Differential distribution of D3 dopamine receptors in the brains of several mammalian species

The D-3 dopamine receptor has been proposed as a potential target for the treatment of schizophrenia and drug abuse. This study compares the distribution of D-3 sites in mouse, rat, guinea pig, and rabbit brain, and dog and human cerebellum using quantitative autoradiography with the putatively selective D-3 receptor radioligand [H-3]PD 128907. In the mouse, rat, guinea pig, and rabbit, specific [H-3]PD 128907 binding was heterogeneously distributed with highest densities observed in the islands of Calleja, followed by the nucleus accumbens. Moderate densities of [H-3]PD 128907 binding were observed in the anteroventral and dorsomedial caudate nucleus. Dense [H-3]PD 128907-labelled sites were observed in the dorsal thalamus, posterior mamilliary nucleus, and dorsomedial interpeduncular nucleus of the rabbit that were not detected in the other species studied. Moderately dense [H-3]PD 128907 binding was also observed in the molecular layer of cerebellar lobule X of the rat but not in the mouse, guinea pig, rabbit, dog, or human. These observations indicate significant inter-species differences in the distribution of D-3 receptors. (C) 1998 Elsevier Science B.V. All rights reserved.