Sulfated cholecystokinin octapeptide (CCK8) failed to modulate basal or dopamine-stimulated adenylate cyclase activity in the rat striatum

1. In view of previously demonstrated modulatory effects of CCK8 on DA-sensitive adenylate cyclase activity in the nucleus accumbens, we examined the effects of this neuropeptide in the striatum. 2. Adenylate cyclase activity was measured by conversion of alpha-[32P]ATP into [32P]cAMP. 3. CCK8, when added to the adenylate cyclase assay in concentrations up to 100 microM, failed to significantly alter, either positively or negatively, basal or DA-stimulated (30 or 100 microM) adenylate cyclase activity. Similar results were obtained in the presence of various peptidase inhibitors. 4. Under the assay conditions employed in these experiments, it would appear that there is no effect of CCK8 on DA-sensitive adenylate cyclase in the striatum.