9600261 Baum This Americas Program award will fund a collaborative research project between Drs. Michael Baum, Boston University, and Raul Paredes, Anahuac University, Mexico City. The researchers will study comparative aspects of brain and behavioral sexual differentiation in two mammalian species, the rat and the ferret. The structure and function of the brain circuit normally undergoes a degree of masculinization in female rats as a consequence of prenatal exposure of the female's brain to testosterone of placental origin. Normally, no such masculinization occurs in the female ferret. Experiments are proposed to treat animals prenatally in order to determine whether circulating androgens and/or estrogens during fetal development are the cause of the more masculine behavior of female rats, and to relate differences in sexual behavior to the functional activation of neurons within regions of the brain that have been sexually differentiated. All the proposed studies involving ferrets will be done in the Boston laboratory, while the comparative work with rats will be done in the Mexican laboratory. The results obtained should improve our understanding of how sex differences in pheromonal communication develop in species representing two different mammalian orders, and will provide basic information concerning the activational and organizational effects of steroid hormones on chemosensory systems important for reproduction. ***
