Gut peptides in lactation.

The circulating levels of prolactin (PRL), vasoactive intestinal polypeptide (VIP), somatostatin (SRIH), cholecystokinin (CCK), pancreatic polypeptide (PP), insulin, motilin and blood glucose were measured in nine nursing women 27-40 days after delivery to establish the possible role of some gastrointestinal regulatory peptides in human breast feeding. During the last 20 min of suckling a significant (P less than 0.05) increase in serum PRL was observed concomitantly with a significant decrease in plasma SRIH levels (P less than 0.05 at 20 min and P less than 0.01 at 30 min). There was a highly significant inverse correlation between mean PRL and SRIH levels during the first 30 min of breast feeding (r = -0.996, P less than 0.001). Pancreatic polypeptide (pp) also increased significantly (P less than 0.01) during nursing, while there were no changes in the plasma levels of the other gastrointestinal regulatory peptides studied.