Distribution of galanin-immunoreactive cells within sexually dimorphic components of the medial preoptic area of the male and female rat.

A high percentage of galanin-immunoreactive (GAL-I) cells within sexually dimorphic components of the medial preoptic area (MPOA) of the rat also concentrate estrogen and GAL microinjected within the medial preoptic nucleus (MPN) facilitates masculine sexual behavior after testosterone priming. Thus, we determined the distribution of GAL-I cells within the MPOA and their response to gonadal steroids. We report significantly greater numbers of GAL-I cells within the central division of the medial preoptic nucleus (MPNc) and fewer within the anteroventral periventricular nucleus (AVPv), of the gonadectomized male than the gonadectomized female; that GAL-I cell numbers and densities within the AVPv are increased significantly in the intact, testosterone- or estrogen-treated male compared to the gonadectomized male and that GAL-I cell numbers and densities within the MPNc and GAL-I cell densities within the medial division of the MPN (MPNm), are increased significantly by gonadal steroids in rats of both sexes. The results suggest an involvement of galaninergic cells within the MPOA in the regulation of sexually dimorphic, gonadal steroid-sensitive functions.