摘要:

WHILE the hypothalamus is fundamental for sleep and circadian regulation, the molecular mechanisms involved are poorly understood. We have used a differential gene expression technique to identify hypothalamic genes which have altered expression in rat sleep periods. Complex cDNA probes from rat hypothalami removed at Zeitgeber times 4 and 15 were hybridised to rat brain cDNA library girds. From 30 differentially expressed clones, six were further analysed and two were confirmed to exhibit increased expression at Zeitgeber time 4. A Northern blot hybridization of brain, heart, kidney, lung, testis and skin mRNA showed that both clones were brain specific. Therefore, we have identified two novel brain specific diurnally expressed hypothalamic genes. Both genes may have roles in sleep or circadian regulation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SINGLE unit recording in rat nucleus accumbens (NAcc) was used to ascertain NAcc neuronal activity in mediating of reward including its anticipation. Of the 103 neurons investigated, 63% showed some response in connection with the task activity. Of these, 20 units responded during delivery of the primary reward (food and/or water) and five responded during the time period preceding reward if the reward was delayed (four to food, one to water). These result suggest that NAcc neurons responded not only to the delivery of primary reward and task inducing anticipation of reward, but also represent the difference of reward quality between food and water specifically.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SERUM deprivation of hippocampal organotypic cultures induced cell death within 6 h in dentate gyrus granule cells and hilar interneurons whereas neurons from other hippocampal regions were spared. Dying neurons exhibited condensed chromatin in the nuclei, as revealed by cresyl violet, Hoescht staining, and electron microscopy. Cell death was abolished by cycloheximide. KA, an agonist of AMPA/KA receptors that induces depolarization, also prevented neuronal death. This effect was antagonized by the AMPA/KA receptor antagonist DNQX, but not by APV, an antagonist of NMDA receptors. PTX, a GABAAreceptor antagonist, reduced neuronal death by 50% after serum withdrawal. These data indicate that protein synthesis-dependent programmed cell death (PCD) occurs in the dentate gyrus upon trophic support withdrawal and suggest that neuronal activity contributes to cellular homeostasis.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

BLOCKADE of adenosine receptors can reduce cerebral infarct size in the model of global ischaemia. Using the potent and selective A2Aadenosine receptor antagonist, SCH 58261, we assessed whether A2Areceptors are involved in the neuronal damage following focal cerebral ischaemia as induced by occluding the left middle cerebral artery. SCH 58261 (0.01 mg/kg either i.p. or i.v.) administered to normotensive rats 10min after ischaemia markedly reduced cortical infarct volume as measured 24 h later (30%vscontrols,p< 0.05). Similar effects were observed when SCH 58261 (0.01 mg/kg, i.p.) was administered to hypertensive rats (28% infarct volume reductionvscontrols,p< 0.05). Neuroprotective properties of SCH 58261 administered after ischaemia indicate that blockade of A2Aadenosine receptors is a potentially useful biological target for the reduction of brain injury.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TO investigate cortical activities related to the visual recognition of characters, we recorded the magneto-encephalography (MEG) in six normal subjects who were encouraged to discriminate capital English letters displayed for a brief period. To reduce the primary responses evoked by the luminance change in the striate cortex (V1), we used a novel stimulus method, random dots blinking (RDB), by means of the temporal changes of patterns using a large number of small random dots. Along with the MEG recording, we also measured the discrimination accuracy rate (%) to know how well the subjects recognized the letters. One clear component, about 30 0 ms in peak latency, was identified in all six subjects. Its peak amplitude and the discrimination accuracy rate increased similarly as the character display duration became longer. Its signal source was estimated in the extrastriate cortex, around the fusiform gyrus, in the right hemisphere. We suspect that the activity in these cortical areas has strong relation to the conscious perception of characters.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE abnormal assembly and accumulation of neurofilaments (NF) in the perikarya and proximal axons of motor neurones is a characteristic of ALS. Deletions in the KSP repeat region of theNF-Hgene have previously been reported in seven patients with sporadic ALS. Here we report the identification of a novel 84bp insertion in theNF-Hgene. This leads to an extra four KSP repeat elements in a highly conserved repetitive region of the gene. Although neurofilament mutations are only associated with a very small proportion of ALS cases, this insertion provides further support of a role for neurofilaments in the pathogenesis of ALS.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE biological basis of the clinical efficacy of lithium in the treatment of mental illness has been extensively studied in neurones, but little is known about the effects of the drug on glia. Recently we showed that treatment of rats with clinically relevant doses of lithium chloride results in a 35% increase in the immunocontent of the astrocyte marker GFAP in the hippocampus. Here we studied the cytology of this phenomenon. Rats were treated for 4 weeks with a lithium diet which resulted in serum Li+concentrations of 0.6–1.2 mmol/l. GFAP immunocytochemistry of the hippocampus revealed a mild gliosis in the CA1 area and the dentate gyrus which was associated with a change in the orientation of astrocytic processes. In control animals astrocyte processes were mainly orientated perpendicular to the stratum pyramidale, whereas in treated animals the cells were predominantly stellar in appearance.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE semaphorin/collapsin family of proteins comprises molecules thought to be important for the guidance of growing axons. All members of this family, which includes both secreted and cell-surface molecules, share a conserved domain of ∼500 amino acids. Here, we report the cloning of a novel murine semaphorin, termedM-sema IV. It displays 96.3% identity to the human semaphorinH-sema IVand is therefore likely to be the respective murine homologue. In addition, an isoform was identified, which contains an additional 31 amino acids in the semaphorin domain.M-sema IVappears to be expressed ubiquitously in adulthood. During embryo-genesis, in situ hybridization revealedM-sema IVexpression in subregions of the central nervous system and various other tissues like skin, kidney, lung and intestine.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

SHORT-LATENCY ocular following responses in monkeys, induced by first-and second-order motion during a fixation task, were sensitive to stimulus size, retinal eccentricity and motion duration. Latency of eye movements was no different for first-or second-order motion and simply marked the occurrence of movement in the visual field. Second-order motion produced higher velocity eye movements than did first-order motion. The velocity of eye movements was influenced by the orientation of second-order pattern components as well as their conspicuous energy. Even when partially suppressed by a fixation task, involuntary eye movements during the initial pursuit remain sensitive to several properties of visual motion.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE recently demonstrated that centrally administered melatonin at low doses inhibits the induction of gastric lesions by water-immersion restraint stress. To investigate the mechanism of the potent anti-ulcer action of melatonin, the central nervous system (CNS) effects of melatonin on gastric acid and pepsin secretion were studied in conscious pylorus-ligated rats. Intracisternal (i.c.) melatonin (1–100 ng) dose-dependently decreased acid and pepsin output, while a higher i.p. dose (1 μg) had no inhibitory effect. The i.c. melatonin did not change serum gastrin concentrations. Serum melatonin concentrations at 1 and 4 h after i.c. administration of 10–100 ng melatonin did not differ from those in rats receiving i.c. vehicle. The present results suggest that melatonin administered centrally modulates the secretion of gastric acid and pepsin which may explain, at least in part, the protective, anti-stress role of melatonin in the gastric mucosa observed in our previous study.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID