BEHAVIORAL DEVELOPMENT PRENATAL HORMONAL INFLUENCES

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The early hormone environment has been thought to influence the development of male/female behavioral and neuroendocrine differences through the life span. This study exposed developing male and female rhesus monkeys to atypical prenatal hormonal environments and has been investigating their behavioral and neuroendocrine development. Treatments were designed to mimic accidental exposure to or suppression of androgens prenatally. This study investigated whether prenatal androgen exposure, social rank, and body weight are factors regulating pubertal development in female rhesus monkeys. Subjects¿ mothers received injections of testosterone enanthate (20 mg/week), flutamide (an androgen receptor blocker, 30 mg/kg twice daily), or vehicle during gestational days 35/40-70 (early) or days 105/110-140 (late). We investigated whether reducing endogenous T prenatally affected adult copulatory behavior in male rhesus monkeys. Treatment with flutamide early in gestation resulted in males with significantly less masculinized genitals that control males or males getting flutamide late in gestation. Twelve hours of mating behavior were collected on each male during the breeding season. When analyses were corrected for social rank, there were no significant effects of treatment on overall sexual activity. Males with poorly masculinized genitals had more mounts without pelvic thrusting and more mounts without intromissions, but ejaculated at comparable levels to other males. This study separates the effects of reduced androgen on genital and behavioral differentiation and suggests that reduced masculinization of genitalia is not associated with reduced copulatory behavior.