Dopamine D-1 and D-2 receptor selectivities of phenyl-benzazepines in rhesus monkey striata

Several phenyl-benzazepine compounds, putatively selective dopanzine D-1 re ceptor agonists, have been used to study the effects of dopamine D-1 recept or stimulation in rodents and nonhuman primates. However, the dopamine rece ptor selectivities of these compounds have not been established in nonhuman primates. Accordingly, the relative selectivities of six phenyl-benzazepin es for dopamine D-1-like and D-2-like receptors were assessed in rhesus mon key and, for comparison, rat striata. The compounds tested had higher affin ity for D-1 than D-2 receptors in both species; however, their selectivity varied by up to three orders of magnitude. GTP (100 mu M) reduced agonist b inding at the high-affinity state of the dopamine D-1 receptor, but the mag nitude of the effect of CTP did not reliably predict a compound's efficacy. Furthermore, a history of cocaine self-administration did not appear to in fluence dopamine receptor binding characteristics in the rhesus monkeys in this study. The present results will aid the comparison of dopamine recepto r binding characteristics and behavioral effects of D-1 dopamine receptor a gonists. (C) 1998 Elsevier Science B.V. All rights reserved.