摘要:

THE present study addressed the hypothesis that the neuronal mineralocorticoid receptor (MR) regulates genes associated with cell death, such as bax and p53, and cell viability, including bcl-2, BDNF, and NT-3. Rats were pretreated with either oil vehicle or the MR antagonist spironolactone (SPIRO) and subsequently injected with saline or kainic acid (KA). MR blockade significantly decreased basal mRNA expression of bcl-2 in CA1 of saline-treated animals and attenuated KA-induced increases in p53 mRNA levels in CA3. SPIRO pretreatment had no significant effect on expression of bax, NT-3, or BDNF mRNAs. The data suggest that the neuronal MR contributes to regulation of select cell survival and cell death-related genes in hippocampal pyramidal neurons.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

CALCIUM transport by the Na+/Ca+exchanger was measured in plasma membranes vesicles purified from rat brain and in primary rat cortical cell culture. Sodium-loaded vesicles rapidly accumulate Ca2+via Na+/Ca2+exchange (Na+i-dependent Ca2+uptake). Extra-vesicular zinc inhibited Na+/Ca2+exchange as evidenced by a reduction of the initial velocity of Ca2+uptake. Significant inhibition of Ca2+uptake was seen at concentrations of zinc as low as μM. Lineweaver–Burk analysis of the data was consistent with noncompetitive inhibition with respect to extravesicular Ca2+concentration. The Kifor zinc inhibition of Ca2+uptake determined from a Dixon plot was 14. μM. This is within the range of zinc concentrations thought to be obtained extracellularly after excitation. When vesicles were preloaded with Ca2+, extravesicular zinc also inhibited reversal of Na+/Ca2+exchange (Na+o-dependent Ca2+release) although its potency was much less: concentrations of ≥ 3 0μM zinc were required. Zinc inhibition of Ca+release was not Na+dependent. Na+i-dependent calcium uptake by rat cortical cells in primary culture also was inhibited by zinc. The extent of inhibition was similar to that seen for inhibition of Na+i-dependent Ca2+uptake in membrane vesicles, but the potency was less. The results suggest that Ca2+transport by the Na+/Ca2+exchanger is inhibited by concentrations of zinc thought to be attained extracellularly after excitation.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE molecular composition of the nicotinic acetylcholine receptors (nAChRs) located on dopaminergic neurons and modulating their activity is unclear. Using the reverse transcriptase-polymerase chain reaction we have analyzed the mRNA for nAChR subunits expressed in the substantia nigra (SN) and ventral tegmental area (VTA) following unilateral 6-hydroxy-dopamine lesion of the dopaminergic system. In contrast to the unlesioned hemisphere, no signal was found in the lesioned hemisphere for α3, α5, alpha;6, and β4 subunits in the SN nor for α2, α3, α5, α6, α7 and β4 subunits in the VTA, indicating the expression of these subunits in dopaminergic neurons. mRNA for α4, β2 and β3 subunits (and α7 in the SN) were still detected after lesion, suggesting that they are expressed in GABAergic neurons and interneurons of these brain areas. These results demonstrate the selective localisation of a number of nAChR subunit mRNA within dopaminergic neurons, strongly suggesting that a heterogenous population of nAChRs play a role in modulating dopaminergic neuronal activity.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

TAURINE is an inhibitory amino acid in the CNS. When supplied to rats it produces analgesia in some acute pain tests. Here we examined the effect of taurine supplementation on sensitivity to pain in intact rats, and whether perioperative dietary supplementation with taurine in rats would suppress autotomy, a behavior produced by peripheral neurectomy and related to neuropathic pain. Thermal pain sensitivity of intact rats consuming 1% taurine in the drinking solution for 2 weeks was not significantly different from that of control rats. Autotomy levels, determined in rats consuming taurine pre-, post- or perioperatively were significantly lower than in matching control groups. We conclude that taurine plays an important role in the autotomy model, presumably by protecting inhibitory neurons in the CNS against an excitotoxic damage triggered by injury discharge and ectopic input from the severed nerves.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

NERVE injury can lead to sympathetically dependent neuropathic pain. A possible site of sympathetic—sensory interaction is the dorsal root ganglion (DRG), where sympathetic axons form pericellular ‘baskets’ around a subpopulation of DRG neurons. Since these structures possibly represent functional units of sympathetic pain, we attempted to characterize the neuropeptidergic phenotype of basketed DRG neurons. We performed double-labeling immunohistochemistry for tyrosine hydroxylase and neuropeptides on DRG sections, 2 weeks following L5 spinal nerve ligation (a well-characterized animal model of sympathetic pain). We found that basketed DRG neurons typically do not contain substance P, calcitonin gene-related peptide, galanin, neuropeptide tyrosine, or vasoactive intestinal polypep-tide, and we conclude that if sympathetic baskets contribute to neuropathic pain, the involvement of these neuropeptides is unimportant.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

EARLY-ONSET familial Alzheimer's disease (early-onset FAD) has been linked with mutations in the presenilin gene, PS1. Mutations in PS1 may affect the processing/trafficking of β-amyloid precursor-protein (βAPP) and favour the productionj of toxic amyloid β-fragments tjat are asspcoated wotj neural degenmeration. This study reports the expression of a PS1-like cDNA in the carp (Cyprinus carpi) retina (the encoded protein shows 76% identity to the human PS1 protein). Carp PS1 mRNA was localized b yin sit uhybridization to the photoreceptor cell, inner nuclear and ganglion cell layers. Expression of the PS1 gene in the rat retina was also confirmed. The retinal expression of PS1 raises the possibility that PS1 mutations also lead to neural degeneration in the retina.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID