Effects of Hyperthermia on Spermatogenesis, Apoptosis, Gene Expression,

Testicular heat shock was used to characterize cellular and molecular mechanisms involved in male fertility. This model is relevant because heat shock proteins (HSPs) are required for spermatogenesis and also protect cells from environmental haz-ards such as heat, radiation, and chemicals. Cellular and molec-ular methods were used to characterize effects of testicular heat shock (438C for 20 min) at different times posttreatment. Mating studies confirmed conclusions, based on histopathology, that spermatocytes are the most susceptible cell type. Apoptosis in spermatocytes was confirmed by TUNEL, and was temporally correlated with the expression of stress-inducible Hsp70-1 and Hsp70-3 proteins in spermatocytes. To further characterize gene expression networks associated with heat shock-induced effects, we used DNA microarrays to interrogate the expression of 2208 genes and thousands more expression sequence tags expressed in mouse testis. Of these genes, 27 were up-regulated and 151 were down-regulated after heat shock. Array data were concor-dant with the disruption of meiotic spermatogenesis, the heat-induced expression of HSPs, and an increase in apoptotic sper-matocytes. Furthermore, array data indicated increased expres-sion of four additional non-HSP stress response genes, and eight cell-adhesion, signaling, and signal-transduction genes. De-creased expression was recorded for 10 DNA repair and recom-bination genes; 9 protein synthesis, folding, and targeting genes; 9 cell cycle genes; 5 apoptosis genes; and 4 glutathione metab-olism genes. Thus, the array data identify numerous candidate genes for further analysis in the heat-shocked testis model, and suggest multiple possible mechanisms for heat shock-induced infertility. apoptosis, gamete biology, gene regulation, spermatogenesis, testi