摘要:

Abstract—Synaptosomes isolated from rat cerebral cortex converted [l‐14C]glucose more rapidly than [6‐24C]glucose to,14CO2. The ratio of C‐l: C‐6 in14CO2was 3‐9, thus suggesting that the hexose monophosphate shunt (HMP) pathway was functional in synapsesin vitro.When changes in the ratio of C‐l: C‐6 in14CO2were used as an index of shunt activity, glucose oxidation by this route was stimulated by electron acceptors as well as by neurohormones, including norepinephrine, acetylcholine and serotonin. Brain mince also exhibited a C‐l: C‐6 ratio of 3‐2 when short (15 min) incubations were employed. Negative results previously reported are attributable to prolonged incubation during which depletion of NADP or randomization of the labelled carbons in radioactive glucose could have occurred. Our experiments excluded the incorporation of glucose into macromolecules as a specific role for the hexose monophosphate pathway. The generation of NADPH for numerous metabolic reactions including the maintenance of membrane SH groups and the oxidation and hydroxylation reactions may represent the functions of the hexose monophosphate in synaptosomes and account for its stimula

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11386.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—Rats were injected intracerebrally with labelled tryptamine, 5‐hydroxytrypt‐amine (5‐HT) and norepinephrine (NE). The disappearance of the amines and their metabolites as a function of time was determined. Tryptamine disappeared very rapidly, with a half‐life of 5 min in normal animals and of 45 min in rats treated with a monoamine oxidase (MAO) inhibitor. The level of radioactive 5‐HT declined in two phases, with half‐lives of 45 min and 3 h respectively. The 5‐hydroxyindoleacetic acid (5‐HIAA) that was formed disappeared with a half‐life of approximately 1 h. After inhibition of monoamine oxidase, there was only a single phase of 5‐HT disappearance (half‐life of 4 h). Reserpine decreased and imipramine increased the amount of 5‐HT remaining 4 h after injection. Of the NE injected, 12 per cent was converted to methoxyhydroxyphenylglycol sulphate (MHPGS), which disappeared with a half life of 3 h. Reserpine doubled the amount of methoxyhydroxyphenylglycol sulfate formed, but did not alter its rate of disappearance, its peak concentration occurring about 30 min after injection of NE in both control a

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11387.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—In further experiments on the effects of antibiotic agents on protein synthesis in the goldfish brain, doses of intracranially‐injected puromycin or acetoxycycloheximide higher than those previously employed did not hasten the onset of inhibition of incorporation of intraperitoneally‐injected [3H]leucine into brain protein.The antibiotic‐resistant incorporation was not due to the presence of labelled blood protein in the brain. After the intracranial injection of labelled puromycin, the appearance of radioactivity in the acid‐soluble fraction of brain was blocked by acetoxycycloheximide. Repeated daily intracranial or intraperitoneal injections of puromycin were lethal, and acetoxycycloheximide was not protective, indicating that peptidyl‐puromycin was present in the brain but did not account for the lethality of puromycin. Behavioural experiments argued against but did not totally exclude the possibility that peptidyl‐puromycin was responsible for the amnestic effect of puromycin. Puromycin aminonucleoside, O‐methyl tyrosine and 5‐guanylyl methylenediphosphonate had little or no effect on protein synthesis in brain, but gougerotin was sl

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11388.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The formation of histamine in brain was studied in mice injected withl‐[14C]‐histidine (ring 2‐14C) intravenously (i.v.) or intracerebrally; [14C]histamine appeared rapidly and exhibited a rapid rate of turnover. Drugs known to block various pathways of histamine catabolism were tested for effects on brain–[14C]histamine and [14C]‐methyl‐histamine in mice given (1) [14C]histamine i.v., (2) [14C]histamine intracerebrally, and (3)l‐[14C]histidine i.v. Blood‐borne histamine did not enter brain; brain histamine was formed locally by decarboxylation of histidine Methylhistamine did cross the blood‐brain barrier. Methylation was the major route of histamine catabolism in mouse brain and some of the methylhistamine formed was destroyed by monoamine oxidase. No evidence for catabolism by the action of diamin

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11389.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The effects of accumulated endogenous GABA on the activity of L‐glutamic acid decarboxylase (GAD) were studied in mouse brain. When the content of GABA in the brain was increased after administrationin vivoof aminooxyacetic acid (AOAA), there was a reduction of GAD activity which could not be reversed by the addition of pyridoxal‐5′‐phosphate (PLP). Since inhibition of GAD activity by AOAA could be readily reversed by PLP, the reduction of GAD activity measured in the presence of added PLP indicated a decrease in the level of GAD apoenzyme. Similarly, increase of GABA content by hydrazine was also accompanied by a reduction in the level of GAD. Thiosemicarbazide and hydroxylamine did not affect the content of GABA appreciably, and in both cases levels of GAD remained unchanged when measured in the presence of added PLP. The correlation of the reduction in the levels of GAD with the increases in content of GABA suggests that GABA may regulate its own synthesizing enzyme by feedback r

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11390.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—The distributions of NADH2dehydrogenase, NADH, cytochromecreductase and cytochrome oxidase have been determined utilizing synaptosomal isolation techniques. Deoxycholate was used to determine compartmentation and/or ‘latency’ of these activities. NADPH, dehydrogenase proved to be a soluble and mitochondrial enzyme and the activity of this enzyme was not appreciably changed by deoxycholate treatment. NADHgcytochromecreductase proved to be a mitochondrial enzyme with considerable activity in microsomal fractions. Deoxycholate treatment increased activity in the synaptosomal fraction 8.3‐fold. A bimodal activation pattern was observed with synaptosomal and mitochondrial NADH, cyrochrome c reductase upon exposure to increasing concentrations of deoxycholate, with enhancement of activity at 0.25 % (w/v) and 0.50 % (w/v) deoxycholate. The enzyme was stable at concentrations of deoxycholate less than 0.25% (w/v) but was irreversibly inactivated at concentrations higher than 0.25% (w/v). The mechanism of this activation pattern appeared to be a combination of enzyme release and inactivation. Similar results were not observed in liver mitochondria.Cytochrome oxidase, a known mitochondrial marker, exhibited a 17‐fold increase in synaptosomal activity with deoxycholate treatment. The synaptosomal cytochrome oxidase activity after deoxycholate treatment approached the activity in the free mitochondrial fraction. The percentage of mitochondrial protein in synaptosomal fractions was estimated to be about 30 per cent from a comparison of the respective total (deoxycholate‐treated) activities. On the basis of these data we suggest that the synaptosomal fraction possesses a relatively sizable energy‐producing potential which may be of signif

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11391.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Abstract—A significant level of alcohol dehydrogenase activity has been demonstrated in the soluble fraction of rat brain. The pH optimum, kinetic properties and response to inhibitors are similar to those of liver alcohol dehydrogenase. The nutritional state of the animal, such as that associated with feeding or fasting, appeared to have no effect on the levels of the alcohol dehydrogenase activities in either liver or brain. A cerebral mechanism for the metabolism of ethanol may be involved in local biochemical adjustments in tissues during exposure to alcohol and may play a significant role in the pathogenesis of the neural disorders which can accompany chronic alcohol ingestion or acute withdrawa

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11392.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11393.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

摘要:

Littlework has been done on the chemical and physical properties of brain nuclear DNA. Recently DuBuy, Matternand Riley(1966) described the heat denaturation of mouse brain nuclear DNA, which apparently differs from the related mitochondrial DNA and the various protozoal DNA's tested. For such studies, it is essential to prepare the nuclear DNA from brain tissues in a native and highly polymerized state. In this brief communication preparation procedures of the native DNA from isolated brain nuclei are described, and some physical and chemical properties are given.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11394.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1970.tb11395.x

出版商:Blackwell Publishing Ltd    

年代:1970

数据来源: WILEY