DIFFERENTIATION OF CENTRAL AND PERIPHERAL CHOLECYSTOKININ RECEPTORS BY NEW GLUTARAMIC ACID-DERIVATIVES WITH CHOLECYSTOKININ-ANTAGONISTIC ACTIVITY

Abstract

Three glutaramic acid derivatives provided with a potent antagonistic activity on the contractions elicited by the carboxyl terminal octapeptide CCK-8 in the guinea pig gallbladder have been evaluated for their capacity to inhibit the binding of [125I]-(Bolton-Hunter)-CCK-8 to both central and peripheric cholecystokinin (CCK) receptors. The most active compound inhibits the CCK binding to rat pancreas acini at a concentration 10-7 mol/l, but only at 10-4 mol/l on cerebral cortex membranes, confirming the existence of at least two different populations of CCK receptors.