ROSEN, G.*; WADE, J.: Androgen metabolism in the green anole lizard brain

5ALPHA-reductase facilitates male courtship behavior in green anole lizards by converting testosterone (T) to dihydrotestosterone. The present study was done to determine whether sex and seasonal differences in the enzyme’s activity occur in the anole brain, reflecting its role in male courtship behavior. The pattern of expression also was assessed for aromatase, which converts T to 17BETA-estradiol. Multiple assays were done to compare enzyme activities in the following: 1) breeding males and breeding females; 2) breeding males and non-breeding males; 3) non-breeding males and non-breeding females. Enzyme activity was assayed in homogenates of individual whole brains. 5ALPHA-reductase was also assessed in brainstem homogenates, since this region contains the greatest level of activity for this enzyme. Breeding males, breeding females and non-breeding males had equivalently high 5ALPHA-reductase activity. In contrast, breeding males had greater aromatase activity than breeding females and non-breeding males. The results are generally consistent with those of other vertebrate species in which sex and seasonal differences are present in aromatase, but not 5ALPHA-reductase. The greater aromatase activity in breeding males indicates that this enzyme might mediate male-specific functions, although the behavioral relevance of this enzyme in male anoles is unclear. The high levels of 5ALPHA-reductase activity in both sexes suggests that the enzyme might have important functions in females as well as in males.