Role of neuroestrogens in the control of male sexual behavior

The conversion of testosterone by brain aromatase is necessay for the activation of several physiological responses and behaviors, including male sexual behavior. Brain-derived estrogens (neuroestrogens) are typically thought to participate to the long-term regulation of behavior by seasonal changes in circulating testosterone, while the moment-to-moment regulation of behavior in response to environmental/social cues would depend on neurotransmitter systems. This view fits in with the classical mode of action of sex steroids which regulate gene expression by acting on nuclear receptors resulting in behavior changes observed within hours to days. Yet, estrogens also exert much faster actions mediated by the activation of membrane-associated receptors that rapidly modulate cellular activity translating behavioral changes detected within minutes. In parallel, brain estrogen production is also rapidly regulated at the presynaptic level by behaviorally relevant cues, thus providing a mechanism for fast and local regulation of estrogenic actions. This talk will summarize our work carried out in Japanese quail demonstrating the dichotomy between these two modes of action of neuroestrogens and how they cooperate to the fine coordination of male sexual behavior within two distinct time frames. Finally, more recent work conducted in mice will also be presented.