Acylated ghrelin levels in pre-pubertal obese children at diagnosis and after weight reduction: Effect of oral glucose ingestion

Abstract

Ghrelin isoforms are involved in energy homeostasis and carbohydrate metabolism. To determine the influence of oral glucose ingestion and weight reduction on acylated ghrelin (AG) serum levels and on the AG to total ghrelin (TG) ratio (AG/TGr) in obese pre-pubertal children. Seventy obese children were studied at diagnosis (D) and after reduction of their body mass index (BMI) of over 1 (-1; no.=51) and 2 SD score (-2; no.=21). Body composition was analyzed and serum levels of glucose, insulin, TG and AG, and the AG/TGr were determined at every time-point in an oral glucose tolerance test (OGTT) at D and at -2. The control group consisted of 32 lean children. At D AG and TG levels were lower in obese children and negatively correlated with BMI. TG levels were negatively correlated with the homeostasis model assessment (HOMA) index in the whole cohort, as with the body fat content (BFC) in the obese patients. Weight loss exclusively reduced BFC and improved HOMA, increasing AG transiently and TG sustainedly, with AG/TGr exclusively decreasing at -2. Glucose ingestion caused a sustained increase in AG and decrease in TG, thus increasing the AG/TGr throughout the entire OGTT; this remained unaltered after weight reduction. TG and AG levels are influenced by BMI, showing an impairment in childhood obesity that can be improved through weight loss. The different fractions of ghrelin appear to play different roles in carbohydrate metabolism and the calculation of AG/TGr could be useful in the follow up of childhood obesity.