Effects of a Simulated Microgravity Model on Cell Structure and Function in Mouse Testis

Decreased testicular blood flow shift occurring under microgravity conditions causes impaired spermatogenesis in males. The tail suspended model has been used mainly in studies of muscle atrophy/osteoporosis and of body fluid shift in few studies aimed at spermatogenesis. We examined serum testosterone levels, testis morphology and apoptotic phenomena in tail suspended mice, a model used to reproduce some of the effects of the absence of gravity. Male C57BL mice (6months old) were divided into two groups: tail suspended (TS) and controls (C). After 14 days of treatment testosterone levels were determined. On fixed sections histological stain (HE) was performed; DNA fragmentation was visualized using TUNEL technique. On the frozen samples immunoblotting for BAX, Bcl2, Caspase 39 and p53 was carried out. Testosterone levels were 0.18±0.09 and 3.74±2.2 ng/ml (mean±DS) in suspended and control animals, respectively. HE staining showed disturbed cell arrangement and a markedly decreased number of spermatozoa in the testes, TUNEL revealed an increased apoptotic index and immunoblotting provided evidence of apoptotic markers in TS animals. These data support results previously obtained by other groups showing a significant influence of short duration microgravity conditions on testicular function.