IDENTIFICATION OF STAGE-SPECIFIC CHANGES IN PROTEIN SECRETION BY ISOLATED SEMINIFEROUS TUBULES FROM RATS FOLLOWING EXPOSURE TO SHORT-TERM LOCAL TESTICULAR HEATING

The objective of this study was to identify the early (after 4 and 24 h) effects of short-term local testicular heating (43 degrees C for 30 min) on the secretion of proteins by seminiferous tubules isolated fr om adult rats at stages II-V, VI-VIII or IX-XII of the spermatogenic c ycle, and cultured in vitro for 24 h with [S-35]methionine. Incorporat ion of [S-35]methionine into secreted and intracellular proteins was a ssessed and the pattern of protein secretion was evaluated using two-d imensional SDS-PAGE. Seminiferous tubules isolated from control rats e xhibited the characteristic, androgen-dependent increase in protein se cretion at stages VI-VIII. At 4h after exposure to local testicular he ating, seminiferous tubules at these stages showed a significant incre ase (P< 0.001) in the overall incorporation of [S-35]methionine into s ecreted proteins, whereas seminiferous tubules at stages II-V and IX-X II showed no significant change. In marked contrast, seminiferous tubu les isolated from rats 24 h after local testicular heating showed a si gnificant decrease in the incorporation of [S-35]methionine into secre ted proteins at stages VI-VIII (P < 0.001) and to a lesser extent at I X-XII (P<0.05), whereas seminiferous tubules at stages II-V showed no change in incorporation. Prior treatment to maintain normal intratesti cular concentrations of testosterone in heat-exposed rats failed to pr event these changes. Similar results were obtained when incorporation of [S-35]methionine into intracellular proteins was evaluated 4 and 24 h after exposure to local testicular heating. Analysis of seminiferou s tubule-secreted proteins by two-dimensional SDS-PAGE identified thre e androgen-regulated proteins that showed reproducible decreases in se cretion following exposure to local testicular heating. These results suggest that changes in overall protein secretion by seminiferous tubu les may explain some of the adverse effects of heat on the testes.