IMPLICATION OF TESTOSTERONE-METABOLISM IN THE CONTROL OF THE SEXUALLYDIMORPHIC NUCLEUS OF THE QUAIL PREOPTIC AREA

In quail, testosterone (T) activates male copulation and affects the v olume and cytoarchitectonic organization of the medial preoptic nucleu s (POM). T metabolism (especially its aromatization) is critical for t he production of these behavioral effects. We wondered whether T metab olism is also playing a role in the induction of the morphological cha nges in POM. We compared the effects of T and of its metabolites in th is nucleus. To obtain an independent evaluation of the role played by aromatase, morphological effects of T associated or not with the aroma tase inhibitor R76713 were also assessed. As previously observed, T in creased the POM volume and the cross-sectional area of the neurons in the lateral part of the nucleus. The effects of T on the neurons in th e lateral POM were mimicked in part by the combined treatment with est radiol and 5alpha-dihydrotestosterone. They were also blocked by the a romatase inhibitor. This suggests that T aromatization plays a critica l role in the mediation of the cytoarchitectonic effects of T. A speci fic role for androgens alone remains to be established.