Androgen threshold to activate copulation differs in male rats prenatally exposed to alcohol, stress, or both factors

Few male rats prenatally exposed to a combination of alcohol and stress cop ulate spontaneously. This study determined adult sensitivity to testosteron e (T) in males prenatally exposed to alcohol, to stress, or to both factors . Sexually naive males were tested with receptive females following castrat ion and implantation of 20-, 30-, or 45-mm Silastic T-filled capsules. Seru m T levels provided by these implants were measured. The behavior shown by males exposed only to prenatal alcohol did not differ from untreated contro l animals at any T dosage. Prenatal stress alone diminished the copulatory potential below control levels only when the intermediate T dosage was prov ided. Few males exposed to both alcohol and stress copulated under the lowe st or the intermediate dose of adult T replacement, but most ejaculated nor mally when the largest capsule was implanted. The threshold to the sexual b ehavior-activating-properties of adult T exposure was moderately raised by prenatal stress but was severely affected when prenatal stress was combined with alcohol. We conclude that a diminished sensitivity to androgen in adu lthood underlies some copulatory deficits resulting from treatments that al ter fetal T levels. Such deficits may be concealed when behavior is evaluat ed in gonadally intact animals. (C) 1999 Academic Press.