EFFECTS OF CCK ANTAGONISTS ON CCK-INDUCED SUPPRESSION OF LOCOMOTOR-ACTIVITY IN MICE

Sulfated cholecystokinin octapeptide (CCK-8) was administered either i ntraperitoneally or into the cerebral ventricle of fully conscious mic e, and locomotor activity was quantified. CCK-8 administered by either route suppressed locomotor activity. Subcutaneously administered sele ctive CCK-A receptor antagonist, L-364.718 (1 mg/kg), reversed the inh ibitory effect of centrally as well as peripherally administered CCK-8 , but the selective CCK-B receptor antagonist, L-365,260 (1 mg/kg), di d not. These results demonstrate that centrally as well as peripherall y administered CCK-8 suppresses locomotor activity in mice through an interaction with CCK-A, but not CCK-B, receptors.