ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

IN primates, histamine activates cerebral endothelial H1-receptors leading to formation of nitric oxide (NO). Twenty migraine patients received pretreatment with placebo or the histamine-H1-receptor antagonist, mepyr-amine, in a randomized, double blind fashion, followed in both groups by i.v. histamine (0.5μgkg-1min-1for 20min). Headache characteristics were subsequently observed for 12 h. In patients given placebo histamine caused immediate headache during the infusion followed by a delayed migraine attack fulfilling IHS criteria for migraine without aura. The temporal profile of induced headache was exactly the same as after glyceryl trinitrate. Mepyramine pretreatment abolished both immediate headache and delayed migraine attacks. Our results suggest that a migraine attack can be caused by NO formation in the endothelium of cerebral arteries.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

THE mechanism of nigral cell death in Parkinson's disease (PD) remains unknown, but it is increasingly proposed that free radical reactions are important in the disease pathology. One of the most striking features of PD is an approximate 40% decrease in the levels of reduced glutathione (GSH) which occurs early in the development of the disease. We describe a possible mechanism of GSH depletion which results from the reaction of L-DOPA and dopamine with the superoxide free radical (O2-) and leads to a very rapid loss of GSH.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

ASCORBATE and glutathione (GSH) are the primary water-soluble antioxidants in the CNS. Oxidative stress, sometimes indicated by loss of these antioxidants, has been linked to several clinical and experimental conditions, including cerebral ischemia. These conditions are also gender-linked, with greater incidence or severity in males than females. To test whether there are gender differences in oxidant/antioxidant regulation, we determined basal levels of ascorbate and GSH in rat brain and their loss after 1 h decapitation ischemia. We found that ascorbate levels in male rat brain were 7–10% higher than in females, depending on region, whereas GSH levels were gender-independent. Significant ascorbate loss (up to 12%) occurred in males during ischemia, with a regional pattern of cerebellum hippocampus>prefrontal cortex. Loss of ascorbate in females was not significant in any region. By contrast, loss of GSH was significant in both males and females. Greater loss of GSH than ascorbate was in agreement with previous studies and was consistent with loss from enzymatic degradation, as well as oxidation. The significant gender difference in ascorbate loss, as a marker of oxidative stress, supports the hypothesis that inherent differences in oxidant/ antioxidant regulation contribute to gender differences in response to ischemia and other pathological conditions.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

IN ORDER to establish possible stimulatory effects of increasing plasma concentrations of pituitary adenylate cyclase-activating polypeptide (PACAP) on arginine vasopressin (AVP) and/or oxytocin (OT) secretion, successively increasing doses of PACAP-38 (2, 4 and 8 pmolkgmin-1; each dose for 20min) were infused in seven normal men. Plasma AVP and OT levels were measured before infusion and every 20min, just before increasing the infusion dose of PACAP. During tests, PACAP infusion did not produce untoward side effects or changes in blood osmolality and/or pressure. Plasma OT levels did not change during PACAP infusion. Plasma AVP concentrations were not modified by infusion of the lowest dose of PACAP, whereas they were significantly increased in a dose-response fashion when higher amounts of PACAP were given. These findings demonstrate for the first time in humans that the systemic administration of PACAP exerts stimulatory effects on AVP, but not OT secretion.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

A total of 140 normal adults participated in one of seven conditions designed to test the hypothesis that memory systems may be distinguished on the basis of their neurobiological substrates. The results revealed a selective disruption of eyeblink classical conditioning (EBCC) when it was performed concurrently with tapping, another cerebellar task. Subjects simultaneously engaged in EBCC and a recognition task or control tasks were relatively unimpaired in EBCC. Results provide evidence for the existence of neurobiologically distinct memory systems, and suggest that the selective disruption of EBCC, when concurrently performed with tapping, may be attributed to cerebellar involvement in both tasks.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

NITRIC oxide (NO), an unconventional neurotransmitter in the brain, has been postulated as a retrograde intercellular messenger necessary for the induction, but not the maintenance phase, of activity-dependent forms of synaptic plasticity in the hippocampus. Here we report on the effects of an inhibitory avoidance learning task on hippocampal NO synthase (NOS) activity and on the effects of intrahippocampal infusion of a NOS inhibitor in the acquisition and consolidation of this task in rats. NOS activity increases by 45% in the hippocampus immediately after training (0 min) but not at 60 min after training. No changes were observed in cerebellar NOS activity. The bilateral intrahippocampal microinjection of nitro-arginine (NO-arg), an NOS inhibitor, provoked retrograde amnesia for the inhibitory avoidance when given 10 min before or immediately after training, but not 60 min after training. These results suggest that NO-regulated processes in the hippocampus play an important role at the time of training or very shortly thereafter of an inhibitory avoidance learning.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

THE role of the noradrenergic system as a modulator of neurotransmission in the chick forebrain was investigated in brain slices containing the medial hyperstriatum ventrale, an area known to be involved in learning and memory. Theα2-agonist clonidine (20 μM) decreased the post-synaptic response to local stimulation at 0.1 Hz, while activation ofβ2receptors increased this response. Induction of persistent potentiation following stimulation at 5 Hz was blocked by drugs (20 μM ICI 118,551; 20μM propranolol) which showed preferential antagonistic activity at theβ2receptor but not by theβ1-preferential antagonist timolol. This effect may be due to an interaction with the NMDA receptor system.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

CHRONIC dialytic intrastriatal co-administration of quinolinic acid (QUIN) and four concentrations of the nitric oxide synthase (NOS) inhibitorNGnitro-L-arginine methyl ester (L-NAME) produced variable results. Low concentrations of L-NAME (1 μM and 50 μM) co-administered with 15 mM QUIN produced lesions not significantly different from those produced by 15 mM QUIN alone. In contrast, higher concentrations of L-NAME (1 mM and 100 mM) co-administered with 15 mM QUIN produced striatal lesions significantly larger than those produced by 15 mM QUIN alone. Administered by itself, 100 mM L-NAME produced little striatal damage. These findings suggest that low levels of NOS inhibition have little or no effect on NMDA neurotoxicity in the striatum, whereas high levels of NOS inhibition increase NMDA-induced striatal lesion volume.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

COGNITIVE effects of experimentally induced hypoglycaemia were investigated by event-related brain potentials (ERPs) in auditory and visual classification tasks. In a cross-over design eight healthy male subjects (age 22–27 years) were studied under control conditions or following administration of 0.15 IU insulin kg-1. The ERPs showed preserved early cortical components, while the N2 component was greatly reduced in both modalities. P3 components did not show an influence of hypoglycemia. These results suggest that the cognitive deficits are due to an impairment of automatic feature extraction from the stimuli.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID