摘要:

Abstract:[3H]Sulpiride bound to rat striatal membrane preparations with a saturable, high affinity component. This binding was displaced potently by dopamine antagonists (both classic neuroleptics and the benzamide, sulpiride) and less potently by dopamine agonists. GTP and its stable analogue Gpp(NH)p did not affect [3H]sulpiride binding to the membranes but altered the affinity for dopaminergic agonists. This effect was specific in that antagonist binding was not affected and only GTP, GDP, and Gpp(NH)p produced the effect. Similar alterations in ligand binding affinity caused by guanine nucleotides have been observed for binding sites linked to an adenylate cyclase. Such an interpretation for the case of [3H]sulpiride is contrary to suggestions that sulpiride labels only those dopamine receptors that are not cyclase linked.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12530.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The distribution of methionine adenosyltransferase (MAT) in the CNS of the rat was studied by use of a rapid, sensitive and specific radiochemical method. TheS‐adenosyl‐[methyl‐14C]l‐methionine ([14C]SAM) generated by adenosyl transfer from ATP to [methyl‐14C]l‐methionine is quantitated by use of a SAM‐consuming transmethylation reaction. CatecholO‐methyltransferase (COMT), prepared from rat liver, transfers the methyl‐14C group of SAM to 3,4‐dihydroxybenzoic acid. The14C‐labelled methylation products, vanillic acid and isovanillic acid, are separated from unreacted methionine by solvent extraction and quantitated by liquid scintillation counting. Compared to other methods of MAT determination, which include separation of generated SAM from methionine by ion‐exchange chromatography, the assay described exhibited the same high degree of specificity and sensitivity but proved to be less time consuming. MAT activity was found to be uniformly distributed between various brain regions and the pituitary gland of adult male rats. In the pineal gland the enzyme activity

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12531.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Chronic administration of morphine to rats for a period of 4 weeks resulted in a 50‐60% decrease in the tissue concentrations of β‐endorphin and in thein vitrorelease from the neurointermediate pituitary. Incorporation of [3H]phenylalanine into isolated intermediate/posterior pituitariesin vitrorevealed a reduction in the amount of label incorporated into the β‐endorphin/ ACTH precursor to a similar extent (about 45%), but essentially no effect on the conversion of the precursor into β‐lipotropin and β‐endorphin. Extraction of mRNA from intermediate/posterior pituitaries followed by cell‐free translation in a reticulocyte system showed no significant decrease in the total level of translatable mRNA. In contrast, the content of translatable mRNA coding for the β‐endorphin/ACTH precursor was significantly reduced by 50‐60%. Thus, long‐term treatment with morphine appears to depress β‐endorphin formation in the rat intermediate pituitary at the pretranslational level by markedly decreasing the activity of mRNA coding for the β‐endorphin/ACTH precursor without any alteration in the

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12532.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Chicken gizzard extract contains a macromolecule(s) that promotes the neurite outgrowth of dissociated neurons from the ciliary ganglia (CG) of chick embryos. The factor in gizzard extract was partially purified and estimated to be about 12S (M.W. 200,000‐300,000) on sucrose density gradient centrifugation. The neurite outgrowth of CG neurons by the factor strictly depends on the embryonal age. The maximal neurite outgrowth was observed when CG neurons were dissociated from the embryos younger than 10 days. After that time the response of CG neurons to the factor rapidly declined and was almost lost at day 14. The amount of factor in the gizzard began to increase rapidly from 12‐day‐old embryo and reached the maximal level at day 16, and thereafter a fairly steady level was maintained. When CG neurons were co‐cultured with rat myotubes, the ratio of muscle cells with synaptic responses (miniature end‐plate potentials) was significantly higher in the presence of gizzard factor than its absence. The results suggest that this factor acts as an external signal on CG neurons to form synaptic connectio

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12533.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The effect of antibodies to GM1ganglioside on release of neurotransmitters from rat brain slices was studied. Depolarization‐induced (40 mM‐KCl or veratrine) release of γ‐aminobutyric acid was markedly enhanced. Depolarization‐induced release of norepinephrine was only slightly enhanced, whereas that of serotonin was unaffected. No effect on spontaneous release was observed for any of these three neurotransmitters. These results show that antibodies that can bind to synaptic membrane antigens may alter neurotransmitter release and that antibodies directed against GM1ganglioside exhibit a measure of specificity in producing such a

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12534.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The sex‐dependent differentiation of monoamine oxidase (MAO) in the hypothalamus of 60‐day‐old, Charles River rats was found to involve only type A (MAO‐A), and not type B (MAO‐B) enzyme.In vivoinhibition of type A by clorgyline, and type B by (−)deprenyl, however, tended to decrease the specific activity of both types of MAO to a smaller extent in the female than in the male hypothalamus. When masculinization was prevented by neonatal administration of estradiol (E) to males, hypothalamic MAO‐A and MAO‐B activities increased in both control and MAO‐inhibited rats. Androgenization of females, however, had little effect on the MAO activity. Whereas the effects of neonatal estrogenization were attributable neither to a direct influence of E nor to a sexual difference in the peripheral clearance of the MAO‐inhibitor used, single, high doses of steroids to adult, but not to newborn rats, did acutely affect the kinetics of MAO‐A. The activity of MAO‐A was also decreased by high concentrations of E or TSin vitro.The imprinting for patterns of hypothalamic MAO‐A and MAO‐B in the two sexes results, probably, from genetic predetermination. Neonatal changes in the homeostasis of gonadal hormones may result in type‐MAO nonspecific effects in adulthood, whereas the short‐term effects of high concentrations of steroids

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12535.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:The neurological mouse mutantdystonia musculorumexhibits bizarre appendicular and truncal dystonia without known cerebellar histopathology. We evaluated striatal dopamine and cerebellar norepinephrine metabolism in this mutant and compared the results with those obtained in wild‐type BALB/c and B6C3 controls. Tyrosine hydroxylase activity and dopamine metabolite levels (homovanillic acid and 3,4‐dihydroxyphenylacetic acid) in the striatum of the mutant were similar to controls. Tyrosine hydroxylase activity and the steady‐state level of 3‐methoxy‐4‐hydroxyphenethyleneglycol, a metabolite of norepinephrine, in the cerebellum were 38% and 42‐66%, respectively, greater in the mutant. However, the level of norepinephrine was similar (∼350 ng/g). Further, a Purkinje cell‐specific marker, cGMP‐dependent protein kinase, was unchanged in the mutant and no Purkinje cell pathology was observed with light microscopy. The lack of Purkinje cell derangement and similar levels of cerebellar norepinephrine and cGMP‐dependent protein kinase activity suggest that increased norepinephrine metabolism in the cerebellum of this mutant is not a morphological response to gross target cell loss during morphogenesis. The observed changes may be a reaction to abnormal impulse traffic or altered input/output pathways to the mutant cerebellum d

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12536.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract.Brains of rodents are primarily dependent on ketone bodies as a source of hydrogen for NADH and of acetyl‐CoA during the perinatal period characterized by suckling. A mouse dam begins to wean her pups at about 14 days of age (DOA), the same age at which the brain reaches near‐adult size and begins to shift to dependence on carbohydrate‐derived sources of acetyl‐CoA for normal function. Also at this time, the ear canals open, and mice of some strains become susceptible to audiogenic seizures (AGS). There may be a genetically determined derangement in the orderly transition from one source of brain energy to the other in AGS‐prone mice, with a concomitant brief (days) reduction in thein situenergy reserve during the transition. In mice with a decreased energy reserve, a large energy expenditure within a short period of time (s), such as that induced by a substantial acoustic stimulus to newly opened acoustic pathways, might briefly lead to CNS disorganization before body energy repletion processes may occur, resulting in the onset of an AGS. Since glucose, glycogen, ATP, and phosphocreatine provide the bulk of the brain energy reserve, a developmental study was performed to measure the concentrations of these metabolites in brain tissues of DBA/2J mice (genetically/developmentally susceptible to AGS: onset at 12–14 DOA, peak at 18–21 DOA, rapid decline until 30 DOA, essentially lost by 42 DOA) and in C57BL/6J mice (not developmentally susceptible to AGS). Samples of frontal, temporal, cerebellar, and diencephalic regions were taken from mice 0–44 DOA and assayed. With the exception of higher glycogen levels in both DBA and C57 mice in cerebellar and diencephalic samples 0–16 DOA, no regional differences were found. A decrease in glycogen in all regions was observed in DBA mice 16–30 DOA, which was the inverse of susceptibility to AGS in these mice. This dip was not found in C57 mice. ATP levels were elevated in DBA mice 14–18 DOA, and glucose levels were decreased in DBA mice 24–40 DOA. These data lend support to the hypothesis that lowered brain energy reserves, or lowered access to brain reserves, underlie

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12537.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:According to their solubilization properties, two classes of acetyl‐cholinesterases (AChE) can be detected in the adult rat brain: a “soluble” species (easily solubilized without detergent), and a membrane‐bound species (solubilized only in the presence of detergent). The latter was found to be homogeneous by gel filtration (Stokes radius 8.05 ± 0.35 nm) and sucrose gradient centrifugation (9.75 ± 0.2 S) in the presence of Triton X‐100. The “soluble” AChE gives three stable species in the presence of the same detergent with Stokes radii and sedimentation constants of 10.9 ± 0.5 nm and 16 ± 2 S; 6.75 ± 0.30 nm and 10.7 ± 0.4 S; 5.37 ± 0.35 nm and 4.37 ± 0.1 S. Co‐chromatography and co‐sedimentation or the reduction and alkylation of disulfide bridges show that all the soluble species are different from the membrane‐bound AChE. The possibility that soluble and membrane‐bound AChE are completely dif

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12538.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Abstract:Chemical ionization mass spectrometry was introduced for the assay of GABA in the cat brain. The method is quite simple, sensitive, and specific for quantitative analysis. Study of the regional distribution of the GABA content within the thalamus disclosed that the ventromedial nucleus (VM) of the thalamus had a high concentration of GABA. The VM receives the afferent projection from the zona reticulata of the substantia nigra. The result, together with the results obtained by physiological as well as pharmacological studies, supports the hypothesis that the transmitter substance of the nigrothalamic pathway is GABA.

ISSN:0022-3042    

DOI:10.1111/j.1471-4159.1982.tb12539.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY