Inhibition of Human Gastric Lipase Secretion by Glucagon-like Peptide-1

Glucagon-like peptide-1 (GLP-1) may be one ofthe enterogastrone hormones of the ileal brakemechanism. We therefore studied its effects on gastriclipase secretion in healthy volunteers and vagotomized patients during infusion of pentagastrin. Theintestinal incretin hormone GLP-1 (glucagon-likepeptide-1, 7-36 amide) was investigated because of itsinhibitory effects on gastric acid secretion andmotility. GLP-1 infused intravenously in amountscorresponding to the postprandial release significantlyinhibited pentagastrinstimulated gastric lipasesecretion and lipolytic activity. The inhibitory effectof GLP-1 persisted in vagotomized patients,suggesting that fundic chief cells, from which gastriclipase is released, or neighboring inhibitory cellscould be equipped with GLP-1 receptors. Vagotomizedpatients had significantly higher plasma concentrationsof gastrin and secretin. No significant changes ofgastrin, secretin, and CCK secretion were seen duringGLP-1 infusion in the vagotomized patients, whereas secretin decreased significantly in the healthyvolunteers. GLP-1 seems to be a naturally occurringinhibitor of gastric lipase secretion acting via anonvagal mechanism. Our results indicate that gastric lipase secretion is subject to hormonalstimulatory as well as inhibitory mechanisms.     

Gastric Emptying of Indigestible versus Digestible Oils and Solid Fats in Normal Humans

Recent scintigraphic studies indicate thatlipolytic products in the small intestine do not inhibitgastric emptying of fat as potently as previouslysuggested by studies that compared a liquid indigestible oil with a solid digestible fat. The olderstudies left open the confounding possibility that solidfats emptied differently than liquid oil. We studiedeight normal subjects who ingested four meals in which fat was (1) liquid, digestible Criscooil, (2) liquid, indigestible sucrose polyester oil, (3)digestible, solid Crisco, and (4) indigestible, solidolestra. Fats were labeled with iodine-123, and their gastric emptying was followed with agamma camera. Indigestible fats (whether liquid orsolid) emptied consistently faster than digestible fats(P < 0.005), although differences were small. Solid fats emptied about as rapidly as oils in thefirst hour; but more slowly thereafter (P < 0.01). Acomparison of present scintigraphic with older studiessuggested that solid fats were not well tracked by duodenal, marker-perfusion techniques, whichmisled previous investigators.