摘要:

AbstractPhenol sulphotransferase activity in homogenates of rat liver and brain was determined spectrophotometrically. Rat liver had about 100‐fold more phenol sulphotransferase activity than brain; however, both tissues showed about the same spectrum of activity towards the phenolic compounds tested. Dopamine and its acidic and neutral metabolites and the neutral metabolites of norepinephrine were the compounds most readily sulphury‐latedin vitro. They were also the compounds most readily sulphurylatedin vivowhen they were injected intraventricularly together with labelled Na2SO4. When labelled Na2SO4was injected alone, we detected conjugation of endogenous phenols. One of the compounds formed was identified by its chromatographic characteristics as 3‐methoxy‐4‐hydroxy‐phenylethyleneglycol sulphate. We detected other conjugates which appeared to be the sulphate esters of 3,4‐dihydroxyphenylethyleneglycol; 3,4‐dihydroxyphenylacetic acid; and homovanillic acid. In brain, sulphate conjugation may be a major route of metabolism for many of the phenolic compounds related to the biogenic amines and possibly for phenolic drugs which

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04220.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe free amino acid levels in the peripheral nerve of the crab,Carcinus maenas, have been measured using various extraction procedures. A comparison of the amino acid levels of the peripheral and central nervous system of the crab has revealed marked differences in the levels of certain amino acids. Aspartate and glutamate were much lower in central nervous tissue than peripheral whilst glycine was much higher. The results are discussed in relation to the extreme steepness of the concentration gradient for amino acids across the neuronal membranes of crustaceans and a comparison is made with other groups. The significance of the differences in amino acid concentration in specific areas of nervous tissue is discussed in relation to the functions of the amino acids and to possible transmitter activity.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04221.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractA method is presented for the rapid separation of cell nuclei from the rabbit cerebral cortex into two populations. The first of these consists largely of nuclei with the morphological characteristics of neuronal nuclei, the second almost entirely of nuclei with the morphological characteristics of glial cell nuclei. From studies based upon sensitivity to the toxin α‐amanitin, the ratio of incorporation of different bases, ionic requirements and differential sensitivity to actinomycin D, it is concluded that under both the classical low and high salt conditions described by other workers, two enzymes are active in RNA synthesis. The presence of a third enzyme of low activity cannot be excluded. No qualitative difference in the number of enzymes involved in RNA synthesis in neuronal and glial cell nuclei has been found, but there are quantitative differences in activity between the two nuclear populatio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04222.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractMonoamine oxidase (MAO) in crude mitochondrial preparations from rat brain was solubilized, and different MAO‐active fractions were separated by agarose columns and by Sephadex electrophoresis. Any combination of these techniques yielded at least three fractions possessing MAO activity as measured by assays using radioactive serotonin and benzylamine as substrates. The molecular weight of one of the MAO forms was found to be approximately 400,000 daltons while another was at least 1.5 × 106daltons. The crude mitochondria1 MAO was inhibited by [14C]‐labelled pargyline and then solubilized and the radioactivity of the soluble and particulate MAO was compared to the enzyme activity found in the soluble and particulate fractions. Our studies suggest that appreciable MAO activity is lost upon solubilization and that the conformation of MAO may be alt

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04223.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe presence of cholest‐5‐ene‐3β, 24‐diol (cerebrosterol) in samples of human, bovine, and rabbit brains has been established by isolation of the sterol therefrom and identification by comparison of physical properties. Cholest‐5‐ene‐3β, 24‐diol was present at the level of 66.5 sg/g of dried tissue in human brain, 42.9 μg/g in cattle brain, and 89.5 pg/g in rabbit brain. Cholest‐5‐ene‐3β, 24‐diol was the only readily detectable hydroxycholesterol derivative in these brain tissues and was concentrated in the 105,000 g pellet (microsomal fraction) of both human and bovine cerebral cortex, with no demonstrable amounts of the sterol present in nuclear or mitochondrial fractions. Incubation of [1,2‐3H]‐ or of [4‐14C]‐cholesterol with the 105,000 g microsomal pellet from bovine cerebral cortical homogenates demonstrated 0.1‐0.38 per cent conversions to radioactive cholest‐5‐ene‐3β, 24‐diol, isolated and purified as the 3β, 24‐dibenzoate. The bioconversion required oxygen, and a stimulation of hydroxylation by added NADPH2was demonstrated. Our observations establish that a sterol 24‐hydr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04224.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe levels of dopamine and norepinephrine were determined in the brains of fetal and newborn rats by means of a sensitive, radiometric‐enzymatic assay. Catecholamines were converted to their 3‐O‐methylated derivatives in the presence of catechol‐O‐methyl transferase (EC 2.1.1.1) and [3H‐methyl]S‐adenosylmethionine; and the [3H]‐derivatives were isolated by selective extraction. The assay had a sensitivity for dopamine and norepinephrine of 100 picograms and was linear to at least 30 nanograms of catecholamines. Both amines were present at 15 days of gestation and increased 15‐fold in content during the last week of gestation. The regional distribution of these neurotransmitters in the brain of the newborn rat correlated with the distribution of their biosynthetic enzymes. An investigation of the effects of reserpine, pheniprazine, α‐methyl‐para‐tyrosine, diethyldithiocarbamate andl‐DOPA on the levels of dopamine and norepinephrine in the brains of the 18‐day gestational fetus indicated that the levels of these neurotransmitters are under controls similar to those known to occur i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04225.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractNewly‐weaned male guinea pigs were fed an ascorbic acid‐deficient dietad libitumand compared with control animals pair‐fed an adequate diet for a similar duration. The ascorbic acid‐deficient animals demonstrated prominent elevations in serum concentrations of tyrosine (+427%), phenylalanine (+36%) and arginine (+21 %) with concomitant depressions in levels of glycine (–57 %), histidine (–39 %), ethanolamine (–38%) and glutamic acid (–22 %). With few exceptions, the alterations in the liver amino acid profiles were in the same directions as those observed in the serum. The scorbutic brains showed 28–36 per cent of the retention of total ascorbic acid found in control animals and were characterized by marked elevation (+83%) in tyrosine content, hardly any alteration in phenylalanine (–9%), and depressed levels of histidine (–33 %), arginine (–25%), phosphoserine (–50%) and GABA (–12%). The implications of such abnormal changes in free amino acid patterns were evaluated in the light of the role of some of these amino acids as precursors for the synthesis of neuroregulatory substances. No difference was observed in the brain polysomal profiles as isolated from the two groups of animals. Incubation of polysomes from ascorbic acid‐deficient brains with autologous pH 5 enzyme derived from cell sap not passed through Sephadex G‐25 revealed low uptake of [14C]phenylalanine in comparison to that for a similar system from control animals. Use of pH 5 enzymes prepared from Sephadex‐treated and dialysed cell saps eliminated the difference in specific activities of the two groups of ribosomes, an observation suggesting that ascorbic acid deficiency either intensified the activity of the inhibitory components or reduced the low molecular weight stimulatory substances present under normal conditions in

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04226.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractFreezing epileptogenic lesions were made unilaterally in rat cerebral cortex. Such lesions were associated with an increase in adenyl cyclase activity and a decrease in the membrane‐associated phosphodiesterase activity, with a concomitant increase in the level of cyclic AMP. Similar, though less striking, changes occurred in homologous contralateral cortex (‘mirror focus’). The effects of cyclic AMP on brain membrane systems are discussed, with the suggestion that this substance may play an important role in the genesis of focal sei

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04227.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractUsing the technique of measuring DNP‐amino acid methyl esters by gas‐liquid chromatography, the distribution of alanine, proline, glycine, GABA, glutamate and aspartate was determined in individual ganglia and the associated nerve bundles between these ganglia after isolation from the nervous system of the lobster,Homarus americanus. The brain or supraesophageal ganglion (27.2 mg) and the next 5 thoracic ganglia (varying from 24 to 10 mg in a rostral–caudal direction) as well as the nerve bundles connecting these ganglia were used. GABA and aspartate values varied the most among the individual ganglia; highest values were found in the second and third thoracic ganglia. The levels of alanine, proline, glycine and glutamate varied very little from ganglion to ganglion; however, the values for these amino acids did exhibit some variability among the individual connectives. The highest value for each was in the nerve bundle between the first and second thoracic ganglion. Glycine was present at the highest level of any of the amino acids whereas GABA was at the lowest level in the individual structures as

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04228.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractDevelopmental changes in mechanisms of synaptosomal amino acid transport have been studied in rat cerebral cortex. Well‐defined changes over an age continuum could be observed in both the rates of amino acid accumulation and the effects of Na+on the accumulation. The uptakes of five amino acids (threonine, serine and valine in Na+‐free medium, aspartic acid and proline in Na+‐containing medium) increased progressively with the age of the animal, whereas the uptakes of leucine and arginine (in Na+‐free medium) decreased steadily. The uptake of serine or threonine by synaptosomal fractions prepared from newborn rats was markedly dependent on the presence of Na+in the incubation media. Na+exerted progressively less effect on the accumulation process with continuing postnatal development and to some extent inhibited uptake by fractions obtained from rats older than about 15 days. Na+significantly enhanced the accumulation of glycine in fractions from newborn and adult rats, but had only a slight effect in fractions prepared from 12 to 17‐day old rats. A detailed study of the accumulation of glycine indicated that the synaptosomal transport of this amino acid proceeded by two independent systems, one of which was totally dependent on external Na+and the and adult animals than in fractions from 12 to 17‐day‐old rats, wheras the Na+‐independent system was most active during this latter period of development. The decline in the Na+‐independent accumulation of glycine from about the 15th day to adulthood was characterized by a decrease in the Vmax. and an i

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1973.tb04229.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY