Serum leptin and leptin receptors in healthy prepubertal children: relations to insulin resistance and lipid parameters, body mass index (BMI), tumor necrosis factor alpha (TNF alpha), heart fatty acid binding protein (hFABP), and IgG anticardiolipin (ACL-IgG).

In a group of randomly selected 29 healthy prepubertal children (16 boys, mean age 9.56 +/- 0.7 years, 13 girls, mean age 9.96 +/- 0.9 years) fasting serum leptin and leptin receptor concentrations were measured by ELISA and compared with insulin parameters (homeostatic model of assessment insulin resistance = HOMA IR, insulin, intact proinsulin, C-peptide) and some metabolic parameters and factors that contribute to insulin resistance: triacylglycerols, high density lipoprotein cholesterol (HDL cholesterol), low density lipoprotein cholesterol, body mass index, tumor necrosis factor, heart fatty acid binding protein, and IgG fraction of anticardiolipin. Statistical analysis was performed using SAS/STAT software and included analysis of normality, analysis of variance, Spearman's correlations, linear and multiple regression analysis with insulin parameters as dependent variables. The subgroups of boys and girls did not differ significantly in any of parameters studied. Serum concentrations of insulin, intact proinsulin, HOMA IR, C-peptide and triacylglycerols appeared to be primarily influenced by serum leptin concentration. Serum leptin concentrations were tightly correlated with body mass indexes and negatively correlated with leptin receptor concentrations, probably as a manifestation of down regulation. The role of other factors studied appeared to be complementary or less significant (hFABP, ACL IgG), or absent (TNF alpha). We concluded that in healthy prepubertal children of both genders serum leptin concentration contributes to insulin resistance and to insulin resistance-related metabolic changes.