Organization and activation of behavior in quail: role of testosterone metabolism.
In quail, the hypothalamus enzymatically transforms testosterone (T) into estradiol (E2), 5 alpha-dihydrotestosterone (5 alpha-DHT), and 5 beta-dihydrotestosterone (5 beta-DHT). During the embryonic life, the 5 beta-reductase activity is very high, which probably protects the brain of males from being behaviorally demasculinized by their endogenous T. 5 beta androstanes are inactive androgens. The decrease of 5 beta reductase with age during sexual maturation corresponds to a potentiation of the effects of T as shown by experiments that compared the effects of T and 5 alpha-DHT in adult and young quail. T metabolism is also involved in the activation of male behavior in the adult. T aromatization is probably essential for behavioral activation, but nonaromatizable androgens such as methyltrienolone, and to some extent 5 alpha-DHT, can also stimulate sexual behavior in castrates. These enzymatic activities show a clear neuroanatomical localization and are sexually dimorphic. Males produce more active metabolites (E2, 5 alpha-DHT) than females, which could explain the male's greater sensitivity to T treatments. It thus appears that T metabolism is involved in the differentiation and activation of behavior in quail.
D000818:Animals; D003370:Coturnix / Q000502:physiology*; D013196:Dihydrotestosterone / Q000096:biosynthesis; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D007031:Hypothalamus / Q000378:metabolism; D008297:Male; D011784:Quail / Q000502:physiology*; D012733:Sex Differentiation; D012726:Sexual Behavior, Animal / Q000502:physiology*; D012741:Sexual Maturation; D013739:Testosterone / Q000378:metabolism*
D013196:Dihydrotestosterone; D013739:Testosterone; D004958:Estradiol