Androgen nuclear exchange activity in rat testis.

Androgen nuclear exchange activity has been measured in the rat testis. Exchange activity was increased 2-10-fold by pretreatment of the tissue with testosterone and persisted for at least 21 days after hypophysectomy in mature animals. Competition for exchange activity using 3H-testosterone or 3H-dihydrotestosterone was significant for a 500-fold excess of testosterone, dihydrotestosterone, progesterone, and cyproterone acetate. The activity was found in tubules and in isolated germ cells from mature rat testes. These results suggest that the molecular mechanism of androgen action in the testis may be quite complex and may involve components both in the more mature germ cells as well.