Effects of 17beta-aminoestrogens on the sexual behavior of female rats

17beta-aminoestrogens (AEs) produce anticoagulant effects in rats contrastingwith 17beta-estradiol (E2) procoagulant effects, their estrogenic effects are similar to E2, decreasing serum luteinizing hormone (LH), increasing uterine weight (Uw), activate transcription through the ERalpha and ERbeta receptors and pentolame induces progesterone (P) receptors in the anterior pituitary of ovariectomized (Ovx) rats similarly to E2, suggesting possible effects on female rats' sexual behavior. This work evaluated the AEs prolame, butolame, pentolame compared to E2 and estradiol benzoate (EB) as facilitators on the rat lordotic behavior. Dose-response curves were performed in rats by single subcutaneous (s.c.) injection (timezero) of: E2 (approximately 0.3, 3, 30, 60, 300 microg/kg); EB (approximately 0.4, 4, 40, 80, 400 microg/kg); prolame, butolame, pentolame (approximately 40, 400, 2000 or 4000 mg/kg), vehicle (corn oil; 300 microL/day; approximately 1.2 mL/kg) as control; 24 h after, P (1 mg/rat in 100 microL of corn oil; approximately 4 to 5 mg/kg) was administered, and 5 to 7 h later LQ was evaluated (number of lordosis displays/number of mounts x 100). E2, EB and AEs followed by P administration, induced lordosis in a dose-dependent manner. Prolame induced an LQEmax of 92, butolame85, EB 81, pentolame 44 and E2 43. The most potent was EB (LQED50 of 4.1 +/- 0.5 microg/kg); then E2 10 microg +/- 2.2/kg; prolame 268 +/- 19 microg/kg; butolame 402 +/- 21 microg/kg, and pentolame 1037 +/- 28 microg/kg. The AEs LQ potency decreases as length substitution on the amine group in C-17 increases. AEs LQDE50 values correlate with previous Uw DE50, LH ID50 and binding studies indicates mediation of the response by estrogen receptors. AEs facilitate sexual behavior of Ovx rats as partial estrogenic agonists.