Cholecystokinin and its COOH-terminal octapeptide in the pig brain.

Two components--one resembling intact cholecystokinin in size and charge and immunologic specificity, and the other resembling the COOH-terminal octapeptide of cholecystokinin--have been found in extracts of the pig cerebral cortex. The relative concentrations of the two peptides in the extracts were dependent on the extractant, boiling 0.1 M HCl being more effective than boiling water for the extraction of intact cholecystokinin but less effective for the extraction of the octapeptide. The physiologic role of these peptides in the brain has yet to be elucidated.