The organization and activation of sexual behavior in quail

Japanese quail are small galliformes, easily raised and maintained in laboratory settings. As their behavior is tightly regulated by sex steroid hormones, they constitute the most studied avian species for the hormonal regulation of sexual behavior. They were used to establish the hormonal specificity of this regulation, to map the brain regions involved in behavior control and to demonstrate the key role of brain aromatization of testosterone in the regulation of male sexual behavior. As the quail brain expresses large amounts of aromatase, the key enzyme for the conversion androgens into estrogens, Japanese quail constitutes an exquisite model to study the role and control mechanisms of this enzyme both in vitro and in vivo. Work conducted in quail contributed to show that along with the long-term regulation of the expression of aromatase by sex steroids, its activity is also rapidly regulated by neuronal activity. More recently, work in quail unraveled a role for brain aromatase in the regulation of female sexual behavior. Finally, Japanese quail have been used to study how sex steroid hormones contribute to the emergence and maintenance of sex differences in brain and behavior. In particular, as the embryo develops outside the mother’s womb, they constitute a suitable model to distinguish between the direct effects of hormonal treatments and their influence through modulation of the maternal environment. Most techniques classically employed in neuroscience and neuroendocrinology have been adapted to this species and more modern techniques such as transgenesis and viral transfection,are now becoming available as well thus expanding the possibilities offered by this model.