摘要:

AbstractThe effects of catecholamines (CA) and certain related compounds in the superfusate were examined on the intracellularly recorded potential from horizontal cells in the fish (Eugerres plumieri) retina. The stimulated retinal area consisted of a central spot 1.0 mm in diameter and an annulus 2.0 mm in inner diameter and 4.0 mm in outer diameter; both forms of monochromatic stimuli were centered relative to the recording microelectrode. Each of the CA (dopamine, noradrenaline, and adrenaline) produced an analogous effect on the hyperpolarizing response of all types of horizontal cells. The depolarizing response of the C (R/G)‐type cells was found to change variably with the CA. The effect of dopamine (DA) among the CA was most pronounced when they were used at an equivalent amount. With 10–50 μM, the action of DA was variable but in general its effect was to increase slightly both center and surround responses. In some cases, however, DA initially augmented the surround and reduced the center response. Large amounts of the CA (100–200 μM) augmented the center response and attenuated the surround response considerably; these reciprocal changes usually were associated with moderate depolarization of the cells (5–10 mV). Recovery then occurred in 15–20 minutes. These results indicate that the CA, up to a certain amount, do not directly affect the transmission from photoreceptors to horizontal cells, since the center response became larger. At the same time, the lateral propagation of an S‐potential appears to be selectively affected by the CA, suggesting that the adrenergic system participates in this phenomenon. When an excess of these compounds (200–500 μM) was given, the cells were rapidly depolarized to near 0 mV and eventually the light‐induced responses were abolished. Large amounts (5–10 mM) of metabolic products of the CA (DOPAC and VMA) were found to reduce the center response slightly more than the surround. α‐Methylnoradrenaline, 5‐hydroxydopamine, and serotonin also caused the same but less effect on horizontal cells as did DA. Reserpine and clonidine mimcked the CA effect only if these compounds had been preceded by repeated applications of one of the CA or if the retina had been pretreated with Marplan®. Propranolol, haloperidol, and apomorphine affected neither the horizontal cell membrane potential nor the CA effect. However, phentola‐mine in large amounts (500 μM) markedly diminished the DA action. Therefore, α‐adrenergic receptors appear to he involved in the UA‐induced changes observ

ISSN:0360-4012    

DOI:10.1002/jnr.490040502

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

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of acetylcholine (ACh) on cone‐ and rod‐connected horizontal cells (generating photopic and scotopic L‐type S‐potentials, respectively) in the fish (Eugerres plumieri) retina was compared with that of dopamine (DA), and some similarities were found in the effects. About two‐thirds of the L‐type horizontal cells examined were sensitive to a test solution containing ACh (10 mM in concentration) and BW‐anticholinesterase (BW; 1.0 mM). ACh with BW augmented a center response and attenuated a surround response as did DA (0.2 mM), although the latter effect was more pronounced and longer‐lasting. ACh with BW frequently produced oscillations of the horizontal cell membrane potential as did DA with clonidine (α‐adrenergic stimulant). Phentolamine (α‐adrenergic blocker) interrupted both the effects of DA and ACh on the center and surround responses, while hexamethonium (cholinergic antagonist) appeared to interfere selectively with the effect of ACh. Therefore, the ACh‐induced changes observed in the horizontal cell membrane potential are assumed to be mediated by the adrenergic sy

ISSN:0360-4012    

DOI:10.1002/jnr.490040503

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

年代:1979

数据来源: WILEY

摘要:

AbstractEffects of some amino acids on horizontal cells were examined in the fish (Eugerres plumieri) retina. L‐aspartate (5 mM in concentration) and L‐glutamate (10 mM) consistently depolarized all types of horizontal cells, although the effect of L‐aspartate was more pronounced. γ‐Aminobutyric acid (GABA; 10 mM) consistently hyperpolarized the cone‐connected L‐ and C‐type horizontal cells, whereas the effect on the rod‐connected cells was slight or nonexistent. The hyperpolarizing effect of GABA on the cone‐horizontal cells was markedly diminished by picrotoxin (0.1 mM). Usually, glycine (10 mM) showed slight and variable effects. It merely depolarized some cone‐horizontal cells but weakly hyperpolarized some rod‐horizontal cells. In a few cases, however, glycine began to drastically hyperpolarize the cone‐horizontal cells in retinas that had been repeatedly treated with certain agents used. Taurine and β‐alanine (10 mM each) had negligible effects, although the former slightly depolarized and the latter merely hyperpolarized both con

ISSN:0360-4012    

DOI:10.1002/jnr.490040504

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

年代:1979

数据来源: WILEY

摘要:

AbstractA sensitive and convenient method of endopeptidase assay using as substrate globin modified with pyridoxal‐5‐phosphate was used for determination of acid proteinases in bovine hypothalamus separated by isoelectric focusing. The soluble protein fraction of hypothalamus upon elution from Sephadex gave five peaks of proteinase activity at pH 3.2. The properties indicate that these peaks of endopeptidase activity are isoenzyme forms of cathepsi

ISSN:0360-4012    

DOI:10.1002/jnr.490040505

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

年代:1979

数据来源: WILEY

摘要:

AbstractAs a follow‐up to a previous study that suggested that acutely administered ethanol could decrease steady‐state brain levels of sialic acid (SA), we evaluated the time course of the ethanol effect and tested the influence of route of administration and sex.Compared to the control treatments, ethanol (2 gm/kg) significantly decreased brain SA in each of the four brain regions that were tested. The decrease was evident by 30 minutes after ethanol administration, but peak effect was reached at about 1–2 hours. The decrease occurred with either injection or self‐administration, but the greatest decrease occurred in the self‐administration group. The SA‐induced decrease was greatest in females.An ancillary part of the study included measurement of brain levels of 2‐deoxyribose (DR). Ethanol given by either route of administration caused a preferential decrease in DR levels in the cerebellum.Lesser, but statistically significant, decreases in SA and DR occurred in controls, suggesting that these chemicals are sensitive to subtle environmental contingencies associated with the experiment

ISSN:0360-4012    

DOI:10.1002/jnr.490040506

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

年代:1979

数据来源: WILEY

摘要:

AbstractLesions of the cerebral cortex alter striatal neuronal vulnerability to locally injected kainic acid. Whereas extensive lesions involving the frontal‐parietal‐occipital cortex are most effective, lesions limited to the frontal or to the dorsal‐lateral parietal cortex offer partial protection. The extensive cortical lesions are associated with selective, marked reductions in the presynaptic markers for glutamatergic afferents in striatum. The protective effects of decortication appear between 6 and 24 hours the lesion and are maintained up to 30 days after decortication. Whereas decortication results in only a transient reduction of specific receptor binding of [3H] kainic acid to striatal membranes, lesion of striatal intrinsic neurons with kainic acid causes a delayed but marked reduction in specific binding of the ligand. Coadministration of L‐glutamic acid (1 μmole) with kainic acid (9 nmoles) partially restores the neurotoxic action of kainic acid in the decorticate striatum; GABA, alanine, and proline (1 μmole) are ineffective with regard to restoring kainate's toxicity for striatal GABAergic neurons. These results suggest that afferent input exerts a permissive effect on the neurotoxic action of kainic acid and that neurotoxicity may involve a cooperative interaction between kainic acid at specific receptors on vulnerable neurons and synaptically released endogenous neurotransmitters, in particular L‐gl

ISSN:0360-4012    

DOI:10.1002/jnr.490040507

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

年代:1979

数据来源: WILEY

摘要:

AbstractExperimental procedures are described which are believed to yield results that reflect, within certain limits, the in vivo changes of the size of the GABA pool in nerve endings in comparison with those of all other GABA pools. Two irreversible GABA‐T inhibitors, vinyl GABA and acetylenic GABA, two GAD inhibitors, 3‐mercaptopropionic acid and pyridoxal phosphate glutamyl‐γ‐hydrazone, and di‐n propylacetate, a clinically useful anticonvulsant, have been studied to determine their effects on GABA compartmentalization in mouse brain cortex.The changes elicited by these drugs in subcellular fractions of brain cortex homogenates support the notion that measurement of amino acid concentrations in crude synaptosomal fractions and in supernatant fractions under controlled conditions allow one to draw conclusions about relative changes of pool sizes in vivo. In particular this work showed that a specific increase in the concentration of GABA within the nerve endings is more important than a large increase of total brain GABA as a means of decreasing susceptibility to a variety of chemically or physically induce

ISSN:0360-4012    

DOI:10.1002/jnr.490040508

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

年代:1979

数据来源: WILEY

摘要:

AbstractAn acute dose of morphine increased brain tryptophan in mice. This effect was not prevented by naloxone nor was it produced by other narcotic analgesics. Dextrorphan, but not levorphanol, had a similar effect to morphine. A large dose of tryptophan had no effect on the antinociceptive action of morphine in mice. Morphine increased brain tryptophan in rats. This effect was prevented by naloxone. A large dose of tryptophan antagonised the antinociceptive action of morphine in the rat.

ISSN:0360-4012    

DOI:10.1002/jnr.490040509

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

年代:1979

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490040510

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

年代:1979

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490040511

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

年代:1979

数据来源: WILEY