ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

THIS study evaluated treatment with riluzole, a neuroprotective agent, following thoracic spinal cord compression in the rat. Animals received riluzole (2 mg kg−1) or vehicle twice daily for 10 days following the trauma. Motor deficits, somatosensory evoked potentials (SEP) and lesion histology were evaluated. Although paralysis was seen following trauma, seven of 10 animals receiving riluzole recovered motor function and nearly normal behaviour, unlike animals receiving vehicle. Trauma dramatically disturbed SEPs with falls in amplitude and increases in latency. After riluzole SEP returned towards pre-injury levels, while untreated animals showed no recovery. Morphological studies revealed significant (53%) reduction in the degree of spinal cord infarcted after riluzole treatment.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

RATS were given lithium either acutely by s.c. injection (4m eq kg1) or chronically by including 0.2% LiCl in their diet for 3 weeks. Microdialysis probes were inserted into the cortex or hippocampus, using re-usable guides, and perfused with artificial CSF. Fractions were collected beginning 18 h after the end of treatment and were analysed for inositol trisphosphate (IP3). Neither acute nor chronic treatment affected basal levels of IP3or stimulation of IP3formation by either carbachol or noradrenaline in the hippocampus. Similarly, neither basal nor carbachol-stimulated IP3levels in rat cortex were affected by acute Li administration. It would appear that the reductions in these parameters previously reported by other workers using brain slices were due to inositol depletion occurring at the stage of brain slice preparation. The inositol depletion hypothesis for the mechanism of action of lithium does not therefore appear to be supported byin vivoevidence.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The effect of systemic treatment with 1-aminocyclopro-panecarboxylic acid (ACPC), a partial agonist at the glycine site of the NMDA receptor, on convulsions and neurodegeneration induced by intrahippocampal injection of NMDA was investigated in mice. Five days after intrahippocampal NMDA infusion, 80–100% pyramidal cell death was observed in the CA1 region of the hippocampus. Pretreatment with ACPC prevented the lethal effects of NMDA and significantly reduced seizure induction. ACPC reduced cell death to 40% of that induced by a dose of NMDA (6 nmol) that damaged 80% of hippocampal CA1 neurones in untreated animals. These findings provide further evidence that ACPC can reduce NMDA receptor functionin vivoand suggest that partial agonists at the glycine site of the NMDA receptor complex may be useful anticonvulsant and neuroprotective agents.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

The veratridine-induced release of glutamate in the striatum of anaesthetized rats was studied using regional brain microdialysis to elucidate the role of extracellular Ca2+and to investigate the exact time course of the glutamate response. In a first series of experiments with Ca2+-depletion starting simultaneously with the veratridine pulse no significant differences were found under Ca2+-replete and Ca2+-free conditions. Strikingly, under both conditions glutamate efflux followed a biphasic time course. When Ca2+depletion preceded veratridine stimulation a significant inhibition of the initial glutamate release was found, indicating that the first glutamate portion originates from Ca2+-dependent vesicular exocytosis. The nature of the second and longer lasting phase of glutamate efflux is not clear, but it may be mediated by reversal of the glutamate uptake system of the plasma membrane located both on neurones and on astrocytes. This points to a possibly important contribution of glial cells to glutamate overflow under pathological conditions and should be subject to further investigations.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Tactile stimulation of the hand interferes with somatosensory evoked brain responses following electrical median nerve stimulation. This effect was studied in eight normal subjects by magnetoencephalography (MEG). When stimulation was applied to the hand ipsilateral to the stimulated nerve, only the third response (3M) was enhanced in five subjects, but other responses were attenuated in all subjects. These interference effects were probably due to interactions in areas 3b and 1. After stimulation of the contralateral hand, only the second response (2M) was enhanced in six subjects. This effect was probably due to the intracerebral interactions mediated through the corpus callosum.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Saccadic latency was studied as a function of the direction of sudden target displacements (steps) and of subsequent smooth target motion (ramps) inMacaca fascicularis.The monkey fixated a central spot that suddenly changed its position and then moved constantly at 10deg s−1, thus eliciting initial saccades and subsequent pursuit eye movements (recorded by a magnetic search-coil technique). Latencies for initial saccades differed markedly in the vertical axis, being shorter in upward than downward directions for both step and ramp components of target motion. Saccadic latency was also related to the mean pursuit velocity, indicating that the oculomotor system accounts for the direction of step and ramp components of target motion in an integrative way.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Event-Related potentials (ERPs) were recorded in rabbits when pitch deviant tones occurred in a series of standard tones (oddball situation). In control recordings, the deviant tones were presented without the standard tones (deviant-alone situation). In the oddball situation, significant difference ERPs (deviant ERPs-standard ERPs) could be found in the hippocampal and cerebellar recordings but not in the visual cortex. All the ERPs to the deviant stimuli observed in the oddball situation were also present in the deviant-alone situation. The difference ERPs were therefore based on reduced responses to the standards. The results are discussed in the context of a mismatch negativity (MMN) in humans.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

To clarify which muscarinic receptor subtype(s) mediate changes in sleep and cortical temperature (Tcort) induced by carbachol microinjections into the medial preoptic area (MPA), pirenzepine, tripitramine and ± p <>-fluoro-hexahydro-sila-difenidol (p-F-HHSiD), which are highly selective muscarinic M1, M2and M3antagonists, respectively, were microinjected into the MPA of rats. Whereas pirenzepine (3.45 and 7.08 nmol) andp-F-HHSiD (3.90 and 7.80 nmol) were without effect, tripitramine (0.67 and 3.37 nmol) enhanced wakefulness, decreased slow wave and desynchronized sleep, and raised Tcortwith the higher dose. The data suggest that in the MPA only M2muscarinic subtypes may be functionally important in mediating the cholinergic effects on sleep and thermoregulation.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

We tested the ability of L-AP4 to modulate high voltage-activated (HVA) calcium (Ca2+) currents in pyramidal neurones acutely isolated from the adult rat (4–8 weeks). Whole cell recordings, with barium (Ba2+) ions as the charge carrier, were performed. L-AP4 reduced HVA Ca2+conductances in 86% of the recorded cells. Saturating concentrations of L-AP4 inhibited about 21% of the current (± 8.3%,n= 8), although great variability was observed. Interestingly, low micromolar concentrations of (1S,3R)-1-aminocyclo-pentane-1,3-di-carboxylic acid (1S,3R-ACPD) and (2S,3S,4R)-α-(carboxy-cyclopropyl)-glycine (1-CCGI) had weaker effects than L-AP4. MAP4 fully antagonized the L-AP4-mediated reduction of HVA Ca2+currents. These findings suggest the involvement of the AP4-sensitive receptor in the control of both cellular excitability and transmitter release in rat neocortical neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1996

数据来源: OVID