Macronutrients act directly on the stomach to regulate gastric ghrelin release

Background : Ghrelin is a gastric secreted hormone deeply implicated in meal initiation and body weight regulation. This peptide is a peripheral orexigenic hormone with a nutritional status-dependent regulation showing a pre-pandrial rise and post-prandial fall pattern. A wide variety of studies have tested the effect of meal different nutrient composition over stomach mucosa ghrelin content and plasmatic ghrelin levels; nevertheless, few and non-conclusive data exist about the direct action of macronutrients on the stomach in order to regulate ghrelin secretion. The recent identification of taste receptors or chemoreceptors in the stomach mucosa would reinforce this paradigm. Aims : To investigate the individual effect of different macronutrients (l-glutamine, lipids, and glucose) over gastric ghrelin secretion by using an in vitro gastric explants model. Results : L-glutamine and intralipid emulsion act locally in the stomach decreasing ghrelin secretion, while no effect was found after glucose exposure. Conclusions : These results show for the first time that macronutrients, and specially amino acids and lipids, act directly in the stomach in order to regulate gastric ghrelin release. Consequently, the chemosensory capacity of the stomach, until now restricted to the oral cavity or intestine, is demonstrated.