Comparison of androgen levels in normal males (Gallus domesticus) and in males made sexually inactive by embryonic exposure to testosterone propionate

Abstract

Testosterone propionate (TP) administered to chicken embryos on the third day of embryonic development will markedly inhibit the development of normal male sexual behavior. This study was conducted to monitor the testosterone and dihydrotestosterone (DHT) levels in the serum of these TP males. Eggs from a New Hampshire strain of chickens were dipped on the third day of incubation in 2% TP solution. Blood samples were collected from TP and control males when they were 12, 16, 20, and 24 weeks old. Radioimmunoassay was used to measure testosterone and DHT in all serum samples. Mating behavior was tested when the birds were 24 weeks old. Testosterone and DHT concentrations were significantly lower in the serum of TP birds than in control birds. Testicular and pituitary gland weights were also decreased significantly in TP males. Mating behaviors of TP birds were markedly inhibited. In explaining the failure of TP males to mate we have entertained a threshold response theory (failure of the mating center to respond), a concentration theory (too low a concentration of incubating androgens), and a barrier theory (failure of the androgens to reach the hypothalamic mating center).