摘要:

Abstract—Incubation with dibutyryl‐cyclic AMP increased levels of both noradrenaline and dopamine‐β‐hydroxylase in isolated rat superior cervical ganglia. Dexamethasone also increased the dopamine‐β‐hydroxylase content but did not affect noradrenaline levels. Cycloheximide blocked the effect of dibutyryl‐cyclic AMP on ganglion dopamine‐β‐hydroxylase but did not affect the rise in noradrenaline content.Dibutyryl‐cyclic AMP increased the synthesis of noradrenaline from [14C]tyrosine but not from [3H]DOPA.The results are discussed in terms of a possible role for cyclic AMP in the control of noradrenaline synthesis

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12171.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The activities and electrophoretic patterns of creatine and adenylate kinases in the mitochondrial and high speed supernatant fractions of adult mouse brain were determined. Approximately 22 per cent of the activities of both kinases is firmly bound to the mitochondria. On acrylamide gel electrophoresis of creatine kinase, in addition to the major band previously described, there were several other bands found. Although present in both the mitochondrial and supernatant fractions these additional protein bands with creatine kinase activity were significantly more intense in the mitochondrial fraction. There was only onesecondary band of adenylate kinase activity in the mitochondrial fraction but additional bands were found in the soluble fractio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12172.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Essential fatty acid deficiency was induced in mice after feeding a fatty acid deficient diet for 6 months. Activity of the (Na++ K+)‐ATPase in the total brain homogenates and in isolated synaptosomal plasma membranes was significantly higher (P< 0 05) in the deficient mice than the controls. Analysis of the acyl group composition of phosphoglycerides in brain as well as in the synaptosomal plasma membranes showed that mice fed the deficient diet had increased levels of 20:3(n‐9) and 22:3(n‐9) and decreased levels of 20:4(n‐6) and 22:4(n‐6). However, acyl group changes varied among individual phosphoglycerides and were most obvious in the two species of ethanolamine phosphoglycerides. A decrease in 22:6(n‐3) level was also observed in some phosphoglycerides of the synaptosomal plasma membranes especially the diacyl‐sn‐glycerophosphorylserine. In this experiment, a new solvent system for chromatographic separation of the diacyl‐sn‐glycerophosphorylserine and diacyl‐sn‐glycerophosphorylinositol was reported. The separation technique was suitable for analysis of acyl group composition of individual phosphoglycerides by gas‐liquid chromatography. The results were consislent with a positive correlation of the non‐polar acyl groups of brain membranes with the active ion transport activity. The increase in enzymic activity during deficient state may be the result of a biological adaptation due to structural alte

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12173.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—Glutamyl, glutaminyl. aspartyl and asparaginyl tRNAs of calf brain were analysed by reverse phase chromatography for isoacceptor tRNAs. The radioactivity profiles revealed two peaks for gluta‐mate. three for glutamine, two for aspartate and one for asparagine. Comparison of brain tRNAs with tRNAs from other sources showed that glutamate and aspartate tRNAs of brain closely resembled a majority of other tRNAs in the number and relative abundance of isoacceptors. Glutamine and asparagine tRNAs from different sources exhibited more marked differen

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12174.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The effect of sleep deprivation on thein vivoandin vitrotritiated amino acid incorporation into brain proteins was studied in the rat at three age levels. Sleep deprivation was induced either by water tank or handling methods. Three experimental groups of animals were used: control, sleep deprived and post deprivation sleeping rats.A significant decrease of protein synthesis was found in the cerebellum, telencephalon and in crude subcellular fractions of brainstem of adult rats selectively deprived of paradoxical sleep. However, no alteration of protein synthesis was observed eitherin vivoorin vitro, in the same brain regions or in the liver after the rebound of paradoxical sleep following deprivation.In four crude subcellular protein fractions a specific increase of thein vitrolabelled amino acid incorporation was observed in the brain stem of 24‐day‐old rats allowed to recuperate after sleep deprivation as compared with the deprived rats. No significant changes were seen in the telencephalon.No alteration of incorporation was found in 7‐day‐old rats deprived of sleep.The possible functional significance of these results is discussed in relation to stress and to variations in the size of the precursor pool for protein

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12175.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The accumulation of calcium ions by brain mitochondria and microsomes and by fractions containing neuronal or glial cells has been studiedin vitrowith techniques involving45Ca and ultramicro‐flame photometry. ATP and substrate‐supported calcium accumulation by brain mitochondria was of the same magnitude as for mitochondria from other organs. Brain microsomes accumulated calcium approximately 15 times less than brain mitochondria. Variations in Na+/K+ratios and in ATP/ADP ratios had a more marked influence on microsomal uptake than on mitochondrial uptake. The passive Ca2+binding by glial cells was higher than neuronal perikarya and synaptosomes. Also the calcium accumulation ability in cell suspensions was slightly higher for glial cells as compared to neuronal perikarya. The calcium uptake by glial cells was stimulated by high external K+concentration, which also was the case for nerve endings. The uptake in neuronal perikarya was unaffected by variations in K+concentration. A comparison between neuronal and glial mitochondria showed that both reach a steady state level of similar magnitude, but that the rate of initial accumulation was greater for glial mitochondria. A high glial calcium accumulation was also observed for the microsomal fra

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12176.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—For the GABA shunt to operatein rivo, GABA must be able to enter brain mitochondria. GABA causes reduction of intra‐mitochondrial NAD+; glutamate or 2‐oxoglutarate stimulate this reduction at concentrations at which they do not themselves cause reduction. This stimulation is not abolished by Triton X‐100. The rates of swelling of brain and liver mitochondria are similar in iso‐osmotic GABA and in several analogues. The rate of swelling is proportional to the concentration of GABA in the iso‐osmotic suspension medium. GABA penetrates 60% of the mitochondrial matrix volume, this value is unaffected by energizing the mitochondria. The activity of GABA‐oxoglutarate aminotransferase is not latent. We conclude that GABA diffuses into both brain and liver mitochondria as a species with no net charge at rates which are able to sustain maximum activity of t

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12177.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The incorporation of14C into amino acids of the brain was determined at different times after injection of [U‐14C]glucose and [U‐14C]ribose to rats maintained on thiamine‐supplemented and thiamine‐deficient diets for 22 days.The14C‐content of amino acids in the brain of thiamine‐deficient rats decreased at times 2–10 min after injection of [U‐14C]glucose. but it increased at 2 min and decreased at times 5–10 min after injection of [U‐14C]ribose.The results of labelling of amino acids indicated that the activitiesin vivoof the thiamine pyrophosphate requiring enzymes, pyruvate oxidase, a‐oxoglutarate dehydrogenase and transketolase were similar in the two groups. It was suggested that the observed decrease in the labelling of amino acids was due to one or more of the following factors: (i) a decrease in the activities of glycolytic enzymes catalysing the conversion of glucose into triose phosphate; (ii) a decrease in the transport of substrate to the active site of the enzymes; or (iii) altered neurohistopathology of the brain.Thiamine deficiency in rats showed a 5% decrease in glutamate (P<0–05), 46% decrease in threonine(P<0001) and 16% increase in glycine (P<0

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12178.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—The spontaneous efflux of [3H]GABA and its metabolites from the frog retina has been studied. The efflux of radioactivity was multiphasic in the presence or absence of amino‐oxyacetic acid (AOAA), an inhibitor of GABA metabolism, and was not affected by light or dark adaptation.Strong retention of radioactivity was evident in the presence of AOAA, about 90% of the label remaining in the tissue after 4 h superfusion. Under these conditions, increases in the rate of release of radioactivity were evoked by electrical stimulation, 40 mm‐potassium. unlabelled GABA (5 mm), ouabain (5 × 10−5m) and the absence of calcium. The amount of [3H]GABA released by electrical stimulation was not markedly calcium dependent, whereas the response to 40 mm‐potassium was reduced by 96% in the absence

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12179.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Abstract—When the electric organ of theTorpedofish was stimulatedin vivoandin vitro, there was a large rapid breakdown of creatine phosphate (CrP), and a slower decrease in the level of ATP. The acetylcholine content showed a parallel fall to that of ATP. Curare was used to interrupt synaptic transmission, allowing the presynaptic nerve endings to remain sensitive to stimulation, but simultaneously keeping electroplaques inactive. In stimulated curarized tissue, the level of ATP was not changed, while the breakdown of CrP was still 25% of that observed in non‐curarized controls. These observations suggest that presynaptic nerve endings, despite their small size, utilize a very high amount of ene

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1974.tb12180.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY