ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE influence of stimulus duration on spinal induction of the c-fos proto-oncogene was analysed in the rat by pinching or heating the skin for periods varying from 20 s to 2 h. At stimulation periods shorter than 20 min, c-fos activation occurred in laminae I-IIi following mechanical stimulation and I-IIo following thermal stimulation. Mechanical stimulation produced delayed activation in laminae III–IV, V and VII at 30 min, 60 min and 2 h, respectively, and thermal stimulation in lamina IIi at 50 min. It is suggested that late c-fos activation signals inflammatory pain and is due to sensitization of primary afferent neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE N-methyl-D-aspartate (NMDA) NR1 glutamate receptor subtype has been proposed to play an important role in the transmission of orofacial sensory information in the spinal trigeminal nucleus (STN). The distribution of NR1 mRNA expression in the STN and its relationship to STN projection neurons has not been investigated previously. Using neuroanatomical tract tracing within situhybridization techniques, we found that neurons in the STN that project to the thalamus, cerebellum and spinal cord expressed more mRNA for NR1 than do nonprojection neurons. Trigeminothalamic neurons were found to express more NR1 mRNA than trigeminospinal or trigeminocerebellar neurons. Thus, NMDA-specific excitatory amino acids may be more efficacious in the relay of orofacial information to the thalamus than to the spinal cord or cerebellum.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE mouse recessive mutationwobbler,carried by the C57BL/6J strain, is a naturally occurring model of motoneurone death. The gene is unknown and in the absence of predictive markers, mutants have to be diagnosed by phenotypic criteria at 4 weeks after birth. We localized thewobblergene to chromosome 11 at 0.98 1.1 cM from the glutamine synthetase (Glns) gene. A polymorphic allele of the Glns gene was then introduced into the congenicwobblerstrain by intraspecific crossing. One-quarter of the offspring expressed the same phenotypic mutation as truewobblerand were detectable by PCR, as they are homozygous for thewobbler-linked Glns allele. The new mutants exhibit motoneurone degeneration despite the new genetic background.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

RETROGRADE tracing experiments suggest that cortico-pulvinar connections originate from at least two subpopulations: medium and giant pyramids in layer 5, each with distinctive dendritic and local axonal arborizations. The present study used extracellular injections of PHA-L to delineate extrinsic axon arbors and to assess the possibility of categories that might correlate with these specific neuronal subpopulations. Two distinct types of terminations were found. Type I have smaller caliber preterminal axons, are generally elongate, and are studded with spinelike terminal specializations. Type II have larger axons (gt 1.0 mUm), spherical arbors, and mainly beaded specializations, some of which are conspicuously large ( 3.0 mUm). These two axon types may differ in conduction velocity and membrane properties, and the interactions of these different features may be important for pulvinar function.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WE investigated the role of nitric oxide (NO) in controlling the rate of occurrence of muscarinic rhythmic slow activity (RSA) episodes induced by carbachol in rat hippocampal slices. Typically, a series of several short intervals (< 40 s) between RSA episodes alternated with one or two longer intervals. Treatments with inhibitors of NO synthesis (NG-nitro- or NG-methyl-L-arginine) or with hemoglobin shortened and stabilized all intervals. By contrast, applications of an NO donor (sodium nitroprusside) or membrane permeant cGMP analogs (8-bromo-cGMP or dibutyryl-cGMP) during blockade of NO synthesis lengthened and destabilized the intervals. The importance of cholinergic mechanisms in learning and memory is well known and our findings suggest that NO could influence synaptic plasticity by modulating the occurrence of a muscarinic component of hippocampal RSA.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

AUDIOGENIC seizures are evoked by acoustic stimulation in susceptible (S) but not in resistant (R) rats. Repeated audiogenic seizures recruit limbic areas, a model called audiogenic kindling. In order to evaluate excretory patterns (urinary volume, Na+and K+excretion), S and R animals were non-stimulated, submitted to one (acute) or 10 (kindled) stimulations or to two aqueous overloads (5% b.w.). Non-stimulated S animals displayed a significant increase (plt 0.05) in Na+excretion at 60, 80, 100 and 120 min. Acutely stimulated S animals showed greater natriuresis than non-stimulated animals at 40, 60, 80 and 100 min. Kindled S animals displayed the greatest natriuresis (plt 0.005) at 40, 60, 80, 100 and 120 min and the highest diuretic response (plt 0.05) at 40, 60 and 80 min. Abnormalities of the endogenous hydroelectrolytic profile of non-stimulated S animals and their overt expression in kindled rats may be related to alterations in neuroendocrine systems regulating hydroelectrolytic balance, in addition to the long-lasting effects of kindled seizures.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

WE have previously shown that a metabolically stable analogue of MPF, the C-terminal tetrapeptide of human β-endorphin of structure Lys-Lys-Gly-Glu, reduces the turning behaviour of rats with unilateral lesions of their nigro-striatal pathways. Transmission electron microscopy (TEM) has now revealed that this effect is related to reversal of the mitochondrial damage to substantia nigra (SN) neurones induced by the lesion. The results are consistent with the concept that an inherited defect in components of the mitochondrial enzyme system is the initial step in the genesis of Parkinson's disease (PD). They also, in conjunction with known neurotropic properties of MPF, and our unpublished finding of high concentrations of an MPF-like peptide in human basal ganglia, suggest that MPF may have physiological significance in the development and regeneration of the human CNS.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

THE retrograde nucleophilic tracer diamidino yellow (DY) was injected into the left superior colliculi of 2-day-old rats. Two days later, right eyes were injected with either neurotrophin NT-4/5, cycloheximide (CHX), MK-801 and DNQX (glutamate receptor antagonists), or saline. Almost all rats were perfused 6–7 h later and the numbers of normal and pyknotic DY-labelled retinal ganglion cells (RGCs) were determined from retinal whole mounts. In controls (no eye injection) the proportion of pyknotic RGCs was 1.04%. This level of naturally occurring death was significantly reduced after injection of NT-4/5 (0.34%); normal RGC density was also higher in this group. RGC pyknosis was increased after saline (1.21%), MK-801/DNQX (1.22%) or CHX (1.48%) injections but only in the latter case was the increase significantly greater than control.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

NESTIN is a neurofilament protein expressed by the immediate precursors to neurons and glia in rats and humans. Nestin immunoreactivity in the rat CNS was studied following kainic acid (KA) hippocampal lesions. Numerous nestin positive cells within the KA lesion were confirmed to be reactive astrocytes by their immunoreactivity for glial fibrillary acidic protein (GFAP). The number of these cells decreased with time after the KA lesion and no astrocyte immunostaining for nestin was observed in control animals. A subset of nestin-positive cells in the ventricular subependymal region appeared to be radial glial cells, extending to cell body layers. Nestin is one of several embryonic markers expressed by reactive astrocytes, suggesting an embryonic reversion induced by the KA lesion, possibly to enhance functional recovery.

ISSN:0959-4965    

出版商:OVID    

年代:1994

数据来源: OVID