Obestatin is not elevated or correlated with insulin in children with Prader-Willi syndrome.

Context: Obestatin is a peptide hormone derived from the proteolytic cleavage of ghrelin preprohormone. In Prader- Willi syndrome ( PWS), the levels of total ghrelin ( TG) and acylated ghrelin ( AG) are increased, and these hormones are regulated by insulin. Objective: Our objective was to analyze the changes in the obestatin levels after glucose loading and to characterize the correlations of obestatin with TG, AG, and insulin. Design: Plasma obestatin, TG, AG, and insulin levels were measured in PWS children ( n = 15) and controls ( n = 18) during an oral glucose tolerance test. Setting: All subjects were admitted to the Samsung Medical Center. Interventions: An oral glucose tolerance test was performed after an overnight fast. Main Outcome Measures: The plasma levels of obestatin, TG, AG, and serum insulin were measured at 0, 30, 60, 90, and 120 min after glucose challenge, and areas under the curves ( AUCs) were calculated. Results: No significant difference inAUCof the plasma obestatin was found between the PWS children and normal obese controls ( P = 0.885), although AUC of AG ( P = 0.002) and TG ( P = 0.003) were increased in the PWS children. Moreover, There was a negative correlation between the AUC of AG and AUC of insulin both in PWS ( r = - 0.432; P = 0.049) and in controls ( r = -0.507; P = 0.016). However, AUC of obestatin was not significantly correlated with AUC of insulin ( in PWS, r = 0.168 and P = 0.275; in controls, r = - 0.331 and P = 0.09). Conclusions: Our results indicate that plasma obestatin is not elevated in PWS children and in obese controls.