Effect of food deprivation on the function of the intestinal cholecystokinin-producing cell in the rat.

The influence of fasting and refeeding on storage and secretion of cholecystokinin (CCK) was investigated in the rat. Groups of rats deprived of food for 12 and 96 h were studied. Animals of each group received 0.75 g of long-chain triglycerides or water via an orogastric tube after the fasting period 15 min prior to exsanguination. Rats fed ad libitum served as controls. Duodenal, jejunal and ileal segments were dissected for tissue extraction and immunohistochemical staining of CCK-containing cells. Fasting over 96 h resulted in a significant reduction of plasma CCK, duodenal CCK concentrations and number of duodenal CCK-containing cells. Changes were less pronounced in the more distal parts of the small bowel. Refeeding caused an increase in plasma and tissue CCK concentrations, thus abolishing all significant differences that occurred during fasting. Gel chromatography of tissue extracts showed a shift towards the bigger molecular forms after 96 h of fasting. We conclude that storage and secretion of gut CCK are reduced during food deprivation in rats. The reduction of tissue CCK appeared at the expense of the lower molecular forms. However, the functional responsiveness of the CCK cell as indicated by the postprandial rise in plasma CCK seems to be maintained after a 4-day fast.