During development, gonadal steroids (androgens and estrogens) confer permanent sex-specific differences (sexual dimorphism) onto the organization and function of the brain. This sexual dimorphism in the brain, in turn, leads to production of behavior that is different in male and female animals. The estrogens and androgens act during a very specific and limited period in early development to induce these permanent sex-specific differences in brain structure and in behavior. The best studied brain structure which is both sexually dimorphic and is known to be critical in mediating sex-specific behavior is the hypothalamus. We know that much of the information transfer in neurons in the hypothalamus depends upon the presence of a class of proteins called GABA (gamma-aminobutyric acid) receptors. The goal of this work is to determine if androgens and estrogens act during this critical period in early development to alter the types of GABA receptors that are expressed in the hypothalamus and to determine if steroid-dependent changes in GABA receptor expression lead to changes in sex-specific behaviors in adult animals. The results from this study may help us to understand how development in the brain is regulated to produce sex-specific behaviors.
