In order to investigate the effects of cholecystokinin octapeptide(CCK₈) on calmodulin activity in rat cerebral cortex，the cerebral cortex neurocytes was used as a model. CCK₈ stimulated the activation of CaM in a time-dependent manner. After 15 minutes of treatment of 1 μmol/L CCK₈，the CaM activity reached the maximum increase. CaM activity was increased in a dose-dependent manner by CCK₈ (10^－12～10^－7 mol/L). The CCK_B-specific receptor antagonist L-365，260 and with a weaker efficiency，the CCK_A-specific receptor antagonist L-364，718，were able to block a maximal effect of CCK₈-induced CaM activation，suggesting that CCK_B receptor may regulate CaM activity in cerebral cortex.