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Biomedical subjects

K S Raevskiĭ

Publications and source records attributed to K S Raevskiĭ.

At least 55 records · Page 3Linked to original sources
PubMed1984

[Effect of the atypical neuroleptics karbidin and sulpiride on the synaptosomal tyrosine hydroxylase of the corpus striatum of rats].

An in vitro study was made of the influence of the atypical neuroleptics sulpiride and carbidine on the activity of synaptosomal tyrosine hydroxylase (TH) of the rat brain striatum. Dopamine was applied as an inhibitor of tyrosine hydroxylation (10(-6) M), dopamine uptake was blocked by nomifensine (10(-5) M). The experiments were performed in two versions: in a medium containing common (5 mM) and depolarizing concentration of potassium ions. In both the cases sulpiride did not exert any noticeable effect on TH activity but significantly lowered the inhibitory action of dopamine. In a medium containing 30 mM potassium, carbidise inhibited the rate of TH hydroxylation and enhanced the inhibitory action of dopamine on TH activity under blockade of its uptake by nomifensine. It is assumed that the mechanisms of the action of carbidine and sulpiride are different.

Animals↗
PubMed1984

[Effect of butaclamol enantiomers on hypothalamic tyrosine hydroxylase in the rat brain].

The authors demonstrate stereospecificity of the action of butaclamol enantiomers on substrate inhibition of hypothalamic tyrosine hydroxylase (TH) and regulation of the tyrosine hydroxylase response by the presynaptic membrane (presynaptic receptors) of rat hypothalamus synaptosomes under membrane activation with dopamine. The effect of (+)-butaclamol on the substrate inhibition of TH was noticeable at a concentration of 10(-8)M, reaching a maximum at 10(-5)M. (-)-Butaclamol administered at the same concentrations did not influence the substrate inhibition of the enzyme. (+)-Butaclamol added to the incubation medium containing hypothalamic synaptosomes concurrently with dopamine (10(-5)M) completely blocked the regulatory action of the latter on TH, with this action mediated via presynaptic receptors. (-)-Butaclamol (10(-5)M) antagonized the action of dopamine under the same conditions. The data obtained indicate high stereo-specificity of butaclamol enantiomers as regards their effect on presynaptic regulation of TH, suggesting that elimination of the substrate inhibition of hypothalamic TH is a stereoselective effect of neuroleptics and can be a prognostically important criterion in the appraisal of compounds with potential neuroleptic activity.

Animals↗
PubMed1982

[Stereospecificity of the effect of flupenthixol isomers on the substrate inhibition of brain tyrosine hydroxylase].

Stereospecificity of the effect of neuroleptics on substrate inhibition of isolated brain tyroxine hydroxylase is shown. Flupentixole cis-isomer eliminates substrate inhibition of the enzyme. The effect is concentration-dependent and is well marked within the tyrosine concentration range 10-6-10-4 M. Flupentixole trans-isomer in the same concentrations has no effect on substrate inhibition of tyrosine hydroxylase. In the presence of cis-flupentixole, the reaction rate plotted against tyrosine concentration is a hyperbole with a plateau at 160-360 microM tyrosine. In the presence of trans-isomer, as in the control sample, the relationships between the reaction rate and tyrosine concentration are depicted by a curve with a maximum (at 110-140 microM tyrosine). Like ftorphenazine, flupentixole isomer fails to eliminate the inhibitory action of alpha-methyl paratyrosine, which indicates the interaction of neuroleptics with the tyrosine-binding site of the enzyme molecules in the noncatalytic centrer. It is suggested that the interaction of the neuroleptics with the regulatory area of tyrosine hydroxylase might by important in the molecular mechanism of their action.

Animals↗
PubMed1982

[Presynaptic component in the mechanism of fenibut action].

Superfusion of crude synaptosomal fractions from the rat brain cortex was used to study in vitro the effect of phenibut (beta-phenyl-GABA), a tranquilizing agent, on spontaneous and K+-stimulated release of 3H-GABA. It was found that phenibut in concentrations of 50 and 100 microM enhanced spontaneous tritium efflux by 15.9 and 30.7%, respectively. The effect of exogenous GABA in a concentration of 100 microM was 5 times more remarkable. The K+-stimulated release of the transmitter significantly increased under the effect of phenibut. Bicuculline counteracted this enhancement while picrotoxin did not effect the K+-stimulated egress of 3H-GABA. It is assumed that the presynaptic component described plays a role in the realization of the tranquilizing action of the tranquilizing action of phenibut.

Animals↗
PubMed1981

[Role of the GABA-ergic link in the development of the tranquilizing effect in cats].

The development of the tranquilizing effect of n-dipropylacetate (n-DPA) selectively increasing the GABA level in the nerve terminals was studied in experiments on cats in comparison with diazepam effect. The changes in the spectrum of emotional-behavioral reactivity were estimated. In doses of 50 and 200 mg/kg n-DPA caused a marked antiphobic effect which was not accompanied by the activating component characteristic of diazepam. The n-DPA-induced increase in the GABA level in the nerve terminals is suggested to be important for the development of the anxiolytic effect of tranquilizers. The total increase in the GABA level in the nerve terminals is suggested to be important for the development of the anxiolytic effect of tranquilizers. The total increase in the GABA content in the brain correlates to a greater extent with the sedative effect of drugs.

Animals↗
PubMed1981

[Nipecotic acid, a competitive inhibitor of the net uptake of 3H-GABA by rat brain synaptosomes].

The kinetics of inhibitory effect of nipecotic acid on two different types of 3H-GABA uptake (apparent uptake by intake and net-uptake by predepolarized synaptosomes) was studied. Nipecotic acid was shown to inhibit the net-uptake of 3H-GABA by competitive route. It is concluded that analysis of inhibitory, action of a substance and of its kinetics should by performed with due regard for at least two components; homoexchange of GABA which might reach 50-60% of total radioactivity taken up and the net-uptake of the neurotransmitter.

Absorption↗
PubMed1980

[Tranquilizing effect of n-dipropylacetate and other GABA-ergic substances in conflict situations].

Effect of n-dipropyl acetate (n-DPA), amino oxyacetic acid (AOAA), pantogam and piracetam on rat behaviour was studied under conflict situation. n-DPA, AOAA and piracetam increased significantly the main index of the tranquilizing action, that is the number of water intakes from the drinking bowl, supported by electric stimulation. This effect was most pronounced in n-DPA. Bicuculline and corasol almost completely eliminated the tranquilizing effect of n-DPA, while this effect was abolished by caffeine only by 50%.

Acetates↗
PubMed1978

[Tryptophan uptake by glia and synaptosomes of rabbit cerebral cortex].

The authors studied the engulfment of L-tryptophane-14C by gliacytes and synaptosomes of the rabbit cerebral cortex. The system of engulfment of the gliacytes was characterized by a high affinity to tryptophane (Km = 0.8 micrometer). Engulfment of tryptophane by synaptosomes had a lower affinity (Km = 50 micrometer). Psychotropic substances--chlorpromazine and imipramine produced an inhibitory influence on glial engulfment. The leading role of gliacytes in the trophic provision of the neurons and the normal course of neurodynamic processes is confirmed.

Animals↗
PubMed1977

[Uptake of gamma-aminobutyric acid by 3H-glial cells and synaptosomes of rat cerebral cortex under the influence of psychotropic substances].

Chlorpromazine was shown to inhibit non-competitively the 3H-GABA uptake both by the glial cells and synaptosomes; synaptosomal uptake was more sensitive to the inhibitor. Only the low-affinity GABA uptake in the glial cells was competitively inhibited by beta-alanine. On the whole, there was a correlation between the inhibition of GABA uptake by psychotropic drugs in the glial cells and in the synaptosomes. It is assumed that there existed two different systems of GABA uptake (of high and low affinity) in the nerve endings and glial cells.

Alanine↗
PubMed1976

[The effect of psychotropic substances on synaptosomal uptake of gamma-aminobutyric H3-acid and the activity of Na,K-ATPase].

The centrally acting drugs belonging to different groups--fluphenazine, trifluperidol, phthoracyzine, imipramine, diazepam, apomorphine, fentanyl, diphneylhydantoin, nonachlazine displayed in vitro an inhibitory effect on the uptake of gamma-aminobutyric acid by rat brain synaptosomes. A decrease in the activity of synaptosomal Na,K-ATPase was found in most cases. Drugs that failed to alter GABA uptake were as a rule found to be ineffective in relation to the enzyme activity (carbidine, morphine). GABA uptake was not affected by certain drugs inhibiting the Na,K-ATPase activity (azabuperon, tetrabenazine). It is supposed that the drugs used had at least two possible sites of action - Na,K-ATPase itself and hypothetic GABA transmembrane carrier.

Adenosine Triphosphatases↗
PubMed1976

[Effect of neuroleptics on tyrosine hydroxylase from rat hypothalamus synaptosomes].

A study was made of the effect of a number of neuroleptics of various chemical structure of tyrosine-hydroxilase isolated from the synaptosomes of rat hypothalamus. A direct spectrophotometric method of determination of the activity of the enzyme was used; it was based on measurement of the absorbence at 335 nm (at the isobestic point for oxidized forms of a synthetic cofactor 6,7-dimethyl-5,6,7,8-tetrahydropterine). At the tyrosine concentration of 0.15 muM haloperidol, haloanizon, and fluorophenazin were found to increase, and triperidol, droperidol and carbidin -- to decrease the initial rate of thyrosinehydroxilase reaction. All the neuroleptics under study proved to be capable of eliminating the substrate inhibition of the enzyme occurring with a rise of tyrosine concentration to 0.3 mM. The KM value for tyrosine failed to alter with the action of neuroleptics. The effect of neuroleptics was assumed to be of allosteric nature.

Animals↗
PubMed1975

[Effect of neuroleptics and antidepressants on the process of gamma-aminobutyric acid-H3 uptake by isolated rat brain nerve endings].

The effects of phenothiazine neuropleptics--chlorpromazine, trifluoperazine, fluphenazine and of antidepressants-imipramine and phthoracizine on the GABA-H3 accumulation by synaptosomes of the rat cerebral cortex were studied. All neuroleptics were found to inhibit the process of neurotransmitter uptake by the brain synaptosomes. Antidepressants were less potent. Chlorpromazine had the highest inhibitory effect on GABA uptake and phthoracizine--the lowest. It is suggested that the influence of neurolptics on GABA uptake could play a certain role in the mode of a synaptic action of these drugs.

Aminobutyrates↗