摘要:

Abstract:The binding of [3H]diazepam and [3H]ethyl‐β‐carboline carboxylate (β‐CCE) to rat brain membranes has been studied following injection of the ligand via a tail vein.“Ex vivo”binding was avoided by homogenising the tissue in an excess of unlabelled ligand. The dissociation rate constant for [3H]diazepam and [3H]β‐CCE was approximately 0.46 min−1at 0°C. Displacement of [3H]diazepam by β‐CCEin vivoshowed regional variation: the dose of β‐CCE required to inhibit 50% of [3H]diazepam binding in the cerebellum was one quarter of that required in the cortex, hippocampus, or striatum. However, when diazepam was used to displace [3H]β‐CCEin vivothe converse occurred: the dose needed for 50% inhibition in the cerebellum was more than four times that required in the other three regions. These findings support suggestions fromin vitroexperiments that two receptors exist with different affinities for benzodiazepines and β‐carbolines. The benzodiazepine receptor antagonist Ro 15–1788 did not differentiate be

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00856.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:In vivospecific binding of [3H]diazepam was not altered by a single electroconvulsive shock given 5, 30, or 60 min, or 24 h previously, nor 24 h after the last of 10 daily shocks. Similarly,in vivo[3H]ethyl‐β‐carboline carboxylate binding was not changed in the brains of animals that had been given a single electroconvulsive shock 30 min previously or a series of 10 daily shocks. Brain areas examined included cerebral cortex, hippocampus, cerebellum, and striatum. However, cortical binding of [3H]diazepam was increased by 32% in animals which were present in the same room while another was being injected and killed. This may represent a response to stress and/or anx

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00857.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The release of endogenous aspartic, glutamic, and γ‐aminobutyric acids (Asp, Glu, GABA, respectively) was measured in the effluent from superfused hippocampal slices using a new and sensitive mass spectrometnc method. The stimulation of the stratum radiatum of the rat dorsal hippocampus caused a Ca2+‐dependent increase in the release of these amino acids. This release was accompanied by an increase in the incorporation of [13C2from [13C]glucose into Asp, Glu, and GABA, suggesting an increase in their neosynthesis. The removal of Ca2+from the superfusion fluid brought about a marked decrease in Asp and Glu release at rest, and prevented their stimulation‐evoked release and the appearance of population spikes. The results support the hypothesis that Asp and Glu are excitatory neurotransmitters in intrinsic hippocampal circuits and are possibly released from the Schaffer collaterals and commissural fibres. The increase in GABA release and neosynthesis during stimulation of the stratum radiatum could be related to recurrent inhibition evoked by transsynaptic stimulation of the pyramidal

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00858.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The use of cholate (in the presence of sodium chloride) is described for solubilising brain D2dopamine receptors. The method described gives in high yield a preparation of solubilised D2receptors which when assayed by [3H]spiperone binding show little interference from nonspecific and nonstereospecific binding sites. Characterisation by ultrafiltration, electron microscopy, gel filtration, and sucrose density gradient centrifugation has been achieved, showing the receptors to be truly solubilised. Pharmacological characterisation using [3H]spiperone binding suggested the presence of serotonergic S2receptors in addition to D2receptors. The pharmacological properties of the solubilised D2receptors show a good correlation with those of membrane‐bound receptors, although ligand binding affinities are lower in the solubilised preparatio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00859.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:To determine the importance of dopamine and noradrenaline as neurotransmitters during chemoreception in the cat carotid body we investigated the contents of both compounds as well as the activity of dopamine‐β‐hydroxylase (DBH) under different arterial Po2and Pco2conditions. The superior cervical ganglion was used as a control organ. In the carotid body and the ganglion an inverse relationship exists between the catecholamine content and the DBH activity. The carotid body has a high catecholamine content with a low DBH activity whereas the superior cervical ganglion has a low catecholamine content and high DBH activity. Hypercapnia did not produce any significant change in the catecholamine content or in the DBH content of the carotid body. However, in comparison with hyperoxia, hypoxia produced a significant change (p<0.05) in the noradrenaline content without changing the DBH activity. The dopamine content under these conditions did not change significantly. The results may indicate that the high catecholamine content of the carotid body is the result of a high retention and/or low rate of degradation rather than of a high rate of synth

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00860.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:Analysis of mouse brain myelin by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed that in the high‐molecular‐weight range it contained, besides the Wolfgram protein doublet, proteins comigrating with actin and with both subunits of tubulin. The occurrence of these α and β subunits was confirmed by peptide mapping in myelin analyzed by two‐dimensional electrophoresis. This tubulin did not arise from an artifactual binding of soluble brain tubulin to the myelin fraction: addition of exogenously labeled tubulin to brain homogenates proved that during myelin isolation by the procedure of Norton and Poduslo (1973) the contaminating tubulin was washed out. On the other hand, the distribution of tubulin isoforms in myelin was investigated by isoelectric focusing and compared with the distribution of the 21 isoforms listed for the whole brain soluble tubulin. It was shown that many isoforms were found in myelin (three isoforms for the α subunit and nine for the β subunit), and that some isoforms were represented both in myelin and in soluble tubulin, but in different relative

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00861.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The binding of agonists and antagonists to muscarinic acetylcholine receptors on intact cultured cardiac cells has been compared with the binding observed in homogenized membrane preparations. The antagonists [3H]quinuclidinyl benzilate and [3H]N‐methylscopolamine bind to a single class of receptor sites on intact cells with affinities similar to those seen in membrane preparations. In contrast with the heterogeneity of agonist binding sites observed in membrane preparations, the agonist carbachol binds to a homogeneous class of low‐affinity sites on intact cells with an affinity identical to that found for the low‐affinity agonist site in membrane preparations in the presence of guanyl nucleotides. Kinetic studies of antagonist binding to receptors in the absence and presence of agonist did not provide evidence for the existence of a transient (>30 s) high‐affinity agonist site that was subsequently converted to a site of lower affinity.Nathanson N. M. Binding of agonists and antagonists to muscarinic acetylcholine receptors on intact cultured hear

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00862.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The effects of temperature on arachidonic acid‐induced cellular edema in the first cortical brain slices of rats were studied. Incubation of the cortical slice in arachidonic acid at 37°C induced cellular swelling, and increased intracellular Na+and lactic acid contents concomitant with decreased intracellular K+When the incubation temperature was reduced these changes were reduced in severity. The uptake of [3H]arachidonic acid in cortical slices was temperature‐dependent. The incorporation of [3H]arachidonic acid into various lipid fractions was further studied by HPLC. The majority of [3H]arachidonic acid was incorporated into triacylglycerol and phosphatidylinositol (PI), but the incorporation of [3H]arachidonic acid into PI was temperature‐dependent, unlike that into other phospholipids and neutrolipids. Further, cortical (Na++ K+)‐ATPase activity was inhibited whereas its subunit K+‐activatedp‐nitrophenyl‐phosphatase was activated by arachidonic acid at various incubation temperatures. The effects of arachidonic acid on these enzymes is similar to that of thimerosal, a lipid removal agent. These data suggest that both temperature and arachidonic acid play an important role in the development of cellular edema associated with membrane perturbation and inactivation of (Na++ K+)

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00863.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:Previously, we described a similar stimulating effect of adrenocorticotrophic hormone (ACTH) and ACTH‐related synthetic peptides on triacylglycerol (TAGL) and acylcholesterol (ACL) lipase activities of rat brain. In present study, TAGL and ACL activities from rat brain were further investigated and compared through the use of tri‐[3H]oleoylglycerol and [14C]oleoylcholesterol, respectively, as the substrates. A number of specific properties proved to be similar for both activities: (a) comparable rates of activity decay were observed upon heat treatment, (b) similar reaction kinetics as determined at different substrate concentrations with and without ACTH (10−4M), (c) both activities showed a common susceptibility to the presence of sodium taurocholate (5 mM) or trace amounts (5 μ/ml) of organic solvent in the assay medium, (d) the distributions of the two activities in various brain regions were comparable. Taken together, these data, along with the similar activability by ACTH, suggest a common structural basis for TAGL and ACL activities in rat

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00864.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Abstract:The relative amounts of the different enolase isozymes present in neuroblastoma cells change during differentiation. When differentiation is induced by low serum in the presence of DMSO (dimethyl sulfoxide), there is a 50% decrease in the concentration of enolase activity associated with the form αα, and an increase in the activity associated with the γ‐containing isozymes (αγ plus γγ); in the absence of DMSO, there is no decrease in αα or in total enolase activity. In order to study the mechanism of the changes in αα, cells differentiated with low serum with and without DMSO were compared. Measurements of the concentration of the α antigen by microcomplement fixation and by immunotitration demonstrate that the decreased enolase activity in DMSO cells is due to a decreased concentration of the α antigen. Measurements of the relative rate of synthesis of the antigen show that the decreased concentration of the α antigen is due to a decreased rate of synthesis. Enolase in differentiated cells is sufficiently stable (t1/2>100 h) that a comparison of the relative rates of degradation has not been possible. The decreased synthesis of the α subunit of enolase that occurs under these conditions appears to be a useful model system for studying the de‐expression of the α gene that occursin vivoduring neuro

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1983.tb00865.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY