The role of dopamine in the nucleus accumbens and striatum during sexual behavior in the female rat

Dopamine in dialysate from the nucleus accumbens (NAcc) increases during se xual and feeding behavior and after administration of drugs of abuse, even those that do not directly activate dopaminergic systems (e.g., morphine or nicotine). These findings and others have led to hypotheses that propose t hat dopamine is rewarding, predicts that reinforcement will occur, or attri butes incentive salience. Examining increases in dopamine in NAcc or striat um during sexual behavior in female rats provides a unique situation to stu dy these relations. This is because, for the female rat, sexual behavior is associated with an increase in NAcc dopamine and conditioned place prefere nce only under certain testing conditions. This experiment was conducted to determine what factors are important for the increase in dopamine in dialy sate from NAcc and striatum during sexual behavior in female rats. The fact ors considered were the number of contacts by the male, the timing of conta cts by the male, or the ability of the female to control contacts by the ma le. The results indicate that increased NAcc dopamine is dependent on the t iming of copulatory stimuli, independent of whether the female rat is activ ely engaged in regulating this timing. For the striatum, the timing of copu latory behavior influences the magnitude of the increase in dopamine in dia lysate, but other factors are also involved. We conclude that increased ext racellular dopamine in the NAcc and striatum conveys qualitative or interpr etive information about the rewarding value of stimuli. Sexual behavior in the female rat is proposed as a model to determine the role of dopamine in motivated behavior.