Subchronic buspirone, mesulergine, and ICS 205-930 lack effects on D1 and D2 dopamine binding in the rat striatum during chronic haloperidol treatment.

We administered the serotonergic agents buspirone, mesulergine and ICS 205-930 during the last two weeks of a 4-week oral haloperidol chronic treatment regimen and determined dopamine receptor binding and apomorphine-induced stereotypic activity after a drug washout period. D1 receptor binding was not affected by any treatment. Chronic haloperidol treatment produced a significant increase in the density of D2 receptors for all groups, including the groups that were administered combination treatment of haloperidol and serotonergic compounds. Apomorphine-induced stereotypic activity measured 4 days after the last haloperidol treatment was elevated to the same extent for all haloperidol treated groups. Contrary to a previous report, subchronic treatment with buspirone did not significantly reverse neuroleptic-induced D2 receptor up-regulation.