The State of the Organs of the Female Reproductive System after a 5-Day “Dry” Immersion

Abstract

The impact of weightlessness on the female reproductive system remains poorly understood, although deep space exploration is impossible without the development of effective measures to protect women’s health. The purpose of this work was to study the effect of a 5-day “dry” immersion on the state of the reproductive system of female subjects. On the fourth day of the menstrual cycle after immersion, we observed an increase in inhibin B of 35% (p < 0.05) and a decrease in luteinizing hormone of 12% (p < 0.05) and progesterone of 52% (p < 0.05) compared with the same day before immersion. The size of the uterus and the thickness of the endometrium did not change. On the ninth day of the menstrual cycle after immersion, the average diameters of the antral follicles and the dominant follicle were, respectively, 14% and 22% (p < 0.05) higher than before. The duration of the menstrual cycle did not change. The obtained results may indicate that the stay in the 5-day “dry” immersion, on the one hand, can stimulate the growth of the dominant follicle, but, on the other hand, can cause functional insufficiency of the corpus lutea.

Comprehensive assessment of physiological responses in women during the ESA dry immersion VIVALDI microgravity simulation

“…This raises a question of cardiovascular risk for long-term missions. Of note, while sharp decreases in plasma progesterone concentration were reported after 5 days of DI compared to ambulatory conditions on the same day of the cycle in healthy females 73 , menstrual cycle was not controlled in our female participants. Although this limitation needs to be acknowledged, we did not observe differential metabolic responses to DI between individuals with high versus low plasma progesterone and estradiol levels, suggesting that the effects of DI may be stronger than hormonal modifications.…”

“…Furthermore, the question of the effect of DI on the cycle and more generally on reproductive system was not explored in our study. Interestingly, the very recent data on the effect of 5-day dry immersion on the female reproductive system 73 show a sharp decrease in progesterone after immersion.…”

“…The skeletal unloading negatively impacts astronauts’ musculoskeletal system when exposed to microgravity. Serum levels of CTx have been shown to increase as early as the 8th day of spaceflight 74 followed by a drop in bone formation markers (P1NP, OC) after the first week of spaceflight 73 – 76 . The decrease in bone mineral density is particularly pronounced at the femoral neck and proximal femur (around −8%) after 4.5–7 months of spaceflight, as shown by DXA 73 .…”

“…Serum levels of CTx have been shown to increase as early as the 8th day of spaceflight 74 followed by a drop in bone formation markers (P1NP, OC) after the first week of spaceflight 73 – 76 . The decrease in bone mineral density is particularly pronounced at the femoral neck and proximal femur (around −8%) after 4.5–7 months of spaceflight, as shown by DXA 73 . Bone mineral density and bone-associated biomarkers did not differ between male and female astronauts 77 .…”

The Oxidative Phosphorylation and Cytoskeleton Proteins of Mouse Ovaries after 96 Hours of Hindlimb Suspension

“…It was shown that after being in "dry" immersion, the content of anti-Mullerian hormone does not change, but inhibin B increases, which is produced by granulosa cells and can be a marker of an increase in their number. Moreover, the size of the antral follicles and the dominant follicle increases, which can be considered a positive criterion for a maturing oocyte [5], which requires direct experimental confirmation.…”