Background: Ghrelin is 28-amino acid peptide predominantly produced by the stomach and have an orexigenic property as well as potent GH-releasing activity. Acylated ghrelin (AG) is the active form of this hormone. Obestatin is a 23-amino acid peptide, is produced by post-translational modification of a protein precursor that also produces ghrelin. Obestatin has the opposite effect of ghrelin on food intake.
Objective and hypotheses: To evaluate acylated ghrelin and obestatin levels in obese and normal weight children and adolescents and their association with metabolic syndrome parameters.
Method: A total of 73 children and adolescents (31 normal weight control and 42 obese), aged 716 years, were recruited into study. Serum AG, obestatin, leptin, insulin (ELISA), fasting plasma glucose (FPG), triglyceride (TG), total cholesterol (TC), LDL-C, and HDL-C were measured. Insulin resistance was calculated by homeostasis model assessment of insulin resistance (HOMA-IR). MetS was determined according to IDF criteria. Data for AG and obestatin were presented as median (25th75th percentiles).
Results: AG levels were significantly lower in obese subjects compared to control group (58.1 (18.9570.0)) pg/ml vs (124.12 (56.28193.11)) pg/ml respectively (P<0.001). AG level was lower in obese children with MetS than subjects without MetS, 22.65 (14.9264.0) pg/ml vs 60.0 (22.0470.0) pg/ml respectively (P<0.01). On the other hand, obestatin levels were significantly higher in obese subjects compared to control group, 267.9 (193.6450.3) pg/ml vs 180.8 (123.2214.8) pg/ml respectively (P<0.001). Obestatin level was higher in obese children with MetS compared to those without MetS, 307.4 (160.7497.4) pg/ml vs 227.9 (193.6300.7) pg/ml respectively (P<0.05). AG:obestatin ratio was significantly lower in obese subjects compared to normal subjects 0.13 (0.070.26) vs 0.68 (0.361.3) respectively (P<0.001). AG had significant negative and obestatin positive correlation with BMI Z-score as well as TG, LDL-C, leptin, and HOMA-IR.
Conclusion: Ghrelin is decreased and obestatin is elevated in obesity. So these are not the cause but are effect of it. Obestatin is a valuable marker to investigate MetS.
Funding: This work was supported by Tehran University of Medical Sciences Research Council (grant number, 91-04-30-20238).
01 Oct 2015 - 03 Oct 2015