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T Torda

Publications and source records attributed to T Torda.

62 records · Page 4Linked to original sources
PubMedDate not supplied

Catecholamines and their enzymes in discrete brain areas of rats after space flight on biosatellites Cosmos.

The activity of the catecholaminergic system was measured in the hypothalamus of rats which had experienced an 18.5-19.5-day-long stay in the state of weightlessness during space flights on board Soviet biosatellites of the type Cosmos. In the first two experiments, Cosmos 782 and 936, the concentration of norepinephrine and the activities of synthesizing enzymes tyrosine hydroxylase and dopamine-beta-hydroxylase and of the degrading enzyme monoamine oxidase were measured in the total hypothalamus. None of the given parameters was changed after space flight. In the light of the changes of these parameters recorded after exposure to acute stress on Earth, this finding indicates that long-term state of weightlessness does not represent an intensive stressogenic stimulus for the system studied. In the space experiment Cosmos 1129, the concentration of norepinephrine, epinephrine, and dopamine was studied in isolated nuclei of the hypothalamus of rats within 6-10 hr following return from space. Norepinephrine was found to be significantly reduced in the arcuate nucleus, median eminence and periventricular nucleus, epinephrine in the median eminence, periventricular and suprachiasmatic nuclei, whereas dopamine was not significantly changed after space flight. The decreased catecholamine levels found in some hypothalamic nuclei of rats which had undergone space flight indicate that no chronic intensive stressor could have acted during the flight, otherwise the catecholamine concentration would have been increased in the nuclei. The decreased levels must have been induced by the effect of a stressogenic factor acting for a short time only, and that either during the landing maneuver or immediately after landing. Thus long-term exposure of the organism to the state of weightlessness does not represent a stressogenic stimulus for the catecholaminergic system in the hypothalamus, which is one of the regulators of the activation of neuroendocrine reactions under stress.

Animals↗
PubMedDate not supplied

[Catecholamines and their metabolic enzymes in the hypothalamus of rats after a flight on the Kosmos-782 biosatellite].

The concentration of catecholamines, and activity of enzymes involved in their synthesis (tyrosine hydroxylase and dopamine-beta-hydroxylase) and degradation (monoamine oxidase) were measured in the hypothalamus of rats flown for 19.5 days aboard the biosatellite Cosmos-782, synchronous and vivarium controls sacrificed on R+O and R+25 days. No significant changes in the above parameters of the flight rats were found. The findings give evidence that a prolonged space flight induces no changes in the content, synthesis or degradation of catecholamines in the rat hypothalamus. This seems to indicate that weightlessness does not act as an acute stressor.

Animals↗
PubMedDate not supplied

[Catecholamines and the enzymes of their synthesis in the adrenal medulla of rats after a flight on the Cosmos-936 biosatellite].

In the adrenals of weightless and centrifuged rats flown for 18.5 days onboard the biosatellite Cosmos-936 indicators of the activity of the adrenomedullary system, i.e. the content of catecholamines and activity of the enzymes involved in their synthesis--tyrosine hydroxylase and dopamine-beta-hydroxylase--were measured. It was found that none of the indicators changed postflight. These findings show that a prolonged exposure of rats to weightlessness does not act as a strong stressor for the adrenomedullary system.

Adrenal Medulla↗
PubMedDate not supplied

[Catecholamines and their metabolic enzymes in the rat myocardium after a flight on the Kosmos-936 biosatellite].

In the myocardium of the weightless and centrifuged rats flown for 18.5 days onboard the biosatellite Cosmos-936 the catecholamine concentration and activity of enzymes involved in their synthesis and degradation--dopamine-beta-hydroxylase, monoamine oxidase and catechol-O-methyl transferase--were measured. The catecholamine concentration in the myocardium of both flight groups significantly increased, and the enzyme activity did not change. These results suggest that an exposure to space flight increases the catecholamine concentration and exerts no effect on their synthesis and degradation in the rat myocardium.

Animals↗
PubMedDate not supplied

[Noradrenaline and the enzymes of its synthesis and breakdown in the rat hypothalamus after a flight on the Kosmos-936 biosatellite].

In the hypothalamus of the weightless and centrifuged rats flown for 18.5 days on board the biosatellite Cosmos-936 the noradrenaline concentration and activity of the enzymes involved in the catecholamine synthesis and degradation were measured. It was found that under the space flight influence the noradrenaline concentration and tyrosine hydroxylase, dopamine-beta-hydroxylase and monoamine oxidase activities remained unaltered. These findings indicate that a prolonged exposure to weightlessness was not a stressogenic agent that could activate the adrenergic system in the rat hypothalamus.

Animals↗
PubMedDate not supplied

[Effect of a prolonged stay in space on the reaction of the adrenal cortical and medullary layers].

Concentrations of corticosteron and catecholamines, and activities of catecholamine synthesizing enzymes, tyrosine hydroxylase, dopamine-beta-hydroxylase and phenyl ethanol amine-N-methyl-transferase, were measured in the adrenals of rats flown for 19.5 days aboard the biosatellite Cosmos-782, synchronous and vivarium control animals sacrificed on R + 0 and R + 26 days. The flown rats showed a moderate but significant increase in the adrenal weight, corticosteron concentration and tyrosine hydroxylase activity on R+0 day. These parameters returned to the normal on R+26 day. This data gives evidence that the adrenocortical and sympathoadrenal systems were not significantly stimulated by the space flight effects; therefore, weightlessness cannot be considered as a potent stressful agent, although its some stressogenic effect has been documented.

Adrenal Cortex↗