Evidence for vagus-dependent pancreatic polypeptide-releasing factor in the antrum: studies with the autotransplanted dog pancreas.

Pancreatic polypeptide (PP) response to food is suppressed by truncal vagotomy, antral vagotomy, and antrectomy. The inhibitory effect of antral vagotomy and of antrectomy may be due to inadvertent vagal denervation of the pancreas, disruption of antropyloric neural reflexes, or inhibition of release of a PP-releasing factor from the antrum. In this study we examined the latter hypothesis by achieving total extrinsic pancreatic denervation by orthotopic autotransplantation of the entire pancreas in four dogs. Total extrinsic pancreatic denervation, which abolished the pancreatic juice protein response to insulin, did not significantly alter plasma PP response to a meal (peak 30-minute PP of 696 +/- 192 pg/ml before transplantation versus 961 +/- 80 pg/ml after transplantation). Therefore, postprandial release of PP is, to a large extent, not mediated either by direct vagal innervation of the pancreas or by neural communications between the pancreas and antrum or the pancreas and the small intestine. In two of the dogs with pancreatic transplants, subsequent antral vagotomy resulted in greater than 80% inhibition of postprandial PP response. These findings are consistent with the hypothesis that a PP-releasing factor is present in the antrum and that the release of this factor is dependent on intact antral vagal innervation.