The primary goal of this research is to gain a better understanding of the physiological mechanisms underlying the hormonal control of behavior. The behavioral actions of androgens such as testosterone appear to be mediated by the interaction of their estrogenic and androgenic metabolites. Both androgenic and estrogenic metabolites are necessary to activate normal male behavior patterns in a wide variety of species. The major focus of the present research is to determine how these two classes of hormones interact within the brain to elicit such behaviors. Levels and turnover of four monoaminergic neurotransmitters, as well as levels of the enzymes responsible for the synthesis and degradation of a fifth neurotransmitter, acetylcholine, will be monitored in specific brain nuclei known to mediate behavior dependent on the combined actions of estrogenic and androgenic metabolites. Examining the responses of these neurotransmitter systems to treatment with androgens alone, estrogens alone, or combined treatment with androgens + estrogens should help us to understand how these two classes of hormones interact in the brain to modulate behavior. Interactions of the androgen and estrogen receptor systems in the same nuclei will also examined. A second line of research investigates the importance of androgen metabolism via the 5 Alpha-reduction pathway to determine whether conversion of androgens to 5 Alpha-reduced metabolites is obligatory for the neural activation of male behavior patterns. A third line of research investigates the importance of estrogenic metabolites in the bloodstream, their binding to serum proteins and how it affects their availability, and examines whether social interactions affect the production rate of estrogenic metabolites from androgens as suggested by earlier data. This research on hormone interactions in the central nervous system, the specificity of hormone-sensitive neural mechanisms, and hormone transport and metabolism should increase our understanding of the organization and functioning of endocrine control mechanisms. Hopefully, it will also contribute to the improved management of endocrine function.
