Prenatal androgen blockade accelerates pubertal development in male rhesus monkeys

Aspects of the prenatal environment, including steroid hormones, modulate the timing of puberty onset in many mammalian species. This study tested whether prenatal androgen manipulations altered pubertal development in male rhesus macaques (Macaca mulatta). Pregnant females received testosterone enanthate (TE), the androgen receptor blocker flutamide, or vehicle during one of two periods of gestation, and their male offspring were observed for morphological, endocrine, and behavioral development from 3 to 4.5 years of age. Males exposed to flutamide early in gestation had a greater response to exogenous GnRH prepubertally, and greater testes volume, elevated testosterone, and elevated LH at age 3.5 than did control subjects. Males exposed to flutamide late in gestation also had greater testes volumes at age 3.5 than did control males. However, these differences between flutamide treated males and control males did not persist postpubertally. By 4.5 years of age, development in control males had reached comparable levels to that of flutamide-treated males. Late gestation treatment with TE had no effect on morphological pubertal development but early TE treatment altered some aspects of endocrine function during puberty. None of the prenatal androgen manipulations affected sexual behavior. These findings suggest that prenatal androgens, in conjunction with social factors, masculinize pubertal timing in rhesus monkey males.