Abstract
We examined the effect of peripheral administration of cholecystokinin (CCK)-8S on spontaneous acetylcholine (ACh) release from the frontal cortex and its prevention by loxiglumide, L-364, 718 and L-365, 260 in freely moving rats using intracerebral microdialysis. Subcutaneously (s.c.) administered CCK-8S at 10 and 30 μg/kg significantly decreased the release of ACh. The inhibitory effect of 10 μg/kg (s.c.) CCK-8S was prevented by loxiglumide, a mixed type of CCK-A and -B-receptor antagonist, at 1 mg/kg (intraperitoneal) and 40 μg/rat (intracerebroventricular, i.c.v.); L-364, 718, a CCK-A-receptor antagonist, at 125 and 250 ng/rat (i.c.v.); and L-365, 260, a CCK-B-receptor antagonist at 250 ng/rat (i.c.v.). These results demonstrate that peripherally administered CCK-8S inhibits spontaneous ACh release from the frontal cortex through both central CCK-A (mainly) and -B receptors.
