Postnatal Testicular Secretions Partially Restore the Disturbances in Reproductive Activity Caused by Prenatal Hormonal Manipulation

Abstract

Vega Matuszczyk, J., R. S. Appa and K. Larsson. Postnatal testicular secretions partially restore the disturbances in reproductive activity caused by prenatal hormonal manipulation. Physiol Behav 62(1) 137–143, 1997.—Male rats that prenatally had been exposed to an antiestrogen, nitromifene 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 undertaken to investigate a possible role of postnatal testicular secretions for the above behavioral effects. Male rats were exposed prenatally to CI 628 (l mg/rat) or saline, and castrated on Day 0, Day 10, or Day 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 acquired sexual experience. The following conclusions were drawn: 1. Permanent deficits of lordotic behavior were observed in all experimental groups, suggesting the importance of prenatal estrogen for the defeminization process. 2. Hop/darting and ear wiggling behaviors were enhanced in Day-0 and Day-10 castrates, and blocked in the Day-90 castrates. The restitution of these behaviors to normal levels in Day-90 castrates suggests that, in addition to prenatal estrogen, postnatal testicular secretions also are involved in the behavioral defeminization process. 3. Prenatal estrogen contributes to masculinization as evidenced by the impaired ejaculatory behavior observed in all experimental groups. 4. Male-typical sexual orientation toward the female seems to be facilitated by prenatal estrogen. Both the masculinization and the defeminization of male-typical sexual orientation toward a female were impaired 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.