Effect of Arginine Infusion on Ghrelin Secretion in Growth Hormone- Sufficient and GH-Deficient Children

Background: the physiological link between ghrelin and growth hormone (gh) has not yet been fully clarified. furthermore, the existence of a negative feedback mechanism between growth hormone–insulin-like growth factor (gh–igf)-i axis and ghrelin and the influence of amino acids on ghrelin secretion in children remain matters of debate. objectives: to understand the regulation of ghrelin secretion and clarify the relationship between ghrelin and gh secretion in gh-deficient (ghd) and gh-sufficient (ghs) children patients and methods: ten ghd (male/female [m/f], 6/4; age [mean ± sem], 10.7 ± 0.9 years) and 10 ghs prepubertal children (m/f, 6/4; age [mean ± sem], 10.3 ± 0.6 years), underwent an arginine (arg) test (infusion, 0.5 g/kg, iv). levels of gh, total ghrelin, and acylated ghrelin (ag) were assayed every 30 min from 0 to +120 min. results: peak gh values were lower in ghd subjects than in ghs subjects (p < 0.0001). the baseline levels, peak levels, or area under the curves (auc) for total ghrelin and ag were similar between ghd and ghs children. arg infusion was followed by a slight to significant decrease in total ghrelin levels, but not ag levels, both in ghd and ghs subjects with a na- dir at +30 min. no correlation was seen between gh, total ghrelin, or ag response and arg infusion. conclusions: total ghrelin and ag levels seemed unaffected by gh status in prepubertal children. arg infusion was unable to blunt ghrelin secretion irrespective of gh status in child- hood. moreover, since arg influences gh secretion via modulation of somatostatin release, ghrelin secretion seems to be partially refractory to somatostatin action.