Abstract
Inter-relations between stimulatory mechanisms of CCK on pancreatic protein synthesis and secretion were investigated in vivo with conscious rats using 14C-leucine and cycloheximide, which is known as a powerful inhibitor of protein synthesis. Continuous intravenous administration of cholecystokinin (250 ng/kg/hour) stimulated pancreatic protein secretion and protein synthesis, but administration of cycloheximide (1 mg/kg) strongly suppressed protein secretion and protein synthesis. Under the condition in which protein synthesis was inhibited by cycloheximide, intravenous infusion of cholecystokinin stimulated protein secretion alone without enhancing protein synthesis. These findings were confirmed by histological examination showing that the number of zymogen granules in acinar cells was lowest in the cycloheximide plus cholecystokinin group. We concluded that cholecystokinin enhanced both pancreatic protein secretion and protein synthesis, and that both mechanisms were closely related, and were simultaneously stimulated by cholecystokinin, but in some parts, independently.
