摘要:

Abstract—Tyrosine hydroxylase (TH), dopa decarboxylase (DDC), glutamic acid decarboxylase (GAD), choline acetyltransferase (CAT), and acetylcholinesterase (AChE) were measured in 18–55 areas of brain from humans post mortem. Individuals meeting sudden and unexpected death (22), patients dying in hospital with non–neurological illness (6), Parkinson's disease (12), Huntington's chorea (8), terminal coma (6) or head injury (2) were included in the series. The absolute values obtained compared favourably with some previous human studies where high values for these enzymes were obtained, as well as with monkey and baboon data. The regional distributions of the enzymes were also comparable to those previously reported in human and animal studies. A number of important points with regard to human tissue seemed to emerge from the study. The mode of death was not a factor in enzyme levels in non–neurological and non‐coma cases. Post mortem delay did not seem to be a major factor either even though a substantial decline in GAD, TH and DDC could be demonstrated in rats left several hours between sacrifice and removal of the brain for assay. Age had a highly significant effect in certain areas of brain. The decline typically followed a curvilinear pattern (activity = A/age + B with the sharpest drops being in the younger age groups). DDC seemed to be the enzyme most severely affected by age but all the enzymes showed declines in certain brain areas, while in other areas there was no significant decline. All the enzymes were very depressed by coma from illness except AChE. TH and DDC in the brain stem were, however, not affected in the head injury cases. The Parkinsonian cases showed a sharply decreased TH activity in the substantia nigra, caudate and putamen. There were decreases in GAD in the globus pallidus (GP) and substantia nigra with marginal decreases in the neostriatum. CAT levels in the extrapyramidal nuclei were normal. In Huntington's chorea there was a substantial decrease in GAD in all the extrapyramidal structures. There was a patchy loss of CAT in the neostriatum and locus

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04437.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The profile of axonally transported [3H]leucine‐labelled proteins in motor fibres of rabbit cervical vagus nerve was studied at time intervals after the appearance of fast‐phase and before the slow‐phase proteins, viz. 16 h after labelling of the cell bodies. No moving peak of radioactivity was seen. The transport blocking agents colchicine and vinblastinein vitroshowed no difference in the mechanisms of anterograde transport between fast‐phase and later‐phase proteins, but differed in their effects on the retrograde flow. Double‐ligature experimentsin vitroindicated the presence of rapidly‐migrating labelled proteins in cervical vagus up to 23.5 h after labelling and demonstrated the retrograde redistribution of proteins from nerve terminals and from a ligature. There was no evidence for an intermediate rate of pr

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04438.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Nipecotic acid, a potent inhibitor of GABA uptake, is taken up by slices of rat cerebral cortex by a sodium‐dependent, ‘high affinity’ system (Km11 μM), and can be released from these slices by an increased potassium ion concentration in a calcium‐dependent manner. Nipecotic acid and GABA appear to be taken up by the same osmotically‐sensitive structures. GABA and substances which inhibit GABA uptake also inhibit the uptake of nipecotic acid. GABA can release preloaded nipecotic acid from brain slices, and nipecotic acid can release preloaded GABA. This indicates that GABA and nipecotic acid can be counter‐transported using the same mobile carrier. Nipecotic acid appears to have a higher affinity than GABA fo

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04439.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Transcription of repeated and unique DNA in rat brain nuclei was examined using a RNA‐DNA hybridization technique. Saturation hybridization experiments with a membrane filter showed that there were differences in the base sequence complements between labelled brain and labelled liver nuclear RNA. In competition hybridization experiments using a membrane filter, brain nuclear labelled RNA was in competition most effectively with unlabelled brain nuclear RNA, but less effectively with kidney or liver nuclear RNA. Experiments using a membrane filter loaded with isolated unique or repeated DNA fragments gave similar results. Furthermore, competition hybridization with a DNA excess also showed similar results at Cot 10,000. These results indicate the existence of tissue‐specificity in the transcription of unique and repeated DNA sequences in brain nuclei. Subsequently, rat brain nuclei were separated into neuronal and glial nuclear fractions for the purpose of detecting the cell‐specificity of RNA. The results of these experiments give evidence of significant differences in the transcription of unique DNA sequences, but indicate no differences in that of repeated DNA sequences between the two nuclear

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04440.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The release of newly synthesized acetylcholine (ACh) by cortical slices from rat brain in the presence of 25 mm‐KCl was studied. The slices were incubated for 5 min in a medium containing both [2‐14C]pyruvate and choline labelled with 3 deuterium atoms (choline‐d3) in order to label at the same time the acetyl moiety and the choline moiety of ACh. The non‐labelled ACh and the ACh‐d3were measured by pyrolysis‐gas chromatography/mass spectrometry, and the [I4C]ACh by liquid scintillation counting. It was found that the newly formed [4C]ACh as well as the newly formed ACh‐d3had a more than 2.5 times greater probability of being released than the preformed non‐labelled ACh. These findings strongly suggest that it is not simply the ACh synthesized immediately inside the nerve ending membrane from incoming undiluted labelled choline, which is preferentially released, but that all newly formed ACh has a greater probability of being released than preformed ACh. No preferential release of newly formed ACh was observed when the incubation medium contained 5.6 mm‐pyruvate instead of 10 mm‐glucose + 0.6 mm‐pyruvate. The cause of this differe

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04441.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—Changes in plasma and brain amino acids have been observed in adult rats 1 h after intraperitoneal injections of histidine and in others maintained on high histidine diets for 8 days. In the injection studies the compounds most consistently affected were the aromatic and branched chain amino acids and methionine. Reductions in their concentrations in the brain were explained by a competition with histidine for uptake into the tissue. There was little change in plasma amino acid levels. In the animals fed the highest concentration of histidine there was a generalized increase in brain, and a reduction in plasma, amino acid concentrations. A decrease in protein synthesis is postulated to explain this effect in brai

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04442.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The conversion of [l‐14C]palmitic acid to [1‐14C]hexadecanol has been demonstrated with a cell‐free system from developing rat brain. ATP, Coenzyme A and Mg2+were required for the activity. Fatty aldehyde was found to be an intermediate in this reaction. The conversion of fatty acid to fatty alcohol was mainly localized in the microsomal fraction and the formation of hexadecanol showed absolute specificity towards NADPH while fatty aldehyde was formed even in the absence of exogenous reduced pyridine nucleotides. The brain microsomes showed maximal activity with stearic acid and the activities with palmitic and oleic acids were 65% and 38% respectively of that with stearic acid. This enzymic reduction increased with age and showed a maximum in the 15‐day old

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04443.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—An unknown radioactive compound was detected in the basic fraction of the trichloroacetic acid extract of rat brain injected with radioactive putrescine. This compound was purified from bovine brain and identified as γ‐glutamylputrescine by comparison of its behaviour with that of the synthesized glutamylamides. The amide seemed to be metabolized as rapidly as putrescine in rat b

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04444.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—A study has been made of the release of glutamate and other amino acids from perfused leg preparations fromCarcinusandSchistocerca,at rest and during stimulation of motor nerves to the leg muscles. Stimulation caused an increase in release af many amino acids. No evidence was obtained to link glutamate release from such preparations with synaptic function. If release of transmitter glutamate is to be demonstrated in arthropods, techniques must be devised to avoid contamination with large quantities of non‐transmitter glutam

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04445.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Abstract—The kinetics of the uptake of various compounds into the crude mitochondrial fraction (P2‐fraction) of the pigeon optic tectum were studied. Aspartate, GABA, glutamate, glycine, proline and choline were taken up by high and low affinity systems. Only low affinity uptake was found for leucine and dopamine. The uptake for taurine was not saturable. The uptakes for all of the above compounds were temperature and sodium dependent. The high affinity system was more effected by sodium withdrawal than the low affinity system. Continuous sucrose gradients from 0.4 to 1.5mwere run with incubated P2fractions. Particle‐bound radioactivity sedimented in a density range of 1.0 to 1.2m‐sucrose. Additional experiments with glutamate showed that its uptake is competitively inhibited by aspartate. The addition of a 1000‐fold excess of glutamate to a P2fraction incubated at a concentration of 10–6m‐glutamate led to a massive decrease of particle‐bound radioactivity, suggesting a coupled action of up

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1976.tb04446.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY