Peptide Tyrosine Tyrosine 3-36 Reduces Meal Size and Activates the Enteric Neurons in Male Sprague-Dawley Rats.

Abstract

Peptide tyrosine tyrosine 3-36 (peptide YY 3-36 or PYY 3-36) reduces food intake by unknown site(s). To test the hypothesis that the gastrointestinal tract contains sites of action regulating meal size (MS) and intermeal interval (IMI) length by PYY 3-36. Peptide YY 3-36 (0, 1, 5, 10 and 20nmol/kg) was injected in the aorta, the artery that supplies the gastrointestinal tract, prior to the onset of the dark cycle in free feeding male Sprague-Dawley rats and food intake was measured. Then, PYY 3-36 (25nmol/kg) was injected intraperitoneally in these rats and Fos-like immunoreactivity (Fos-LI, a marker for neuronal activation) was quantified in the small intestinal enteric neurons, both myenteric and submucosal, and the dorsal vagal complex (DVC) of the hindbrain. PYY 3-36 reduced first MS, decreased IMI length, shortened duration of first meal and increased Fos-LI in enteric and DVC neurons. However, PYY 3-36 failed to change the size of the second meal, satiety ratio, latency to first meal, number of meals and 24h intake relative to saline control. The gastrointestinal tract may contain sites of action regulating MS reduction by PYY 3-36.