Effects of acute stanozolol treatment on puberty in female rats

The effects of anabolic-androgenic steroid (AAS) abuse on the onset of pube rty in female adolescents are largely unknown. This study assessed the acut e effects of one AAS, stanozolol, on pubertal onset in the female rat. A si ngle injection of stanozolol (5 mg/kg) on Postnatal Day (PN) 21 advanced va ginal opening but did not alter the onset of vaginal estrus. Higher doses o f stanozolol treatment (10 and 25 mg/kg) also advanced vaginal opening but had no effect on vaginal estrus. The advancement of vaginal opening by stan ozolol (5 mg/kg) was prevented by the concomitant administration of the pur e antiestrogen ICI 182,780 (1 mg/kg) on PN20-22. Administration of the andr ogen receptor antagonist flutamide (10 mg/kg twice daily) on PN20-22 had no effect on the advancement of vaginal opening by stanozolol. Stanozolol tre atment also advanced vaginal opening in ovariectomized rats. Perivaginal in jections of a low dose of stanozolol (0.05 mg) on PN21 and PN23 also advanc ed vaginal opening. These results suggest that stanozolol is acting directl y at estrogen receptors in the vaginal epithelium to advance vaginal openin g and that prepubertal stanozolol treatment does not induce true precocious puberty.