Testosterone and "5alpha-dihydrotestosterone" levels in peripheral plasma of male and female ring doves (Streptopelia risoria) during and reproductive cycle.

Abstract

Testosterone (T), 5α-dihydrotestosterone (DHT), and androstenedione (A) were measured by radioimmunoassay in peripheral plasma of paired male and female ring doves throughout the reproductive cycle. Before the males were moved to the breeding cage for pairing, their T levels were 183.4 ± 28.1 pg/ml and their DHT levels were 129.5 ± 16.3 pg/ml. Within 4 h after pairing with a female, male androgen levels rose (T = 322.8 ± 136.5 pg/ml, DHT = 1043.8 ± 247.3 pg/ml) and by three days after pairing T and DHT had reached peak levels (701.4 ± 116.8 pg/ml and 1279.5 ± 241.1 pg/ml, respectively). By the time the female laid her first egg, marking the end of the courtship phase and the beginning of the incubation phase, T and DHT levels had declined to 189.6 ± 26.1 and 200.0 ± 41.9. Androgen remained at approximately these low baseline concentrations throughout incubation and squab rearing, and showed a second elevation only at the beginning (courtship phase) of the next reproductive cycle. Androstenedione levels never exceeded 10 pg/ml. In the absence of females, neither removal of a male from his home cage to a novel cage, nor pairing of a male with another male resulted in elevation of T or DHT above baseline values. Castrated males paired with females also exhibited no rise in T or DHT concentrations above baseline values. It is concluded that female doves induce increased androgen secretion in males during the coutship phase of the reproductive cycle, that the major source of the androgen surge is testicular, and that the predominant circulating androgens in male doves are T and DHT. T and DHT were also detected in females, with somewhat higher concentrations tending to occur during courtship than at other phases of the cycle. However, androgen concentrations in females were lower than those of males at all stages of the reproductive cycle.