An Evaluation of Acylated Ghrelin and Obestatin Levels in Childhood Obesity and Their Association with Insulin Resistance, Metabolic Syndrome, and Oxidative Stress

Abstract

Background: Ghrelin is a 28-amino acid peptide with an orexigenic property, which is predominantly produced by the stomach. Acylated ghrelin is the active form of this hormone. Obestatin is a 23-amino acid peptide which is produced by post-translational modification of a protein precursor that also produces ghrelin. Obestatin has the opposite effect of ghrelin on food intake. The aim of this study was to evaluate acylated ghrelin and obestatin levels and their ratio in obese and normal-weight children and adolescents, and their association with metabolic syndrome (MetS) parameters. Methods: Serum acyl-ghrelin, obestatin, leptin, insulin, fasting plasma glucose (FPG), lipid profile, and malondialdehyde (MDA) were evaluated in 73 children and adolescents (42 obese and 31 control). Insulin resistance was calculated by a homeostasis model assessment of insulin resistance (HOMA-IR). MetS was determined according to IDF criteria. Results: Acyl-ghrelin levels were significantly lower in obese subjects compared to the control group and lower in obese children with MetS compared to obese subjects without MetS. Obestatin was significantly higher in obese subjects compared to that of the control, but it did not differ significantly among those with or without MetS. Acyl-ghrelin to obestatin ratio was significantly lower in obese subjects compared to that in normal subjects. Acyl-ghrelin showed significant negative and obestatin showed significant positive correlations with body mass index (BMI), BMI Z-score, leptin, insulin, and HOMA-IR. Acyl-ghrelin had a significant negative correlation with MDA as an index of oxidative stress. Conclusion: Ghrelin is decreased and obestatin is elevated in obesity. Both of these hormones are associated with insulin resistance, and ghrelin is associated with oxidative stress. The balance between ghrelin and obestatin seems to be disturbed in obesity.

Ghrelin Axis Reveals the Interacting Influence of Central Obesity and Hypertension

“…Total ghrelin/obestatin ratio has been demonstrated to correlate negatively with body mass index, waist circumference, waist/hip ratio and insulin ( 16 ). More recently, AG/obestatin ratio was shown to be significantly lower in children and adolescents with obesity compared to their normal-weight counterparts ( 35 ). In addition, the total ghrelin/obestatin ratio was also reduced in hypertensive individuals compared with normotensive control ( 18 ).…”

Body composition, appetite-related hormones, adipocytokines, and heart failure in adult patients with congenital heart disease: A preliminary study

“…Ghrelin also has direct metabolic effects in the periphery, such as endopancreatic function and altered glucose metabolism . Intravenous ghrelin administration in humans has been demonstrated to promote a favorable effect on glucose metabolism, insulin sensitivity, and lipolysis inhibition . Decreased ghrelin levels in patients with type 2 diabetes mellitus are associated with an increase in abdominal adiposity and insulin resistance .…”

“…30 Intravenous ghrelin administration in humans has been demonstrated to promote a favorable effect on glucose metabolism, insulin sensitivity, and lipolysis inhibition. [30][31][32] Decreased ghrelin levels in patients with type 2 diabetes mellitus are associated with an increase in abdominal adiposity and insulin resistance. [30][31][32] Overall, ghrelin as an AGR-conscious therapeutic strategy might also be associated with a significant reduction in cardiovascular events.…”

Serum complement factor 5a levels are associated with nonalcoholic fatty liver disease in obese children

“…Besides, the current data showed serum concentration of obestatin was decreased in obese children and were negatively associated with C5a. Taskin et al's study showed that serum obestatin levels were significantly lower in an obese polycystic ovary syndrome group, while Razzaghy‐Azar found that obestatin was significantly higher in 73 obese children and adolescents . Although the obestatin serum concentration in obesity is controversial, its effect on food intake and obesity is not disputed.…”