Abstract
The aim of this study was to develop a method to test the anti-androgenic effects of chemicals in birds. Male Japanese quail were castrated to lead the regression of cloacal protrusion, and they were treated with testosterone or flutamide, an anti-androgenic chemical, after 3 weeks of castration. Then changes in the size of cloacal protrusion area were measured. The cloacal protrusion area increased until Day 14 in birds implanted with silastic tube containing testosterone. In testosterone-stimulated birds, the growth of cloacal protrusion was significantly suppressed by injection with a dose of 10,000μg/100g BW of flutamide. However, significant suppressive effects of flutamide were not observed with doses lower than 10,000μg/100g BW. The size of cloacal protrusion reached the maximum by Day 8 followed by decreasing from Day 13 in the birds implanted with silastic plate containing 1mg testosterone. The growth of cloacal protrusion was significantly suppressed by daily i.p. injection with 10,000μg flutamide. These results suggest that the cloacal protrusion of Japanese quail is a useful marker to test the anti-androgenic effects of chemicals in avian species.
