Pancreatic polypeptide secretion before and after gastric bypass surgery for morbid obesity.

Basal, meal-stimulated, and insulin-stimulated secretion of pancreatic polypeptide (PP) has been measured before and 3 and 12 months after gastric bypass surgery in 10 obese patients. The basal serum concentration of PP was significantly reduced after the operation. After a meal there was a significant increase in PP concentration both before and after operation. The early phase of meal-stimulated PP release was similar before and 12 months after surgery, but during the late phase the concentrations were 30% lower after the operation than preoperative values. Insulin-stimulated PP release was significantly reduced postoperatively. It is concluded that both basal and stimulated secretion of PP is significantly affected by gastric bypass surgery. The results indicate that the distal part of the stomach and the duodenum play no role in the early phase of meal-stimulated PP release and a minor role in the late phase of meal-stimulated PP release. The reduced basal level of PP and reduced PP response to insulin postoperatively indicate that gastric bypass surgery leads to impaired secretion of PP from the pancreas.