Effects of confinement (110 and 240 days) on neuroendocrine stress response and changes of immune cells in men

Abstract

The aim of the study was to evaluate the effects of long-term confinement on stress-permissive neuroendocrine and immune responses in humans. Two groups of four male subjects were confined 240 days (group 240) or 110 days (group 110) in two space modules of 100 or 200 m3, respectively. During confinement, none of the volunteers developed psychic stress as could be examined and verified by a current stress test. However, in group 240 but not in group 110, the diurnal rhythm of cortisol secretion was slightly depressed and the urine excretion of norepinephrine significantly increased. The innate part of the immune system became activated as seen by a rise in the number of circulating granulocytes and the enhanced expression of beta2-integrins. In contrast, the ratio of T-helper to T-suppressor cells decreased. All these effects, observed during confinement, were even more pronounced in both groups when values of endocrinological and immunological parameters were compared between before and 1 wk after the end of the confinement period. Hence, return to normal life exerts pronounced effects to a much higher degree, irrespective of how long or under which conditions individuals were confined. Because the delayed-type hypersensitivity skin reaction against recall antigens remained unaffected, it is to be presumed that confinement appears to induce distinct sympathoadrenergic activation and immunological changes but no clinically relevant immunosuppression.

Gravity changes during animal development affect IgM heavy‐chain transcription and probably lymphopoiesis

“…The lack of effect of confinement on IgM mRNA levels is not surprising, because the density of embryos or larvae per milliliter of water in miniaquariums was similar to the density used in our animal facility to rear them under classic conditions. Moreover, a previous study demonstrated that after 110 or 240 d of confinement, the numbers of B and T cells in human peripheral blood were unaffected (42).…”

The impact of long-term confinement and exercise on central and peripheral stress markers

“…As proof of existing stress and stressors, we used cortisol measurements in this study. Cortisol has also been used in previous isolation studies, which described a connection between cortisol levels and isolation related stressors [21]. As anticipated, longterm isolation had a significant effect on cortisol levels.…”

Hormonal changes during long-term isolation

“…This sympathoadrenergic stimulation reflects a stressful adaptation back to normal life. Chouker et al (2002) Fig. 3A, B Heart rate in the morning (open squares) and in the evening (black squares) before, during and after the 240-day isolation (A), and during the 110-day isolation (B).…”