ABSTRACT
The experiment on Cosmos 1129 was based on our results obtained in rats exposed to single or repeated restrain stress in the laboratory. These results have convincingly demonstrated a significant increase of serotonin concentration (5-HT) in the hypothalamus in acutely stressed rats. This response, which was found also in the isolated hypothalamic nuclei, was diminished in repeatedly (40 times) immobilized rats. While the concentration of 5-HT was unchanged in the majority of the hypothalamic nuclei of animals subjected to cosmic flight, an increase was recorded only in the supraoptic nucleus (NSO) and a decrease in the periventricular nucleus. These findings demonstrate that only few areas of the hypothalamus respond to cosmic flight with changes of 5-HT concentration and suggest either that long-term cosmic flight cannot be an intensive stressor or that during the flight the rats became already adapted to its long-term effect. However, the exposure of flight rats to repeated immobilization stress resulted in a significant increase of 5-HT in the NSO, para-ventricular and dorsomedial (NDM) nuclei. It should be noted that we have never seen any changes of 5-HT concentration, tryptophan hydroxylase and monoamineoxidase activities in repeatedly (40 times) immobilized rats. On the other hand, the increase of 5-HT concentration in the NDM is a typical finding after seven exposures of rats to immobilization on Earth, daily for 150 min. In the experiment COSMOS 1129 such an increase of 5-HT concentration in the NDM was found not only in the flight group but also in the control group of rats subjected to five daily exposures of immobilization stress. With respect to these findings, the increased 5-HT concentrations observed in some isolated hypothalamic nuclei in the flight group of rats exposed after landing to repeated immobilization stress suggest that long-term space flight and the state of weightlessness do not represent a stressogenic factor with respect to the serotoninergic system in the hypothalamus.
Subject(s)
Immobilization/adverse effects , Serotonin/metabolism , Space Flight , Stress, Physiological/metabolism , Weightlessness , Animals , Hypothalamus/enzymology , Hypothalamus/metabolism , Immobilization/physiology , Male , Rats , Restraint, Physical , Stress, Physiological/etiology , Tryptophan Hydroxylase/metabolismABSTRACT
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.
Subject(s)
Catecholamines/metabolism , Hypothalamus/metabolism , Space Flight , Weightlessness , Animals , Dopamine/metabolism , Dopamine beta-Hydroxylase/metabolism , Hypothalamus/enzymology , Immobilization , Male , Monoamine Oxidase/metabolism , Rats , Stress, Physiological/metabolism , Tyrosine 3-Monooxygenase/metabolismABSTRACT
The present paper deals with the activity of the sympatho-adrenal system (SAS) in the third international crew of the scientific orbital station "Salyut-6" on the basis of catecholamines (CA) as well as of some of their primary stages and metabolites. Plasma adrenaline (A), noradrenaline (NA), and dopamine (DA) were determined on the 30th day before the flight and on the first day after landing. The parameters of A, NA, DA, DOPA, metanephrine (MN), and normetanephrine (NMN) as well as their conjugates were analysed in urine on day 30 and from days 5 to 1 before launching the spaceship and from days 0 to 5 after landing. Moreover, at the same occasions the urinary excretion of vanillilmandelic acid (VMA) and homovanillic acid (HVA) was measured. For a qualitative evaluation of the responses of SAS indices were computed providing information on the activity of the single links of CA metabolism. During the last five days before launching a gradual increase of A, NA, DA, and DOPA excretion with the urine was found in both the cosmonauts. The A/NA quotient rose to 360% in the commander and to 200% in the spacecraft engineer. The inactivation processes of A (MN/A) and NA (NMN/NA) were clearly reduced in both crew members before launching. The highest excretion of A, NA, DA and their conjugates as well as of DOPA was observed on the day of landing. The total results ascertained in the post-flight period indicate psychonerval strains experienced by the cosmonauts. However, marked stress reactions were not found. This conclusion is drawn on the basis of general criteria of the indices of CA metabolism during stress (increased secretory activity of SAS and excretion of free CA, synthesis activation, relative hypometabolism of conjugation). The rapid normalisation of the investigated parameters after the flight gave evidence of the cosmonauts' quick readaptation, which again is an expression of a high state of preparatory training.
Subject(s)
Adrenal Glands/physiology , Space Flight , Sympathetic Nervous System/physiology , Adrenal Glands/metabolism , Catecholamines/blood , Catecholamines/urine , Dopamine/blood , Epinephrine/blood , Female , Germany, East , Humans , Normetanephrine/blood , Stress, Physiological , USSRABSTRACT
In the present study the attempt was made to evaluate the functional state of the adrenal cortex after space flight by means of the urinary corticosteroid content. The urine collected over 24 hours was analysed. The following parameters were determined: Total 17-hydroxycorticosteroids (17-OHCS), their free forms, glucuronides and sulphates; cortisol (F), cortisone (E), corticosterone (B), 11-desoxycortisol (S), 11-dehydrocorticosterone (A), tetrahydrocortisol (THF), tetrahydrocortisone (THE), tetrahydrocorticosterone (THB), tetrahydro-11-desoxycortisol (THS), and aldosterone. In order to characterize the activity of the 11-hydroxylase the quotient of THS + S/THF + F + THE + E was formed. The activity of the 17-hydroxylase was determined indirectly by the quotient of THF + THE + THS + F + E + S/THB + B + A = 17-OHCS/17-DOHCS. The expected distinct increase of the 17-OHCS after the space flight failed to appear. This finding may be due to an adrenocortical dysfunction. In the space ship commander the quotients indicate a reduced 11- and 17-hydroxylation during the process of synthesis of the glucocorticoids. In the flight engineer they give evidence of an unchanged biosynthesis except on the day of landing. A hitherto not fully intensified substance ("white spot") was found in the chromatogram of the space ship commander on the first and second day after the flight. Moreover, the investigations show that the reaction of the adrenal cortex after space flights exhibits a number of individual characteristics.
Subject(s)
Adrenal Cortex Hormones/urine , Space Flight , Germany, East , Humans , Male , USSRABSTRACT
Cortisol, insulin, somatotropin, thyreotropin, thyroxine, triiodothyronine, testosterone, aldosterone, c-AMP, c-GMP, prostaglandins (PGF1-x, PGF2-x, PGA + E), and renin concentrations in serum or plasma of the venous blood of the third international crew of the scientific orbital complex of "Soyuz 29 - Salyut 6 - Soyuz 31" were determined following the 7-day space flight. The increased activity of the renin-angiotensin-aldosterone system before the flight as well as variations in the pressor/depressor prostaglandin ratios indicate an increased strain during the pre-flight period. During the first stage of the post-flight period some parameters were changed due to the landing process and the returning to earth gravity. The associated physical load and the onset of reactions for enhancement of the orthostatic tolerance resulted in an increase of cyclic nucleotid and thyroxine concentrations. The relatively higher levels of the pressor PGs of group F in comparison with the prostaglandins A + E could be evaluated as a compensatory reaction for enhancement of the orthostatic tolerance. The cortisol and STH concentrations increased with growing motor activity. The variations seen after the 7-day space flight were essentially within the reference areas. It may be assumed that the readaptation was not yet totally accomplished by the 8th day after landing.
