Role of cholecystokinin in the control of nociception and food intake.

Intraperitoneal administration of cholecystokinin (CCK) potently attenuated opiate analgesia produced by footshock. CCK also inhibited opiate footshock analgesia when delivered intrathecally to the lumbosacral spinal cord, a critical site of opiate action in mediating this form of analgesia. However, opiate-independent footshock analgesia was not attenuated by CCK. Morphine analgesia was attenuated by CCK and potentiated by sequestration of peripheral CCK through an active immunization procedure. CCK also was found to suppress food intake in rats when microinjected into the hypothalamic paraventricular nucleus, a site known to mediate opiate-induced feeding. Collectively, the findings reviewed here suggest that an opiate antagonistic action may underlie several of the effects of CCK.