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Biomedical subjects

V A Isachenkov

Publications and source records attributed to V A Isachenkov.

At least 19 recordsLinked to original sources
PubMed1990

[Effects of piracetam on pain sensitivity and levels of beta-endorphin in blood and cAMP in the cerebral cortex of rats].

It has been shown, that piracetam by i.p. injection (10, 100, 400 mg/kg) or by consumption with drinking water 10, 100, 1000 mg/kg/day during 12 days delays extinction of conditioned reflex of passive avoidance and dose-dependence elevates exploratory activity in "open field", pain sensitivity threshold reduces to 70-75%. Prolonged consumption of 1000 mg/kg/day piracetam results in 3-fold decrease of beta-endorphin concentration in plasma (p less than 0.01) and 100 mg/kg/day--in 35% increase of cAMP content in rat brain cortex.

Animals↗
PubMed1982

[Dependence on androgen metabolism in the hypophysis and hypothalamus on age in rats].

The in vitro metabolism of 3H-testosterone, 3H-dihydrotestosterone, 3H-5 alpha-androstan-3 alpha, 17 beta-diol and 3H-5 alpha-androstan-3 beta, 17 beta-diol was studied in hypophyses and hypothalamuses of the rats at the age from 5 to 60 days. The androgen metabolites were separated by means of chromatography in thin layers of silicogel. The rate of androgen metabolism in the organs studied from the 5th till the 23rd day of development was dozens of times that in the adult animals. Sexual dimorphism was also shown. 3H-5 alpha-androstan-3 beta, 17 beta-diol transforms in hypothalamuses and hypophyses of the rats of all age groups of both sexes into polar metabolites only. A suggestion is put forward to the effect that the extensive metabolism of androgens in the brain until the 23rd day of development is due to the development of the system hypothalamus-hypophysis-gonads, depends on the concentration of androgens circulating in the blood and is directed to control the secretion of gonadotropins. The above period of development is termed as "critical".

Aging↗
PubMed1981

[[125I]-antigammaglobulin antibodies as universal reagents in radioimmunochemical methods of investigation].

A new indirect radioimmunochemical method based on the use of [125I]-anti-IgG-antibodies as universal detecting reagents is proposed. Its first step consists in the antibody binding to the antigen to be analyzed; the second step -- in immunoadsorption of the non-bound antibodies by water-insoluble sorbents prepared by chlorocarbonic acid isobutyl ester copolymerization of antigens with serum albumin or by immobilization of the antigen on Sepharose. The third step is the determination of the amount of sorbent-bound antibodies by means of [125I]-anti-IgG-antibodies. The method proposed was used for quantitative estimation of prolactin, somatotropin, lutropin, BB-isoenzyme of human creatine phosphokinase, testosterone and 5 alpha-dihydroxytestosterone. The method does not employ labelled antigens and is highly sensitive and highly specific.

Antibodies, Anti-Idiotypic↗
PubMed1981

[Extrapituitary localization of luteinizing hormone in rats].

After hypophysectomy luteinizing hormone /LH/ did not disappear from rat blood serum within 2 months; but concentration of the hormone decreased 2-fold. Administration of luliberine into the hypophysectomized rats led to approximately 3-fold increase of the LH concentration in blood serum within 20 min. The hormones from blood serum of the hypophysectomized rats, from hypophysis and blood serum of intact rats exhibited similarity in their immunochemical and chromatographic properties. The data obtained suggest the presence of extrahypophyseal sources of LN in rats. By means of radioimmunochemical procedure immunoreactive LH was found in 14 structures of the central nervous-system/brain cortex, hypothalamus, hippocampus, medulla oblongata etc/as well as in some peripheral tissues and glands/heart, liver, pancreas etc/. Chromatographically pure LH from liver tissue of the hypophysectomized rats exhibited the biological activity similar to that to the hypophyseal hormone, which was estimated by stimulation of testosterone biosynthesis in the testicular tissue in vitro.

Animals↗
PubMed1981

[Daily variations in S-adenosylmethionine content and oxyindole-O-methyltransferase activity in rat epiphysis].

Rat epiphysis was found to contain a relatively high amount of S-adenosylmethionine (SAM), which undergoes daily variations with a maximum in the middle of the daytime period and a minimum at the night-time phase. The variations are of endogenous type and are persistent in blinded animals. On the contrast, upon continuous illumination the SAM level in rat epiphysis is decreased and impaired. The activity of oxyindole-O-methyltransferase, the terminal enzyme of epiphysial melatonin biosynthesis which consumes methyl groups of SAM, is not subjected to daily variations. It is demonstrated that the artefact of the previously observed daily variations in the oxyindole-O-methyltransferase activity is due to day-to-night changes in SAM content.

Acetylserotonin O-Methyltransferase↗
PubMed1980

[Changes in the concentration of luteinizing hormone in the blood serum and of luliberin in the hypothalamus of castrated rats after the administration of testosterone and its 5 alpha-reduced metabolites. I].

Luteinizing hormone concentration in the blood serum and luliberin content in the hypothalamic arcuate body and medial eminence were determined in castrated mature rats 1, 3, 6, 12, 24 hours afte single injections of testosterone and its 5 alpha-reduced metabolites (dihydrotestosterone, 5 alpha-androstane-3 alpha, 17 beta-diol and 5 alpha-androstane-3 beta, 17 beta-diol) at a dose of 2.5 x 10(-7) kg/kg body weight by radioimmunoassay. Principal differences between testosterone and its 5 alpha-reduced metabolite action on the hypothalamohypophyseal system were detected from the stand point of their effectiveness and the effect realization rate.

Animals↗
PubMed1979

[Action of luliberine on the Na,K-ATPase and Ca-ATPase activity of the sarcolemma of the rat heart].

The effect of luliberine, one of the hypothalamic releasing-factors, upon the ATPase activity in the rat heart sarcolemma was investigated. A decrease in the (Na+-K+)-ATPase activity and stimulation of Ca-ATPase activity under the influence of luliberine were demonstrated. Inhibition of (Na+-K+)-ATPase by cAMP and noradrenaline was also revealed. A possibility of the direct and cAMP-mediated action of luliberine on the Na+-K+)-ATPase activity is suggested.

Animals↗
PubMed1979

[Cardiotropic effects of luliberin. Effects of luliberin on the activities of phosphorylase A and ornithine decarboxylase and concentration of 3', 5'-AMP].

The level of luliberin, the luteinizing hormone-releasing hormone (LH-RH), and the possibility of the hormonal control of metabolic and biosynthetic processes in the heart were studied. It was shown that the rat heart contains a factor, which is immunochemically and chromatographically related to LH-RH (19--46 picograms per organ). Intraperitoneal injection of LH-RH increases the activities of phosphorylase A and ornithine decarboxylase and the concentration of 3',5'-AMP and potentiates the stimulating effect of adrenaline on ornithine decarboxylase.

Animals↗
PubMed1979

[Cardiotropic effects of luliberin. Interaction with rat heart sarcolemmal membrane].

Studies of the effects of luliberin (luteinizing hormone-releasing hormone) on cardiac cells showed that the hormone is specifically bound by the sarcolemmal membrane. The activity of the membrane enzyme -- reception of luliberin involves two types of binding sites with high (K' = 10(7) M-1) and low (K'' = 10(5) M-1) affinities for the hormone, respectively. The hormone has no effect on the activities of adenylate cyclase and phosphodiesterase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1979

[Substrate specificity of peptidases catalyzing LH-RH degradation in hypothalamus, liver and heart of rat].

Degradation of [125I]-LH-RH by peptidases of hypothalamus, liver and heart of the rat and the effects of LH-RH, LH-RH antagonist D-Phe2-Phe3-D-Phe6-LH-RH, LH-RH5-10, oxytocin, bradikinin, thyrotrophin-releasing hormone, melanocyte-inhibiting factor, luteinizing, follicle-stimulating, lactogenic and growth hormones were studied. It was shown that the degradation was inhibited with maximal efficiency by non-labelled LH-RH (Ki = 1,7--2,0 . 10(-6) M). This observation is indicative of peptidase specificity for LH-RH. It is assumed that specific peptidases of liver and heart are involved in the reglation of LH-RH concentration in these organs.

Animals↗
PubMed1979

[Effect of hypothalamic lHRH (luliberin) on the electrical activity of isolated rat heart].

Decelerating effect of LH--RH upon the frequency of contraction of the rat isolated perfused heart was revealed. The neurohormone was also shown to change the heart electrical activity causing elongation of the systole due to an increase in repolarization period. Simultaneous application of LH--RH and norepinephrine to the rat isolated perfused heart did not alter the frequency of contractions. The LH--RH seems to take part in the regulation of the myocardium excitability by means of its effect on the membrane permeability for monovalent cations.

Animals↗
PubMed1979

[Immunoreactive luliberin in the visceral organs of rats].

The distribution of luliberin (luteinizing hormone-releasing hormone, LH-RH) was studied. LH-RH-like factor showing analogous immunochemical and chromatographic properties was detected in the liver, kidneys, duodenum, pancreas, adrenal glands and heart of rats. The concentration of immunoreactive LH-RH in the liver, kidneys, duodenum, pancreas and adrenal glands was nearly equal (5 to 7 pg per mg of methanol extract obtained from acetic acid extract of acetone powder), its concentration in the heart being somewhat lower (2 pg per mg of extract). Only minute amounts of this factor were present in blood cells. Immunoreactive LH-RH found in visceral organs may be of hypothalamic origin or may be synthesized in these organs (in situ).

Adrenal Glands↗
PubMed1979

[Effect of luliberin on the activities of mitochondrial respiratory enzymes].

Luliberin, a luteinizing hormone-releasing hormone, was shown to inhibit the respiratory enzymes of rat liver mitochondria and submitochondrial particles prepared from beef heart mitochondria. At the hormone concentration of 8.10(-6) M the NADH-oxidase activity of the submitochondrial particles was inhibited by 50%. The fragments of the hormone and its analogs and pyroglutamic acid, oxytocin and bradikinin possessed practically no inhibiting effects. In the case of submitochondrial particles the inhibition was only observed in the presence of Ca2+ and was significantly decreased after addition of bovine serum albumin and phospholipase inhibitors -- butacaine and dicaine. It is assumed that the effect of luliberin on the respiratory chain is mediated through mitochondrial phospholipase.

Animals↗
PubMed1979

[Circadian rhythm of ornithine decarboxylase and its endogenous high molecular weight inhibitor in rat pineal gland].

The biochemical mechanisms involved in circadian variations of the activity of ornithine decarboxylase (EC 4.1.1.17)--the rate-limiting enzyme of polyamine biosynthesis in rat pineal gland were studied. The enzyme was separated from its endogenous high molecular weight inhibitor by gel-filtration of the cytosol fraction from this organ through Sephadex G-100 in the presence of 250 mM NaCl. The inhibitor was similar in its molecular weight (30 000) and activity to ornithine decarboxylase inhibior from rat liver. The amount of the enzyme in the pineal gland undergoes much smaller circadian variations as compared to that of the inhibitor. It is concluded that the circadian variations of the ornithine decarboxylase activity in the pineal gland may be largely due to the changes in the enzyme/inhibitor ratio.

Animals↗
PubMed1978

[Interaction of human creatine phosphokinase isoenzymes with rabbit antibodies and their Fab-fragments].

The interaction of human creatine phosphokinase isoenzymes with rabbit antibodies and their Fab has been studied. It has been shown that Fab of the antibodies against MM or BB isoenzymes preserve high specificity of intact antibodies and the ability to inhibit creatine kinase isoenzymes. Differences between antibodies and their Fab have been found to exist with respect to the kinetics of binding with homologous isoenzymes: the rate of the complex formation for Fab is significantly higher. The interaction of creatine kinase isoenzymes with intact antibodies and their Fab is not affected by the addition of creatine kinase substrates. The antibodies against MM and BB isoenzymes have been used to study the individual properties of each subunit of the M- and B-type in a hybrid dimer MB. It has been shown that such properties of these subunits as the Michaelis constants, pH dependence and inhibition by homologous antibodies are identical to those of non-hybrid MM and BB isoenzymes, respectively.

Animals↗