摘要:

A pre-embedding double immunostaining technique was used to determine the role of βb-endorphin in synapse, particularly in neurons with a postsynaptic membrane containing μ-1 orβ-1 opioid receptors. A small number of β-endorphin immunoreactive axon terminals in the dorsal raphe nucleus was found to make direct synapses on μ-1 or δ-1 opioid receptor-immunoreactive dendrites, some of which showed immunostaining of their postsynaptic membranes, although with low frequencies. These results suggest that β-endorphin can play a direct role through the μ-1 or δ-1 opioid receptors at synapses, but the main route would be through other opioid receptor at the synapse or even not through the synapse.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PREVIOUS study has shown that the treatment of PC12 cells with manganese, a MPTP-like neurotoxin, causes transcription-dependent apoptosis. This is a useful model system for the study of neuronal cell death. Manganese-induced apoptosis is accompanied by the induction of DNA fragmentation, expressions of c-Fos and c-Jun, and activation of the c-Jun N-terminal kinase (JNK) pathway. Here, we report that manganese induces phosphorylation of p70 S6 kinase at Ser411 and Thr421/Ser424, and activates the enzyme. Thus, phosphorylation and activation of p70 S6 kinase are accompanied by transcription-dependent apoptosis, suggesting a role for p70 S6 kinase in this type of apoptosis.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

PROTON magnetic resonance spectroscopy (1H-MRS) was used to measure thein vivosignal ofN-acetylaspartate (NAA), a putative neuronal marker, in the brain of the mutant wobbler mouse, a model of motor neuron disease. The ratio of NAA to creatine-phosphocreatine, an internal standard, was significantly lower in five affected wobbler mice (0.79 ± 0.05; mean ± s.d.) than in five unaffected littermates (0.98 ± 0.10,p= 0.006). Ubiquitin and phosphorylated heavy neurofilament immunoreactivities were increased in cortical neurons of affected animals. This is the first demonstration of cerebral neuronal pathology in the wobbler mouse, supporting its use as a model of amyotrophic lateral sclerosis.In vivo1H-MRS and correlative postmortem study of wobbler mouse brain will allow temporal monitoring of neuronal degeneration and responsiveness to neuro-protective pharmacotherapies.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE examined the neural bases of song preferences in female zebra finchesTaeniopygia guttat a). Females performed more courtship displays in response to conspecific songs than to heterospecific songs. Following electrolytic lesion to the HVc (sometimes referred to as high vocal center), females maintained normal song preferences. However, following lesion to cHV (caudal hyperstriatum ventrale, an auditory area) females performed courtship displays at high rates in response to both conspecific and heterospecific song. Thus cHV, but not HVc, must be intact for female zebra finches to exhibit normal song preferences. Differences between this study and those showing HVc lesions disrupting song preferences in female canariesSerinus canari aindicate interspecific variation in the function of HVc in female songbirds.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE have cultured neurones from the developing cortex of mice that have had the amyloid precursor protein gene deleted (APP-null). Neurones cultured for a period of 24 h show similar neurite outgrowth and survival responses to wild-type neurones. Similar neurite outgrowth responses were also seen when neurones from APP-null mice were treated with a neurotrophic peptide derived from the APP sequence and compared with wild-type neurones. Finally, cortical cultures derived from APP-null mice showed similar survival responses to the toxic amyloid-β peptide.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

EMBRYONIC rat hippocampal neurons were cultured on poly D-lysine (PDL) or on cortical astrocytes, some of which had been pretreated for 2 4 h with amyloid β-protein (β-AP). Amino acid-induced currents were quantified. Membrane capacitance (Cm), as well as the amplitude and density of amino acid-evoked currents recorded in neurons cultured on untreated astrocytes were all statistically greater than those recorded in neurons grown on PDL. However, compared to untreated astrocytes, those treated wit h β-AP led to significantly lower values in neurons for Cmand GABA, kainate- and NMDA-induced currents, while glycine-activated current values were not significantly different. Furthermore, β-AP treatment abolished spontaneous Cac2+fluctuations in astrocytes, which may account for their impaired ability to promote the expression of functional transmitter receptors in neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE auditory afterimage is a sensation which occurs for several seconds after the exciting acoustic signal has been switched off, and which roughly corresponds to the inverse of the spectrum of the exciting signal. In contrast to the well-known visual afterimage, the physiological mechanism generating the auditory afterimage has been questionable so far. Neuromagnetic source imaging revealed that the source of cortical neural activity which coincides with the sensation of the afterimage is located in the auditory cortex and exhibits a tonotopic organization similar to that of the sustained response which occurs during continuous presentation of an acoustic stimulus. It is concluded that the neural processes leading to the generation of the two phenomena −sustained response and auditory afterimag e—are similar.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THIS study examined the effects of neurosteroids dehydroepiandrosterone sulfate (DHEAS) and pregnenolone sulfate (PS) and progesterone on the Porsolt forced swim test of depression in mice, and investigated the possible involvement o σ receptors. The immobility time in the mouse forced swimming test was significantly reduced by DHEAS (5 and 2 0 mg/kg, s.c.) and PS (5 mg/kg) without accompanying changes in the ambulatory or open-field activity. Pretreatment with DHEAS (&PHgr; mg/kg) or PS (10 and &PHgr; mg/kg), however, failed to modify the immobility. The relief of behavioral despair in the immobility test by DHEAS (5 and 20 mg/kg) was dose-dependently blocked by preadministration of NE-100 (N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl-ethylamine monohydrochloride; 0.5 and 1 mg/kg), a putativeσ1receptor antagonist, or progesterone (1 0 mg/kg), aσ receptor antagonistic neurosteroid. On the other hand, PS (5 mg/kg)-induced decrease in the immobility was significantly blocked by NE-100 (0. 5 mg/kg), but not by progesterone (1 0 mg/kg). Neither NE-100 nor progesterone influenced the immobility alone. These data suggest a role for centralσ receptor in the antidepressant-like effects of neurosteroids, and reinforced their potential therapeutic use in depression.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE neuroprotective role of 17 β-estradiol in the hippocampal dentate gyrus of adult rats treated with kainic acid has been investigated. The systemic injection of a single low dose (7 mg/kg) of kainic acid to ovariectomized rats produced a marked loss of Nissl-stained and somatostatin-immunoreactive hilar neurons. A single simultaneous systemic dose of estradiol (150 μg per animal) prevented the kainic acid-induced decrease in Nissl-stained and somatostatinergic hilar neurons. These results indicate that estradiol may protect adult hilar neuronsin vivofrom neurotoxic-induced cell death.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE report an investigation into the processing of symmetrical lexical stimuli by a patient with moderate visual neglect. This subject's neglect dyslexia was significantly less pronounced when presented with symmetrical lexical stimuli (palindromes) than with matched non-symmetrical words. We discuss the hypothesis that symmetry facilitates processing.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID