Hypophysectomy does not alter the increase in striatal dopamine receptor density produced by 6-hydroxydopamine lesions in male rats.

While hypophysectomy can alter the increase in striatal dopamine (DA) receptor density observed after estrogen, haloperidol or prolactin treatments, it does not alter the increase in density found after 6-hydroxydopamine lesions of the DA neurons in male rats. This observation suggests that striatal DA receptors can be regulated by at least two distinct mechanisms, only one of which requires the availability of pituitary hormones.