摘要:

WHOLE-CELL recordings in rat olfactory bulb slices showed that bath application of 5 mM taurine produces a potent and reversible inhibition of identified mitral and tufted cells. Under current-clamp conditions, a shift of the membrane potential toward the chloride equilibrium potential and a 75% reduction in the membrane resistance were observed. These effects were strongly blocked by bicuculline (10 μM), but not by GABABantagonist and strychnine, and completely maintained under the blockage of synaptic transmission. The results suggest that inhibition of bulbar relay neurons produced by taurine is primarily due to direct activation of somatic GABAAreceptors and initiation of chloride conductance. This study demonstrates for the first time the actions of taurine in the olfactory system.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WHEN young zebra finch males who have been reared in isolation court a female for the first time they develop a stable preference for females of this species (sexual imprinting). During this first courtship, two areas of the forebrain show a reversible enhancement of spine density, while in two other areas, spine density decreases irreversibly. Here we show that the same alterations can be induced by application of tetraethylammonium (TEA) to slices of adult, previously isolated males. TEA application induces an enhancement of spine density in two forebrain areas and leads to a decrease of spine density in two others. Although the exact mechanisms are unknown, our results indicate that potentiation phenomena are involved in the spine density changes induced by first courtship.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE studied the effect of the cyclooxygenase (COX)-2 inhibitor nimesulide on experimental allergic neuritis (EAN). In rats fed with nimesulide starting on day 1 post inoculation, the clinical EAN score was significantly lower and the maximal clinical score was reduced compared with the control group. Even if given after the onset of clinical signs, the clinical score was reduced and improvement was faster than the control group. Nimesulide inhibited decreases in weight in the experimental group. The histopathological observations of the sciatic nerve showed a decreased incidence of degenerated nerve fibers in the experimental group. Although the exact mechanism of its efficacy is not clear, a COX-2 inhibitor may have potential as an additional therapeutic agent in human inflammatory neuropathies.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE have examined the functional coupling of the human metabotropic glutamate receptor type 2 (mGluR2) with the regulation of the mitogen activated protein kinase (MAP kinase) signal transduction cascade. We demonstrated that L-glutamate stimulation of the human mGluR2 receptor transiently expressed in chinese hamster ovary (CHO) cells leads to a rapid increase in the activity of p42/p44 MAP kinase (also known as the extracellular signal regulated kinases, ERK1 and ERK2). Activation of p42/p44 MAP kinase has been demonstrated in a peptide phosphorylation assay and through the demonstration of a shift in electrophoretic mobility of p42 MAP kinase following activation. In both assay systems L-glutamate stimulation of MAP kinase was inhibited by pertussis toxin and by the MEK (MAP/ERK activating kinase) inhibitor PD 98059. We conclude that L-glutamate stimulation of the mGluR2 receptor in CHO cells mediated regulation of p42/p44 MAP kinase following the activation of pertussis toxin-sensitive GαiG-proteins via a distinct protein kinase signalling pathway that utilizes MEK.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CARBON monoxide (CO) is an endogenously produced gas sharing many properties with nitric oxide (NO), notably activating soluble guanylate cyclase and relaxing blood vessels. The brain can generate high quantities of CO from a constitutive enzyme, haem oxygenase (HO-2). To determine whether CO is involved in the regulatory mechanisms of cerebral blood flow (CBF), two conditions associated with a reproducible CBF increase were studied in rats: epileptic seizures induced by kainate, and hypercapnia. The HO inhibitor tin protoporphyrin (Sn-PP) did not modify the basal level of CBF, significantly reduced the increase in CBF during status epilepticus, and did not affect the cerebrovascular response to hypercapnia. It is concluded that CO participates in the regulation of CBF in specific conditions, notably those associated with glutamate release.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

NEUROPEPTIDE Y-Y2receptor mRNA and binding were investigated after local injection of excitatory amino acid receptor agonists into the rat hippocampus. The general metabotropic glutamate receptor (mGluR) agonist (1S,3R)ACPD (200 and 400 nmol) and the group I mGluR agonist DHPG (50 nmol) enhanced Y2receptor mRNA levels in granule cells (by up to 470%) and [125I]PYY (3–36) binding in mossy fibers. The group I mGluR antagonist 4-CPG (200 nmol) inhibited the action of (1S,3R) ACPD. On the other hand, AMPA and NMDA enhanced Y2receptor expression only at neurodegenerative doses (> 0.3 and 3 nmol, respectively). It is suggested that seizure-induced Y2receptor expression in granule cells may be mediated by group I mGluRs.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE mechanism by which neuronal cell viability in culture is dependent on cell plating density is unclear. To address this question, dissociated cells from the neonatal rat cortex were cultured in a chemically defined medium. Medium conditioned with cortical cells plated at high density (2000 cells/mm2) promoted the survival of neurons grown at low cell density (100 cells/mm2) in a dose-dependent manner. Data obtained from molecular sieving suggested that the molecule(s) promoting the survival of neurons was smaller than 1000 Da. Amino acid analysis of the conditioned medium revealed the release of a mass of glutamine from cortical cells in culture. L-Glutamine mimicked the conditioned medium in action promoting the viability of neurons. These findings suggest that the effect of plating density on neuronal cell viability is mediated at least in part by glutamine released from cultured cells.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CEREBELLAR activation was measured using functional magnetic resonance imaging, while seven normal subjects tapped their fingers paced by tone sequences with or without tone omission. The cerebellar anterior lobe (Larsell's H IV-V) ipsilateral to the movement was activated to a similar degree irrespective of the presence or absence of the tone omission. In contrast, the lateral part of the bilateral posterior lobe (H VIIa) was significantly highly activated for the tone sequence with random omission, compared with either that without omission or that with regular omission. The result suggests that the H IV-V is involved in motor execution, while the lateral part of H VIIa is involved in online motor adjustment to unpredictable sensory stimuli.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

GLIAL cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor β superfamily and acts as a neurotrophic factor for the nigrostriatal dopaminergic system. GDNF was injected stereotaxically into the striatum of young (2 months old) and aged (12 months old) C57BL/6 mice that were treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) 1 week earlier. Immunocytochemical and neurochemical analyses showed significant recovery of the nigrostriatal dopaminergic system both in young and in aged mice. Since Parkinson's disease is a neurodegenerative disorder mainly affecting elderly people, this result demonstrates the potential usefulness of GDNF in treating Parkinson's disease.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE examined whether 53 adult non-aphasic patients with either left (22) or right temporal lobe lesions (31) demonstrate dissociable patterns of hemispheric asymmetries in category-specific word fluency tasks. The patients were asked to articulate as many appropriate words as possible within 60 or 90 s in response to six target categories. There was no effect of patient groups on the overall fluency. However, patients with a leftsided temporal lobe lesion were impaired retrieving words to ‘initial letters’ and to the category ‘animals’. Right temporal lobe patients were impaired retrieving ‘tools’ and words referring to specific visual attributes. There were no fluency differences for ‘food-supermarket goods’ and ‘flat interior’. We conclude that temporal lobe damage can result in category-specific impairments in word retrieval depending on the affected hemisphere.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID