Heat-induced testicular apoptosis occurs independently of hormonal depletion.

Previous studies have demonstrated that testicular germ cell apoptosis can be induced both by heat stress and by withdrawal of androgens and gonadotrophins. To investigate whether heat-induced germ cell apoptosis occurs independently of the altered levels of hormones that occur with heat exposure, mouse testicular apoptosis was studied using an in vitro system with controlled levels of testosterone, FSH and LH. It was observed that cells underwent apoptosis sooner in the absence of hormones at the same temperature. Apoptosis also occurred earlier at abdominal temperature compared to scrotal temperature with the same hormonal levels. No somatic tissues studied underwent apoptosis at 37 degrees C under the same culture conditions. These results suggest that heat stress may independently activate an apoptotic pathway in the testis, and that hormone deprivation may induce apoptosis via a separate mechanism.