Glucagon given to healthy adults in doses of 1-1.5 mg i.m. has been shown to result in a peak glucagon level in the circulation after 30 min, followed by an increase in glucose and insulin levels. The subsequent decline in glucose, insulin and glucagon was followed by an increase in cortisol and GH. Ghrelin is a 28 amino acid peptide which is released from the fundus of the stomach, within the oxyntic glands and the small intestine. It circulates in two major forms, acylated and des-acylated ghrelin. Acylated ghrelin has strong GH-releasing effects which are mediated via the G-protein coupled ghrelin receptor. The proposed study will test the concept that with the fall in blood glucose during a glucagon test it is likely that there is a sympathetic discharge which contributes to the increase in acyl ghrelin and indirectly leads to the increase in GH and cortisol.
Glucagon has been used for decades as a test of growth hormone (GH) reserve. The pathway by which GH is stimulated by glucagon is not established. Acyl ghrelin has been shown to increase GH levels and to be stimulated by an increase in adrenergic activity. The proposed study will test the concept that with the fall in blood glucose it is likely that there is a sympathetic discharge which contributes to the increase in acyl ghrelin and indirectly leads to the increase in GH and cortisol.