Phorbol esters stimulate the potassium-induced release of cholecystokinin from slices of cerebral cortex, caudato-putamen and hippocampus incubated in vitro.

Incubation of slices of caudato-putamen, cerebral cortex and hippocampus for 5 to 15 minutes with phorbol 12,13-dibutyrate (PDB) or phorbol 12-myristate 13-acetate (PMA) increased potassium evoked cholecystokinin (CCK) release from 139% to 296% of control. The inactive 4 alpha phorbol and 4 alpha PDB did not alter CCK release. None of the active or inactive phorbols tested altered basal CCK release. These results suggest that there may be similarities in the regulation of CCK release in different brain regions. Although the physiological factors which regulate CCK release may differ in these tissues, it is possible that their common action is mediated by the products of inositol phospholipid turnover.