Perinatal activity of the hypothalamic-pituitary-gonadal axis in the lamb. II. In vitro testicular response to human chorionic gonadotropin and choleratoxin in the first 2 months of life.

Testicular response to human chorionic gonadotropin (hCG) was studied in male lambs. Adenosine 3':5'-cyclic monophosphate (cAMP), testosterone (T), delta 4-androstenedione and 17 alpha-hydroxyprogesterone content and cAMP and T production by dispersed interstitial cells were assessed in control and hCG-pretreated animals. Plasma T levels increased after hCG at 1, 4 and 8 weeks. Increments in the testicular content of cAMP, delta 4-androstenedione, and T were greater at 8 weeks and that of 17 alpha-hydroxyprogesterone and 125I-hCG binding to dispersed interstitial cells were identical at all ages. cAMP and T production by dispersed interstitial cells from nonstimulated animals and the response to hCG and choleratoxin were similar in all lambs. In contrast, cAMP and T production were higher at 1 week only in animals pretreated with hCG in vivo. These data are compatible with hCG-induced desensitization at 4 and 8 weeks.