Interactions of 7-[3-(4-[2,3-dimethylphenyl]piperazinyl)-propoxy]-2(1H)-quinolinone binding in rat striatum: effects of lesions

Abstract

7-[3-(4-[2,3-Dimethylphenyl]piperazinyl)propoxy]-2(1H)-quinolinone (OPC-4392), a presynaptic dopamine autoreceptor agonist and postsynaptic D-2 receptor antagonist (Yasuda et al., Life Sci. 42: 1941-1954, 1988), was studied for its binding characteristics at 3H-SCH 23390-labeled dopamine D-1 receptors and 3H-spiperone-labeled dopamine D-2 receptors in rat striatum. The binding affinity of OPC-4392 for 3H-spiperone-labeled D-2 receptors was 500 times higher than for 3H-SCH 23390-labeled D-1 receptors. 6-Hydroxydopamine lesions of striatum and high-frequency current lesions of medial forebrain bundle did not affect the competition of OPC-4392 for 3H-spiperone binding. Kainic acid lesions of striatum significantly changed the one-site model fit to a two-site model fit of the competition curve of OPC-4392 for 3H-spiperone binding, suggesting that OPC-4392 competed with 3H-spiperone binding differently for postsynaptic dopamine D-2 receptors and for presynaptic dopamine autoreceptors.