Reference : Sexual Differentiation of Brain and Behavior in Quail and Zebra Finches: Studies with...
Scientific journals : Article
Social & behavioral sciences, psychology : Animal psychology, ethology & psychobiology
Human health sciences : Endocrinology, metabolism & nutrition
Social & behavioral sciences, psychology : Neurosciences & behavior
Sexual Differentiation of Brain and Behavior in Quail and Zebra Finches: Studies with a New Aromatase Inhibitor, R76713
Foidart, Agnès mailto [Université de Liège - ULiège > Services généraux (Faculté de médecine) > Service administratif de la Faculté (Médecine) >]
Balthazart, Jacques mailto [Université de Liège - ULiège > Département des sciences biomédicales et précliniques > Biologie de la différenciation sexuelle du cerveau >]
Journal of Steroid Biochemistry & Molecular Biology
Yes (verified by ORBi)
[en] In many species of vertebrates, major sex differences affect reproductive behavior and endocrinology. Most of these differences do not result from a direct genomic action but develop following early exposure to a sexually differentiated endocrine milieu. In rodents, the female reproductive phenotype mostly develops in the absence of early steroid influence and male differentiation is imposed by the early action of testosterone, acting at least in part through its central conversion into estrogens or aromatization. This pattern of differentiation does not seem to be applicable to avian species. In Japanese quail (Coturnix japonica), injection of estrogens into male embryos causes a permanent loss of the capacity to display male-type copulatory behavior when exposed to testosterone in adulthood. Based on this experimental result, it was proposed that the male reproductive phenotype is "neutral" in birds (i.e. develops in the absence of endocrine influence) and that endogenous estradiol secreted by the ovary of the female embryo is responsible for the physiological demasculinization of females. This model could be recently confirmed. Females indeed display a higher level of circulating estrogens that males during the second part of their embyronic life. In addition, treatment of female embryos with the potent aromatase inhibitor, R76713 or racemic vorozole which suppresses the endogenous secretion of estrogens maintains in females the capacity to display the full range of male copulatory behaviors. The brain mechanisms that control this sexually differentiated behavior have not been identified so far but recent data suggest that they should primarily concern a sub-population of aromatase-immunoreactive neurons located in the lateral parts of the sexually dimorphic preoptic nucleus. The zebra finch (Taeniopygia guttata) exhibits a more complex, still partly unexplained, differentiation pattern. In this species, early treatment with exogenous estrogens produces a masculinization of singing behavior in females and a demasculinization of copulatory behavior in males.(ABSTRACT TRUNCATED AT 400 WORDS)

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