摘要:

THE anticonvulsant effects of intra-hippocampal thyrotropin-release hormone (TRH) were examined in amygdala kindled rats. Subjects were implanted unilaterally with an electrode in the amygdala and bilaterally with guide cannulae in the hippocampus, aimed at the dorsal and ventral dentate gyri. Rats were kindled daily with suprathreshold electrical stimulation (800 μA, 1 ms pulse width, 100 Hz, duration 0.5 s) until seizures were reliably elicited. The afterdischarge (AD) duration, seizure duration, and seizure stage were recorded daily, and AD thresholds were determined after kindling was completed. TRH was infused into each of the four cannulae of freely moving rats at doses of 0 (vehicle), 1.25, 2.5 and 5 μg/site. Five minutes after the last infusion, the rats received electrical stimulation at their AD threshold (mean = 135 μA) + 50 μA. TRH reduced the AD and seizure duration in a dose-dependent manner. At the dose of 2.5 μg/site, TRH also reduced AD and seizure duration in rats stimulated with suprathreshold current (800 μA). However, TRH had minimal effects on seizure stage irrespective of the stimulation intensity. These results suggest that the seizure-induced elevations of TRH in the hippocampus, as demonstrated in previous studies, may be part of an endogenous anticonvulsant compensatory mechanism and that further elevations of TRH in the hippocampus can produce anticonvulsant effects mainly by reducing the AD and seizure duration.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

INHIBITION of the enzyme inositol monophosphatase (IMPase) (E.C. 3.1.3.25) has been linked to the therapeutic action of lithium in the treatment of manic-depression (bipolar) disorder. Because of the link between bipolar and IMPase, we felt it would be of considerable importance to determine the human chromosomal localization of the IMPase gene. Fluorescencein situhybridization analysis using a human cDNA clone, which included the 5′-UTR and the complete coding region, mapped the human IMPase gene to chromosome 8q21.2–21.3. No gene locus for manic-depressive disorder has yet been identified. Further studies on this IMPase gene, and other potential gene variants and mutations, should help to determine if specific subgroups of patients with manic-depressive disorder can be determined on a molecular basis, with regard to the IMPase gene.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE examined the effects of nerve growth factor (NGF) on free radical neurotoxicity in striatal cell cultures. Following exposure to 30 μM Fe2+or 1 mM L-buthionine-[S, R]-sulfoximine (BSO), an inhibitor of γ-glutamylcysteine synthetase, striatal neurons underwent cell body swelling and then widespread death over the next 2 4 h. The degeneration was prevented by addition of 100 μM trolox, an antioxidant. Addition of 100 ng/ml BDNF beginning 1 2 h before Fe2+or BSO potentiated necrosis of most striatal neurons after exposure to 1 μM Fe2+or 1 mM BSO. In contrast, treatment with 10 μng/ml NGF selectively potentiated the oxidative degeneration of striatal cholinergic neurons. The present findings provide additional evidence that NGF, like other neurotrophins, can potentiate oxidative neuronal cell necrosis.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

RESULTS from a computer model of a thalamic network predict that agents augmenting GABAA-mediated inhibition in the reticular thalamic (RE) nucleus will be antiepileptic or desynchronizing. This provides support for the hypothesis that antiepileptics like benzodiazepines may exert their effects through an isolated increase of inhibition in the RE nucleus. When desynchronized, the model thalamocortical neurons showed a decreased probability of firing a low threshold spike, a decreased secondary inhibitory postsynaptic potential and a higher frequency of oscillations. The transition to desynchrony was also accompanied by an increased frequency in the firing of the model RE neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE time course of the expression of Dp116, talin, vinculin and vimentin in rat sciatic nerve was investigated after experimental transection. Dp116 was still found at 5 days after experiment in some degenerating myelinated fibers of both proximal and distal stumps. The findings are consistent with the known preservation of electrical excitability of the distal nerve in the first days after injury. Some regenerating nerve fibers into the neuroma also expressed Dp116 at 25 and 40 days after nerve transection. Talin and vinculin markedly and diffusely immunostained the neuroma. Talin in the distal stump and vimentin in both proximal and distal stumps were found decreased during the time course of the experiment. Vinculin binding increased in the distal stump, due to a real overexpression or simply to a cross-reaction to degeneration products.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BOTH deprenyl and rasagiline (R(+)-N-propargyl-1–aminoindane mesylate), at a concentration of 1–1 μM, increased survivalin vitroof rat E14 mesencephalic dopaminergic neurons that had been primed with 10% serum for 1 2 h (p< 0.05). Rasagiline, but not deprenyl, also increased total neuronal (MAP2–positive) survival (p< 0.05) Under serum-free conditions, rasagiline, but not deprenyl, retained its neuroprotective action on dopaminergic neurones. GABAergic neurons were not affected by either deprenyl or rasagiline. Clorgyline, an MAO-A inhibitor, did not exert any of these effects. The protective action of rasagiline on dopaminergic neurons, even under stringent serum-free conditions, is striking, and warrants further investigation for a role in the treatment of Parkinson's disease.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

IN this study we investigated primary cultures obtained from two glioblastomas surgically removed from a 64-year-old man and a 50-year-old woman, respectively. The presence of the tethered ligand thrombin receptor PAR1 (protease-activated receptor 1) in these cells was demonstrated at the level of receptor binding by using immunofluorescence studies with the monoclonal anti-PAR1 antibody Mab 31–2. Stimulation of human glioblastoma cells both wit hα-thrombin and the thrombin receptor activating peptide TRAP-6 resulted in a series of [Ca+]ispikes as shown by confocal laser fluorescence microscopy with fluo-3 as calcium sensitive fluorescence indicator. This effect was completely blocked with the thrombin receptor antagonist peptide T1. Our results demonstrate functional thrombin receptors (PAR1) in primary cultures of human glioblastomas for the first time.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ECHOPLANAR functional magnetic resonance imaging (fMRI) was used to localize the cortical areas involved in the analysis of spatially transformed letter strings. Significant increases of the blood oxygen level-dependent (BOLD) signal for transforme dvsnormal reading were observed in the superior parietal lobule (SPL), along the intraparietal sulcus (IPS), in the frontal eye fields (FEF), and in the latero-occipital area LO. The respective contributions of oculomotor and spatial transformation areas to this activation pattern were separated by means of a control condition involving the execution and suppression of eye movements. Areas activated in association with the control of eye movements included the superior parietal lobule and the frontal eye fields. The cooperation of different brain areas was analysed by correlating the time course of task-dependent BOLD signal changes in these areas. This correlation analysis revealed coactivation of occipitotemporal object recognition areas and a spatial transformation area in the intraparietal sulcus during the reading of transformed letter strings. We suggest that cortical systems that are coactivated during complex cognitive tasks can be differentiated by the correlation analysis of BOLD signal time courses in spatially separate brain areas.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE show here, by means of evolutionary spectral analysis and synthesis of cytosolic Ca2+([Ca2+]c) spiking observed at the single cell level using digital imaging fluorescence microscopy of fura-2-loaded mouse cerebellar granule cells in culture, that [Ca2+]cspiking can be resolved into evolutionary spectra of a characteristic set of frequencies. Non-delayed small spikes on top of sustained [Ca2+]cwere synthesized by a main component frequency, 0.13 2 ± 0.01 2 Hz, showing its maximal amplitude in phase with the start of depolarization (2 5 mM KCl) combined with caffeine (1 0 mM) application. Delayed complex responses of large [Ca2+]cspiking observed in cells from a different set of cultures were synthesized by a set of frequencies within the range 0.018–0.11 7 Hz. Differential frequency patterns are suggested as characteristics of the [Ca2+]cspiking responses of neurons under different conditions.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

ADULT and aged mice were submitted to a discrimination task in a radial maze (regular trials), and then to probe trials requiring them to form relational representations. Three weeks later, animals were again tested for regular and probe trials. Following another interval of 3 weeks, individual hippocampal cytosolic calcium-dependent and -independent PKC activities were measured. Performance of aged animals was impaired on probe but not regular trials and aged mice had lower hippocampal cytosolic calcium-dependent and -independent PKC activities than adults. Performance on probe trials was specifically correlated with calcium-dependent PKC activity. This suggests a specific relationship between the ability to form relational representations and hippocampal cytosolic calcium-dependent PKC activity.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID