Effects of Feeding Pattern on Plasma Ghrelin Concentrations in Pigs

Abstract

The independent role of ghrelin regulation continues to be controversial. Ghrelin, a 28 amino acid peptide identified as the endogenous ligand for growth hormone (GH) secretoagogue receptor, is found in the gastrointestinal tract, predominantly the stomach. Ghrelin stimulates GH secretion, increases feed intake, adipose tissue, and decreases gastric acid. The aim of this study was to determine if a change in meal patterns might affect ghrelin levels in barrows. Twelve crossbred barrows (67.1 + 4.5 kg BW) were used. The pigs were placed on their corresponding diets on day 0. Six pigs were placed on continuous access to feed using a typical finishing diet and the treatment group was fed 2.73 kg of feed at 1200 and the remaining feed was removed at 1600. Catheters were placed in the jugular vein on day 7 and samples were taken on day 8, 9, and 11. Plasma ghrelin concentrations were measured every 15 minutes for 4 hours and then every 30 minutes the remaining 2 hours on days 8 and 9 using a commercially available RIA for active ghrelin. A glucose challenge (500 mg/kg BW) was administered on day 11 and a sample was taken before the infusion and then every 15 minutes for 3 hours after the infusion. Average daily gain during the experiment was 0.43 kg and 0.87 kg for the limited compared to continuous access to feed groups. Plasma ghrelin concentrations increased (20%) (P<.01) prior to feeding and decreased (20%) after feeding (P<.01) relative to baseline in the meal fed pigs. Ghrelin concentrations were decreased after glucose infusion (P<.01). Concentrations decreased by 40% after the initial infusion and then remained steady for approximately 2 hours post-infusion. In agreement with reports from other species, ghrelin increased before and decreased after feeding in meal-fed animals. Ghrelin may be an important regulator of feed intake in swine.