Effects of Different Feeding Programs and Ghrelin Injection on Plasma Ghrelin Concentrations and Distribution of the Ghrelin Positive Cells in the Abomasum of Awassi Male Lambs

Abstract

Ghrelin is a novel 28-amino acid peptide isolated from the rat and human stomach. This study was conducted to determine the influence of the feeding program and of ghrelin injection in lambs on the density of the ghrelin immunopositive cells in the abomasum and on the circulating ghrelin concentrations. For that, 16 Awassi male lambs, 2 month old, were allotted in 4 equal groups (group I: fed ad libitum; group II: fed ad libitum and intravenously injected with ghrelin (1 μg/kg), group III: fed once a day, group IV: fed twice a day). When lambs weighing 43 kg (around 3 month old), plasma ghrelin concentrations were measured 30 minutes before and 60 minutes after feeding by radio-immuno-assay, and after slaughtering, ghrelin positive cells were detected by immunohistochemistry (labeled avidin-biotin technique) in the cardia, fundus and pylorus regions of abomasum. Ghrelin immunoreactive cells, mainly glandular cells and some epithelial cells in the pylorus area, were scattered throughout the mucosal layer in the whole organ. The staining intensity and the density of positive cells have not significantly differed according to the stomacal zone or to the rhythm of food distribution. Furthermore, plasma ghrelin concentrations remained stable before and after feeding and although they were weakly lowered in lambs fed ad libitum, no significant difference in this parameter was evidenced between groups. These results showed that glandular cells from the abomasum expressed ghrelin and that the pattern of the peptide secretion was not closely related to the feeding program or to the ghrelin injection in lambs.