Aromatase inhibition blocks the expression of sexually-motivated cloacal gland movements in male quail.

In Japanese quail (Coturnix japonica), activation of appetitive and consummatory aspects of male sexual behavior requires aromatization of testosterone (T) into estrogens. Appetitive male sexual behavior (ASB) is usually assessed with the use of a learned social proximity procedure. In the present experiment, we investigated the role of estrogens in the activation of an another index of ASB, the female-induced activation of rhythmic cloacal sphincter movements (RCSMs) that are produced in reaction to the visual presentation of a female. Consummatory sexual behavior (CSB) was also assessed by the frequency and latency of copulatory behaviors. Castrated male quail were treated with Silastic implants filled with T in association with chronic injections of the aromatase inhibitor Vorozole (R83842; 1mg/kg twice a day; CX + T + VOR group). Control birds were implanted with T capsules only (CX + T group). CSB was almost completely blocked by injections of the aromatase inhibitor. The RCSM frequency decreased progressively in the CX + T + VOR group by comparison with the CX + T group and was therefore significantly reduced at the end of the experiment. These results demonstrate that the frequency of RCSM, a second measure of ASB is, like the social proximity response and CSB, blocked by inhibition of estrogen production. It was shown previously that lesions of the preoptic area inhibit both aspects of the appetitive sexual behavior (proximity response and RCSM). It is therefore, likely that both responses are controlled, like copulation, by aromatase-containing neurons of the preoptic area.