Sex differences in gamma-aminobutyric acid and glutamate concentrations in discrete rat brain nuclei.

gamma-Aminobutyric acid (GABA) and glutamate concentrations were measured in discrete brain nuclei in adult male and female rats. Significant sex differences in GABA and glutamate concentrations were found in the medical preoptic area (MPA) and ventromedial hypothalamic area (VMH) as well as the lateral hypothalamus, habenula and diagonal band for glutamate. Significant differences in GABA and glutamate concentrations were also observed throughout the estrous cycle in several brain areas. These results suggest that these neuronal systems are sexually differentiated as well as involved in the expression of gonadal steroid feedback.