The nigrostriatal dopamine system shows marked gender differences that, in many cases, can be attributable to estrogen. However, the virtual absence of conventional estrogen receptors within the nigrostriatal dopamine system has made it difficult to understand how estrogen can function within this system. Recent findings have helped to uncover how estrogen can affect a discrete function of striatal dopamine-containing neurons--transporter activity--in a manner similar to that achieved through alterations in dopamine D(2) receptors and their associated G protein. These findings suggest that the effects of estrogen on dopamine transporter function could result from a signal transduction interaction involving D(2) receptor-G protein coupling.