Experimental studies of the regulation of the dopamine (DA) D-3 receptor have utilized techniques causing massive depletions of the DA system. Zitter mutant rats exhibiting a heterogeneous loss of striatal DA innervation were examined for DA transporter (DAT) binding and DA D-3 receptor number by autoradiography and compared with Sprague-Dawley rats. A significant loss of DAT binding was observed with the greatest in the lateral caudate-putamen (72% loss) and the least in the nucleus accumbens (45% loss). DA D-3 receptors were reduced by >70% in all regions, even in the nucleus accumbens that exhibited considerably smaller depletions of DAT binding, indicating that loss of D-3 receptors may occur prior to massive loss of DA innervation. NeuroReport 11:2173-2175 (C) 2000 Lippincott Williams & Wilkins.