摘要:

HUMAN foetal dorsal root ganglia were grafted in place of native lumbar dorsal root ganglia in adult rat hosts. Between 4 weeks and 4 months later, the dorsal root entry zone (DREZ) in the grafted roots showed extensive peripheral outgrowth of astrocytic processes, in contrast to the normal smooth‘ interface between the peripheral and central nervous system compartments of the DREZ. Fibres originating from the grafted neurones and approaching the DREZ changed their direction of growth and entered the spinal cord through the pia by following blood vessels, grew into the grey matter and ramified there. These findings suggest that the DREZ astrocytesin vivoare non-permissive not only to mature peripheral regenerating axons, but also to growing axons from immature neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

IN the rat central nervous system (CNS), inositol 1,4,5-trisphosphate receptor (IP3R) type 3 was immunolocalized with a type 3-specific monoclonal antibody (mAb). The protein was expressed principally in prototype astrocytes, ependymal cells around the ventricle, and Bergmann glial cells in the cerebellum. These cells were stained by antibody against glial fibrillary acidic protein (GFAP), indicating the coexistence of GFAP and IP3R type 3. Immunoblot analysis using a brain homogenate detected a 240 kDa protein, verifying that the observed immunoreactivity is from the IP3R type 3 protein. IP3R type 1 and type 2 were not detected immunohistochemically in astrocytes. These results suggest that IP3-induced Ca2+release (IICR) in astroglia is directed by IP3R type 3, whereas IICR in neuronal cells is mediated by IP3R type 1.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

STATUS epilepticus (SE) produced by excitatory amino acids is a well established model in adult rodents. Limbic neuronal degeneration and synaptic reorganization observed after, for example, kainic acid-induced SE are considered relevant to human epilepsy. Kainic acid also produces severe seizures in infant rats, but neuronal injury and sprouting have not been demonstrated. The results of the present study show that corticotropin releasing hormone (CRH)-induced SE causes limbic neuronal death and reorganization in infant rats. In adults, CRH produced seizures at much higher doses, and no neuronal degeneration. As a modulator of the CNS stress response, CRH is activated in various stressful' circumstances. Its age-dependent ability to kill neurons represents a unique form of cell death potentially important in human medicine.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

LATEXIN is a novel 29 kDa protein which is expressed in a subpopulation of neurones in the lateral cerebral cortex of adult rats. Here, we report the distribution of immunohis-tochemically detectable latexin in the rat brain during early phases of development. Latexin was first detected at embryonic day 11 (E11) along the dorsal midline of the diencephalon. At E12, the expression domain of latexin corresponded to the dorsal midline regions of the dien-cephalon and also of the mesencephalon. At E14, the expression domain was more restricted than that at E12. Strong latexin expression was restricted within the pineal anlage, and dorsal midline cells anterior to the pineal anlage did not express latexin. These findings suggest that latexin plays a role in regional specification and/or morphogenesis of the forebrain, especially of its dorsal midline structures including the pineal gland.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

CHANGES in the metabolic activity of embryonic chick spinal cords were examined following α-bungarotoxin (α-BTX) administration, in order to investigate a potential mechanism by which this toxin arrests motoneurone apoptosis during neurogenesis. Chick embryos were injected i.p. with α-BTX and after 25 h the metabolic markers 2-deoxyglucose and cytochrome oxidase were examined in alternate serial sections of the brachial and lumbar spinal cord. Glucose uptake and cytochrome oxidase activity were reduced throughout the spinal cord and pronounced in the lateral motor columns. Iodinated α-BTX reaches and binds to neuronal α-BTX-sensitive nicotinic cholinoceptors. Binding of α-BTX to these neuronal receptors and to those at the neuromuscular junction has now been shown to have a demonstrable effect on neuronal metabolism. The decreased metabolic activity in spinal cord neurones as a result of toxin treatment may have an important role in the prevention of motoneurone apoptosis at a critical developmental phase.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

IMMUNOREACTIVITY to 2',3'cyclic nucleotide 3'phosphohydrolase (CNPase; EC 3,1,4.37) was studied in the developing opossum brain stem and cerebellum. Regional differences were found in oligodendrocytes concerning the time of appearance (early: medial longitudinal fascicle [mlf]; intermediate: inferior colliculus [IC], deep layers of the superior colliculus [SC] and white matter of cerebellar folia; late: optic layer of SC) and duration of immunoreactivity (short: optic layer of SC; intermediate: mlf; long: cerebellar folia, etc). The results suggest that regional heterogeneities in CNPase expression are linked to intrinsic properties of local and afferent axons.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

THYROID hormone T3and conditioned medium from cerebellar T3-treated astrocytes induced proliferation in astroglial cells. In addition, T3treatment promoted alterations in the organization of cytoskeleton (GFAP) and extracellular matrix (fibronectin) in these cerebellar astrocytes in culture. GFAP filaments that normally spread in the cytoplasm of astrocytes became organized around the cell nucleus. Fibronectin that had a punctate distribution on control cell surface, became diffused in T3-treated astrocytes. This hormone also induced growth factor(s) secretion by astrocytes. These results suggest that T3may be an important regulator of astrocyte growth and differentiation.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

IN order to investigate phosphorylation-dephosphorylation processes underlying long-term depression (LTD) in cerebellar Purkinje cells, the protein phosphatase inhibitors calyculin A and microcystein-LR were applied to Purkinje cells in guinea pig cerebellar slices either by bath application or by intracellular pressure injection. Under the influence of these protein phosphatase inhibitors, excitatory post-synaptic potentials evoked by stimulation of parallel fibres exhibited marked depression which developed at a rate dependent on the rate of parallel fibre stimulation. The protein phosphatase inhibitors thus substitute climbing fibre signals which induce LTD when combined with parallel fibre signals. Peculiarly, this is opposite to the effect in pyramidal cells, where protein phosphatase inhibitors block LTD.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

THE inhibitory glycine receptor (GlyR) is composed of polypeptide subunits that contain intracellular consensus sequences for phosphorylation by protein kinase C (PKC). During whole-cell recording from rat hippocampal neurones, we observed a time-dependent increase of the glycine-induced membrane current. After 22 min the amplitude was 260 + 13% of the initial control response. PKC was involved in the modulation of hippocampal glycine receptors, since the observed effect was more prominent when the phorbol ester PMA, an activator of PKC, was included in the patch pipette. The action of PMA was mimicked by applying the ***'5-HT2receptor agonist, α-methyl-serotonin, to the cells. The time-dependent increase in glycine responses was reduced by either tamoxifen, an inhibitor of PKC, or by alkaline phosphatase. Protein kinase A and tyrosine kinase were not involved as modulatory drugs of these kinases had no effect. These results provide direct evidence for the regulation of GlyR function by PKC in rat hippocampal neurones.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

WE have investigated the action of ciguatoxin (CTX) in the mouse following i.p. administration. CTX (0.5 mouse units) induced a rapid (10–20 min) decrease in body temperature that persisted for several hours. This corresponded closely with a neuroexcitatory action of ciguatoxin on c-fosmRNA in the brain. We identified the neuronal pathways activated by CTX action in the mouse brain by immunostaining of c-fostranslational product, a biomarker for neuroexcitability. c-fos-like immunoreactivity was prominent in the hypothalamus, including the medial preoptic and supraoptic nuclei. Immunostaining was also evident in certain regions of the brain stem, including the locus coeruleus, dorsolateral parabranchial nucleus, area postrema and the nucleus of the solitary tract. These studies indicate that CTX has neuroexcitatory actions on brain stem regions receiving vagal afferents and ascending pathways associated with visceral and thermoregulatory responses.

ISSN:0959-4965    

出版商:OVID    

年代:1995

数据来源: OVID