Testosterone suppression of ornithine decarboxylase activity in rat Sertoli cells.

The effect of testosterone on the induction of Sertoli cell ornithine decarboxylase (ODC) activity was investigated in highly purified cultures derived from testes of 20-day-old rats. Sertoli cell cultures were maintained in serum-free Ham's F-10 medium, with refeeding on days 2 and 4. Before refeeding on day 4, ODC activity was 7.4 U (1 U = 1 pmol 14CO2 released/mg protein.60 min at 37 C). After a medium change, ODC activity increased (41.6 U at 10 h; 180.0 U at 24 h) and then returned to near-basal activity (26.3 U) after 48 h. Simultaneous addition of testosterone (150 ng/ml; 5.2 X 10(-7) M) with the day 4 medium change suppressed the increase in ODC induction (7.53 U at 10 h, 91.6 U at 24 h). Addition of testosterone 24 h before refeeding resulted in greater inhibition of ODC induction (6.9 U at 10 h; 45.4 U at 24 h) than when added simultaneously. Other androgens, 5 alpha-dihydrotestosterone, androsterone, and 5 alpha-androstane-3 alpha,17 beta-diol, also suppressed induction of ODC, whereas 17 beta-estradiol was ineffective, illustrating the steroid specificity of the effect. Coadministration of the antiandrogens hydroxyflutamide or cyproterone acetate partially blocked the testosterone effect. Induction of ODC activity by ovine FSH (10 ng/ml) was also suppressed when Sertoli cells were cultured in the presence of testosterone (150 ng/ml) from the time of isolation. However, induction of ODC activity by (BU)2cAMP was uncompromised by testosterone. These results suggest that testosterone may repress ODC activity and, hence, polyamine biosynthesis in the Sertoli cell, but that cAMP, acting through the trophic hormone FSH, can overcome this suppression of putrescine biosynthesis. Intratesticular and hypophyseal modulation of polyamine biosynthesis may influence not only cellular processes in the Sertoli cell itself but also its role in spermatogenesis.