POSTNATAL TESTICULAR SECRETIONS PARTIALLY RESTORE THE DISTURBANCES INREPRODUCTIVE ACTIVITY CAUSED BY PRENATAL HORMONAL MANIPULATION

Male rats that prenatally had been exposed to an antiestrogen, nitromi fene citrate (CI 628), showed evidence of impaired defeminization and masculinization in adulthood, suggesting a role of endogenous estrogen for the sexual differentiation of the male. The present study was und ertaken to investigate a possible role of postnatal testicular secreti ons for the above behavioral effects. Male rats were exposed prenatall y to CI 628 (1 mg/rat) or saline, and castrated on Day 0, Day 10, or D ay 90 after birth. After treatment with gonadal hormones in adulthood, the males were tested for feminine and masculine sexual behavior and for sexual orientation, both when sexually naive and after they had ac quired sexual experience. The following conclusions were drawn: 1. Per manent deficits of lordotic behavior were observed in all experimental groups, suggesting the importance of prenatal estrogen for the defemi nization process. 2. Hop/darting and ear wiggling behaviors were enhan ced in Day-0 End Day-10 castrates, and blocked in the Day-90 castrates . The restitution of these behaviors to normal levels in Day-80 castra tes suggests that, in addition to prenatal estrogen, postnatal testicu lar secretions also are involved in the behavioral defeminization proc ess. 3. Prenatal estrogen contributes to masculinization as evidenced by the impaired ejaculatory behavior observed in all experimental grou ps. 4. Male-typical sexual orientation toward the female seems to be f acilitated by prenatal estrogen. Both the masculinization and the defe minization of male-typical sexual orientation toward a female were imp aired by castration at birth and at Day 10 in the experimental animals , but a full restoration of the sexual orientation toward females was seen in Day-90 castrates, suggesting the restorative role of postnatal testicular secretions for these processes. (C) 1997 Elsevier Science Inc.