PLASMA STEROID-HORMONE PROFILES IN HCG-INJECTED MALE WALKING CATFISH CLARIAS-BATRACHUS

The present experiment was performed in order to investigate the respo nse of matured male walking catfish to human chorionic gonadotropin (H CG). Short-term experiment. Mature male walking catfish received a sin gle intramuscular injection of HCG (0.2 and 1 IU/g BW) or saline. Bloo d samples were taken at 0, 6, 12, 18, 24, 36, 48 and 72 hr. Long-term experiment. Mature male walking catfish received a single intramuscula r injection of HCG (1 IU/g BW) or saline. Blood samples were taken at 2-day intervals until day 10. In both experiments, plasma testosterone , 11-ketotestosterone (11-KT), 17alpha-hydroxyprogesterone, 17alapha,2 0alpha-dihydroxy-4-pregnen-3-one and 17alpha,20beta-dihydroxy-4-pregne n-3-one levels were measured by radioimmunoassay, and 17alpha,20beta,2 1-trihydroxy-4-pregnen-3-one levels were measured by enzyme immunoassa y. Results can be summarized as follows. 1) HCG firstly induces an inc rease in plasma testosterone and 11-KT levels. 2) Thereafter, 11-KT le vels decrease and progestin levels increase. 3) Finally,progestin leve ls decrease, and 11-KT levels increase again. These results clearly in dicate that a shift in the steroidogenic pathway is induced in males i n response to HCG.