Daily, intermittent intravenous infusion of peptide YY(3-36) reduces daily food intake and adiposity in rats

The gut hormone peptide YY(3-36) [PYY(3-36)] decreases food intake when administered by intravenous infusion to lean and obese humans and rats. Whether chronic administration of PYY(3-36) produces a sustained reduction in food intake and adiposity is the subject of intense debate. Batterham et al. (R. L. Batterham, M. A. Cowley, C. J. Small, H. Herzog, M. A. Cohen, C. L. Dakin, A. M. Wren, A. E. Brynes, M. J. Low, M. A. Ghatei, R. D. Cone, and S. R. Bloom. Nature 418: 650 - 654, 2002) first reported that PYY(3-36) reduces food intake and weight gain in rats when injected into the peritoneal cavity twice daily for 7 days. Numerous laboratories have failed to confirm that daily injections of PYY(3-36) decrease body weight. Continuous subcutaneous administration of PYY(336) by osmotic minipump has been reported to reduce daily food intake in rodents but only during the first 3 - 4 days of administration. Here we show the effects of different daily patterns of intravenous infusion of PYY(3-36) on food intake, body weight, and adiposity in rats tethered via infusion swivels to computercontrolled pumps. Measurement of food bowl weight recorded by computer every 20 s permitted daily assessment of the instantaneous effects of PYY(3-36) administration on food intake and meal patterns. One- hour intravenous infusions of PYY(3-36) at 30 pmol (.) kg(-1) (.) min(-1) every other hour for 10 days produced a sustained reduction in daily food intake of similar to 20% and decreased body weight and adiposity by 7 and 35%, respectively. Thus dosage pattern is critical for producing a sustained effect of PYY(3-36) on food intake and adiposity.