A high-protein dietary treatment to intestinally hypotrophic rats induces ghrelin mRNA content and serum peptide level changes

Ghrelin is a peptide mainly secreted in stomach with a potent growth hormone releasing activity both in vitro and in vivo. The trophic mucosal effect of an enriched protein diet may be related with ghrelin and growth hormone plasma levels since peptides from the somatotrophic axis are well-known trophic factors. The possible relationship between nutritionally regulated active ghrelin plasma levels and the intestinal trophic effects of a high-protein diet was probed in rats with intestinal hypotrophy induced by an elemental diet. Normal and elemental-diet-induced intestinally hypotrophic rats were treated with either a normoproteic or a high-protein diet for 1 week. It was determined ghrelin and IGF-1 plasma levels, fundic and duodenal ghrelin concentrations, ghrelin mRNA content and intestinal morphometric, proliferative and apoptotic parameters were determined. Growth hormone plasma levels were measured indirectly through IGF-1 plasma levels. Ghrelin plasma levels increased in elemental diet-induced intestinally hypotrophic rats fed either diet. Duodenum mRNA content, but not fundus, increased under the same conditions where plasma was studied. Dietary treatment did not modify the IGF-1 plasma levels. However, animals previously fed an elemental diet to induce intestinal hypotrophy had significantly lower levels of IGF-1. The trophic effects on the intestine of an enriched protein diet are associated with increased ghrelin serum peptide level and mRNA content, and this increase might be related to the IGF-1 plasma levels in elemental diet-induced intestinally hypotrophic rats.