Endocrine Abstracts (2009) 20 OC6.3

Ghrelin and obestatin levels in normal weighted and obese prepubertal children

Flavia Prodam, Simonetta Bellone, Letizia Trovato, Erica Grassino, Stefania Moia, Irene De Marchi, Francesca De Rienzo & Gianni Bona

Division of Pediatrics, Department of Medical Sciences, University of Piemonte Orientale, Novara, Piemonte, Italy.

Introduction: Three peptides, acylated ghrelin (AG), unacylated ghrelin (UAG) and obestatin are derived from a common prohormone, preproghrelin by posttranslational processing, originating from endocrine cells in the stomach. Circulating ghrelin levels are decreased in obese subjects and increased by fasting and in patients with anorexia nervosa, but the physiological role of the three peptides is poorly understood in particular in childhood.

Aim: In order to understand the biological implications of these three peptides, we measured AG, UAG, obestatin, IGF-I, cortisol, TSH, prolactin, glucose, insulin, AST, ALT, and ALP levels at fasting in 25 normal weight (NW) and 35 obese (OB) prepubertal children.

Results: AG (8.62±1.10 vs 21.66±5.8 pg/ml; P<0.005), UAG (25.91±3.16 vs 63.36±8.20 pg/ml; P<0.0001) and obestatin (0.163±0.040 vs 0.655±0.134 ng/ml; P<0.007) levels were lower in OB when compared to NW children. The levels of the three peptides were positively correlated each others (P<0.004). AG levels were negatively correlated with height, height-SDS, weight and BMI (P<0.01), and positively with AST (P<0.002). UAG levels were negatively correlated with age, height, height-SDS, weight, BMI, ALP, IGF-I, cortisol, glucose, and insulin levels (P<0.01), and positively with AST (P<0.01). Obestatin levels were negatively correlated with height, BMI, and glucose (P<0.03). In the regression analysis, the best predictors were: 1) obestatin (β: 0.753) for AG; 2) IGF-I (β: −0.707), AG (β: 0.405), and glucose (β: −0.368) for UAG; 3) AG (β: 0.853) and glucose (β: −0.448) for obestatin.

Conclusions: OB children show lower levels of AG, UAG and obestatin. The evaluation of the two forms of ghrelin demonstrates a peculiar relationship between UAG levels and metabolic parameters. On the other hand, obestatin seems to be a regulator of AG circulating form.

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