Apomorphine affects cholecystokinin content via preferentially D1 or D2 dopamine receptor according to the regions of the rat brain.

Cholecystokinin octapeptide-like immunoreactivity (CCK-8IR) was measured in several regions of the rat brain after the intraperitoneal administration of apomorphine, SKF-38393 (D1 agonist), LY-171555 (D2 agonist). In the medial prefrontal cortex and striatum, apomorphine and SKF 3839 decreased CCK-8IR. In the anterior and posterior nucleus accumbens, on the other hand, the inhibitory effect of apomorphine was mimicked by LY-171555. These results suggest that apomorphine affects CCK-8IR via either the D1 dopamine (DA)-receptor or D2 DA-receptor according to the brain region.