Dopamine release in the medial preoptic area of female rats in response tohormonal manipulation and sexual activity

Dopamine (DA) is responsive to hormonal manipulations and has been implicat ed in the regulation of female rat sexual behavior. In the present studies, extracellular DA levels were assessed in the medial preoptic area (MPOA) o f ovariectomized female rats in response to exogenous ovarian hormones and during sexual activity. In female rats primed with a low dose of estradiol benzoate (2 mu g), but not with a higher dose (20 mu g), a 500-mu g progest erone injection increased extracellular DA and facilitated copulatory behav ior. Extracellular DA levels in the MPOA were further augmented during sexu al interactions with a male rat in a nonpacing copulatory chamber by either perineal or vaginal stimulation. However, in a pacing chamber, DA efflux d id not increase, although the metabolites rose significantly during copulat ion. Together, these findings suggest that extracellular DA in the MPOA res ponds to the hormonal state of the female rat and may contribute to her exp ression of sexual behavior.