Leptin Receptor Concentrations Research Articles

Glycemic status and soluble tumor necrosis factor receptor levels in relation to plasma leptin concentrations among normal weight and overweight US men.

Leptin, an adipocyte-derived protein product of the obesity (ob) gene, is a multifunctional polypeptide associated with the development of obesity-related disorders in humans. There is considerable inter-individual variation in plasma leptin even among subjects with comparable obesity levels, which suggests that factors other than adipose mass may be involved in the regulation of leptin expression and/or production. The purpose of this study was to evaluate the potential role of glycemic status and adipose-derived cytokines in regulating plasma leptin levels among normal and overweight men. Cross-sectional study. We measured plasma leptin, insulin, c-peptide and plasma soluble tumor necrosis factor receptor (sTNF-R) concentrations in 178 men. The subjects were selected from the Health Professionals Follow-up Study (HPFS), and aged 47-64 y in 1994, were free of cardiovascular disease, diabetes mellitus, malignant neoplasms, and had provided a fasting blood sample and a detailed lifestyle questionnaire. Men in the highest quintile of plasma leptin (mean = 12.7 ng/ml) weighed more, were less physically active and had higher circulating insulin, c-peptide, sTNF-R1 and sTNF-R2 concentrations than men in the lowest quintile (mean = 2.8 ng/ml). We found a significant correlation between plasma insulin, c-peptide, glycosylated hemoglobin (HbA1c), and sTNF-R1 on leptin concentrations (with Spearman correlation coefficients ranging from 0.17 to 0.48 and all P < 0.05). Only HbA1c and sTNF-R1 were independently and positively associated with plasma leptin after further adjusting for body mass index and other metabolic parameters of interest. Interestingly, these observed associations were limited to men with a BMI > or = 25 kg/m2. Our results suggest that glucose homeostasis and the activity of the TNF system may modulate leptin secretion and production among overweight men. Glucose homeostasis and TNF-alpha is important in metabolic disorders related to hyperleptinemia.

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.

Large-for-gestational age infants. Delivery, neonatal course and neurological condition : O. Finnström, I. Leijon, G. Otamiri, G. Rydén and A. Selbing, Departments of Paediatrics and Gynaecology/Obstetrics, University Hospital, S-581 85 Linköping, Sweden

Overweight gravidas and gravidas with a robust weight gain have an accrued risk of delivering a large-for-gestational age (LGA) baby. Here, we examined whether the measurement of insulin and adipokines—peptides secreted mainly by adipose tissue—at the glucose challenge test (GCT) improves the prediction of birth weight. We studied 631 singleton pregnancies at 24 to 29 weeks' gestational age (GA) with data on height, baseline body weight (BW), and BW change between baseline and the GCT. In addition to glucose and insulin, we measured adiponectin, leptin, soluble leptin receptor (the main leptin-binding protein), and tumor necrosis factor α. We found that birth weight was related to maternal height, baseline BW, and BW change, and also—albeit less strongly—to insulin, adiponectin, leptin, and soluble leptin receptor concentrations. In multiple regression analyses, body size parameters explained ∼10% of the variance in birth weight, of which BW change was the most important correlate, but the metabolic markers added only ∼2% variance, with leptin alone adding 1.4%. Gravidas carrying a small-for-GA (SGA) fetus were more likely to have a leptin value in the highest quartile than those with an appropriate-for-GA fetus (odds ratio, 2.6; 95% confidence interval, 1.1-6.3; P = .04), but there were no other differences in the metabolic markers between SGA or LGA and appropriate-for-GA pregnancies. In conclusion, measuring insulin and adipokines at the GCT has limited, if any, clinical benefit to predict which fetuses will be SGA or LGA at birth.