Catalepsy-associated behavior induced by dopamine D 1 receptor antagonists and partial dopamine D 1 receptor agonists in squirrel monkeys

Abstract

Observational procedures were used to compare the behavioral effects of dopamine D 1 receptor antagonists and partial dopamine D 1 receptor agonists in squirrel monkeys. The dopamine D 1 receptor antagonists SCH 39166 ((−)- tran-6- 7,7a,8,9,13b-hexahydro-3-chloro-2-hydroxy-N-methyl-5H-benzo(d)naphtho-(2,1-b)azepine) and BW 737C89 ([ S]-6-chloro-1[2,5-dimethoxy-4-propylbenzyl]- hydroxy-2-methyl-1,2,3,4-tetrahydroisoquinoline) produced dose-related increases in the duration of static and unusual postures, indicative of catalepsy. R-SKF 38393 ( R(+)-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-[1 H]-3-benzazepine) and SKF 75670 (7,8-dihydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-[1 H]-3-benzazepine), which are considered partial dopamine D 1 receptor agonists, also consistently produced dose-related increases in catalepsy-associated behavior and had effects comparable in magnitude to those of dopamine D 1 receptor antagonists. In contrast, the higher efficacy D 1 agonists SKF 81297 (6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-[1 H]-3-benzazepine) and SKF 82958 (6-chloro-7,8-dihydroxy-1-phenyl-2,3,4, 5-tetrahydro-3-allylp-[1 H]-3-benzazepine) did not produce catalepsy-associated behavior at any dose tested. The results indicate that dopamine D 1 agonists differ with respect to cataleptogenic activity, possibly reflecting differences in intrinsic activity.