Growth hormone and somatostatin directly inhibit gastric ghrelin secretion. An in vitro organ culture system

Ghrelin is a 28-amino-acid hormone produced mainly by the stomach which strongly promotes food intake. It is the only known peripheral orexigenic hormone that induces the release of GH. Ghrelin has been proposed as a link between the enteric system and central regulation of energy balance and growth. Although it has recently been the focus of extensive study, the secretion mechanism is not yet well characterized. The aim of this study was to test the direct effect of hormones from the somatotropic axis on ghrelin release directly from the stomach. To this end, an organ culture model of gastric tissue explants from rat donors was used. These stomach explants were incubated in 6 well plates for 1, 2, and 3 h after treatment with either GH, GHRH, SS or IGF-I, all them at 10(-6) M. After incubation, the medium was collected and the amount of ghrelin secreted by the gastric tissue was measured by radioimmunoassay. It was observed that GH and SS significantly decreased gastric ghrelin secretion, while GHRH and IGF-1 had no effect on the present model. These results would confirm the capacity of GH and SS to act directly upon gastric level, inhibiting ghrelin secretion in vitro.