摘要:

THE effect of transecting the vestibular nerve on the vestibular sensory epithelium was studied in adult guineapigs. When denervation was complete, after fifteen days, the vestibular hair cells began to show morphological features of immaturity. After two months, the majority of hair cells showed a supporting cell phenotype. By four months, both hair cells and supporting cells had become morphologically similar to the epithelial cells which line the vestibular cavities. When denervation was incomplete, hair cells and supporting cells retained their normal phenotype. This, plus the dedifferentiation after complete denervation, indicates that the phenotypes of the hair cells and supporting cells are innervation-dependent.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

STUDIES of motor neurons are difficult because of limitations in their isolation and culture. One solution is to produce clonal neural hybrid cells that can express motor neuron characteristics; we fused an aminopterin-sensitive and neomycin-resistant mouse neuroblastoma cell line to isolated embryonic mouse spinal cord motor neurons. Several hybrid neuron cell lines expressing high levels of choline acetyltransferase (CHAT) enzyme activity were found. These were cloned and clones with high CHAT activity isolated. The hybrid nature of cloned cells was confirmed by karyotyping and determining glucose phosphate isomerase allozymes. The availability of these embryonic clonal hybrid cells will enable molecular, physiological, and biochemical studies to define motor neuron-specific properties.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

IN the awake, freely moving rat we showed, by means of single-unit recordings and antidromic spinal cord activation, that at the ventromedial medulla level, in these particular experimental conditions, the ‘multimodal, multireceptive’ units excited by auditory, cutaneous non-noxious and noxious stimuli are possibly involved in a spinal descending control system. These neurons were back-fired from the medial part of the lateral funiculus, hence they probably projected to the dorsal and intermediate horn of the cord, and not to the ventral horn, which emphasizes a role in the control of nociception. Due to their convergent properties, these units are probably involved in nonspecific aspects of nociception such as alertness or stress.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A monoclonal antibody, 2F7, raised against a nuclear protein subfraction recognized the nuclear membrane of nervous and muscular tissues of guinea pig, rat and rabbit, but no other tissue was stained. In the nervous system, both neurons and glial cells were labelled. An electron microscopic immunohistochemical study demonstrated that 2F7 antibody labelled the inner surface of the nuclear membrane. Western blot analysis on the nuclear envelope fraction containing nuclear lamina revealed that this antibody reacted to two minor component proteins of 80 and 82KDa. These 2F7 antigens expressed preferentially in the nervous and muscular tissues were distinct from the major nuclear envelope proteins reported so far and might be related to neuronal or muscular tissue-specific functions.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

STIMULATION of the quisqualate (QA) subtype of glutamate receptor increased the expression of phosphate activated glutaminase (needed for neurotransmitter glutamate synthesis) and the ability to release neurotransmitter glutamate in cultures of glutamatergic cerebellar granule neurons. In contrast, QA had no significant effects on the lactate dehydrogenase activity and amount of protein. The QA-mediated elevation in glutaminase activity was blocked by the ionotropic QA receptor antagonist CNQX and mimicked by the ionotropic QA receptor agonist AMPA, but not by the metatropic QA receptor agonist t-ACPD. The increase in Ca2+influx essentially through activation of L-type channels, and not the mobilization of internal Ca2+stores, was responsible for these QA receptor-mediated long-term changes in cerebellar granule neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

THE culture of hepatocytes dissociated from adult mice by the collagenase perfusion method enables neurons or neuronal tissues to be cultured with hepatocytes or in hepatocyte-conditioned media. Co-culture with hepatocytes or hepatocyte-conditioned media enhances neurite regeneration and their survival from nerve-transected terminals of dorsal root ganglia with nerve fibers dissected from adult and aged mice. Hepatocytes secrete a factor which enhances not only neurite regeneration but also neurite survival. Activities of other known neurotrophic factors were not as crucial as those of the hepatocyte-conditioned medium, suggesting that this factor may differ from other trophic ones.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

THE antidepressants, mianserin (MIA) and fluoxetine (FLU), were examined to see if they could induce regeneration of catecholaminergic axons in the rat cerebral cortex. MIA, which has a small or no effect in noradrenaline (NA) reuptake but may enhance release by blocking presynaptic inhibition mediated by α2-adrenoceptors, induced regeneration of catecholamine fibers. In contrast, FLU, a potent reuptake blocker of serotonin was ineffective. This finding suggests that the antidepressant-induced regeneration of cortical catecholamine fibers is associated, at least in part, with enhanced noradrenergic transmission.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

IN seeing rats light flashes inhibit acoustic startle reflexes at short lead times. In contrast, visually impaired (light-blinded) rats show an early phase of exaggerated reflex expression, revealing the presence of pathological visual processing, and then an aberrant late phase of delayed inhibition. Grafting fetal retinal cells into the damaged retina entirely removed reflex facilitation and restored a modest degree of properly timed and statistically significant reflex inhibition. This restoration of visually-mediated behaviour, observed in two independent groups, reveals that intraretinal grafts provide useful information to blinded hosts.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

IN guinea pig hippocampal slices, a tetanic stimulation of the stratum radiatimi caused long-term potentiation (LTP) of the excitatory postsynaptic potential (EPSP) but not of the GABABreceptor-mediated slow inhibitory postsynaptic potential (IPSP) in the CAI neurons. In neurons in which Ca2+was chelated with l, 2-bis(2-amino-phenoxy) ethaneN, N, N‘, N’-tetra-acetic acid (BAPTA) or ethylene-bis(oxyethylenenitrilo)tetra-acetic acid (EGTA), tetanic stimulation of the stratum radiatum caused LTP of the slow IPSP but not of the EPSP. These results indicate that a reciprocal relationship exists between LTP of the EPSP and LTP of the slow IPSP as far as the involvement of the postsynaptic Ca2+is concerned.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

PERIVASCULAR nerves of the uterine artery were studied in four-month-old pregnant and non-pregnant guinea-pigs. In pregnancy, the uterine artery hypertrophies (more than two-fold growth in diameter and length and 50% increase in wall thickness), but its density of innervation remains high, because of the growth of many new axons. The axons in a complete transverse section of the vessel increase by 40%. The nerve bundles grow by 100%. Small nerve bundles increase more than large bundles: nearly 70% of the nerve bundles contain 10 or fewer axons in pregnant guinea-pigs (37% in non-pregnant animals). The increase in axon number is accompanied by formation of new varicosities, hence presumably of new neuromuscular junctions.

ISSN:0959-4965    

出版商:OVID    

年代:1991

数据来源: OVID