Striatal dopamine receptor supersensitivity after long-term haloperidol treatment of hypophysectomized rats

Dopamine (DA) receptor sensitivity was studied after long-term treatment with haloperidol (0.5 and 3.0 mg/kg, ip, single daily dose) or saline in hypophysectomized and intact rats. Haloperidol treatment for seven days produced a 25 to 125% increase in [3H]-spiroperidol binding to striatal DA receptors in a dose-dependent fashion. The increase in binding sites (Bmax) was similar in both hypophysectomized and intact rats when compared to controls. The present results show that hypophysectomy does not effect the supersensitivity of striatal DA receptors induced by long-term haloperidol treatment.