INFLUENCE OF THE TYPE OF DIETARY-FAT UPON THE PLASMA-LEVELS OF SECRETIN AND PANCREATIC-POLYPEPTIDE IN CHOLECYSTECTOMIZED HUMANS

Previous investigations performed in dogs have shown that fat must be hydrolyzed for an adequate release of some gastrointestinal hormones. The aim of this study was to examine endogenously stimulated release o f secretin and pancreatic polypeptide (PP) in cholecystectomized human s, and, therefore, in a situation that may be associated with an impai rment of lipid digestion. The effects of two types of dietary fat on t he secretion of the above hormones was also investigated. The pH and b ile acid concentration in duodenal contents, as well as the plasma lev els of secretin and PP were determined before, and after the administr ation of isocaloric liquid meals containing olive (Group O) or sunflow er oil (Group S) to cholecystectomized subjects that, before the surgi cal procedure, had been consuming (30 days) diets in which olive (Grou p O) and sunflower oil (Group S) were the main source of dietary fat. Food ingestion induced no appreciable changes in plasma secretin in ei ther group. In contrast. PP levels increased marked and significantly (P<0.05) in all the patients after the meal ingestion, though the horm one concentration was significantly higher (P<0.05) in Group O during the entire digestive period. Our results seem to indicate that after c holecystectomy, and as a result of a low luminal postprandial bile aci d content, there may be not only a defective lipolytic phase but also an impaired micellar phase, the release of secretin being affected esp ecially. In addition, it is demonstrated that PP release is differentl y stimulated by dietary fats of different degrees of unsaturation (oli ve and sunflower oil).