摘要:

THE aim of the study was to test the hypothesis that a 16 week endurance training program would alter the abundance of endplate-associated nicotinic acetylcholine receptors (nAChR) in various rat skeletal muscles. We found a 20% increase in endplate-specific [125I]α-bungarotoxin binding in several muscles of trained rats, accompanied by equal susceptibility of toxin binding to the inhibitory effect of D-tubocurarine in sedentary and trained muscles. We conclude that the neuromuscular junction adaptations that occur with increased chronic activation include an increase in nAChR number. Results of experiments designed to determine nAChR turnover also suggest that this effect is mediated by an alteration in the receptor's metabolic state. The potential implications and mechanisms of this adaptation are discussed.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE function of deleted in colorectal cancer (DCC) protein, a member of the immunoglobulin superfamily of cell adhesion molecules, in the adult CNS is unknown. Recently the transcript encoding DCC has been shown to be expressed in a variety of rat brain regions, including the substantia nigra pars compacta and the striatum, which encompasses the nigrostriatal dopaminergic system. In the present study DCC mRNA expression in substantia nigra, striatum, dentate gyrus and piriform cortex was investigated in adult rats usingin situhybridization histochemistry following unilateral injections of 6-hydroxydopamine (6-OHDA) in the median forebrain bundle. DCC mRNA levels were greatly reduced in the substantia nigra ipsilateral to the 6-OHDA lesion compared to those on the contralateral side while there was no apparent effect on DCC mRNA levels in the other regions analysed. These data indicate expression of DCC mRNA in dopamine neurones of the substantia nigra pars compacta and support a role for DCC in the adult CNS, with potential involvement in the function of central dopamine neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

HERE we report that training-associated changes in neural activity can precede behavioral learning. This finding suggests that speech-sound learning occurs at a pre-attentive level which can be measured neurophysiologically (in the absence of a behavioral response) to assess the efficacy of training. Children with biologically based perceptual learning deficits as well as people who wear cochlear implants or hearing aids undergo various forms of auditory training. The effectiveness of auditory training can be difficult to assess using behavioral methods because these populations are communicatively impaired and may have attention and/or cognitive deficits. Based on our findings, if neurophysiological changes are seen during auditory training, then the training method is effectively altering the neural representation of the speech/sounds and changes in behavior are likely to follow.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TRANSGENIC mouse strains were generated that over-express human APP or clinical mutants of APP. All transgenic mouse strains that over-express APP displayed essentially the same phenotype of disturbed behaviour, differential glutamatergic responses, deficits in maintenance of long-term potentiation and premature death, but formation of amyloid plaques was seen in the highest expressing APP/London transgenic mice only. Apart from cognitive deficits, the APP transgenic mice were characterized by aggressive behaviour, which was pharmacologically alleviated with 8-OH-DPAT and buspirone, two serotonergic agonists. The atypical neuroleptic drug risperidone was equally active in this regard. The data establish an important aspect of the transgenic mice as experimental models for behavioural aspects of Alzheimer's disease, in addition to other early and late symptoms.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

USINGin situhybridization histochemistry we have studied the effect of glucose and fat deprivation on galanin-R1 receptor (GAL-R1-R) mRNA levels in the rat paraventricular (PVN) and supraoptic (SON) nuclei after single and repeated i.p. administration of a glucose antimetabolite 2-deoxy-D-glucose (DG), as well as of a fatty acid antimetabolite, sodium mercaptoacetate (MA), treatments known to increase food intake. Both DG and MA injections caused an increase in levels of GAL-R1 mRNA transcripts in the PVN and SON. These results indicate that glucose and fat deprivation increase the sensitivity of PVN and SON neurons to galanin, and that regulation of receptor levels may be an important mechanism in galaninergic signalling.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FOCAL hand dystonia involves a loss of motor control of one or more digits; it is associated with the repetitive, synchronous movements of the digits made by musicians over periods of many years. Magnetic source imaging revealed that there is a er distance (fusion) between the representations of the digits in somatosensory cortex for the affected hand of dystonic musicians than for the hands of non-musician control subjects. The data suggest that use-dependent susceptibility to digital representation fusion in cortex may be involved in the etiology of focal dystonia. A successful therapy for the condition has been developed based on this consideration.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

A new protein with nerve growth promoting activity was purified from the crude venom of theAgkistrodon halys Pallas, a Chinese snaker . Its amino-terminal sequence unexpectedly showed high homology with serine proteases, suggesting that it is a new member of the serine protease family. It also cross-reacted with antibodies against thrombin-like enzyme and possessed weak arginine esterase activity, amounting to about 3% of the activity of trypsin. However, its nerve growth promoting activity was comparable to that of nerve growth factor (NGF). It was named NGF-like protease (NLP). Northern blot analysis further demonstrated different patterns of induction of c-myc, vgfandtrkAmRNA transcription in PC12 pheochromocytoma cells treated with NGF and NLP, respectively. These data suggested that NLP represents a novel potent neurotrophic factor.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

DYSTROPHIN, utrophin and dystroglycan are present not only in muscle but also in brain. In muscle, they link the extracellular matrix to the cytoskeleton. Their function in brain is not understood. Here we show their presence in the hypothalamo-neurohypophysial system which secretes the neurohormones oxytocin and vasopressin. Using immunocytochemistry, we showed that dystrophins are present in the neurohypophysis of control rats. After water deprivation, immunoreactivity dramatically decreased and appeared in axonal swellings in the hypothalamic tract. Dystrophin immunostaining can be ascribed to dystrophin and/or utrophin as well as the DMD (Duchenne Muscular Dystrophy) gene short products Dp140 and Dp71 as revealed by Western immunoblots of synaptosomes isolated from neurohypophyses of control rats. In synaptosomes isolated from rats under water deprivation, the immunoreactivity entirely disappeared. Further biochemichal characterization of isolated neurosecretory granules (NSG) showed that Dp140 and Dp71 are enriched in the NSG stored in the swellings of the neurohypophysis whereas the NSG of the nerve endings are devoid of these proteins. In addition we observed that the presence of β-dystroglycan and actin correlates with the presence of dystrophins. Our data favor a direct implication of the dystrophins and/or utrophin, dystroglycan and actin in the neurosecretory processes of the hypothalamoneurohypophysial system.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

REPRODUCTIVE experience influences basal and pregnancy profiles of circulating prolactin levels in women and female rats, respectively. Endocrine responses to dopaminergic antagonists are modified by reproductive experience as well. Striatal extracellular dopamine metabolites were measuredin vivoby HPLC-ED in perfusates obtained by microdialysis in non-anaesthetized, freely moving, intact and ovariectomized, nulliparous and primiparous rats. Data were collected for at least 7 h. This period always included the light-dark shift at 18:00 h. In a second experiment, microdialysis was performed in ovariectomized nulliparous and primiparous rats treated with haloperidol (1.0mg/kg s.c.). During the 1 h before and after the onset of the light-dark shift, HVA concentrations in the perfusates increased in nulliparous compared with primiparous rats. The haloperidol-induced increase in DOPAC and HVA was less intense in primiparous rats than that in nulliparous ovariectomized rats. These data revealed a different pattern of striatal dopaminergic anticipation and response to the shift in the light-dark cycle in nulliparous as compared with primiparous intact females. In addition, a distinct striatal dopaminergic response to haloperidol was observed in primiparous as compared to nulliparous ovariectomized rats. The results suggest that reproductive experience can modulate the activity of dopaminergic terminals in the striatum.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

IN a family-based association study we investigated transmission of a multiallelic CAG repeat in a novel neuronal potassium channel gene,hSKCa3, in 59 parent/ offspring trios. In contrast to recent reports of an association of moderately large repeats with schizophrenia in case-control studies, our findings indicate that short CAG repeats (≤ 19 repeats) are transmitted at an increased frequency to schizophrenic offspring (p= 0.014), particularly among familial cases (p= 0.007). No evidence for a parent-of-origin effect was found. Multiallelic TDT procedure showed no association of individual CAG repeats to schizophrenia. Further studies using family-based designs should clarify whetherhSKCa3is a susceptibility factor to schizophrenia or co-segregates with a major disease gene in tight linkage.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID