AROMATASE-ACTIVITY AND REGULATION OF SEXUAL BEHAVIORS IN THE GREEN ANOLE LIZARD

Sexual behaviors in green anoles are regulated by steroid hormones. An drogens activate the display of masculine courtship and copulatory beh aviors, and estradiol activates feminine receptivity. Testosterone can also facilitate receptivity in females. The present study was conduct ed to test the role of converting testosterone to estradiol (aromatiza tion) in the regulation of sexual and aggressive behaviors. Adult male s and females were gonadectomized and implanted with a Silastic capsul e containing either testosterone propionate (T) or estradiol benzoate (E) or with an empty (blank, BL) capsule. T- and BL-treated animals we re then given injections of either Fadrozole (FAD, an aromatase inhibi tor) or saline (SAL). E-treated animals received saline injections. Ea ch individual was then tested alternately with male and female stimulu s animals. Overall, T stimulated masculine sexual behaviors and recept ivity, but the androgen had little effect on the display of aggressive behaviors. The inhibition of aromatase activity by treatment with Fad rozole eliminated the effect of T on receptivity. In contrast, Fadrozo le treatment had no effect on mounting behavior or the frequency of co urtship bouts. The inhibition of aromatase activity did increase the n umber of dewlap extensions (the display of a red throat fan) during co urtship. These results suggest that the metabolism of testosterone to estradiol is a mechanism through which androgens can facilitate recept ivity, and that such aromatization of testosterone is not required for the display of masculine sexual behaviors. In addition, females perfo rmed courtship and mounting behaviors less frequently than males, sugg esting that an organizational component to steroid hormone regulation of sexual behaviors may exist in the anole. (C) 1998 Elsevier Science Inc.