Impaired pancreatico-biliary response to vagal stimulation and to cholecystokinin in human obesity

Abstract

We previously found that massively obese patients respond with less gastric acid secretion in response to vagal stimulation. This is compatible with the described association between experimental obesity and altered vagal function in the rat. To confirm this observation, the pancreatic and biliary responses to vagal stimulation were examined in nine nondiabetic obese patients against a background secretin infusion of 15 CU × h⁻¹, and monitored after a subsequent injection of 75 IDU of cholecystokinin. Two separate marker perfusion systems were used in the stomach and duodenum, respectively, and blood samples were drawn for hormone analyses. In contrast to controls having normal body weight, the obese patients failed to respond with increments of pancreatic enzyme secretion and duodenal bile acids after stimulation with modified sham feeding. Cholecystokinin stimulated the pancreatic secretion of trypsin, amylase, and lipase, the emptying of bile acids, and the release of gastrin, but the patients' responses were only half that of the controls. In the resting state the obese had higher outputs of bile and pancreatic enzymes and higher plasma levels of pancreatic polypeptide compared with controls, but the pancreatic bicarbonate secretion rate was not different. The almost complete suppression of the basal gastric acid secretion by a low dose of intravenous (IV) secretin in controls did not occur in the obese. We conclude that massive obesity is associated with a reduced pancreatic and biliary response to vagal stimulation. Compared with controls, the digestive functions of the obese patients seem to be less sensitive to stimulation by exogenous cholecystokinin. In addition, the normal release pattern of digestive hormones in the resting state and after stimulations showed multiple alterations in massive obesity.