Effects of dexamethasone on steroidogenesis in Leydig cells from rats of different ages.

The effects of 0.1 microM dexamethasone on cytochrome P450 content, 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity, and basal and LH-induced testosterone production of Leydig cells from rats 3, 5, 7 and 10 weeks old were examined. The cytochrome P450 content of Leydig cells from rats 3 weeks old was increased by treatment with dexamethasone for 22 h, while 3 beta-HSD activity was decreased. The cytochrome P450 content of Leydig cells from rats 5 weeks old was increased after 3 and 22 h of culture, while 3 beta-HSD activity was decreased after 22 and 44 h of treatment. The cytochrome P450 content of rats 7 weeks old was increased after 3 h of culture, while 3 beta-HSD activity was decreased after 22 and 44 h of culture. Leydig cells from rats 10 weeks old showed increased cytochrome P450 content upon dexamethasone treatment after 3 h. The activity of 3 beta-HSD was decreased after 44 h of treatment. In Leydig cells from rats 3 and 5 weeks old, dexamethasone decreased basal testosterone production after 22 h of treatment, but not after 44 h, and did not affect LH-induced testosterone production. Leydig cells from rats 7 weeks old showed decreased basal and LH-induced testosterone production, when treated with dexamethasone for 22 and 44 h. Basal testosterone production was unaffected by dexamethasone in rats 10 weeks old, while LH-induced testosterone production was decreased after 44 h of treatment. The effect of dexamethasone on testosterone secretion changed during development, as a transient, early effect on basal testosterone secretion was observed in Leydig cells from prepubertal and pubertal rats. These data suggest that dexamethasone affects Leydig cells differently, depending on the age of the rat, the older rats being more sensitive than the younger rats.