ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03384.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Bulk‐isolated astrocytes from rats with early hepatogenic encephalopathy (HE) induced with thioacetamide responded to the increase of potassium in the incubation medium from 5 mMto 75 mMwith a markedly enhanced release of previously taken up [14C]γ‐aminobutyric acid ([14C]GABA). The process was not affected by omission of calcium and/or addition of EGTA to the incubation medium. Only a slight stimulation of GABA release by high potassium was observed in astrocytes from control rats. In contrast, histamine and histidine were vigorously released from control astrocytes in high‐potassium medium, and their release was not enhanced by HE, indicating that the observed phenomenon is specific fo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03385.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Purified tetrameric detergent‐soluble acetylcho‐linesterase (DS‐AChE) from human caudate nucleus was analyzed by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis in the absence as well as in presence of a reducing agent. Staining for protein revealed a main band at 66,000 daltons (light monomer) with additional bands at 78,000 daltons (heavy monomer) as well as 130,000 and 150,000 daltons (light and heavy dimers). The same four polypeptides were also detected by Western blotting and by autoradiography of [3H]diisopropylphosphoryl enzyme. Labeling of the enzyme with 3‐trifluoromethyl‐3‐(m‐[125I]‐iodophenyl)diazirine showed that the heavy monomer contained the hydrophobic anchor of the enzyme, whereas the light monomer was practically not labeled. The hydrophobic anchor was susceptible to proteolytic degradation by proteinase K. The functional molarity of DS‐AChE was determined by two independent methods. Four active sites for the tetrameric enzyme were estimated. The turnover number per site was 1.7 ± 107mol of acetylthiocholine iod

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03386.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Accumulation of inositol‐1‐phosphate after labeling with [3H]inositol and stimulation with noradrenaline, carbachol, and serotonin was measured in rat cortical, caudate nucleus, and hippocampal slices. The response to noradrenaline was significantly increased in cortical slices from animals that had received either a single electroconvulsive shock (ECS) or a series of 10 daily ECS but was unchanged in caudate nucleus or hippocampal slices. The response to carbachol, a muscarinic cholinergic agonist, was unchanged in cortical or caudate nucleus slices but was significantly reduced in hippocampal slices from animals that had received chronic ECS. The response to serotonin in cortical slices was not affected by the treatment. The results are correlated with changes in receptor number, which have been demonstrated to occur after administration of

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03387.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Traumatic injury of the spinal cord leads to a series of pathological events that result in tissue necrosis and paralysis. Among the earliest biochemical reactions are hydrolysis of fatty acids from membrane phospholipids, production of biologically active eicosanoids, and peroxidation of lipids. This study examines the effect of agents purported to improve recovery following spinal cord trauma, methyl‐prednisolone sodium succinate (MPSS) and the combination of α‐tocopherol and selenium (Se), on the posttraumatic alterations of membrane lipid metabolism. Pretreatment with either MPSS or a‐tocopherol and Se reduced the trauma‐induced release of total FFA including arachidonate in the injured spinal cord tissue. In addition, these agents decreased the postinjury levels of prostanoids. Pre‐treatment with either MPSS or a‐tocopherol and Se also completely prevented the trauma‐induced loss of cholesterol while inhibiting the increase of a cholesterol peroxidation product, 25‐hydroxycholesterol. These data suggest that: (a) perturbation of membrane lipid metabolism may contribute to the tissue necrosis and functional deficit of spinal cord injury and (b) MPSS or the combination of a‐tocopherol and Se may protect injured spinal cord tissue, at least in part, by limiting these posttraumatic memb

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03388.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:The effect of administration of chlorpromazine on the activity of glutamine synthetase and glutaminase and the content of glutamate and γ‐aminobutyric acid (GABA) in different regions of rat brain was studied in an investigation of the possible role of these amino acids in the lowering of the seizure threshold following prolonged administration of chlorpromazine. Chlorpromazine was administered at a dose of 20 mg/kg of body weight s.c. For the acute study, the animals were killed 20 min after a single injection. For the long‐term study, the animals were treated every day with the same dose for 21 days and were killed 20 min after the last injection. The results showed an increase in glutamate level in each brain region investigated following long‐term administration, but only in the cerebral cortex after a single dose. GABA levels showed an increase in the brainstem only in acute experiments. Glutamine synthetase activity was increased in all three regions after a single dose and only in cerebral cortex after long‐term administration. Glutaminase activity showed a decrease in cerebral cortex only after long‐term administration of the drug. These results suggest the possible occurrence of a state of increased excitability in the brain as a result of long‐term administration of chlorpromazine, thus contributing to the known complication

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03389.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:Putrescine, spermidine, and spermine levels were measured in the cortex, caudoputamen, and hippocampus of rats during 30 min of severe forebrain ischemia (induced by occlusion of both carotid and vertebral arteries) and subsequent recirculation. During ischemia, polyamine levels did not change significantly. During postischemic recirculation, however, putrescine levels dramatically increased whereas those of spermine and spermidine did not change, with the exception of the severely damaged caudoputamen, where the concentration declined after 24 h. The increase of putrescine is explained by postischemic activation of ornithine decarboxylase and inhibition ofS‐adenosylmethionine decarboxylase. It is suggested that the accumulation of putrescine during postischemic recirculation may be responsible for the delayed neuronal death occurring after ischemi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03390.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:The carboxyl methylation of secretory proteins in vivo was investigated in bovine adrenal medullary cells in culture. Chromogranin A., the major intragranular secretory protein in adrenal medullary cells, and other secretory proteins were found to be carboxyl‐methylated within secretory vesicles. The in vivo labeling pattern using [methyl‐3H]methionine and the in vitro labeling pattern usingS‐adenosyl‐[methyl‐14C]methionine of intravesicular secretory proteins were similar. The detection of methylated chromogranin A in mature secretory vesicles required 3–6 h, a time consistent with the synthesis and storage of secretory proteins in this tissue. Carboxyl‐methylated chromogranin A was secreted from medullary cells by exocytosis via activation of nicotinic cholinergic receptor and recovered still under the methylated form in the incubation medium. Since protein‐carboxylmethylase is cytosolic, these results suggest that methylation of secretory proteins is a co‐transla

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03391.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:The lipid composition of the nervous system of the leechHirudo medicinaliswas investigated following acclimatization of animals at 25°C and 5°C. Choline, ethanolamine, and serine plus inositol phosphoglycerides are the major phospholipid classes of the leech ganglionic chain; minor amounts of lysophosphatidylcholine, phosphatidic acid, and sphingomyelin are also present. Neither the phospholipid pattern nor the cholesterol to total phospholipid molar ratio was dependent on the acclimatization temperature, whereas the fatty acid patterns of choline and serine plus inositol phosphoglycerides were significantly affected. Both for choline and serine plus inositol phosphoglycerides, a significant increase of the unsaturation index and a decrease of saturated to unsaturated fatty acid ratio was observed in animals acclimatized at 5°C in comparison with those acclimatized at 25°C. These observations, which point to increased lipid fluidity of the nervous system of cold‐adapted leeches, are strengthened by results obtained by the fluorescence polarization method using 1,6‐diphenyl‐1,3,5‐hexatriene as a probe: a decrease of the fluorescence polarization value was observed throughout the temperature range select

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03392.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract:An enzyme‐linked fluorometric assay is described for the continuous monitoring of the unidirectional efflux of glutamate from guinea‐pig synaptosomes. Glutamate efflux from freshly suspended, polarized synaptosomes occurs at 0.35–0.39 nmol min−1mg of protein−1and is not significantly affected by external Ca2+. KC1 depolarization (30 mMKCI) in the absence of Ca2+doubles this rate, whereas in the presence of Ca2+, the initial kinetics of the assay are consistent with the release in the first 5 s of 0.6 nmol mg of protein−1. The final extent of Ca2+‐dependent release amounts to 1.9 nmol mg of protein−1, or 8.5% of the total intrasynaptosomal glutamate content. Preincubation of synaptosomes at 30°C for 2 h before depolarization leads to a decrease in Ca2+‐independent release and an increase in Ca2+‐dependent release, consistent with an intrasynaptosomal relocati

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1987.tb03393.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY