Rapid effects of ovarian hormones in dorsal striatum and nucleus accumbens.

Contribution to Special Issue on Fast effects of steroids. Estradiol and progesterone rapidly induce changes in dopaminergic signaling within the dorsal striatum and nucleus accumbens of female rats. In ovariectomized females, estradiol rapidly enhances dopamine release and modulates binding of dopamine receptors. Progesterone further potentiates the effect of estradiol on dopamine release. The effects of both estradiol and progesterone are time course dependent, with increases in dopamine release immediately after acute hormone administration followed by later inhibition of dopamine release. Importantly, these changes are also seen in naturally cycling females, indicating their importance for normal physiological states and relevant reproductive behaviors. Here, we summarize the literature establishing the rapid effects of estradiol and progesterone on dopamine release and receptor expression in dorsal striatum and nucleus accumbens of both males and females. Integrating this literature with the larger body of work focusing on dopamine regulated behaviors, we propose hypotheses for adaptive reasons (i.e., ultimate causes) as to why changes in ovarian hormones modulate dopamine release. Finally, we note the importance of these studies for understanding sex differences in vulnerability to drug addiction. Research on how dopaminergic systems regulate behavior in both males and females is crucial for developing a full appreciation of dopamine's role in both natural and drug-induced behaviors.