摘要:

OPTICAL signals were recorded in thein vivorat piriform cortex (PC) in response to olfactory bulb (OB) electrical stimulations delivered at 4 different sites. Afferent activity had a relatively wide (26.6% of the recorded area) but non-homogeneous distribution on the PC surface. The different patterns of afferent activity observed in response to the 4 OB stimulations were intermixed with an overlap of only 38.5%. This activity was redistributed to the whole PC by intrinsic association fibres. The increase in the delay (from 4 ms to 12 ms) between afferent and redistributed activities along the antero-posterior axis indicated that the rostral to caudal association fibre system originating in the anterior PC was mainly responsible for the redistribution.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ACTIVITY of the enzyme which synthesizes acetylcholine, choline acetyltransferase, was estimated in the neocortex of three series of control and demented cases. Clinically demented cases were divided into those with the classical neuropathological features of Alzheimer's disease (numerous neocortical plaques and tangles) and those with Lewy bodies in the brain stem and cortex (together with plaques and variable neurofibrillary pathology). In the Lewy body cases neocortical choline acetyltransferase was consistently lower than in the classical Alzheimer-type cases. Two of the Lewy body cases with extremely low cholinergic activity were responders in therapeutic trials of the cholinesterase inhibitor, tacrine, and the combined data suggest that cholinergic therapy may be particularly relevant to patients with Lewy body type dementia.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WE examined the effects of intrathecal oxytocin over a wide dose range (10 ng to 10 μg) on the spinal nociceptive flexor reflex in decerebrate, spinalized, unanaesthetized rats. Oxytocin facilitated the flexor reflex at all doses. The duration, but not magnitude, of facilitation was dose-related. No reflex depression was observed with intrathecal oxytocin at any dose. It is suggested that activation of spinal oxytocin receptors excites the spinal cord and therefore intrathecal oxytocin is unlikely to be an analgesic agent.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WE report on cytoarchitectonic neocortical findings in a patient with Williams syndrome (WS), a rare genetic disorder resulting in characteristic facies, heart defect, other connective tissue anomalies, and a unique neurobehavioral profile. Cytoarchitectonic anomalies include exaggerated horizontal organization of neurons within layers, most striking in area 17; increased cell packing density throughout brain regions; abnormally clustered and oriented neurons. Overall, posterior forebrain areas were markedly diminished in volume. The results suggest that brain anomalies may relate to the extreme visuospatial deficit in WS, the dysregulation of apoptotic cell death, and the genetic basis of WS, a hemizygous deletion including the elastin locus on chromosome 7. This case provides opportunities for linking brain findings to cognitive deficits and their genetic underpinnings.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

NADPH-d activity is a marker for neurones which synthesize nitric oxide (NO). In the present paper we study the NAOPH-d activity in the human brain stem between 16 and 24 gestational weeks (GW). The adult distribution of NADPH-d containing neurones is established at 24 GW. Between 19 and 21 GW, neurones of the facial, hypoglossal and ambiguus nuclei show transient NADPH-d positivity. Therefore, in the human brain stem there are two chronological patterns of neuronal nitric oxide synthase (NOS) expression, one that appears during prenatal development and persists during the whole life, and another one, present only at a precise foetal moment. The transient NADPH-d activity in motor nuclei suggests that NO is involved in early regulatory processes of the human brain development.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

DOPAMINERGIC and cannabinoid receptors are localized in the outflow nuclei of the basal ganglia. We have investigated the possible interrelation of these receptors in the regulation of motor activity in male rats. To this end we have first studied the behavioural effects of the highly potent cannabinoid receptor agonist (-) 11-hydroxy-δ8-tetrahydrocannabinol-dimethylheptyl (HU-210, 20 μg kg-1) after chronic stimulation of dopamine D1and D2receptors. The catalepsy induced by the synthetic cannabinoid, measured as the descent latency in the bar test, was enhanced in male rats chronically treated with the dopamine D1receptor agonist SKF38393 (8 mg kg-1, twice a day during 21 days). However, animals exposed to the dopamine D2agonist quinpirole (1 mg kg-1daily during 21 days) displayed the same degree of catalepsy as those exposed to HU-210 alone. Although a possible involvement of D2receptors cannot be excluded, this finding suggests a predominant role for dopamine D1receptors in the regulation of the cataleptic response to cannabinoids. The possible cross-talk between dopamine D1and cannabinoid receptors is further supported by the decreased responsiveness to the acute behavioural effects of SKF38393 (8 mg kg-1) observed in animals chronically exposed to HU-210 (20 μg kg-1daily during 14 days).

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE effects of NG-substituted L-arginine (ARG) analogues on striatal ARG and citrulline (CIT) levels were investigated usingin vivomicrodialysis technique. A microdialysis probe was implanted into the striatum of anaesthetized Sprague-Dawley rats. Direct intrastriatal perfusion with 1 mM NG-nitro-L-arginine methyl ester (n= 8) increased striatal ARG release and decreased CIT release, suggesting suppressed NO synthase activity in the tissue. On the other hand, 1 mM NG-monomethyl-L-arginine (L-NMMA) (n= 6) evoked a persistent increase in both ARG and CIT. Considering that 4–320 μM L-ARG (n= 8) failed to increase CIT formation, CIT seems to be synthesized in the striatal tissue from L-NMMA by the enzyme that has been demonstrated in the kidney and aortic endothelium (NG, NG-dimethylarginine dimethyl aminohydrolase).

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ACETYLCHOLINESTERASE (AChE) is released from dopaminergic dendrites in the guinea-pig substantia nigra. This release, measured by a chemiluminescent assay, is increased following electrical stimulation of the dorsal raphé nucleus, which sends a 5-hydroxytryptaminergic input to the substantia nigra. Application of exogenous 5-hydroxytryptamine (5-HT) directly to the substantia nigra similarly enhanced release of AChE, whilst local application of cinanserin, a 5-HT antagonist, inhibited electrically-evoked release. Although the substantia nigra possesses a dense localization of 5-HT1Dreceptors, application of the 5-HT1Dagonist sumatriptan did not effect AChE release. The results indicate that 5-HT, released from raphé-nigral afferent nerves, enhances the dendritic release of AChE, although this effect is unlikely to be mediated via 5-HT1Dreceptors.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

UPTAKE of acetylcholine was studied in a synaptic vesicle fraction isolated from rat brain. Hyposmotically treated P3 vesicles took up acetylcholine (ACh) in the presence of MgATP, and the uptake was inhibited by low temperature, ammonium ions, the protonophore carbonyl cyanidep-(trifluoromethoxy)phenylhydrazone (FCCP) and bafilomycin A1, a specific inhibitor of the vacuolar H+-ATPase. Uptake was also inhibited by drugs that bind allosterically to the ACh transporter, namely vesamicol (IC50value of 170 nM) and 4-aminobenzovesamicol (IC50value of 25 nM). KMand Vmaxvalues for ACh active transport were estimated to be 5 mM and 4 nmol min-1mg-1of cholinergic vesicles, respectively. Active transport of ACh by synaptic vesicles partially purified from brain is mediated by a vesamicol-sensitive transporter and is dependent on a proton gradient generated by the vesicular H+-ATPase.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

ALTHOUGH glycine does not cross easily the blood-brain barrier, it exhibits at very high doses (10–40 mmol kg-1) a modest anticonvulsant activity. In this study, carbamate derivatives—N-benzyloxycarbonylglycine (Z-glycine) andN, tert-butoxycarbonylglycine (Boc-glycine)—have been compared with glycine. Z-glycine (1 mmol kg-1), but not Boc-glycine, reduces the number of tonic convulsions in the 3-mercaptopropionic and in the bicuculline tests, increases the latency of seizures in the strychnine test and is as active 3 h after administration as sodium valproate 30 min after administration in the maximal electroshock seizure test. Overall, milacemide, a precursor of glycine, and Z-glycine have rather similar anticonvulsant profiles in mice. The lack of Z-glycine affinity for the strychnine sensitive glycine receptor and the strychnine insensitive glycine receptor associated with the NMDA receptor may indicate that Z-glycine acts either via a prodrug mechanism orper sevia an alternative mechanism.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID