Ghrelin immunoreactivity in human plasma is suppressed by somatostatin

Summary objective Ghrelin was recently identified as a specific endogenous ligand for the growth hormone secretagogue receptor (GHS‐R). This new hormone was isolated from rat and human stomach and was reported to circulate in human plasma, but the regulation and physiological significance of ghrelin in humans have not been clarified. The present study was undertaken to test the following hypotheses: (1) prolonged fasting, which is known to stimulate GH secretion, is associated with changes in ghrelin immunoreactivity; (2) somatostatin in the systemic circulation regulates ghrelin secretion; and (3) GH affects ghrelin levels. design and patients The study population included normal subjects investigated on three occasions (fasting alone, fasting and somatostatin infusion ± GH); GH‐deficient adults investigated after 12 and 36 h of fasting ± GH, as well as patients with active acromegaly before and after somatostatin analogue treatment. results Somatostatin infusion lowered ghrelin levels 70–80% (P