[Effect of 120-day antiorthostatic hypokinesia on the reproductive function in women]

Original data on the peculiarities of adaptation to and functional status of the reproductive system in long-term antiorthostatic hypokinesia (AOH) have been obtained. The studies involved eight healthy female volunteers aged 26-37 years who were exposed to the head-down tilt (-6 degrees) for 120 days. The test subjects were divided into 2 groups of 4 persons each. In Group A, the countermeasures, i.e. physical exercise and pharmacological means, were used. In Group B, at no time did the test subjects use the countermeasures throughout the 120-day AOH. With and without the countermeasures, hypokinesia was found to impact the female reproductive system developing clinical symptoms of deficiency of the menstrual lutein phase and giving rise to small inclusions of functional fluids in the ovaries. Within 6 months after AOH, the ovarial function of the test subjects was fully recovered which may be indicative of the functional character of changes. These changes can be explained by dissociation of the functional relations in the hypothalamo-hypophyseal-ovarial system manifested by increases in the plasmic concentrations of luteinizing hormone (LH) against normal levels of follicle-stimulating hormone (FSH) and prolactin, and moderately increased levels of testosterone, relative hyperestrogenemia and hypoprogesteronemia. These clinical and hormonal developments are contrary to the observations usually made in various models of stress. Similarity of the hormonal profiles under hypokinesia and long-term immersion of female swimmers may be ascribed to common mechanisms underlying the disturbance of the reproductive function.