[Change in the gravitation level as a stressor]

Animal (rats, mice) experiments have shown that a gravity change within the range of +/- 1 g relative to the Earth gravity field (zero g in space flight, increased gravity in centrifugation experiments) results in the development of similar reactions--growth delay, involution of lymph organs, lymphopenia. These are classic signs of stress reactions. Centrifugation experiments have demonstrated that the stress-effect of increased gravity can be counteracted by intermittent pretraining on the centrifuge. With respect to the literature data and the authors' own experimental findings, the ratio of specific and nonspecific components in animal responses to gravity changes as well as the contribution of animal reactivity and resistance to these responses were discussed.