No evidence of an additive inhibitory feeding effect following PP and PYY3-36 administration

Pancreatic polypeptide ( PP) and peptide YY (PYY) are released by the gut in response to nutrients and inhibit food intake in ;rodents and humans. We hypothesized that PP and PYY(3-36) would inhibit feeding additively. Fasted male C57BL/6 mice were injected intraperitoneally with saline, PP, PYY(3-36) or PP+PYY(3-36) (n=7-10). Food intake at 1 h was significantly inhibited by 6 nmol kg(-1) PP and by 6 nmol kg(-1) PYY(3-36) (P<0.05) but not significantly following 3 nmol kg(-1) PP+3 nmol kg(-1) PYY(3-36). In a higher dose study 30 nmol kg(-1) PP, 30 nmol kg(-1) PYY(3-36) and 30 nmol kg(-1) PP+30 nmol kg(-1) PYY(3-36) all inhibited 1 h food intake compared with saline (P<0.05) but there was no significant difference in the food intake of the combined group compared with either hormone individually. Subsequently, 16 fasted lean healthy human volunteers ( 6 men and 10 women) received, in random order, 90 min intravenous infusions of saline, 4 pmol kg(-1) min(-1) PP, 0.4 pmol kg(-1) min(-1) PYY(3-36) and 4 pmol kg(-1) min(-1) PP+0.4 pmol kg(-1) min(-1) PYY(3-36). A pasta lunch was served 60 min following infusion. There was no evidence of a greater decrease in food intake with the combined PP+PYY(3-36) treatment (buffet meal energy intake (KJ): saline 2633 +/- 204, PP+PYY 2693 +/- 254, PP 2367 +/- 199, PYY 2511 +/- 196). These results suggest that PP and PYY(3-36) do not inhibit feeding additively in rodents or humans.