摘要:

AbstractWe examined the development of cholinergic transmission at synapses formed in culture by retinal neurons derived from the embryonic chick. In our experimental system, striated muscle cells served as postsynaptic targets for cholinergic retinal neurons. Functional retina‐muscle synapses could be formed in cultures containing either retinal explants or dissociated retinal cells. Plating a low density of dissociated cells permitted the study of relatively isolated, visually identifiable, cholinergic neurons. We found that, early in the functional maturation of retina‐muscle synapses, the release of acetylcholine occurs spontaneously, but cannot be evoked by the putative excitatory transmitter, glutamate. This stage is followed by the emergence of transmitter release that is evocable by glutamate in a receptormediated and calcium‐dependent manner. This ability to transmit excitatory information across a synapse is expressed in culture by neurons derived from retinas that are at an early stage of morphoge

ISSN:0360-4012    

DOI:10.1002/jnr.490100302

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractCatechol estrogens, such as 2‐hydroxyestriol, 2‐hydroxyestradiol, and 2‐hydroxyestrone, inhibit human liver dihydropteridine reductase noncompetitively with Kivalues ranging from 1.5 to 4.6 × 10−6M. Catechol estrogens lose approximately half of their inhibitory potency if the C‐2 hydroxyl groups are methylated. Thus, 2‐methoxyestrogens have inhibitory potencies equivalent to those of their parent estrogens—estriol, estradiol, and estrone. Aromatization of ring B or stereoisomerism at C‐17 does not affect the inhibitory potency of estrogens, although stereoisomerism at C‐16 enhances the inhibitory potency of estriol. These results support the hypothesis that catechol estrogens may interfere with catecholamine metabolism by acting as inhibitors of enzymes involved in catecholamine metabolism, such as dihydrop

ISSN:0360-4012    

DOI:10.1002/jnr.490100303

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractEffects of glutamic, aspartic, and cysteic acid, and of kainic acid and N‐methyl aspartate on the release of labeled GABA, glycine, and taurine were examined in isolated, perfused chick retina. Glutamic acid (0.5‐2 mM), increased the release of3H‐GABA by more than four times and that of14C‐glycine by about two times. The release of GABA decreased 50% and that of glycine 95% in the presence of the antagonist of glutamic acid receptors, glutamate diethyl ester (300 m̈M). N‐methyl aspartate, used as an agonist of aspartic acid receptors, preferentially increased the release of GABA (seven times) over that of glycine (three times). The stimulatory effect of N‐methyl aspartate was antagonized by D‐α aminoadipate and by Mg. Kainic acid (10 m̈M) induced the release of glycine but not that of GABA. Cysteic acid failed to modify the release of any of the amino acids examined. The efflux of labeled taurine was practically unaffected by all the compounds utilized. The release of GABA by the excitatory amino acids and agonists was Ca‐independent but Na‐dependent, whereas the release of glycine was markedly Ca‐dependent. The evidence presented here suggests that experimental conditions activating receptors of excitatory amino acids differently affect the release of

ISSN:0360-4012    

DOI:10.1002/jnr.490100304

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThree incremental doses of recombinant α‐interferon (IF) were applied iontophoretically to hippocampal and hypothalamic cells. IF produced a dose‐dependent long‐lasting excitation in hippocampal neurons, whereas, in the hypothalamus α‐IF elicited biphasic responses. The highest IF currents induced changes in the amplitude of the action potentials on both structures. Our observations suggest that IF could have a selective effect on the specific area

ISSN:0360-4012    

DOI:10.1002/jnr.490100305

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractUptake and incorporation of3H‐valine into soluble protein of cultivated astroglial cells from newborn rat cerebral hemispheres increased after incubating the cells for 4 hr in 10−6or 10−5M morphine. The effects, inhibited by high naloxone concentrations, were not mediated by cyclic adenosine monophosphate (cAMP) activated binding sites for morphine or D‐alanine2‐methionine‐enkephalin‐amide (D‐ala2met‐enk‐amide). The cultures consisted of 60‐70% astrogliallike cells. By changing the kinetics of labeling it was shown that morphine affects protein synthesis of the cells in a concentration‐ and time‐dependent way. Even in the incubation medium increased amounts of labeled proteins were found in a time‐dependent way after morphine administration in different doses.Gel electrophoresis in sodium‐dodecyl sulphate (SDS) revealed that proteins with subunits in molecular weight (m.w.) regions of 40,000‐50,000 were increased in the cells and in the medium after morphine (10−6or 10−5M) treatment. Labeled proteins with subunits of ∼ 40,000 and ∼ 70,000 in the cells and medium, respectively, were decreased after morphine treatment.By exploring the field of glial protein metabolism after morphine treatment, information could be obtained on the interactions between astroglia and neurons in opiate

ISSN:0360-4012    

DOI:10.1002/jnr.490100306

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractThis paper analyzes the distribution of radioactivity in the different amino acids of brain myelin protein for up to 6‐7 weeks after an intracranial pulse administration of radioactive leucine, glycine, or methionine. Results show that there is no significant accumulation or reutilization of protein radiactivity in any form other than the one administere

ISSN:0360-4012    

DOI:10.1002/jnr.490100307

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractIn incubations of dissociated adult rat anterior pituitary cells with [32P]orthophosphate, carbamylcholine causes an increase in phosphatidic acid labeling accompanied by a small reduction in phosphatidylinositol labeling. Carbamylcholine and oxotremorine produce about the same maximum change while that caused by pilocarpine is smaller. Low concentrations of atropine, quinuclidinyl benzilate, and scopolamine completely inhibit the effect caused by carbamylcholine, whereas d‐tubocurarine does not decrease the stimulation, even at higher concentrations. The muscarinic antagonists alone produce a rise in phosphatidylinositol labeling and a drop in phosphatidic acid labeling, an effect opposite from that produced by the agonists, but d‐tubocurarine alone has no effect. Thus changes in phospholipid metabolism are mediated through muscarinic cholinergic receptors in dissociated rat anterior pituitary cells, confirming the presence of functional binding sites. The present studies also demonstrate the utility of experiments on precursor incorporation into phospholipids in identifying the existence on cells or tissues of certain receptor clas

ISSN:0360-4012    

DOI:10.1002/jnr.490100308

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractCultures of PC12 pheochromocytoma cells were established on a polyornithine substratum in medium supplemented with the chemically defined N1 mixture in the presence or absence of Nerve Growth Factor (NGF). Normal cell proliferation in the absence of NGF was equally competent when fetal calf serum (FCS) was replaced with N1‐supplemented medium. The differentiation of PC12 cells, which occurs upon NGF treatment, ultimately results in cell death without the addition of 0.1% FCS to the N1‐supplemented medium. The combination of N1, 0.1% FCS, and NGF permits the PC12 cells to develop a neuritic outgrowth much earlier than when higher (1—10%) FCS levels are used. Neurite retraction is caused in a dose‐dependent manner by a delayed presentation of FCS. Within 2 days of serum presentation, however, neurites regrow to achieve that percentage of neurite‐bearing cells which is seen without a serum challenge. Moreover, the retraction response becomes less pronounced with time over the 8‐day culture period for any given serum concentration. Among the N1 ingredients, only insulin and transferrin are needed by PC12 cells for survival whether in the dividing state or not. Neurite growth was not dependent on any of the N1

ISSN:0360-4012    

DOI:10.1002/jnr.490100309

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

摘要:

AbstractAssay conditions sensitive enough to measure prostaglandin (PG) biosynthetic capacity in discrete brain areas have been developed. Serial sections of the rabbit hippocampal formation were dissected from the brain, frozen, and 16 m̈m sections were cut and freeze dried. The assay was performed with 40—200 m̈g dry weight of tissue in a 30 m̈l incubation volume containing high specific activity arachidonic acid. The whole hippocampal formation slice or its subdivisions (subiculum, dentate gyrus, and hippocampus) when assayed individually demonstrated the ability to produce approximately 30—50 pmol/mg dry weight PGF2α, PGE2, and lesser amounts of PGD2(in a ratio of 1:0.8:0.3). A modest yet significant increase in PGE2production was measured in the dentate gyrus when compared to PGE2formation in the subiculum or hippocampus. An intact PGE2isomerase was confirmed in the hippocampal formation slice by incubations with PGH2endoperoxide. These results demonstrate that quantitative histochemical techniques can be used to measure PG metabolism in microscopic regions o

ISSN:0360-4012    

DOI:10.1002/jnr.490100310

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490100311

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1983

数据来源: WILEY