Abstract
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.
Highlights
Leptin is a protein coded by the ob gene and released by adipose tissue into the circulation
In 1988, Reaven suggested that insulin resistance may underlie a number of diseases, including hypertriglyceridemia accompanied by lowering of HDL lipoprotein level, hypertension, impaired glucose tolerance leading to type 2 diabetes mellitus, and hyperinsulinemia[22]
Even in non-diabetic individuals, both insulin resistance and compensatory hyperinsulinemia are associated with increases in hepatic
Summary
Leptin is a protein coded by the ob gene and released by adipose tissue into the circulation. Linear regression and multiple regression analyses were performed using the insulinresistance parameter (HOMA IR) and insulin-secretion parameters (fasting serum insulin, and C-peptide) as dependent variables, and various other hormonal and metabolic factors (leptin, leptin receptors, TNFa, hFABP, ACL IgG, BMI and lipid papameters) as independent variables. Serum concentration of proinsulin depended significantly on serum leptin concentration and ACL IgG (note a drop of R2 in bottom part of Table 5), while hFABP and TNFa seem not to play a significant role.
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