Central administration of cholecystokinin potentiates evoked potential amplitude in the hippocampal dentate gyrus.

Cholecystokinin and related ligands were injected into a lateral ventricle and recordings made of the field potential in the hippocampal dentate gyrus evoked by stimulation of the medial entorhinal cortex. With the exception of the unsulfated octapeptide, these compounds induced an increase in population action potential amplitude. The unsulfated octapeptide was found to inhibit the action of its sulfated congener, and alone induced a decrease in response amplitude. These results suggest a modulation of intracortical activation of the dentate gyrus by cholecystokinin, and that this action is probably mediated by a central-type receptor.