Circulating preprandial ghrelin to obestatin ratio is increased in human obesity

Abstract

Context: Obestatin, a sibling of ghrelin derived from preproghrelin, opposes ghrelin's effects on food intake. Plasma obestatin profiles in relation to ghrelin have not been fully investigated in human obesity. Objective: We hypothesize that obesity might present with imbalance of circulating ghrelin and obestatin levels. Participants and Setting: Sixteen obese (eight men, aged 58.8 ± 4.9 yr; eight women, aged 59.9 ± 9.6 yr) and 14 normal-weight individuals (seven men, aged 52.7 ± 5.9 yr; seven women, aged 56.1 ± 4.9 yr) were evaluated at the in-patient department of Changhai Hospital, Shanghai, China. Main Outcome Measures: Total plasma ghrelin and obestatin levels, 1 h before and 2 h after breakfast, were measured by RIA. Results: Both preprandial plasma ghrelin levels (P < 0.01) and obestatin levels (P < 0.01) were lower in the obese compared with normal-weight controls. However, unexpectedly, the ratio of preprandial ghrelin to obestatin was higher in obese compared with normal-weight controls (P < 0.01) even after adjustment for gender and age (P < 0.01). The ratio of postprandial ghrelin to obestatin was decreased both in obese (P < 0.05) and controls (P < 0.01) compared with their preprandial levels. There were no significant differences in the ratio of postprandial ghrelin to obestatin between obese and normal-weight controls. Body mass index was positively correlated with and was a significantly independent determinant of the preprandial ghrelin to obestatin ratio. Conclusion: Circulating preprandial ghrelin to obestatin ratio is elevated in human obesity. We suggest that high preprandial ghrelin to obestatin ratio may be involved in the etiology and pathophysiology of obesity. Copyright © 2007 by The Endocrine Society.