339, 2003. © 2003 Wiley-Liss, Inc. [source] Down-regulation of neurocan expression in reactive astrocytes promotes axonal regeneration and facilitates the neurorestorative effects of bone marrow stromal cells in the ischemic rat brainGLIA, Issue 16 2008Li Hong Shen Abstract The glial scar, a primarily astrocytic structure bordering the infarct tissue inhibits axonal regeneration after stroke. Neurocan, an axonal extension inhibitory molecule, is up-regulated in the scar region after stroke. Bone marrow stromal cells (BMSCs) reduce the thickness of glial scar wall and facilitate axonal remodeling in the ischemic boundary zone. To further clarify the role of BMSCs in axonal regeneration and its underlying mechanism, the current study focused on the effect of BMSCs on neurocan expression in the ischemic brain. Thirty-one adult male Wistar rats were subjected to 2 h of middle cerebral artery occlusion followed by an injection of 3 × 106 rat BMSCs (n = 16) or phosphate-buffered saline (n = 15) into the tail vein 24 h later. Animals were sacrificed at 8 days after stroke. Immunostaining analysis showed that reactive astrocytes were the primary source of neurocan, and BMSC-treated animals had significantly lower neurocan and higher growth associated protein 43 expression in the penumbral region compared with control rats, which was confirmed by Western blot analysis of the brain tissue. To further investigate the effects of BMSCs on astrocyte neurocan expression, single reactive astrocytes were collected from the ischemic boundary zone using laser capture microdissection. Neurocan gene expression was significantly down-regulated in rats receiving BMSC transplantation (n = 4/group). Primary cultured astrocytes showed similar alterations; BMSC coculture during reoxygenation abolished the up-regulation of neurocan gene in astrocytes undergoing oxygen-glucose deprivation (n = 3/group). Our data suggest that BMSCs promote axonal regeneration by reducing neurocan expression in peri-infarct astrocytes. © 2008 Wiley-Liss, Inc. [source] The presence of active Cdk5 associated with p35 in astrocytes and its important role in process elongation of scratched astrocyteGLIA, Issue 6 2007Yi He Abstract Cyclin-dependent kinase 5 (Cdk5) is a unique member of the Cdk family; its kinase activity requires association with its activator, p35 or p39. p35 is the strongest and best characterized activator. Previous studies showed that p35 is a neuron-specific protein that restricts Cdk5 activity in neurons. However, a high expression level of Cdk5 is found in astrocytes, which raises the possibility that astrocytic Cdk5 is functional. Here we show the presence of functional Cdk5 associated with p35 in astrocytes and demonstrate its important role in process elongation of scratched astrocytes. We found that p35 and glial fibrillary acidic protein (GFAP) were co-localized in primary cultured and acute isolated brain cells. Cdk5 could form an immunocomplex with p35 and its activity was shown in pure primary cultured astrocytes. p35 was upregulated in astrocytes injured by scratching, concomitantly with upregulation of Cdk5 kinase activity. Pretreatment of the scratched astrocytes with a Cdk5 inhibitor, roscovitine, could delay wound healing by inhibiting the reorganization of tubulin, GFAP, and the extension of hypertrophic processes. Moreover, overexpression of dominant negative Cdk5 could shorten the length of extending protrusion of reactive astrocytes. Thus, our findings demonstrated that functional Cdk5, associated with p35, was expressed in astrocytes and its activity could be upregulated in reactive astrocytes, a new role of Cdk5 that has never been reported in the nervous system. The present study may provide new insight for understanding the multifunctional protein complex Cdk5/p35 in the nervous system. © 2007 Wiley-Liss, Inc. [source] Chlorotoxin-sensitive Ca2+ -activated Cl, channel in type R2 reactive astrocytes from adult rat brainGLIA, Issue 4 2003Stanislava Dalton Abstract Astrocytes express four types of Cl, or anion channels, but Ca2+ -activated Cl, (ClCa) channels have not been described. We studied Cl, channels in a morphologically distinct subpopulation (, 5% of cells) of small (10,12 ,m, 11.8 ± 0.6 pF), phase-dark, GFAP-positive native reactive astrocytes (NRAs) freshly isolated from injured adult rat brains. Their resting potential, ,57.1 ± 4.0 mV, polarized to ,72.7 ± 4.5 mV with BAPTA-AM, an intracellular Ca2+ chelator, and depolarized to ,30.7 ± 6.1 mV with thapsigargin, which mobilizes Ca2+ from intracellular stores. With nystatin-perforated patch clamp, thapsigargin activated a current that reversed near the Cl, reversal potential, which was blocked by Cl, channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoate (NPPB) and Zn2+, by I, (10 mM), and by chlorotoxin (EC50 = 47 nM). With conventional whole-cell clamp, NPPB- and Zn2+ -sensitive currents became larger with increasing [Ca2+]i (10, 150, 300 nM). Single-channel recordings of inside-out patches confirmed Ca2+ sensitivity of the channel and showed open-state conductances of 40, 80, 130, and 180 pS, and outside-out patches confirmed sensitivity to chlorotoxin. In primary culture, small phase-dark NRAs developed into small GFAP-positive bipolar cells with chlorotoxin-sensitive ClCa channels. Imaging with biotinylated chlorotoxin confirmed the presence of label in GFAP-positive cells from regions of brain injury, but not from uninjured brain. Chlorotoxin-tagged cells isolated by flow cytometry and cultured up to two passages exhibit positive labeling for GFAP and vimentin, but not for prolyl 4-hydroxylase (fibroblast), A2B5 (O2A progenitor), or OX-42 (microglia). Expression of a novel chlorotoxin-sensitive ClCa channel in a morphologically distinct subpopulation of NRAs distinguishes these cells as a new subtype of reactive astrocyte. GLIA 42:325,339, 2003. © 2003 Wiley-Liss, Inc. [source] Cellular localization and expression patterns of interleukin-10, interleukin-4, and their receptors in multiple sclerosis lesionsGLIA, Issue 1 2002Sandra Hulshof Abstract Cytokines have been shown to play a crucial role in the pathogenesis of multiple sclerosis (MS). However, still limited data are available on the expression of anti-inflammatory cytokines within the central nervous system (CNS) during MS lesion development. Therefore, we have examined the expression of the anti-inflammatory cytokines, interleukin-10 (IL-10) and IL-4, and their specific receptors, IL-10R and IL-4R, in postmortem human brain tissue obtained from MS patients. Specific patterns of protein localization and expression for both proteins could be observed within active and chronic MS lesions. Strongest IL-10 immunoreactivity was observed in reactive astrocytes within active demyelinating lesions and the hypercellular rim of chronic active MS lesions. Moreover, perivascular macrophages were immunoreactive for IL-10 in (chronic) active MS lesions. Most intense IL-4 immunoreactivity was detected in reactive fibrillary astrocytes within the hypocellular regions of chronic active and chronic inactive MS lesions. Strong immunoreactivity for IL-10R and IL-4R was detected on macrophages in both parenchymal and perivascular areas and on reactive astrocytes in active and chronic MS lesions. Our results indicate that IL-10 and IL-4 have an active role in CNS immune responses. The specific patterns of protein localization and protein expression for both IL-10 and IL-4 in MS lesions at different stages of development suggest that these anti-inflammatory cytokines and their receptors participate in processes leading to the formation of chronic MS lesions. GLIA 38:24,35, 2002. © 2002 Wiley-Liss, Inc. [source] Cyclosporine A and its non-immunosuppressive derivative NIM811 induce apoptosis of malignant melanoma cells in in vitro and in vivo studiesINTERNATIONAL JOURNAL OF CANCER, Issue 1 2005Iwona Ciechomska Abstract Advanced melanoma is a highly malignant tumor with an increasing incidence that has a poor prognosis due to resistance to common therapeutic strategies. We have demonstrated previously that cyclosporine A (CsA) induces apoptosis of rat glioma cells, reactive astrocytes, and fibroblasts. In our present study, we investigated effects of CsA and its nonimmunosuppressive derivative NIM811 on survival of human and murine melanoma cells. We demonstrated that CsA and NIM811 affect survival of human and murine melanoma cells and induce morphological changes, alterations in nuclear morphology and an internucleosomal DNA fragmentation, consistent with an apoptotic type of death. Western blot analysis showed an activation of caspases 9, 7, 3 and PARP cleavage detectable at 24 hr after exposure of human melanoma cells to the drugs. CsA and NIM811 induced a significant increase in subG1 population of murine B16F10 melanoma cells indicative of apoptotic DNA fragmentation. Studies in murine model of melanoma showed that NIM811, but not CsA, retards tumor progression and significantly decreases tumor volume after intratumoral application. Our findings indicate that CsA and its derivatives may be new candidates for the treatment of melanoma patients. © 2005 Wiley-Liss, Inc. [source] Cyclic GMP phosphodiesterase inhibition alters the glial inflammatory response, reduces oxidative stress and cell death and increases angiogenesis following focal brain injuryJOURNAL OF NEUROCHEMISTRY, Issue 3 2010Paula Pifarré J. Neurochem. (2010) 112, 807,817. Abstract Recent evidence obtained in cultured glial cells indicates that cGMP-mediated pathways regulate cytoskeleton dynamics, glial fibrillary acidic protein expression and motility in astrocytes, as well as inflammatory gene expression in microglia, suggesting a role in the regulation of the glial reactive phenotype. The aim of this work was to examine if cGMP regulates the glial inflammatory response in vivo following CNS damage caused by a focal cryolesion onto the cortex in rats. Results show that treatment with the cGMP phosphodiesterase inhibitor zaprinast (10 mg/kg i.p.) 2 h before and 24 and 48 h after the lesion results 3 days post-lesion in notably enhanced astrogliosis manifested by increased glial fibrillary acidic protein immunoreactivity and protein levels around the lesion. In contrast, zaprinast decreased the number of round/ameboid lectin-positive cells and the expression of the activated microglia/macrophage markers Iba-1 and CD11b indicating decreased recruitment and activation of these cells. This altered inflammatory response is accompanied by a decrease in protein oxidative stress, apoptotic cell death and neuronal degeneration. In addition, zaprinast enhanced angiogenesis in the lesioned cortex probably as a result of vascular endothelial growth factor expression in reactive astrocytes. These results suggest that regulation of the glial inflammatory response may contribute to the reported neuroprotective effects of cGMP-phosphodiesterase inhibitors in brain injury. [source] JAK-STAT signaling pathway mediates astrogliosis in brains of scrapie-infected miceJOURNAL OF NEUROCHEMISTRY, Issue 2 2007Yeo-Jung Na Abstract Scrapie is characterized histologically, in part, by astrogliosis in brain and spinal cord. However, the mechanisms of astrogliosis in brain injury occurring during prion infection are not well understood. In this study, we investigated the expression levels and cellular localization of Janus kinase (JAK) -signal transducers and activators of transcription (STAT) signaling molecules and growth factors such as leukemia inhibitory factor (LIF) and ciliary neurotropic factor (CNTF) by western blot analysis and immunohistochemistry. We found that expression levels of LIF and CNTF were increased in scrapie-infected brains and phosphorylated (p)-JAK2, p-STAT1 (Ser727 and Tyr701), p-STAT3 (Tyr705), and glial fibrillary acidic protein were expressed strongly in scrapie-infected brains. Moreover, we found that p-STAT1 and p-STAT3 were found mainly in the nucleus in scrapie-infected brains. Immunohistochemically, p-STAT1 was colocalized with LIF and CNTF and p-JAK2 in many reactive astrocytes in scrapie-infected brains. In contrast, immunostaining for p-STAT3 was found in comparatively few astrocytes in limited regions; p-STAT3 staining merged with p-JAK2 in hippocampus sections of scrapie-infected brains. Taken together, our results suggest that activation of JAK2-STAT1 signaling pathway occurred in reactive astrocytes in hippocampus of scrapie-infected brains. [source] Rapid Upregulation of Aromatase mRNA and Protein Following Neural Injury in the Zebra Finch (Taeniopygia guttata)JOURNAL OF NEUROENDOCRINOLOGY, Issue 4 2001R. Scott Peterson Abstract The expression of aromatase (oestrogen synthase) within the vertebrate central nervous system (CNS) is key in the provision of local oestrogens to neural circuits. Aromatase expression appears to be exclusively neuronal under normal conditions. However, some in vitro studies suggest the presence of astrocytic aromatase in songbirds and mammals. Recently, aromatase in reactive astrocytes has been demonstrated in response to neural injury in the mammalian CNS. Since the glial aromatase expression first documented in cultures of the songbird telencephalon may reflect processes similar to those in response to mammalian neural injury, we investigated whether injury alters the pattern of aromatase-expression in the zebra finch, a species with very high levels of forebrain aromatase expression. Adult males received a penetrating neural injury to the right hemisphere and were killed either 24 or 72 h later. Controls were anaesthetized and otherwise unmanipulated. We determined the expression of aromatase mRNA and protein using in situ hybridization and immunocytochemistry, respectively. Both the transcription and translation of aromatase is dramatically upregulated around the lesion site in response to neural injury in the zebra finch forebrain. This effect is robust and rapid, occurring within 24 h of the injury itself. Cells that upregulate aromatase appear to be reactive astrocytes based upon morphology. The hemisphere contralateral to the injury and both hemispheres in control birds showed the normal, exclusively neuronal pattern of aromatase expression. The upregulation of aromatase in astrocytes may provide high levels of oestrogen available to modulate processes such as CNS repair. Injury-induced upregulation of astrocytic aromatase may be a general characteristic of the injured vertebrate brain. [source] Expression of plasminogen activator inhibitor-1 and protease nexin-1 in human astrocytes: Response to injury-related factorsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 11 2010Karin Hultman Abstract Astrocytes play a diverse role in central nervous system (CNS) injury. Production of the serine protease inhibitors (serpins) plasminogen activator inhibitor-1 (PAI-1) and protease nexin-1 (PN-1) by astrocytes may counterbalance excessive serine protease activity associated with CNS pathologies such as ischemic stroke. Knowledge regarding the regulation of these genes in the brain is limited, so the objective of the present study was to characterize the effects of injury-related factors on serpin expression in human astrocytes. Native human astrocytes were exposed to hypoxia or cytokines, including interleukin-6 (IL-6), IL-1,, tumor necrosis factor-, (TNF-,), IL-10, transforming growth factor-, (TGF-,), and TGF-, for 0,20 hr. Serpin mRNA expression and protein secretion were determined by real-time RT-PCR and ELISA, respectively. Localization of PAI-1 and PN-1 in human brain tissue was examined by immunohistochemistry. Hypoxia and all assayed cytokines induced a significant increase in PAI-1 expression, whereas prolonged treatment with IL-1, or TNF-, resulted in a significant down-regulation. The most pronounced induction of both PAI-1 and PN-1 was observed following early treatment with TGF-,. In contrast to PAI-1, the PN-1 gene did not respond to hypoxia. Positive immunoreactivity for PAI-1 in human brain tissue was demonstrated in reactive astrocytes within gliotic areas of temporal cortex. We show here that human astrocytes express PAI-1 and PN-1 and demonstrate that this astrocytic expression is regulated in a dynamic manner by injury-related factors. © 2010 Wiley-Liss, Inc. [source] Genetic fate mapping of Olig2 progenitors in the injured adult cerebral cortex reveals preferential differentiation into astrocytesJOURNAL OF NEUROSCIENCE RESEARCH, Issue 16 2008Kouko Tatsumi Abstract Olig2 is a basic helix-loop-helix (bHLH) transcription factor essential for development of motoneurons and oligodendrocytes. It is known that Olig2+ cells persist in the central nervous system (CNS) from embryonic to adult stages and that the number of Olig2+ progenitors increases in the injured adult CNS. Recent studies have demonstrated an inhibitory action of Olig2 on neurogenesis in adult CNS, but the fate of Olig2+ cells in the injured state remains largely unknown. To trace directly the fate of Olig2 cells in the adult cerebral cortex after injury, we employed the CreER/loxP system to target the olig2 locus. In this genetic tracing study, green fluorescent protein (GFP) reporter-positive cells labeled after cryoinjury coexpressed glial fibrillary acidic protein (GFAP), an astrocytic marker. Electron microscopy also showed that GFP+ cells have the ultrastructural characteristics of astrocytes. Furthermore, GFP+ cells labeled before injury, most of which had been NG2 cells, also produced bushy astrocytes. Here we show direct evidence that Olig2+ cells preferentially differentiate into astrocytes, which strongly express GFAP, in response to injury in the adult cerebral cortex. These results suggest that reactive astrocytes, known to be the main contributors to glial scars, originate, at least in part, from Olig2+ cells. © 2008 Wiley-Liss, Inc. [source] Activation of epidermal growth factor receptors in astrocytes: From development to neural injuryJOURNAL OF NEUROSCIENCE RESEARCH, Issue 16 2007Bin Liu Abstract The epidermal growth factor receptor (EGFR) pathway controls the phenotypic characteristics of astrocytes. In the developing central nervous system (CNS), activation of the EGFR pathway induces astrocyte differentiation, forming the cribriform structure that surrounds axons and providing a supportive environment for neurons. In the adult CNS, the EGFR pathway is absent from astrocytes but is highly up-regulated and activated following neuronal injury. Activation of the EGFR pathway triggers quiescent astrocytes to become reactive astrocytes. Although astrocytes regulated by the EGFR pathway play constructive roles in the developing CNS, astrocytes that become reactive in response to activation of the EGFR pathway appear to be destructive to neurons in the adult CNS. The reappearance and activation of EGFRs in astrocytes under pathological conditions may activate a developmental process in an adult tissue. Regulation of EGFR function in astrocytes may be a new therapeutic strategy for the treatment of neural disorders. © 2007 Wiley-Liss, Inc. [source] Alterations of hHrd1 expression are related to hyperphosphorylated tau in the hippocampus in Alzheimer's diseaseJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Hai-Long Hou Abstract The degradation of aberrantly phosphorylated tau in neurons plays an important role in the pathogenesis of Alzheimer's disease (AD). hHrd1 is a newly identified ubiquitin ligase involved in the endoplasmic reticulum (ER)-associated protein degradation. The expression and function of hHrd1 in AD brain remains elusive. In the present study, the expression of hHrd1 in AD hippocampus and the morphological relations between hHrd1 expression and pretangle formation were studied by using immunohistochemical single- and double-labeling methods. The results showed that hHrd1 was expressed in neurons and reactive astrocytes, especially in the CA2,CA4 hippocampal subfields. The ratio of hHrd1-positive neurons/astrocytes to total neurons/astrocytes was increased in the CA1 subfield in AD hippocampus compared with the age-matched controls (P < 0.05). Most Alz-50 labeled pretangles were colocalized with hHrd1, and the expression levels showed an inversed change, implied that hHrd1 might be associated with the degradation of hyperphosphorylated tau. © 2006 Wiley-Liss, Inc. [source] Long-lasting coexpression of nestin and glial fibrillary acidic protein in primary cultures of astroglial cells with a major participation of nestin+/GFAP, cells in cell proliferationJOURNAL OF NEUROSCIENCE RESEARCH, Issue 8 2006Solène Sergent-Tanguy Abstract Nestin, a currently used marker of neural stem cells, is transiently coexpressed with glial fibrillary acidic protein (GFAP) during development and is induced in reactive astrocytes following brain injury. Nestin expression has also been found in cultures of astroglial cells, but little is known about the fate and the mitotic activity of nestin-expressing cells in this in vitro model. The present study reveals a long-lasting expression of nestin in primary cultures of astroglial cells derived from the rat brain. Over 70% of the cells were nestin+ at 12 weeks, with a large majority coexpressing the GFAP astrocytic marker. Time-course analyses supported a transition from a nestin+/GFAP, to a nestin+/GFAP+ phenotype over time, which was further increased by cell cycle arrest. Interestingly, double staining with Ki67 revealed that over 90% of cycling cells were nestin+ whereas only 28% were GFAP+ in a population consisting of almost equivalent numbers of nestin+ and GFAP+ cells. These observations indicated that nestin+/GFAP, cells are actively engaged in mitotic activity, even after 2 weeks in vitro. Part of these cells might have retained properties of neural stem cells, insofar as 10% of cells in a primary culture of glial cells were able to generate neurospheres that gave rise to both neurons and astrocytes. Further studies will be necessary to characterize fully the proliferating cells in primary cultures of glial cells, but our present results reveal a major contribution of the nestin+/GFAP, cells to the increase in the number of astrocytes, even though nestin+/GFAP+ cells proliferate also. © 2006 Wiley-Liss, Inc. [source] Neuroprotective mechanisms of curcumin against cerebral ischemia-induced neuronal apoptosis and behavioral deficitsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 1 2005Qun Wang Abstract Increased oxidative stress has been regarded as an important underlying cause for neuronal damage induced by cerebral ischemia/reperfusion (I/R) injury. In recent years, there has been increasing interest in investigating polyphenols from botanical source for possible neuroprotective effects against neurodegenerative diseases. In this study, we investigated the mechanisms underlying the neuroprotective effects of curcumin, a potent polyphenol antioxidant enriched in tumeric. Global cerebral ischemia was induced in Mongolian gerbils by transient occlusion of the common carotid arteries. Histochemical analysis indicated extensive neuronal death together with increased reactive astrocytes and microglial cells in the hippocampal CA1 area at 4 days after I/R. These ischemic changes were preceded by a rapid increase in lipid peroxidation and followed by decrease in mitochondrial membrane potential, increased cytochrome c release, and subsequently caspase-3 activation and apoptosis. Administration of curcumin by i.p. injections (30 mg/kg body wt) or by supplementation to the AIN76 diet (2.0 g/kg diet) for 2 months significantly attenuated ischemia-induced neuronal death as well as glial activation. Curcumin administration also decreased lipid peroxidation, mitochondrial dysfunction, and the apoptotic indices. The biochemical changes resulting from curcumin also correlated well with its ability to ameliorate the changes in locomotor activity induced by I/R. Bioavailability study indicated a rapid increase in curcumin in plasma and brain within 1 hr after treatment. Together, these findings attribute the neuroprotective effect of curcumin against I/R-induced neuronal damage to its antioxidant capacity in reducing oxidative stress and the signaling cascade leading to apoptotic cell death. © 2005 Wiley-Liss, Inc. [source] Differential expression of Musashi1 and nestin in the adult rat hippocampus after ischemiaJOURNAL OF NEUROSCIENCE RESEARCH, Issue 6 2002Yoshiki Yagita Abstract Both nestin and the neural RNA-binding protein Musashi1 (Msi1) are expressed in neural stem cells in the subventricular zone. Neurogenesis in the hippocampus has received much attention, so we evaluated the expression of Msi1 and nestin in the adult rat hippocampus after transient forebrain ischemia. Both Msi1 and nestin were induced in the reactive astrocytes after ischemia, especially in the CA1 region, until 35 days after ischemia. Induction of both molecules suggested that reactive astrocytes might have immature characteristics. In the subgranular zone (SGZ) of the hippocampal dentate gyrus, Msi1-positive cells formed clusters after ischemia. These cells were labeled by bromodeoxyuridine (BrdU) but did not express glial fibrillary acidic protein. In contrast, very few nestin-positive cells were labeled by BrdU. Our results suggest that neuronal progenitor cells in the SGZ expressed Msi1 but not nestin. © 2002 Wiley-Liss, Inc. [source] Pathogenic role of glial cells in Parkinson's diseaseMOVEMENT DISORDERS, Issue 2 2003Peter Teismann PhD Abstract An erratum for this article appears in the January, 2004 issue of Movement Disorders (Mov Disord 2004;19:119). Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the progressive loss of the dopaminergic neurons in the substantia nigra pars compacta (SNpc). The loss of these neurons is associated with a glial response composed mainly of activated microglial cells and, to a lesser extent, of reactive astrocytes. This glial response may be the source of trophic factors and can protect against reactive oxygen species and glutamate. Alternatively, this glial response can also mediate a variety of deleterious events related to the production of pro-oxidant reactive species, and pro-inflammatory prostaglandin and cytokines. We discuss the potential protective and deleterious effects of glial cells in the SNpc of PD and examine how those factors may contribute to the pathogenesis of this disease. © 2002 Movement Disorder Society [source] Activation of STAT3 and inhibitory effects of pioglitazone on STAT3 activity in a mouse model of SOD1-mutated amyotrophic lateral sclerosisNEUROPATHOLOGY, Issue 4 2010Noriyuki Shibata Signal transducer and activator of transcription-3 (STAT3) is a member of the proinflammatory transcription factor STAT family. Several studies have documented implications for neuroinflammation in amyotrophic lateral sclerosis (ALS). We recently demonstrated activation of STAT3 in spinal cords obtained at autopsy from sporadic ALS patients. To determine the involvement of STAT3 and effects of pioglitazone on STAT3 activity in familial ALS with superoxide dismutase-1 (SOD1) mutation, we performed immunoblot and immunohistochemical analyses of the active form of STAT3 (p-STAT3) in spinal cords from mice overexpressing mutant SOD1 (ALS mice) and nontransgenic littermates (control mice). Immunoblot analysis delineated significant increases in nuclear p-STAT3 levels in non-treated ALS mice as compared with pioglitazone-treated ALS mice and non-treated and pioglitazone-treated control mice. Immunohistochemical analysis revealed prominent p-STAT3 accumulations in the nucleus of motor neurons, reactive astrocytes and activated microglia in non-treated ALS mice but not pioglitazone-treated ALS mice and non-treated and pioglitazone-treated control mice. The present results provide in vivo evidence for increased phosphorylative activation and nuclear translocation of STAT3 in motor neurons and glia in mouse motor neuron disease, suggesting a common pathological process between sporadic and SOD1-mutated familial forms of ALS. Moreover, it is likely that pioglitazone may exert inhibitory effects on STAT3-mediated proinflammtory mechanisms in this disease. [source] Hereditary cerebral hemorrhage with amyloidosis-Dutch typeNEUROPATHOLOGY, Issue 4 2005Marion Maat-Schieman The amyloid ,-protein (A,) E22Q mutation of the rare disorder hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D) causes severe cerebral amyloid angiopathy (CAA) with hemorrhagic strokes of mid-life onset and dementia. The mutation does not affect total A, production but may alter the A,1,42:A,1,40 ratio, and affect the proteolytic degradation of A, and its transport across the blood,brain barrier. A, E22Q aggregates faster into more stable amyloid-like fibrils than wild-type A,. Non-fibrillar A,(x-42) deposits precede the appearance of fibrils and the deposition of A,(x-40) in the vascular basement membrane. CAA severity tends to increase with age but may vary greatly among patients of comparable ages. Lumenal narrowing of affected blood vessels, leukoencephalopathy, CAA-associated vasculopathies, and perivascular astrocytosis, microgliosis, and neuritic degeneration complicate the development of HCHWA-D CAA. Parenchymal A, deposition is also enhanced in the HCHWA-D brain with non-fibrillar membrane-bound A,(x-42) deposits evolving into relatively fibrillar diffuse plaques variously associated with reactive astrocytes, activated microglia, and degenerating neurites. Plaque density tends ,to ,decrease ,with ,age. ,Neurofibrillary ,degeneration is absent or limited. HCHWA-D dementia is associated with CAA severity independently of Braak stage, age, and plaque density. Particularly, microaneurysms may contribute to the development of (small) hemorrhages/infarcts and the latter to cognitive decline in affected subjects. However, the relative importance of cerebral hemorrhages/infarcts, white matter damage and/or other CAA- or A,-related factors for cognitive deterioration in HCHWA-D remains to be determined. [source] Defense mechanism to oxidative DNA damage in glial cellsNEUROPATHOLOGY, Issue 2 2004Takashi Iida Astrocytosis is a sequential morphological change of astrocytic reaction to tissue damage, and is associated with regulation of antioxidant defense mechanisms to reduce oxidative damage. The repair enzymes to oxidative DNA damage, oxidized purine-nucleoside triphosphatase (hMTH1) and a mitochondrial type of 8-oxoguanine DNA glycosylase (hOGG1,2a) in brain tumors and neurons of Alzheimer's disease, were previously reported. In the present study, glial expression of these repair enzymes under such pathological conditions as cerebrovascular diseases and metastatic brain tumors, were investigated. Furthermore, an in-vitro experiment using a glioma cell-line under oxidative stress was performed to verify the immunohistochemical results of post-mortem materials. As a result, hOGG1,2a immunoreactivities in reactive astrocytes were more intense than those to hMTH1. Oligodendrocytes of acute or subacute stage of brain infarction were strongly immunoreactive to both repair enzymes. In-vitro study revealed that, hOGG1,2a is constitutively expressed in both untreated glioma cells and the glioma cells under oxidative stress. However, although no immunoreactivity to hMTH1 was found in the control cells, accumulation of hMTH1 was rapidly induced by oxidative stress. These results indicate that the two repair enzymes to oxidative DNA damage are differentially regulated in glial cells, and that there is a difference in the expression of the repair enzymes between reactive astrocytes and oligodendrocytes. [source] Ultrastructural and MRI study of the substantia nigra evolving exofocal post-ischemic neuronal death in the ratNEUROPATHOLOGY, Issue 3 2002Fengyu Zhao To clarify the morphological characteristics of exofocal post-ischemic neuronal death (EPND) in the substantia nigra (SN), we investigated the course of light- and electron-microscopic changes of the SN of rats subjected to occlusion of the left middle cerebral artery (MCA) for 1, 2, 4, 7 and 12 days. To assess cellular edema, sequential magnetic resonance (MR) mapping of the apparent diffusion coefficient (ADC) and the T2 value test was performed. Histological and electron-microscopic examination on day 1 showed dotted chromatin clumps in the nuclei of some neurons and mild swelling of the perivascular endfeet of astrocytes in the ipsilateral SN. On day 2, a few cells of the ipsilateral SN pars reticulata (SNr) revealed key morphological signs of apoptosis , apoptotic body-like condensation and segregation of the chromatin and DNA fragmentation-like nuclear remnants. On day 4, 38% of neurons became swollen (pale neurons) with cytoplasmic microvacuoles, which appeared to originate from rough endoplasmic reticulum (rER), mitochondria and Golgi apparatus. Twenty percent of neurons showed massive proliferation of the cisternae of the rER, some of which were fragmented or had lost their normal parallel arrangement. In addition, MR mapping revealed a transient ADC decrease with a T2 increase (signifying a phase of cellular edema), which coordinated with the phase of ultrastructural cellular swelling. Further, the total number of neurons started to decrease gradually, the perivascular endfeet of astrocytes were markedly swollen, and the neuropil became loose on day 4. On day 7, reactive astrocytes and dark neurons occurred most frequently. These results suggest that the EPND in the SN after occlusion of the MCA in adult rats is due to both apoptosis and necrosis, although necrosis seems to be the dominant mechanism of the EPND. However, the morphologic resemblances of EPND to delayed neuronal death suggest these processes have a common pathomechanism. [source] Small heat shock proteins, the cytoskeleton, and inclusion body formationNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 4 2000M. W. Head Since first being implicated in central nervous system disease 10 years ago, much has been learned concerning the regulation and function of the small heat shock protein ,B-crystallin. Neuropathological, cellular and molecular studies all now point to a functional relationship between ,B-crystallin and intermediate filaments. ,B-crystallin accumulation marks reactive astrocytes in general in a wide variety of disorders and specifically intermediate filament-based glial inclusion bodies such as Rosenthal fibres found in astrocytes in Alexander's disease. In vitro, ,B-crystallin expression suppresses intermediate filament aggregation and can prevent or reverse experimentally induced glial inclusion body formation. Conversely, dysregulation of glial fibrillary acidic protein expression in vivo results in Rosenthal fibre formation and upregulation of endogenous ,B-crystallin expression. These data and those from studies recently carried out on other tissues strongly suggest that one function of this small heat shock protein is to modulate intermediate filament organization under conditions of physiological stress and neurodegenerative disease. [source] Spatiotemporal characteristics of astroglial death in the rat hippocampo-entorhinal complex following pilocarpine-induced status epilepticusTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2008Duk-Soo Kim Astroglial reactive gliosis in the rat hippocampus at 8 weeks after pilocarpine-induced status epilepticus. GFAP (red) positive reactive astrocytes in the stratum lacunosum-moleculare show strong GS (green) immunoreactivity, while GFAP-positive astrocytes show no GS immunoreactivity in the molecular layer of the dentate gyrus. Blue is DAPI counterstaining. J. Comp. Neurol. 511:581,598, 2008. © 2008 Wiley-Liss, Inc. [source] Ectopia of meningeal fibroblasts and reactive gliosis in the cerebral cortex of the mouse model of muscle-eye-brain diseaseTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 5 2007Yuan Yang Abstract Congenital muscular dystrophies with brain malformations, such as muscle-eye-brain disease, exhibit neural ectopias caused by overmigration of neurons. Such overmigration is evident in protein O-mannose ,-1,2-N-acetylglucosaminyltransferase (POMGnT1) knockout mouse, a model of muscle-eye-brain disease, caused by breaches in the pial basement membrane. We hypothesize that breaches in pial basement membrane disrupt the neural-meningeal boundary, resulting in ectopia of meningeal fibroblasts in the cerebral cortex and reactive gliosis. To test this hypothesis, the cerebral cortices of developing and adult POMGnT1 knockout mice were analyzed by immunostaining with cell-specific markers and by electron microscopy. The upper half of the cerebral cortex in the knockout mouse contained increased numbers of fibroblasts closely associated with capillaries. During development of the cerebral cortex in the knockout mice, breaches in pial basement membrane allowed emigration of overmigrated neurons into the developing pia-arachnoid, scattering its mesenchymal cells throughout the diffuse cell zone and resulting in ectopia of mesenchyme-derived fibroblasts in the upper half of the cortex. Glial fibrillary acidic protein (GFAP) immunostaining revealed that the upper half of the cerebral cortex in the knockout also contained increased numbers of cells with morphologies typical of reactive astrocytes compared with the wild type. Moreover, most of the GFAP-positive reactive astrocytes were in close contact with ectopic fibroblasts, suggesting that they were induced by the fibroblasts. Collectively, the data support the hypothesis that the cerebral cortex of POMGnT1 knockout mice is characterized by migration defects leading to disruption of the pia-arachnoid, ectopia of fibroblasts in the cortex, and reactive gliosis. J. Comp. Neurol. 505:459,477, 2007. © 2007 Wiley-Liss, Inc. [source] Sustained neocortical neurogenesis after neonatal hypoxic/ischemic injuryANNALS OF NEUROLOGY, Issue 3 2007Zhengang Yang PhD Objective Neocortical neurons are sensitive to hypoxic-ischemic (H-I) injuries at term and their demise contributes to neurological disorders. Here we tested the hypothesis that the subventricular zone of the immature brain regenerates neocortical neurons, and that this response is sustained. Methods Systemic injections of 5-bromo-2,-deoxyuridine (BrdU) and intraventricular injections of replication-deficient retroviruses were used to label newly born cells, and confocal microscopy after immunofluorescence was used to phenotype the new cells from several days to several months after perinatal H-I in the postnatal day 6 rat. Quantitative polymerase chain reaction was used to evaluate chemoattractants, growth factors, and receptors. Results Robust production of new neocortical neurons after perinatal H-I occurs. These new neurons are descendants of the subventricular zone, and they colonize the cell-sparse columns produced by the injury to the neocortex. These columns are populated by reactive astrocytes and microglia. Surprisingly, this neuronogenesis is sustained for months. Molecular analyses demonstrated increased neocortical production of insulin-like growth factor-1 and monocyte chemoattractant factor-1 (but statistically insignificant production of erythropoietin, brain-derived neurotrophic factor, glial-derived neurotrophic factor, and transforming growth factor-,). Interpretation The young nervous system has long been known to possess a greater capacity to recover from injury than the adult system. Our data indicate that H-I injury in the neonatal brain initiates an enduring regenerative response from the subventricular zone. These data suggest that additional mechanisms than those previously surmised contribute to the remarkable ability of the immature brain to recover from injury. Ann Neurol 2007 [source] | |||||||||||||