摘要:

Abstract—The uptake of [2,3‐3H]γ‐aminobutyric acid (GABA) by bulk prepared neuronal perikarya, nerve endings and glial cells has been studied in anin vitro‐system. The uptake in the different fractions had a similar dependence for sodium, potassium and magnesium. Calcium stimulated the synaptosomal GABA uptake at concentrations which inhibited the glial uptake. Bicuculline strongly inhibited the uptake in all fractions. Picrotoxin and strychnine had little effect on the neuronal uptake whereas glial uptake was stimulated.l‐2,4‐di‐aminobutyric acid and chlorpromazine inhibited GABA uptake in all fractions. The effect of cyclic AMP was n

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03646.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—In Lewis rats with experimental allergic encephalomyelitis (EAE), quantitative histochemical techniques were used to measure the activities of several hydrolytic enzymes, especially acid proteinases, and their levels were correlated with the concentrations of DNA and total lipids. Only those samples which contained lesions (visualized directly or in stained nearby sections) had elevated acid hydrolase activities. A lipase‐esterase hydrolysing a fluorogenic substrate at pH 5.0 was more active in lesions; activity on the same substrate at pH 7.2 was not elevated. β‐Glucuronidase rather than acid proteinase or cathepsin D was the enzyme showing the greatest differences. In a monkey with EAE, studied for comparison, a massive inflammatory lesion appeared to leak β‐glucuronidase to a distance of about 2.5 mm beyond i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03647.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Activities of acid phosphatase, alkaline phosphatase and β‐glucuronidase have been estimated in the brain tissues, using various subcellular particles, in growing thyroidectomized rats and also using cytoplasmic extracts free from debris and nuclear fraction in young hypothyroid animals. Hepatic glucose‐6‐phosphate dehydrogenase activity was markedly reduced after thyroidectomy but the enzyme was brought back to normal levels by thyroxine treatment. There was no change, however, in the activity of neural glucose‐6‐phosphate dehydrogenase after thyroidectomy. In the thyroidectomized animals an increase only in the free acid phosphatase activity in the neural synaptosomes was found and this increase in activity was not counteracted by administration of thyroxine. In the hypothyroid young animal β‐glucuronidase, acid phosphatase and alkaline phosphatase activities were found to be affected dur

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03648.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—The effect of 1‐hydroxy‐3‐aminopyrrolidone‐2(HA‐966), a CNS depressant, was studied on the metabolism of [14C]glucose and [3H]acetate in the brain in mice. HA‐966 had a marked effect on glucose metabolism. The conversion of glucose carbon into amino acids associated with the tricarboxylic acid cycle (‘cycle’) was severely reduced, while the concentration of brain glucose was approximately doubled. Relative to the specific radioactivity of glucose in the brain, the specific radioactivity of alanine was 60–70 per cent of the control, indicating a reduction in the rate of glycolysis, and those of the‘cycle’amino acids were also lowered. A reduction in‘cycle’flux of 30–35 per cent was estimated. It was established that the depressed glucose utilization flux was not due to either impaired uptake of glucose from blood to brain or to hypothermia. In contrast to [14C]glucose, there was no change in the labelling of the amino acid fraction from [3H]acetate, which is preferentially metabolized in the 'small’compartment believed to be associated with glia. Thus it seems that CNS depression caused by HA‐966 resulted in a selective decrease in energy production in the‘large’metabolic compartment where glucose is oxidized preferentially and which is believed to be associated with neuronal structures.The results also suggested that communication between the metabolic compartments mediated via glutamine and GABA was reduced, since the labelling from [3H]acetate of glutamine was increased

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03649.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—l‐Glutamine is taken up into rat brain slices by a specific‘high affinity’uptake system (Km52 μm) which is not influenced by high concentrations ofl‐glutamate andl‐asparagine. The uptake system appears to be associated with cellular structures that do not survive homogenization under conditions which yield synaptosomes. The‘high affinity’uptake of glutamine is dependent on the external sodium ion concentration and can be inhibited byp‐chloromercuriphenylsulphonate, amino‐oxyacetic acid, ouabain, dibenamine and allylglycine. The effects of several inhibitors indicate thatl‐asparagine uptake is mediated by a system different from the‘high affinity’system m

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03650.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Isolated rat posterior pituitary glands were incubated with [14C]glucose or [14C]acetate and the incorporation of radioactivity into several amino acids was followed. The results indicated that radioactivity was incorporated from [14C]glucose into a large pool of glutamate which appeared to be responsible for a large proportion of GABA synthesis in the gland. The specific activity of glutamine was always less than that of glutamate when [14C]glucose was the precursor employed, whereas [14C]acetate labelled a glutamate pool which had approximately the same specific activity as that of glutamine. The results are discussed with reference to the compartmentation of amino acid metabolism in the nervous syste

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03651.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—An attempt was made to isolate the saturable uptake from the unidirectional influx of amino acids into tissue slices and to estimate the transport constants and maximal velocities of saturable transport. The method was applied to studies on the inhibition of phenylalanine in the saturable influx of tyrosine, tryptophan, histidine and leucine into brain cortex slices from adult and 7‐day‐old rats. In both age groups phenylalanine inhibited the influx of the other amino acids, and vice versa. The apparent transport constants of the other amino acids increased in the presence of phenylalanine more noticeably in the slices from 7‐day‐old rats than in those from adult rats, whereas the concomitant influx of phenylalanine was inhibited less in the slices from 7‐day‐old rats. In immature animalsin vivocompetition between amino acids may play a more marked role in the supply of amino acids from plasma to brain, as the transport systems in brain slices from 7‐day‐old rats become saturated with extracellular amino acids more readily than do the transport systems in brain slice

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03652.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—Methods for the determination of methyl‐lysine, methyllarginine and methylhistidine residues of tissue proteins are described. They consist of preliminary purification of basic amino acids, enzymic removal of lysine, arginine and histidine followed by amino acid analysis. Recovery rates and specificities of the method were satisfactory. The contents of methylamino acids in proteins of mammalian organs were determined.The distribution of proteins containing the methylamino acids in human brain showed that the concentrations of methyl‐lysine andNG,N′G‐dimethylarginine were highest in the gray matter of the cerebellar cortex and relatively high in regions rich in gray matter, while those ofNG‐mono‐ andNG,N′G‐dimethylarginine were highest in the white matter. The following findings suggest that most of theNG‐mono‐ andNG,N′G‐dimethylarginine was associated with the myelin basic protein. The distribution of the methylarginine residues of acid‐soluble proteins in bovine brains coincided with the cerebroside pattern. The concentrations of the amino acids in acid‐soluble proteins of rat brain increased concomitantly with the increase of cerebroside. The methylamino acid content in proteins increased during the purification of the myelin basic protein from the white matter of human and bovine brains.Proteins containingNG,NG‐dimethyiarginine and di‐ and trimethyl‐lysine are concentrated in cell nuclei. The first amino acid was found mainly in nucleoplasmic proteins and the other two were found in histones. The concentration of 3‐methylhistidine residue, highest in muscular proteins, is low in cerebral proteins and is probably derived from proteins o

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03653.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—In the hypothalamus, the highest GABA content (approx. 26 nmol/mm3) was constantly observed in the lateral hypothalamic area (LHA). In other parts of the hypothalamus uneven distribution of GABA was also observed, but areas showing high concentration of GABA did not coincide with the locations of various hypothalamic nuclei. In the LHA, which is known to contain a feeding centre, the anterior part (6.4 and 6.0 mm anterior (A 6.4 and A 6.0) respectively to the vertical zero plane of de Groot) showed a remarkably high content of GABA. The GABA content in the LHA at A 6.4 was decreased during the initial phase of insulin hypoglycemia and, in contrast, showed a significant increase following hyperglycemia induced by alloxan administration. In the ventromedial nucleus (VMH) of the hypothalamus, which is known to contain a satiety centre, the GABA content was increased during the initial phase of insulin hypoglycemia.The results suggest that both certain parts of the LHA and VMH contain or receive GABA‐inhibitory neurons and that these neurons may play important physiological roles in controlling functional states of the feeding and satiety centres in the hypothala

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03654.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Abstract—The two enzymes methylating myelin basic protein and histone were purified 170‐ and 250‐fold respectively from the cell sap fraction of rat brain. These enzymes methylated only arginine residues of the two proteins. The enzyme activities were present in all organs tested. Testis has the highest, brain a moderate and liver the lowest activity. Most of the activities were present in the cell sap fraction in brain, liver and testis. Methylation of myelin basic protein and histone was examined in both the cell sap and solubilized nuclear fraction of rat brain during life span after birth. The myelin basic protein methylating activity in the cell sap fraction increased during myelination. Histone methylase from the nuclear fraction was highest at birth and dropped rapidly thereafter. The other activities remained unchanged. The natural occurrence ofNG‐mono‐ andNG,NG‐dimethylarginine residues in histones prepared from rabbit liver was d

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1975.tb03655.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY