bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spinal cord neuron death in methyl‐4‐phenyl‐1,2,3,6 tetrahydropyridine induced Parkinsonism
Authors: Chera Bhishamjit S. , Schaecher K. , Ray S. , Rocchini A. , Imam S. , Ali S. , Banik N. 
Published: July 2010

Parkinsonism is a movement disorder characterized by rigidity, tremor, and bradykinesia, originating from abnormalities in and death of monoaminergic neurons (dopamine, serotonin, and norepinephrine) in the substantia niagra, retrorubral area, and locus ceoruleus. Calpain has been implicated in the pathophysiology of neurodegenerative diseases (Alzheimers and Parkinsons Disease (PD)). Since the spinal cord (SC) and brain are integrally connected and calpain is involved in cell death, we hypothesized that SC neurons are also affected in PD. To test this hypothesis, we examined SC from 1‐methyl‐4‐phenyl‐1,2,3,6 tetrahydropyridine (MPTP) induced PD in mice. To identify cells expressing calpain, double immunofluorescent staining with calpain and cell marker antibodies (NeuN, OX42, and GFAP for neuron, microglia, and astrocytes, respectively) was used to observe changes in the SC. Double TUNEL staining was used to identify apoptotic cells. There was an increase in calpain expression in neurons, microglia, and astrocytes in brain and SC of MPTP‐treated animals at 1 and 7 days compared to controls. TUNEL positive neurons in the SC showed morphological apoptotic signs. The NeuN stain was less concentrated around the nuclear membrane at 1 day post exposure, while at 1 week calpain content in NeuN+ cells was greatly increased in substantia niagra and SC. Also, MPTP‐exposure up‐regulated calpain activity and expression in the SC. These results demonstrated neuron death in the SC of MPTP‐treated mice, and has provided evidence for a possible calpain‐mediated neuron death in SC of MPTP‐induced PD in mice.Acknowledgements:  Supported in part by NIH and MUSC Summer Student Research Program.
Does tissue transglutaminase play a role in Huntington's disease?
Authors: Johnson G. V. W. , Tucholski J. , Lesort M. , Bailey C. D. C. , Chun W. 
Published: July 2010

Tissue transglutaminase (tTG) catalyzes the incorporation of polyamines into substrates, or the formation of isopeptide bonds. tTG also binds and hydrolyzes GTP/ATP. Huntington's disease (HD) is caused by a pathological expansion of the polyglutamine domain in the protein huntingtin (htt). Because a polypeptide bound Gln residue is the primary determining factor for a tTG substrate, it has been hypothesized that due to the increase in Gln content, mutant htt may modified by tTG and this event may contribute to the pathogenesis of HD, possibly by facilitating the formation of htt aggregates. tTG is increased in HD, suggesting involvement in the pathogenic process. However, tTG is not required for aggregate formation. Further, tTG is excluded from htt aggregates and increasing or decreasing tTG has no effect on the frequency or localization of the aggregates. Considering these and other data, tTG is unlikely to play a major role in the formation of htt inclusions in HD brain. tTG may play a role in modulating neuronal cell death in response to specific stressors. If a stress increases the transamidating activity of tTG (e.g. increases in Ca++ levels), then tTG facilitates the cell death process. In contrast, if a stress does not result in an increase in the transamidating activity of tTG, then tTG protects against cell death. The protective effects of tTG are independent of its transamidating and hence likely dependent on its GTP/ATP binding and hydrolytic activity. Therefore the increase in tTG levels in HD brain could either be helpful or harmful depending on the cellular mechanisms that contribute to neuronal death.Acknowledgements:  Supported by NIH grant AG12396.
Age‐related alterations of extracellular signal‐regulated kinase 2 mRNA expression in the rat brain
Authors: Simonyi A. , Murch K. , Sun G. Y. 
Published: July 2010

Aging is accompanied by the loss of memory and cognitive functions. Recent studies indicated that extracellular signal‐regulated kinases (ERKs) play an essential role in synaptic plasticity and memory. A selective activation of ERK2 has been demonstrated in the hippocampus during long‐term potentiation and in different in vivo learning paradigms. In this study, we investigated age differences in the expression of ERK2 by quantitative in situ hybridization using male Fisher 344 rats 3, 12 and 25 months of age. The results show an intense expression of ERK2 mRNA in many brain regions including the hippocampus, the cerebral cortex, the caudate‐putamen and the cerebellum. Moderate expression was found in the thalamus and the hypothalamus. No age‐dependent changes in ERK2 mRNA expression were detected in most cortical areas except for a slight decreasing trend in the pyriform cortex. ERK2 mRNA expression remained stable in the dentate gyrus and CA1 region of the hippocampus during aging. However, an early decline in ERK2 mRNA level was found in the CA3 region. Several behavioral studies have provided evidence that new protein synthesis in the CA3 region is necessary for memory consolidation during the first 1–2 days after learning. ERK2 is a regulator of neuronal gene expression and hippocampal ERK2 activation has been demonstrated in vivo in different learning paradigms. Thus, the early decrease in ERK2 mRNA in the CA3 region may underlie age‐related impairments in learning and memory.Acknowledgements:  PO1 AG 18357 from NIH.
Poster Sessions CP04: Axonal Growth and Transport. Neurotrophin‐3 expressed in situ induces axonal regeneration in the injured spinal cord
Authors: Zhou L. , Zheng X. , McGowen L. R. , Baumgartner B. J. , Shine H. D. 
Published: July 2010

Neurotrophins support neuronal survival and axonal regeneration after injury. To test whether local expression of Neurotrophin‐3 (NT‐3) would elicit axonal regeneration we lesioned the corticospinal tract (CST) at the level of the hindbrain and measured the number of axons that would grow from the unlesioned CST to the contralateral side where NT‐3 was over expressed at the lumbar level of the spinal cord. An adenoviral vector that carried the rat NT‐3 gene and the NGF signal peptide driven by the EF1α promoter (Adv.EF‐NT‐3) was used. This model enabled us to test the effects of NT‐3 on axonal regeneration without confounding injury processes. Biotinylated dextran amine (BDA) was injected into the rat cortex on unlesioned side to mark CST axons 10 days postlesion. Adenoviral vectors (1 × 109 pfu, Adv.EF‐NT‐3 or Adv.EF‐LacZ) were delivered to lumbar spinal cord by retrograde transport from the sciatic nerve 4 days later. Histological examination 3 weeks later revealed that more BDA‐labelled axons had grown from the unlesioned CST to the denervated side at the lumbar level. Morphometric measurements showed that a significantly larger number of BDA‐labelled CST axons (p < 0.001) were present in the animals that were treated with Adv.EF‐NT‐3 than those treated with Adv.EF‐LacZ. These data demonstrate that local expression of NT‐3 will support axonal regeneration in the injured spinal cord without adverse effects and suggest that gene delivery of neurotrophins may be an effective strategy for nervous system repair after injury.Acknowledgements:  Funded by NIH Grant NS35280 and by Mission Connect of the TIRR Foundation.
Poster Sessions CP05: Intracellular Transport and Vesicle Trafficking. MBP mRNA trafficking factor HNRNP A2 interacts with microtubules binding protein TOG
Authors: Barbarese E. , Kosturko L. , D'Sa C. , Carson J. H. 
Published: July 2010

HnRNP A2 is an RNA trafficking protein that binds to a specific cis‐acting RNA trafficking element (A2RE) in myelin basic protein RNA and other transported RNAs. A2RE/hnRNPA2 determinants mediate several different steps in RNA trafficking including granule assembly, transport to the plus ends of microtubules and translational activation. A yeast two hybrid screen designed to identify proteins that interact with hnRNP A2 selected a clone corresponding to the carboxyl terminal portion of TOG (tumor overexpressed gene), a microtubule‐associated protein that regulates microtubule dynamics. Co‐immunostaining of oligodendrocytes with antibody to hnRNPA2 and TOG revealed extensive colocalization of TOG with hnRNP A2 granules in the dendrites. A small population of hnRNP A2 granules lacked TOG and some regions of TOG staining lacked hnRNP A2. In oligodendrocytes injected with fluorescent A2RE RNA and stained for TOG, granules containing fluorescent RNA colocalized with TOG. Co‐injection of anti‐TOG antibody with fluorescent A2RE RNA decreased colocalization with TOG and increased transport of the injected RNA. These observations suggest that molecular interaction between hnRNP A2 and TOG serves to anchor A2RE mRNAs/hnRNPA2 granules at plus ends of microtubules.Acknowledgements:  Supported by NIH NS19943 (EB) and NS15190 (JHC), and NMSS RG2843 (EB).
Regulation of JNK signalling pathway by GM1
Authors: Mo L. , Neff N. H. , Hadjiconstantinou M. 
Published: July 2010

The ganglioside GM1 exerts pleitropic trophic actions in both the central and peripheral nervous systems in vivo and in vitro. Our previous research has shown that in brain tissue, GM1 is capable of inducing tyrosine phosphorylation of Trk receptors for the neurotrophins and initiating signaling via the MEK/ERK pathway. In order to better understand the intracellular signalling events associated with GM1, we investigated the effects of GM1 on the JNK pathway and its downstream transcriptional factor targets. Incubating slices from hippocampus of young or aged rats with GM1 increased the content of phosphorylated (p) JNK and augmented JNK kinase activity. The GM1‐induced phosphorylation/activation of JNK was accompanied by an increase in phosphorylated (p) c‐Jun and (p) Elk1, but not (p) ATF, transcription factors. Furthermore, addition of GM1 to hippocampal slices induced enhanced AP‐1 DNA binding activity. A similar response was observed when slices were treated with the neurotrophins NGF and BDNF. Both the GM1‐ and neurotrophin‐induced activation of the JNK pathway were blocked by the selective Trk kinase inhibitor AG879. Taken together, these data suggest that the molecular mechanisms of GM1 actions may include recruitment of the JNK pathway.Acknowledgements:  Supported, in part, by grant AG10530.
Poster Sessions CP10: Blood–Brain Barrier. Expression of vitamin C transporter SVCT2 in hypothalamic glial cells. An immunohistochemical and kinetic analysis
Authors: García M. A. , Montecinos H. , Balmaceda‐Aguilera C. , Millán C. , Nualart F. 
Published: July 2010

Kinetic analysis of vitamin C uptake has demonstrated that specialized cells take up ascorbic acid (AA), the reduced form of vitamin C, through sodium‐AA cotransporters. Recently, two different isoforms of sodium‐vitamin C cotransporters (SVCT 1, 2) that mediate high affinity Na+‐dependent l‐ascorbic acid have been cloned. SVCT2 was detected mainly in choroid plexus cells and neurons, however, there are no evidences of SVCT2 expression in glial cells. High concentrations of vitamin C has been demonstrated in brain hypothalamic area. The hypothalamic glial cells, known as alpha and beta tanycytes, are specialized ependymal cells that bridge the cerebrospinal fluid and the portal blood of the median eminence. Our hypothesis postulates that tanycytes take up reduced vitamin C from the portal blood and cerebrospinal fluid generating an high concentration of this vitamin in brain hypothalamic area. In situ immunohistochemical analyses demonstrated that SVCT2 transporter is selectively expressed in apical region of tanycytes. A newly developed primary culture of mouse hypothalamic tanycytes was used to confirm the expression and function of SVCT2 isoform in these cells. Reduced vitamin C uptake was temperature and sodium dependent. Kinetic analysis showed an apparent Km of 20 μm and a Vmax of 45 pmol/min per million cells for the transport of ascorbic acid. The expression of SVCT2 was confirmed by immunoblots and RT–PCR. Tanycytes may perform a neuroprotective role concentrating the vitamin C in the hypothalamic area.Acknowledgements:  Supported by Grands FONDECYT 1010843 and DIUC‐GIA 201.034.006‐1.4 from Concepción University.
Interleukin‐1 increases expression of cytosolic and membrane PGE synthase in mouse astrocytes and brain
Authors: O'Banion M. K. , Maida M. E. , Moore A. H. 
Published: July 2010

Increased production of prostaglandin E2 (PGE2) accompanies inflammatory responses, both peripherally and in the brain. Previous studies have demonstrated marked up‐regulation of cyclooxygenase‐2 (COX‐2) expression by IL‐1β in mouse astrocytes and brain. However, selective increases in PGE2 production are dependent on expression of downstream PGE synthases. Therefore, we have investigated regulation of two PGE synthase isoforms in cultured murine astrocytes and in mouse brain treated with IL‐1β. In astrocytes exposed to 10 ng/mL IL‐1β we see an early and dramatic increase in cytosolic PGE synthase mRNA and protein expression at 4 and 8 h that largely subsides by 24 h. This pattern is similar to that observed for COX‐2 expression. Interestingly, increases in membrane PGE synthase levels also occur, but with a delayed time course. Similar increases in both isoforms are observed following intraparenchymal injection of 5 ng recombinant IL‐1β. More specifically, the in vivo increase in COX‐2 mRNA was accompanied by an increase in membrane PGE synthase mRNA levels 6 h following IL‐1β injection. Subsequently, protein expression of both the cytosolic and membrane PGE synthases was elevated at 24 h. Interestingly, administration of NS‐398, a COX‐2 specific inhibitor, attenuated IL‐1β‐induced changes in PGE synthase expression, suggesting regulation of these isoforms by a COX‐2‐dependent mechanism. Together these data suggest that up‐regulation of both PGE synthase isoforms contributes to cerebral inflammatory responses to IL‐1β.Acknowledgements:  Supported by RO1 NS33553 to MKO.
NMR study of 13C‐glucose and 13C‐acetate metabolism in the brain of rats with acute liver failure
Authors: Zwingmann C. , Chatauret N. , Leibfritz D. , Butterworth R. F. 
Published: July 2010

Acute liver failure (ALF) is characterized by hepatic encephalopathy (HE) with brain edema as the main cause of death. The role of brain energy failure in ALF is still controversial. In the present study we investigated the association of encephalopathy with brain energy metabolism in rats with ALF induced by liver devascularization. Using [1–13]glucose and [2–13C]acetate combined with [1H, 13C]NMR spectroscopy anaerobic and aerobic carbon fluxes were studied in brain extracts from ALF rats. The anaplerotic flux of 13C‐label from glucose was found to be stimulated resulting in a 10‐fold increase of [13C]glutamine (Gln) starting at precoma stages of encephalopathy. In contrast, de novo synthesis of alanine and lactate increased to 320 and 210% in precoma, followed by a further elevation at coma stages to 615 and 425% of sham‐operated control values. Using [2–13C]acetate, the higher 13C‐enrichment of C‐2 in Gln, glutamate (Glu) and the corresponding C‐4 in GABA compared to C‐3 of either compound suggests cleavage of [2–13C]citrate and formation of [3–13C]oxaloacetate, which enters the glial TCA cycle. On the other hand, decreased synthesis of [4–13C]Glu and [2–13C]GABA was observed. This may result from decreased neuronal oxidative metabolism, since the ratio of [4–13C]Glu/[2–13C]GABA is unchanged and increased [2–13C]Glu and corresponding [4–13C]GABA suggests a stimulated flux of astrocytic label to neurons. Impaired neuronal energy metabolism and selective stimulation of lactate synthesis may contribute to the pathogenesis of HE in ALF.Acknowledgements: Funded by CIHR Canada.
Poster Sessions CP11: Neurotoxicity and Neuroprotection. Secretory phospholipase A2 signalling partly overlaps glutamate‐mediated events
Authors: Kolko M. , Rodriguez de Turco E. B. , Diemer N. H. , Bazan N. G. 
Published: July 2010

Here we explored the mechanisms of secretory phospholipase A2 (sPLA2) and glutamate (glu) in neuronal signalling and cell damage. Rats or primary neuronal cultures were treated with MK‐801 and injected with/exposed to sPLA2 or glu. MK‐801 partially inhibited sPLA2‐ and glu‐induced neuronal death as well as [3H]arachidonic acid release. The involvement of cytosolic PLA2 (cPLA2) and plateletactivating factor (PAF) in sPLA2 or glu signalling was explored by treating cells with the selective cPLA2 inhibitor, AACOCF3, PAF‐acetyl hydrolase (PAF‐AH) or the presynaptic PAF‐receptor antagonist, BN52021. AACOCF3 blocked sPLA2‐ and glu‐induced neuronal death by 26 and 77%, respectively. PAF‐AH ameliorated sPLA2 as well as glu neurotoxicity by 31 and 47%, whereas BN52021 inhibited sPLA2 induced neurotoxicity by 11% but did not significantly protect against glu‐induced neurotoxicity. Expression in neurons of early response genes in response to sPLA2 or glu was further examined. An up‐regulation of COX‐2, c‐fos, and c‐jun, but not COX‐1, was observed at earlier time points after rat striatal injection of glu as compared to sPLA2 injection. Moreover we treated neuronal cells with COX‐2 inhibitors and found that neuronal cell death after sPLA2 and glu exposure was inhibited by 35 and 33%, respectively. Thus sPLA2 activates a neuronal signalling cascade that includes activation of cPLA2, AA‐release, production of PAF and induction of COX‐2. Hence sPLA2 and glu signalling are overlapping, but not identical. Cytosolic PLA2 may primarily drive glutamatergic neurotransmission, whereas PAF plays a more crucial role in sPLA2 neuronal signalling.Acknowledgements:  Supported by EPSCoR grant NSF/LEQSF(2001‐04)‐RII‐01 from the National Science Foundation.
MDMA‐ and METH‐induced neurotoxicity in mice: sensitization and desensitization to psychostimulants effects
Authors: Ali S. F. , Itzhak Y. 
Published: July 2010

Methylenedioxymethamphetamine (MDMA; ‘ecstasy’) and methamphetamine (METH)‐induced neurotoxicity, however, little is known about the behavioral consequences of exposure to neurotoxic doses of these substituted amphetamines. In the present study two behavioral paradigms were monitored after the exposure of mice to METH and MDMA. Swiss Webster mice were treated with METH (5 mg/kg × 3) which caused 50–65% depletion of striatal dopaminergic markers. This treatment resulted in long‐lasting sensitization to the psychomotor stimulating effect of METH (74 days after the initial exposure to METH). In the CPP paradigm, control saline pretreated mice acquired significant CPP following METH administration (0.5 mg/kg), while the METH pretreated mice acquired very low conditioned response. Following the extinction of CPP, the conditioned response to METH was completely reinstated in the control but not the METH group. The administration of MDMA (30 mg/kg × 2) resulted in 40–60% depletion of striatal and cortical dopaminergic and serotonergic markers, respectively. This treatment was associated with marked sensitization to the psychomotor stimulating effects of MDMA, METH and cocaine as determined at various intervals after the initial exposure to MDMA. These results suggest that amphetamines‐induced neurotoxicity is associated with two opposing behavioral outcomes: (1) sensitization to the psychomotor stimulating effects and (2) desensitization to the rewarding effects of related drugs. These consequences may be relevant to the psychopathology of METH and MDMA abuse.Acknowledgements:  Supported by NIDA DA08584 and DA12867.
Estrogen attenuates oxidative stress‐induced apoptosis in C6 glial cells
Authors: Sur P. , Sribnick E. A. , Wingrave J. M. , Nowak M. F. , Ray S. K. , Banik N. L. 
Published: July 2010

The neuroprotective effects of estrogen have been previously implicated in neurodegenerative diseases. In order to examine whether estrogen protects cells from calpain‐mediated death, we investigated the mechanism of estrogen's inhibitory effects of apoptotic death in C6 (rat glioma) cells following exposure to H2O2. Cells were preincubated with 4 μm estrogen for 2 h and then exposed to 100 μm H2O2 or 2 μm ionomycin for 24 h. Intracellular free calcium (Ca2+) was quantified using Fura‐2. Levels of cell death were measured by colorometric assay. Bax/Bcl‐2 ratio and calpain activity, as measured by calpain‐cleaved spectrin degradation, were monitored by Western blot. Apoptosis was evaluated morphologically by Wright staining. Treatment with H2O2 caused significant increases in intracellular [Ca2+] which were attenuated by preincubation with estrogen. H2O2 and ionomycin caused cell death in a dose‐dependent manner. Preincubation with estrogen increased viability in cells treated with H2O2 but not in cells treated with ionomycin. Western blotting showed an increase in Bax/Bcl‐2 ratio and calpain activity following treatment with H2O2, and estrogen pretreatment decreased levels of both. Cell morphology indicated apoptosis in cells treated with H2O2, and pretreatment with estrogen reduced apoptosis. These results indicate a role for estrogen in preventing apoptosis in C6 glial cells exposed to H2O2. Our results suggest that estrogen may have a protective role in minimizing glial cell death in neurological diseases.Acknowledgements:  Supported in part by grants from NIH‐NINDS and South Carolina Electric and Gas.
Mechanism of the protective effect of hypothermia on ammonia toxicity in astrocytes
Authors: Zwingmann C. , Leibfritz D. , Butterworth R. F. 
Published: July 2010

Ammonia is a key factor in the pathogenesis of hepatic encephalopathy (HE). Acute ammonia treatment causes energy failure of astrocytes, which are able to compensate partly by increased anaerobic metabolism as a means of making up for the energetic shortfall. As hypothermia offers protection from severe encephalopathy and lactate accumulation in liver failure, we investigated the mechanism by which hypothermia protects against ammonia toxicity by multinuclear NMR spectroscopy. 12 h exposure to 5 mm NH4CL decreased the phosphocreatine (PCr)/creatine (Cr) and ATP/ADP ratios to 65 and 76% of control, increased synthesis and release of glutamine to 200–250% and led to a significant stimulation of glycolytic activity reflected by increased uptake and consumption of glucose and accumulation of de novo synthesized intra‐ and extracellular lactate to 161 and 230% of control. The protective effect of mild hypothermia was evident from inhibiton of lactate accumulation and restoration of ammonia‐induced depletion of PCr/Cr. Moderate hypothermia led to an increase of PCr/Cr ratio and inhibited lactate synthesis to 14% of normothermic control, but did not prevent the ATP decrease. While hypothermia inhibited glycolytic flux, intracellular glutamine remained elevated. The results suggest that hypothermia‐induced protection against ammonia toxicity results from reduction of cellular energy demand leading to inhibition of anaerobic glucose metabolism and a compensatory stimulation of mitochondrial energy production.Acknowledgements:  Funded by CIHR Canada.