摘要:

Abstract—Following head X‐irradiation (750 r) of 2‐day‐old rats the aerobic formation of lactate in the presence or absence of chloral was markedly increased in medulla slices but remained unchanged in cerebral cortex and brain stem slices. The ratio of lactate dehydrogenase (EC 1.1.1.27) to glycerolphosphate dehydrogenase (EC 1.1.1.8) was slightly increased in cortex and brain stem but more than doubled in medulla. The relation of the increased aerobic formation of lactate in irradiated medulla to the lactate dehydrogenase:glycerolphosphate dehydrogenase ratio is di

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06823.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Following hypophysectomy or adrenalectomy, glycerolphosphate dehydrogenase (GPDH) (EC 1.1.1.8) activity decreased exponentially in the cerebral hemispheres and brain stem of adult male rats. The latter region was more affected than the former. Malate dehydrogenase (EC 1.1.1.40), isocitrate dehydrogenase (EC 1.1.1.42), lactate dehydrogenase (EC 1.1.1.27) and mitochondrial glycerolphosphate dehydrogenase (EC 1.1.95.5) activities remained unchanged. Injection of adrenocorticotrophic hormone or cortisol in hypophysectomized rats or cortisol in adrenalectomized rats restored GPDH activity. Thyroidectomy and gonadectomy had no effect on GPDH activity. Liver GPDH was not decreased by hypophysectomy or adrenalectomy. Muscle GPDH was diminished slightly by adrenalectomy and as much as brain GPDH by hypophysectomy. In young rats GPDH developmental increase in activity was inhibited by hypophysectomy. These results clearly show that brain GPDH activity is specifically regulated by cortisol (and probably closely related corticosteroids

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06824.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Maternal pyridoxine deficiency begun 2 weeks before mating and continued throughout pregnancy and the nursing period resulted in diminished wt. gains in the brain, the liver and the body in the first 16 days of life, as well as lowered levels of the aromaticl‐amino acid decarboxylase in both brain and liver tissue. The fetus was protected from the effect of vitamin B6deficiency during pregnancy, since at birth the body wt., organ weights, and decarboxylase levels in these tissues were comparable to those of control litters. The brain was affected less than the liver, both in rate of wt. increase and decarboxylase activity.The cerebellum normally developed measurable decarboxylase activity only during the second week of life. The cortex normally slowly increased its low decarboxylase activity during the first week postnatally, with a more rapid increase during the second week. This rapid increase was primarily in the holoenzyme moiety. The rest of the brain, which had well developed levels of decarboxylase activity at birth, normally showed a sharp increase during the second week of life which was also largely in the holoenzyme portion. When the increasing weights of these tissues were considered, it became obvious that the total amount of apoenzyme as well as the amount of holoenzyme were increasing in the normally developing rat, although the greatest amount of the change was in the holoenzyme form.The liver normally showed a much more rapid increase in decarboxylase activity than did the brain, and showed the increase much earlier. The holoenzyme normally increased rapidly after the first 4 days, whereas the apoenzyme concentration levelled off at this time.The effect of the pyridoxine deficiency on decarboxylase activity was almost entirely on the holoenzyme form of the decarboxylase, since the apoenzyme form generally remained the same in the control and the deficient pups during development.There appeared to be no decarboxylase inhibitor present in pyridoxine deficient tissues, nor any evidence in control tissues for an enzyme required for the activation of the decarboxylase by cofac

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06825.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The effect of 4‐hydroxybutyrate (GHB) on cerebral glucose metabolism has been studied. GHB increases the glucose level, decreases the lactate concentration and diminishes the incorporation of glucose carbon into glutamic acid, glutamine, aspartic acid and GABA in the brain of the rat in a state of general anaesthesia. The data reported here suggest that GHB interferes in the metabolism of glucose in br

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06826.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Using either tryptophan or 5‐hydroxytryptophan as the precursor, and examining the metabolites in whole rat brain and in brain regions of dog, the pattern of metabolites resembled that found under physiological conditions only after tryptophan administration. From these and other observations on the cerebral 5‐hydroxyindoles the main conclusions are firstly, that there are regional differences within brain in storage, turnover or metabolic fate of 5‐HT. Secondly, that the normal pathway appears to be well localized biochemically with linking of its succeeding steps, and thirdly, that turnover through the system is normally controlled by intracerebral tryptophan 5‐hydroxylase in both rats and dogs although there are differences between the species in the cerebral metabolis

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06827.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Investigations of rat brain RNA were carried out by phenol extraction of the whole brain and chromatographic fractionation into ribosomal RNA and transfer RNA.(1) The amounts of both RNA species increase in the course of the animal's development reaching a maximum at about the tenth week of life. The ratio of both species remains constant throughout the growth to the twentieth week. After the rats had been trained how to reach their forage by balancing on a stressed rope, the rRNA content was found to be significantly higher, whereas the tRNA content was unchanged.(2) The portion of ribosomes bound in polysome complexes decreases with increasing age of rats. Conditioning of the animals brings about again an increase in polysome content. It is supposed that this reflects an enhanced synthesis of specific proteins in young developing rats and in the course of conditioning.(3) In young rats a second valine specific tRNA could be found as a minor component in addition to the major valyl‐tRNA. This additional component disappears as the animals advance to an age of 3 weeks and it could not be detected in the brains of rats after training experiments. In tRNAs specific for the amino acids leucine, lysine and phenylalanine no kind of deviation could be sta

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06828.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—The quantitative method of Ellman, Courtney, Andresand Featherstone(1961) was adapted to a differential assay for the determination of acetyl‐ and pseudocholinesterase activities of sympathetic ganglia of rats. The activities of the cholinesterases of superior cervical, stellate and thoracic chain ganglia and of the abdominal ganglionic complexes in apposition to the superior mesenteric and coeliac arteries (superior mesenteric, coeliac and cardiac ganglia) were measured. B.W.284C51 dibromide, 5 × 10−5m, and ethopropazine hydrochloride, 3·15 × 10−5m, were employed to inhibit selectively acetyl‐ and pseudocholinesterases, respectively. Linearity was shown to be maintained with enzyme concentrations corresponding to 0·12‐0·5 mg of ganglion (wet wt.)/incubation. Under the experimental conditions of this assay, the rates of the reaction of ganglionic acetyl‐ and pseudocholinesterases were linear for time periods greater than those employed for calculating the rates of hydrolysis in the homogenates of sympathetic ganglia. Several experimental approaches were used to ascertain the specificity of the inhibitors and of the reaction.Of the total cholinesterase activity of sympathetic ganglia of rats, 55‐63 per cent was due to acetylcholinesterase and 31‐39 per cent to pseudocholinesterase. On the basis of the specific enzyme activity, superior cervical, stellate and superior mesenteric ganglia contained higher acetyl‐ and pseudocholinesterase activities than did thoracic chain, coeliac and cardiac (abdominal) ganglia. The specific activity of acetylcholinesterase was similar in rat and cat superior cervical ganglia and sympathetic cervical trunks while the pseudocholinesterase activity of these two tissues was somewhat lo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06829.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Acetylcholine, 5‐hydroxytryptamine, and norepinephrine concentrations were measured in the telencephalon, diencephalon plus mesencephalon (midbrain), and pons‐medulla oblongata of rats exhibiting behavioral excitation while working on a Sidman avoidance schedule and injected with 50 mg/kg iproniazid 16 hr before being given 2 mg/kg tetrabenazine. Acetylcholine concentrations in all three brain areas decreased and returned to normal levels at different times. The time course of increased response rates correlated best with the acetylcholine levels in the telencephalon. Both the 5‐hydroxytryptamine and norepinephrine concentrations remained similar to the iproniazid control values during the period of behavioural excitation. However, the norepinephrine concentration in the midbrain showed a continuous decreasing trend toward naive control levels. These data suggest that changes in a cholinergic system in the telencephalon and a noradrenergic system in the midbrain operate in the maintenance of behavioural exc

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06830.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—A rapid accumulation of [3H]GABA occurs in slices of rat cerebral cortex incubated at 25° or 37° in a medium containing [3H]GABA. Tissue medium ratios of almost 100:1 are attained after a 60 min incubation at 25°. At the same temperature no labelled metabolites of GABA were found in the tissue or the medium. The process responsible for [3H]GABA uptake has many of the properties of an active transport mechanism: it is temperature sensitive, requires the presence of sodium ions in the external medium, is inhibited by dinitrophenol and ouabain, and shows saturation kinetics. The estimatedKmvalue for GABA is 2·2 × 10−5m, andVmaxis 0·115 μmoles/min/g cortex. There is only negligible efflux of the accumulated [3H]GABA when cortical slices are exposed to a GABA‐free medium. [3H]GABA uptake was not affected by the presence of large molar excesses of glycine,l‐glutamic acid,l‐aspartic acid, or β‐aminobutyrate, but was inhibited in the presence ofl‐alanine,l‐histidine, β‐hydroxy‐GABA and β‐guanidinopropionate. It is suggested that the GABA uptake system may represent a possible mechanism for the inactivation of GABA or some related substance at in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06831.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY

摘要:

Abstract—Monoamine oxidase (MAO) activity in the nuclei and tracts of the medulla and pons of the rat from birth to 90 days is reported.Prominent MAO activity was present in the locus coeruleus and nucleus ambiguus at birth. At 5 days a weak reaction localized mainly within the neuropil and glia cells was detected in several other nuclei. By 10 days all nuclei were identified with MAO activity varying from weak to intense, the activity showing further increases at 15 and 20 days. Staining in nerve fibres was negligible at 5 days but increased rapidly to 15 days in some tracts when the characteristic beading pattern was distinct. At 30 days differentiation in intensity of MAO activity between the nuclei diminished and no increase was apparent after 55 days.The results are compared with the distribution of brain stem acetylcholinesterase during maturation and also with regions specific in catecholamine or serotonin content in the adult rat brain stem.This and an earlier study on the cerebrum suggest that MAO is another component of the brain that falls into the caudal‐rostral concept of biochemical maturation and that it fits into a group of enzymes exhibiting a similar pattern of increase in activity during developm

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1968.tb06832.x

出版商:Blackwell Publishing Ltd    

年代:1968

数据来源: WILEY