The neuroendocrinology of testosterone - sociosexual behavior relations

Steroids produced in the periphery have long been of interest to reproductive biologists. The emergence of neuroendocrinology as a dominant subfield of behavioral studies appeared to demote steroids to a lesser status than the exciting neuropeptides that clearly interacted with many regions of the brain. Seminal findings in recent years, however, have propelled the study of steroids back onto center stage. In this chapter we identify the seminal findings and describe why they are revolutionary. These new findings have demonstrated steroids have the capacity to modify the structure and function of brain regions both related to and unrelated to reproduction. The consequences on behavior are likely to be profound. This chapter focuses on one steroid, testosterone, because it occupies a strategic position in the metabolic cascade of the sex steroids. It is a position that can influence the actions of androgens and estrogens, as well as the adrenal precursors of testosterone and the recently identified neurosteroids, on the brain and behavior. We believe future research will reveal testosterone to have behavioral effects extending well beyond those related to reproduction. Still, the massive literature on testosterone - sociosexual behavior provides a solid background on which to begin that work.