ORIGINAL ARTICLE Aromatase mRNA in the Brain of Adult Green Anole Lizards: Effects of Sex and Season

Steroid hormones are important for the expression of sexual behav-iours in a variety of animals. Specifically, the neural metabolism of testosterone to oestradiol (E2) by aromatase regulates expression of these behaviours in vertebrates, including Japanese quail, midship-man fish, musk shrews, songbirds and mice (1–5). In males, inhibition of aromatase blocks normal copulatory behaviours in Japanese quail, and aromatase knockout mice do not display complete sexual behav-iour unless given oestrogens (5, 6). Aromatase is also important for the expression of female behaviours. Inhibitors of this enzyme decrease female canary sex behaviours and aromatisable androgens facilitate copulatory behaviour in female musk shrews (3, 7). In most species, aromatase is concentrated in the limbic regions of the brain, including those important for the expression of male specific sexual behaviours such as the preoptic area (POA) and amygdala (AMY), as well as the ventromedial hypothalamus (VMH)