Effects of the antiandrogens cyproterone acetate and flutamide on male reproductive behavior in a lizard (Anolis sagrei).

This study examined the effects of the antiandrogens cyproterone acetate (CA) and flutamide (F) on male reproductive behavior in the lizard Anolis sagrei. Reproductively active males were implanted with subcutaneous pellets of either CA, F, or placebo (P). Pellets delivered CA and F at a constant rate of 0.1 mg/day. Three weeks after implantation, males were tested with stimulus males and two days later with stimulus females. Cyproterone acetate inhibited aspects of male aggressive and sexual behavior, and reduced testis weight and size of the renal sex segment. Plasma testosterone (T) levels in CA-treated males were not significantly different than those of P-treated males. Flutamide did not inhibit aggressive or sexual behavior, but did decrease testis weight as well as the size of the renal sex segment. Plasma T levels were significantly higher in F-treated males than in P-treated males. These data suggest that CA, an antiandrogen with antigonadotropic activity, may be used to inhibit reproductive behavior in male lizards.