Differences in the androgen response between two mouse species.

Renal weight and beta-glucuronidase activity are two of several well-characterized androgen-responsive parameters in Mus musculus. A similar sexual dimorphism was not reported for a second mouse species, Mus caroli, however. Since this was not associated with a general absence of androgen action, we considered whether a localized defect in androgen receptors or a difference in renal androgen-responsive endpoints in the two species existed. Only minor differences in the characteristics of renal androgen receptors from the two species were found when they were analyzed by two different methods. These differences were not thought to be sufficient to account for the apparent renal androgen unresponsiveness. No differences were found in androgen receptors from brain. Subsequently, a third renal endpoint, ornithine decarboxylase activity, was found to respond to androgen stimulation in Mus caroli. Control of renal androgen action in these two mouse species thus differs at the level of genetic regulatory elements.