Effects of androgens on isolated rat uterus.

The 5 alpha- and 5 beta-dihydrotestosterone (DHT) androgens relax KCl-induced tonic contraction in rat uterus, in a dose-dependent way. The 5 alpha and 5 beta-DHT relaxing effect is counteracted by CaCl2 (0.1-10 mM). The 5 alpha-DHT, but not the 5 beta-DHT, effect was reduced by cycloheximide (10 micrograms/ml) and by actinomycin D (5 micrograms/ml). Flutamide at 10(-6) M shifted the effect of 5 alpha-DHT to the right. However, other doses of flutamide or cyproterone acetate did not modify the effect of both androgens. We suggest a non-genomic effect of 5 alpha-DHT and 5 beta-DHT in rat uterus contraction but that intracellular and genomic actions play a part in the relaxing effect of 5 alpha-DHT.