Effects of ciprofibrate on testicular and adrenal steroidogenic enzymes in the rat.

Testicular and adrenal steroidogenic enzymes were measured radiometrically following oral dosing of rats with ciprofibrate (2-[4-(2,2-dichlorocyclopropyl) phenoxyl]-2-methylpropinoic acid), a peroxisome proliferator. Six-week-old male Fisher 344 rats were fed a diet containing ciprofibrate (0.025%, w/w) for 3, 7, 14, 28, 56, 84, 112 or 140 days leading to a daily ciprofibrate intake of approximately 15 mg/kg body weight/day. Ciprofibrate caused a marked inhibition of testicular 3beta-hydroxysteroid dehydrogenase-isomerase (3beta-HSD) activity that was significant after 3 days and subsequently decreased to 40% of control level. Ciprofibrate treatment also reduced 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity to a lesser extent but had no effect on 17-hydroxylase (17-OHase) activity. Immunoblot analyses indicated that ciprofibrate treatment did not alter enzyme protein levels and semi-quantitative RT-PCR analysis also revealed no significant changes in testicular 3beta-HSD mRNA levels. Furthermore, in addition to the enzyme-specific effect of ciprofibrate on 3beta-HSD in the testes, a tissue-specific effect was also evident, since no significant effects of ciprofibrate were seen on the activities of 3beta-HSD or 21-OHase in the adrenal glands from the same animals.