SEXUAL-ACTIVITY INCREASES DOPAMINE TRANSMISSION IN THE NUCLEUS-ACCUMBENS AND STRIATUM OF FEMALE RATS

In vivo microdialysis was used to monitor extracellular concentrations of dopamine (DA), and its metabolites dihydroxyphenylacetic acid (DOP AC) and homovanillic acid (HVA) in the nucleus accumbens and dorsal st riatum of sexually active female rats during tests of locomotor activi ty, exposure to a novel chamber, exposure to sex odors, the presentati on of a sexually active male rat, and copulation. DA increased slightl y but significantly in the nucleus accumbens when a sexually active ma le was placed behind a wire-mesh screen, and further during copulation . DA also increased significantly in the dorsal striatum during copula tion; however, the magnitude of this effect was significantly lower th an that observed in the nucleus accumbens. The metabolites DOPAC and H VA generally followed DA with a delay, and increased significantly dur ing copulation in both regions. In contrast, forced locomotion on a ro tating drum, exposure to a novel testing chamber, and exposure to sex odors did not increase DA significantly in either region, although for ced locomotion increased DOPAC significantly in both regions, and HVA significantly in the nucleus accumbens. The magnitude of DA release in the nucleus accumbens was significantly greater during copulation tha n running, whereas no significant difference was detected for striatal DA release between these two behavioral conditions. These results ind icate that novelty or locomotor activity alone do not account for the increase in DA observed in the nucleus accumbens of female rats during copulation, and suggest that DA transmission in the nucleus accumbens is associated with anticipatory and consummatory aspects of sexual ac tivity, as it is in male rats. In the dorsal striatum, however, DA rel ease during copulation may reflect an increase in locomotor activity a ssociated with active pacing of the male.