[An audio monitor for physiological research].
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Animals↗
Biomedical subjects
V N Gurin
Publications and source records attributed to V N Gurin.
[A simple device for the electrical cleaning of glass microelectrodes].
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Animals↗
Inhibition of calcium spikes by gamma-amino-butyric acid in the neurons of Lymnaea stagnalis L.
The modulation of action potentials (APs) and high-threshold calcium currents by gamma-aminobutyric acid (GABA) and GABAB receptor agonist baclofen was investigated in identified internally perfused neurons of Lymnaea stagnalis using current-clamp and whole-cell voltage-clamp techniques. GABA (5 x 10(-5) M) and baclofen (5 x 10(-5) M) reversibly reduced overshoot and afterhyperpolarization phase of the action potentials. Application of GABA or baclofen inhibited inward and outward voltage-gated ionic currents. GABA (10(-8)-10(-4) M) was found to suppress high-threshold calcium current in voltage- and dose-dependent manner. These effects were mimicked by baclofen (5 x 10(-5) M) but not by muscimol (5 x 10(-5) M). Inhibition of Ca(2+)-currents could not be prevented by pentylenetetrazole (5 x 10(-5) M) or with pertussis toxin (1 microgram/ml). These results provide evidences for the presence of GABAB receptors in the identified central neurons of Lymnaea stagnalis L.
Action Potentials↗
[The firing of the preganglionic fibers of the splanchnic nerve in the temperature exposure of the nucleus magnus raphae].
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Animals↗
[Function of the hypothalamus-thyroid system long after radiation and neurotropin correction of the disorders detected].
In experiments on Wistar male rats exposed to single X-ray radiation 0.5 Gy and combination of X-ray 0.5 Gy and 131I 6.5 microCi/kg inhibition of activity of excitatory and inhibitory neurotransmitter processes in the mediobasal hypothalamus was observed 6 months after radiation. This was accompanied by a prolonged hypofunction of the thyroid gland related to disorders with glandular stromal follicles and secretion of hormones into the bloodstream. Application of neurotropin that normalizes to a certain extent the transmitter relationship in the hypothalamus does not act positively on the thyroid functional activity. All this indicates a necessity of combined correction of the disorders found not only with neurotropic drugs but also with directional therapy of the affected organs and systems.
Animals↗
[The pulse trains of the splanchnic and vagus nerves during changes in the temperature of the gastric mucosa].
In anesthetised cats, impulse activity of splanchnic afferents increased after a temperature rise by 2 degrees C and a drop by 2 degrees C, then the firing rate decreased during heating and increased during cooling. The activity of vagal afferents increased during heating and decreased during cooling of the mucosa. The firing rate of splanchnic efferents changed similarly to the afferents. The magnitude of the responses to these stimuli sharply decreased during hypothermia. The data obtained suggest a secondary nature of gastric temperature reception and its relative specifics.
Afferent Pathways↗
[The action of pyrogenal and endogenous pyrogen on visceral afferent systems].
Pyrogenal in the dose 5 mcg increased the adrenaline release in dogs. Interleukin-1 increased the noradrenaline release. Neither capsaicin, nor M- and N-cholinoreceptor blockade, nor pre-decentralization of the inferior mesenteric ganglion, abolished the effects. Mechanical and chemical stimuli during continuous perfusion of the colon with subliminal doses of pyrogenal increased the adrenaline release, too. A possible direct effect of endotoxins on peripheral adrenergic neurons, is discussed.
Afferent Pathways↗
[The organization of the microcirculatory bed of the vascular plexus of the lateral cerebral ventricles in rabbits].
Electron microscopic studies of the choroid plexus' microvessels in the rabbit brain revealed diaphragm-covered caveolae and fenestrae in them. Some endotheliocytes possess outgrowths and sprouts on the abluminal surface that penetrate through the basal membrane of the capillaries into the brain and make contacts with its neurosecretory cells. The choroid capillaries were shown to be innervated by nerve fibers and terminals adjoining the basal membrane of the endothelium. Fever induced by i.v. pyrogenal was accompanied by changes in the organisation and permeability of the capillaries. These changes seem to be due to the action of interleukin-I released from activated blood and endothelial cells under the influence of pyrogenal.
Animals↗
[Effect of temperature and emotional factors on the catecholamine content in intestinal and splenic adrenergic plexuses of celiac plexus-decentralized rats].
Effects of temperature and emotive factors on the catecholamine content in intestinal and splenic adrenergic plexuses of celiac plexus-decentralized rats have been studied using histofluorescence and computer analysis. It is shown that the catecholamine content in the plexuses gets higher during hypothermia and remains unchanged during hyperthermia and emotional stress.
Animals↗
[Modifying effects of neurotropin on post-radiation disorders of neuromediator processes in the autonomic function regulation centers].
In experiments on Wistar rats, it was shown that 6 months after exposure to ionizing radiation (X-radiation 0.5 Gy and intraperitoneal 131I 6.5 mCu/kg) the hypothyroid state was accompanied by changes in inhibitory and excitatory mediation that are characteristic of chronic radiation stress in cerebral structures responsible for regulation of autonomic and animal functions and a relative deficiency of the hypothalamopituitary-adrenocortical axis. Application of therapeutic doses of neurotropin 3 months after radiation levelled the pattern of chronic radiation stress and diencephalic disorders that underlie disturbances of some systemic functions of the organism.
Adjuvants, Immunologic↗
[Activity of blood interleukin-1 in dogs during work hyperthermia].
The activity of interleukin-1 (IL-1) in blood plasma of the dogs in conditions of working hyperthermia was studied. The animals performed static exercise of submaximal capacity. Data on IL-1 circulation at different time after the onset of physical exercise were obtained. Cessation of exercise is accompanied by degradation of an IL-1 molecule to shorter fragments. The existence of the reserve pool of this biologically active substance released during intense muscle activity is suggested.
Animals↗
[The content of catecholamines in the adrenergic plexuses of the spleen and intestines during cold and emotional stresses].
The content of catecholamines in adrenergic plexuses of the spleen and small intestine of rats has been studied histochemically using a computer analysis. It is shown that the content increases both during the short-term cold and emotional stress. Intraperitoneally administered guanethidine (10 mg/kg) does not prevent cold-induced accumulation of catecholamines in these adrenergic plexuses, but the emotional-induced one remains. Putative mechanisms of the catecholamine accumulation in the splenic and small intestinal adrenergic plexuses during different stresses are discussed. It is suggested that the cold stress induces an increase of the catecholamine synthesis in adrenergic terminals of prevertebral ganglion neurons, whereas emotional stress leads to the catecholamine uptake by adrenergic terminals from the blood.
Adrenergic Fibers↗
[Antipyrogenic properties of oxytocin].
Effects of oxytocin on pyrogenal or endogenous pyrogen-induced fever were studied. Intramuscular injection of oxytocin (0.2 micrograms/kg every half an hour) did not significantly affect the pattern of pyrogenal-induced fever. Constant intravenous injection of oxytocin (0.4 and 4 micrograms/kg/h) 2-4.5 h after pyrogenal decreased the rectal temperature, on an average, by 24% and 31%, respectively. Endogenous pyrogen fever was not attenuated by intravenous oxytocin (4 micrograms/kg/h). The antipyrogenic effect of oxytocin is related to inhibition of endogenous pyrogen synthesis rather than to blockade of its action, which is indicated by a decreased second peak of the temperature curve, inhibition of endogenous pyrogen synthesis in vitro, and persistence of the hyperthermic effect of endogenous pyrogen.
Animals↗
[The problem of the influences of brain cholinergic mechanisms on lipoprotein metabolism in disorders of heat exchange and in emotional stress].
The contribution of central cholinoreactive systems to the control of plasma lipoprotein metabolism was studied in white rats exposed to cold, overheating and immobilization stress. Possible mechanisms of shifts in fatty-acid composition, as well as high-density lipoprotein cholesterol and total very low and low density lipoproteins, associated with hypothermia, hypertermia and emotional stress under conditions of excitement and blockade of cerebral m- and n-cholinoreceptors, are discussed. Changes in hypothalamic acetylcholin metabolism in stress-exposed animals are demonstrated. It is suggested that central cholinoreactive systems may play an important role in the control of adaptive metabolic reactions involving composite lipids under exposure to low and high environmental temperatures and emotion factors.
Animals↗
[Ultrastructural organization of the hypothalamic medial preoptic area and its changes under the effect of pyrogens].
In order to study structural bases of central mechanisms of thermoregulation, a comparative electron microscopic analysis of various cellular groups in one of thermosensitive zones of the cat hypothalamic area--the medial preoptic area--have been carried out under conditions of experimental fever. The latter is produced by injection of pyrogen of bacterial origin--pyrogenal--to the animals. Pyrogenal, increasing the body temperature, produces a stimulatory effect on various cellular elements, first of all on leucocytes, monocytes and macrophages in the medial preoptic area, as well as on endotheliocytes of the terminal vessels. Under pyrogenal effect activation of microglial cells and pericytes also takes place, and as a result of the rearrangements, occurring in the structure, they change into macrophages. This is an evidence of their active participation in the immune protection of the brain. According to the data from other investigations, all these activated cells produce peptide interleukin-1, one of the mediators of fever and stimulator of the immune system. Pyrogenal is stated to produce a stimulating effect on the astroglia and on some neurons of the medial preoptic area, that respond with cytoplasm increase and accumulation of numerous organelles. The reactive changes at fever in some neurons of the medial preoptic area can demonstrate that they belong to the thermosensitive pool. A conclusion is made, concerning a complex effect of pyrogenal, that results in a cooperative response of a number of cellular systems of the organism.
Animals↗
[Changes in the catecholamine level and energy metabolism of the myocardium in rats during cold and emotional stress].
The catecholamine content in adrenergic plexuses and the oxidative enzyme activity (succinate dehydrogenase, lactate dehydrogenase) during cold and emotional stress were studied histochemically in the rat myocardium. An acute short-term cooling led to an increase in the catecholamine fluorescence intensity and succinate dehydrogenase activity, whereas a short-term emotional stress resulted in a decrease in both these parameters.
Adrenergic Fibers↗
[Temperature dependence of neuronal activity in hypothalamic and hippocampal slices of the guinea-pig].
Unit activity in slices of the hippocampus and medial preoptic area of the hypothalamus of guinea-pigs was extracellularly recorded under conditions of temperature changes. Seven out of nineteen hypothalamic neurons showed changes in the firing rate at threshold temperatures of 36-38 degrees C. In the suprathreshold range the activity of these neurons depended on the temperature level. It is suggested that such neurons may form a sensory part of the system controlling brain temperature within a narrow (1-2 degrees C) range. The pyramidal layer cells of the control structure (hippocampus) were insensitive to the temperature level within 32-40 degrees C.
Animals↗
[Ultramicroscopic organization of the vascular plexus in the rabbit cerebral lateral ventricles and its changes under the effect of pyrogens].
By means of electron microscopical methods organization of various components of the vascular plexus in the rabbit cerebral lateral ventricles--ependymal and supraependymal cells, as well as capillaries, making the base of the hemato-encephalic and hemato-liquor barriers of the plexus have been studied. Injection of bacterial pyrogen (pyrogenal) to the animals is accompanied with an increasing permeability in the barriers of the vascular plexus for certain blood cells (lymphocytes, monocytes), their activation and transformation into plasma cells and macrophages. Under pyrogenal effect in the ventricle cavities activation of the supraependymal cells and intensification of their interaction with the underlying ependyma take place. In the ependymal layer local dilatation of intercellular spaces and intensification of exocytic processes are observed. The changes revealed demonstrate an active reaction of some elements of the vascular plexus to fever, dependent on injection of the bacterial pyrogens into the organism.
Animals↗