Aromatase inhibition in adolescence impairs sexual performance in adulthood without affecting anxiety-like behaviour in male rats.

Adolescence is a developmental period during which rising gonadal hormones drive the maturation of neural circuits underlying adult behaviour. Testosterone acts directly via androgen receptors (AR) or indirectly through aromatization to estradiol, yet the role of estradiol signalling in refining sexual behaviour during adolescence in male rats remains unclear. We tested whether inhibiting aromatase with fadrozole (FAD) from postnatal day 38 to 48 (around the time of puberty) affects adult sexual behaviour. To determine whether any deficits in sexual behaviour were secondary to anxiety-like behaviour and/or altered stress responding, anxiety-like behaviour and corticosterone release in response to a stressor also were measured. As adults, FAD males did not differ from control (CTL) rats in anxiety-like behaviour, in corticosterone release in response to stress, nor in testosterone concentrations. Aromatase inhibition impaired sexual performance: FAD males mounted, intromitted, and ejaculated less frequently, though sexual motivation and partner preference were preserved. The groups did not differ in AR densities or immunoreactive cell counts in either the medial amygdala or medial preoptic area. Estrogen receptor alpha (ERα) was reduced in the medial amygdala only. These results suggest that aromatization during adolescence refines circuits underlying male sexual behaviour.