摘要:

Abstract:The levels of epinephrine, norepinephrine, and dopamine and the activities of tyrosine hydroxylase and monoamine oxidase were estimated in four regions of rat brain during alloxan‐induced hyperglycemia and insulin‐induced hypoglycemia. Catecholamine levels were estimated by HPLC, and the insulin levels were quantified by radioimmunoassay. The results demonstrated significant increases in the activities of the metabolizing enzymes and levels of catecholamines during experimental conditions. The levels of catecholamines were highest in the cerebral hemispheres, the region associated with high activities of the metabolizing enzymes. Insulin‐induced hypoglycemia caused a decrease in the activities of the metabolizing enzymes followed by their recovery withi

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09282.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Levels of dopamine (DA), 3,4‐dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), noradrenaline (NA), 3‐methoxy‐4‐hydroxyphenylglycol (MHPG), and 5‐hydroxyindoleacetic acid (5‐HIAA) in the CSF of patients with Huntington's disease (HD) were measured by HPLC. CSF DA, DOPAC, and MHPG levels were found to be increased in HD patients. Levels of HVA, 5‐HIAA, and NA in the CSF of HD patients did not differ from those of controls. Changes in CSF DA and DOPAC levels were consistent with previous findings of increased DA tissue content in some brain areas of patients with HD. These results suggest that CSF DOPAC levels could be a more reliable index of over‐active dopaminergic brain systems in HD than

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09283.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The effect of hydroperoxy fatty acids on reactions involved in the acylation‐deacylation cycle of synaptic phospholipids was studied in vitro, using nerve ending fraction isolated from rat forebrain. 15‐Hydroperoxyeicosatetraenoic acid (15‐HPETE), 13‐hydroperoxylinoleic acid (13‐HP 18: 2), and hydroperoxydocosahexaenoic acid (22:6 Hpx), at 25 μMfinal concentration, all inhibited the incorporation of [1‐14C]arachidonate into synaptosomal phosphatidylinositol (PI), phosphatidylcholine (PC), and triacylglycerides by 50–80%. The lowest effective concentration of 15‐HPETE and 13‐HP 18:2 resulting in significant inhibition of the reacylation of PI was 5 μM, whereas the inhibition of [1‐14C]arachidonate incorporation into PC required 10 and 5 μMhydroperoxy fatty acids, respectively. Cumene hydroperoxide andtert‐butyl hydroperoxide at concentrations of 100 μMdid not inhibit reacylation of PI and PC. Synthesis of labeled arachidonoyl‐CoA from [1‐14C]arachidonate was decreased by about 50% by 25 μMhydroperoxy fatty acids both in synaptosomes and in the microsomal fraction. Use of [1‐14C]arachidonoyl‐CoA as a substrate, to bypass the fatty acid activation reaction, revealed that activity of acyltransferase was not affected significantly by 25 μM15‐HPETE and 13‐HP 18:2. At the same time, however, the hydrolysis of labeled arachidonoyl‐CoA was substantially enhanced. Exposure of synaptosomes to 25 μMfatty acid hydroperoxides did not affect significantly the endogenous concentrations of five major free fatty acids. It is concluded that (1) among synaptic phospholipids, reacylation of PI and PC is the most susceptible to the inhibitory action of fatty acid hydroperoxides, and (2) the enzymes affected by these compounds in nerve endings are

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09284.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The concentrations of acidic metabolites derived from the biogenic amineso‐, m‐, andp‐tyramines (o‐, m‐, andp‐hydroxyphenylacetic acids),p‐octopamine/p‐synephrine (p‐hydroxymandelic acid), and dopamine (homovanillic acid and 3,4‐dihydroxyphenylacetic acid) were measured in human aqueous humour obtained from patients undergoing elective surgery for cataract removal or for trabeculectomy as a treatment for chronic open‐angle glaucoma. There were no clear differences in the pattern of metabolism of neurotransmitters between the two groups. An unexpected finding was that theo‐tyramine metabolite,o‐hydroxyphenylacetic acid, was

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09285.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:An in vivo voltammetric technique was used to determine whether striatal nondopaminergic neurons take up and decarboxylate exogenousl‐3,4‐dihydroxyphenylalanine (L‐DOPA) and release it as dopamine. After the striatal serotonergic neurons of the rat had been destroyed by intraventricular injection of 5,7‐dihydroxytryptamine,l‐DOPA was administered intraperitoneally. It was found that changes in the dopamine concentration in the striatal extracellular fluid of the rat were the same as those in the nonlesioned rat.l‐DOPA was also administered to the rat after the striatal perikarya had been destroyed by the intrastriatal injection of kainate. The striatal dopamine concentrations of the lesioned rat changed in parallel with 5,7‐dihydroxytryptamine‐lesioned rats, as well as the nonlesioned rats. Moreover, when normal rats were administeredl‐DOPA, the dopamine concentration was not increased in the cerebellum, where dopamine neurons do not exist. From these observations, it is concluded that exogenousl‐DOPA is taken up, decarboxylated to dopamine, and released only in the striat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09286.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:For the quantitative analysis of vitamin D‐dependent 28‐kDa calcium‐binding protein (calbindin‐D) in the CNS, we have established a highly sensitive immunoassay method. The antisera were raised in rabbits with purified calbindin‐D from rat kidneys, and the antibodies were purified with a calbindin‐D‐coupled Sepharose column. The purified antibodies were specific for calbindin‐D, showing a single band on the immunoblot with the extract of rat kidney or cerebellum. The sandwich‐type immunoassay system was prepared by the use of purified monospecific antibodies, and the minimum detection limit of the assay was 0.1 pg or 3.6 amol of calbindin‐D, which was sufficiently sensitive for the measurement of calbindin‐D content in isolated Purkinje cell bodies at the level of single cells. The average content of calbindin‐D in a single Purkinje cell was 0.05 pg. Calbindin‐D was detected in most of the rat tissues examined, but it was present predominantly in the kidney and CNS, especially in the cerebellum. Calbindin‐D was detected at a similarly low level in the cerebral cortex, cerebellum, and brainstem of rat embryos of 15 gestational days, and it increased gradually but differently in these regions, reaching the respective adult levels by 4–5 weeks of postnatal age. In contrast, kidney calbindin‐D increased sharply between 15 gestational days and 3 postnatal days, reaching the adult level by 6 days of age. Calbindin‐D levels in the adult rat CNS were affected little by age, whereas the concentrations in human cerebral cortices were significantly low in the aged brain as compared with those in the young brain. However, the concentrations in various regions of cerebral cortex from patients with Alzheimer's disease showed values similar to those in the relevant regions of

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09287.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Neuropathy target esterase from hen brains was radiolabelled at the active site with [3H]diisopropyl phosphorofluoridate. The labelled protein was purified by differential centrifugation and Nonidet P40 solubilization, detergent phase partitioning, anion exchange, and preparative sodium dodecyl sulphate–polyacrylamide gel electrophoresis (SDS‐PAGE). The volatilizable counts assay and analytical SDS‐PAGE were used to monitor the protein. The 150‐kDa subunit polypeptide appears as a single band on analytical S

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09288.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:In vivo microdialysis in the frontal cortex of the freely moving guinea‐pig was used to measure extracellular 5‐hydroxytryptamine (5‐HT) and study terminal autoreceptor control of its release. The indoleamine levels were determined by HPLC with electrochemical detection. Release of extracellular 5‐HT and, to a lesser extent, 5‐hydroxyindoleacetic acid was sensitive to tetrodotoxin, confirming the neuronal origin of measured neurotransmitter levels. Both systemic and local administration of the 5‐HT1agonist 5‐carboxamidotryptamine caused inhibition of extracellular 5‐HT levels, confirming the regulatory role of the terminal, and possibly also the somatodendritic, 5‐HT autoreceptor on neuronal 5‐HT release. Levels of extracellular 5‐hydroxyindoleacetic acid were not affected by 5‐carboxamidotryptamine following either central or pe

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09289.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The conditions for optimal solubilization and reconstitution of bovine brain synaptic plasma membrane Na+/Ca2+exchange activity were examined and a series of chromatographic procedures were used for the isolation of a protein involved in this transport activity. The zwitterionic detergent 3‐[(3‐cholamidopropyl)dimethylammonio]‐1‐propanesulfonate in the presence of 20% (vol/vol) glycerol led to optimal solubilization, and soybean phospholipids in low‐pH medium were found to produce optimal reconstitution of activity after dialysis to remove the detergent. Sequential chromatography steps involving the use of gel filtration on Sephacryl S‐400 HR, ion exchange on diethylaminoethyl‐Sephacel, and metal chelate chromatography on tris‐(carboxymethyl)ethylenediamine loaded with LaCl3led to the isolation of a fraction highly enriched in both Na+/Ca2+exchange activity and two protein bands identified by denaturing electrophoresis. The estimated molecular masses of the two proteins were 50 and 36 kDa. Development of polyclonal antibodies to the 36‐kDa protein permitted immunoextraction of>95% of the antiporter activity from solubilized synaptic plasma membranes. These antibodies cross‐reacted with the electroeluted 50‐kDa protein on enzyme‐linked immunosorbent assays, suggesting a close relationship between the two proteins. These results indicate that the 36‐kDa protein is at least a component of the brain me

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09290.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The regulation of glutamate decarboxylase (GAD; EC 4.1.1.15) was studied by using cultures of cerebral cortical neurons from rat brain grown in serum‐free medium. About 50% of the neurons in the cultures were γ‐aminobutyric acid (GABA)ergic as determined by two double‐staining procedures. Immunoblotting experiments with four anti‐GAD sera that recognize the two forms to varying degrees, demonstrated that the cultures contained the two forms of GAD that are present in rat brain (apparent molecular masses = 63 and 66 kDa). GAD activity was reduced by 60–70% when intracellular GABA levels were increased by incubating the cultures with the GABA‐transaminase inhibitor γ‐vinyl‐GABA for>5–10 h or with 1 mMGABA itself. Neither baclofen nor muscimol (100 μM) affected GAD activity. Immunoblotting experiments showed that only the larger of the two forms of GAD (66 kDa) was decreased by elevated GABA levels. These results, together with previous results indicating that the smaller form of GAD is more strongly regulated by pyridoxal 5′‐phosphate (the cofactor for GAD), suggest that the two forms of GAD are regulated

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1992.tb09291.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY