Pía Riestra

Leptin and adiponectin levels in pubertal children: relationship with anthropometric variables and body composition.

Abstract Background: Adipocytokines play an important role in controlling energy homeostasis, and in various metabolic processes related to obesity. The aim of this study was to describe serum leptin and adiponectin concentrations in a sample of pubertal Spanish children and to evaluate their association with anthropometric parameters and body composition. Methods: The study included 833 pubertal boys and girls. Serum leptin and adiponectin concentrations were determined by ELISA. Results: Leptin concentrations were significantly higher (p<0.0001) in obese or overweight (OW) children compared with children with normal weight (NW). Adiponectin was significantly lower (p<0.01) in obese or OW girls compared with girls of NW, although these findings were not the same for boys. Weight, body mass index (BMI), waist circumference (WC), hip circumference (HC), and waist to hip ratio were significantly correlated (p<0.01) with leptin concentrations in both genders. Correlation of leptin with fat mass and % fat mass was strong, particularly in boys. The association of adiponectin concentrations with anthropometric variables was weaker in both genders. No significant correlations were found between adiponectin concentrations and fat mass or % fat mass. Conclusions: In summary, our study showed that, in pubertal children, leptin is related to weight, BMI, WC and HC and correlates even more strongly with % fat mass. However, adiponectin was weakly related to anthropometric variables and was not correlated with body fat. Clin Chem Lab Med 2010;48:707–11.

Relationship of adiponectin with metabolic syndrome components in pubertal children

OBJECTIVE Adiponectin is an adipose tissue-derived adipocytokine which appears in decreased concentrations in obese patients and in several processes related to cardiovascular disease, such as type 2 diabetes or metabolic syndrome. The aim of this study was to analyze the relationship between adiponectin and components of metabolic syndrome (lipid profile, blood pressure, insulin and insulin resistance) in pubertal Spanish children. METHODS The population-based sample included 810 healthy children (382 boys and 428 girls) 12-16 years of age. Anthropometric parameters and blood pressure were measured. Lipid levels were determined by standard methods, and insulin and adiponectin concentrations were measured by ELISA. Insulin resistance index was assessed by HOMA-IR. RESULTS Adiponectin levels were negatively correlated with insulin and HOMA in both boys and girls, and remained significant after adjustment for BMI z-score in girls. After this adjustment, adiponectin maintained a positive correlation with HDL-cholesterol and HDL-phospholipids in both genders, and correlated with triglycerides in girls. Multiple linear regression analysis showed that, after adjustment for BMI z-score, adiponectin accounted for 15.8% of the variation of HDL-cholesterol in girls and for 5% of its variation in boys; meanwhile, it accounted for 15.8% and 12.7% of the variation of HDL-phospholipids in girls and boys, respectively. CONCLUSIONS Adiponectin levels in 12- to 16-year-old children appear to be more strongly related to better lipid profile and insulin sensitivity in girls than in boys. Our study shows, for the first time to our knowledge, a significant positive correlation between adiponectin and HDL-phospholipids in pubertal children.

Sex‐specific association between leptin receptor polymorphisms and leptin levels and BMI in healthy adolescents

Aim:  To examine the relationship of three common polymorphisms in the leptin receptor (LEPR) gene, implicated in the regulation of body weight, with leptin levels and obesity‐related phenotypes in a population‐based sample of healthy pubertal children in Spain.

Resistin levels are related to fat mass, but not to body mass index in children.

The relationship of resistin levels with obesity remains unclear. The aim of this study was to determine resistin levels in prepubertal children and adolescents and evaluate their association with anthropometric parameters and body composition. The study population included 420 randomly selected 6-8-year-old children and 712 children aged 12-16 years. Anthropometric data were measured and body mass index (BMI) and waist-to-hip and waist-to-height ratios were calculated. Body composition was assessed using an impedance body composition analyzer. Serum resistin levels were determined using a multiplexed bead immunoassay. Resistin levels were not significantly different between sexes. No significant differences in serum resistin concentrations were found between obese, overweight, and normal weight children at any age, and no significant correlations were observed between resistin concentrations and weight or BMI. However, resistin levels showed a significant positive correlation with fat mass in 12-16-year-old children, particularly in girls. In addition to describing serum resistin levels in prepubertal children and adolescents, our study suggests that resistin is related to body fat rather than to BMI in adolescents.

Influence of the leptin G‐2548A polymorphism on leptin levels and anthropometric measurements in healthy Spanish adolescents‡

Polymorphisms in the leptin gene (LEP) have been associated with leptin levels and obesity in some studies in adults though this link has scarcely been investigated in children. In our study, we examined the relationship of the LEP G‐2548A polymorphism with leptin levels, anthropometric variables and body composition in a population‐based sample of pubescent children. Our study included 880 healthy schoolchildren (419 males and 461 females), 12–16 years of age. Plasma leptin levels were determined by ELISA. The LEP polymorphism was determined by allelic discrimination TaqMan® assay. Male carriers of the AA genotype had significantly lower plasma leptin levels than GA (p < 0.008) and GG (p < 0.001) carriers and significantly lower mean hip circumference (HC) values than GG carriers (p = 0.04). In girls, leptin levels were also lower in A‐allele carriers than in GG carriers, and BMI and HC were significantly lower in AA carriers as compared with GG carriers. In addition, the frequency of the A allele was significantly lower (χ2: 4.58, p = 0.032) in the OW‐obese than in the NW group. In conclusion, the LEP G‐2548A polymorphism is associated with variations in leptin levels, BMI and HC in Spanish pubertal children, and evidence suggests a link between the G allele and presence of overweight in girls.

Relationship of Adiponectin with Sex Hormone Levels in Adolescents

Background/Aims: Adiponectin is an adipose tissue-derived adipocytokine which, starting at puberty, is present in lower levels in males than in females. In adults, a relationship between adiponectin levels and sexual hormones has been suggested, but this association remains unclear in children. Our study aimed to analyze the relationship of adiponectin with dehydroepiandrosterone sulfate, testosterone, estradiol, and sex hormone-binding globulin (SHBG) in adolescents. Methods: The population-based sample included 785 healthy 12- to 16-year-old children. Testosterone, estradiol, and dehydroepiandrosterone sulfate levels were assessed by radioimmunoassay. SHBG was measured by immunoradiometric assay. Adiponectin concentrations were measured by ELISA. Results: Adiponectin levels were positively correlated with SHBG and negatively correlated with the free androgen index independently of body mass index (BMI) and fat mass. No significant correlations were observed between adiponectin and total testosterone or estradiol. Multiple linear regression analysis showed that, after adjustment for BMI, SHBG appears as the primary predictor of adiponectin levels in both sexes, accounting for 5.7% of the variation in adiponectin levels in boys and 7.5% in girls. Conclusion: Adiponectin is related to free androgen index and SHBG levels in adolescents after adjusting for BMI and fat mass, thus suggesting an association between adiponectin levels and androgen bioavailability that would explain the sex-based differences in adiponectin levels through life.

Sex hormone‐binding globulin levels and metabolic syndrome and its features in adolescents#

Oya I, Schoppen S, Lasunción MA, Lopez‐Simon L, Riestra P, Oya M, Garcés C. Sex hormone‐binding globulin levels and metabolic syndrome and its features in adolescents.

Fat Intake Influences the Effect of the Hepatic Lipase C-514T Polymorphism on HDL-Cholesterol Levels in Children:

Polymorphisms in the hepatic lipase gene have been associated with variability in plasma HDL-C concentrations, but contradictory results have been reported regarding the effect of diet on this association in adults. In our study, we examined whether dietary fat intake modified the association between lipid levels and the C-514T polymorphism in the hepatic lipase gene (LIPC C-514T) in prepubescent children. The LIPC C-514T polymorphism was determined by PCR and restriction analysis in 1260 healthy school children, aged 6–8. Information on the children’s nutrient intake was obtained by means of a validated food frequency questionnaire. We found that regardless of gender, carriers of the minor allele had significantly higher apo A-I levels compared to noncarrier subjects. The effect of the polymorphism, however, was modified by dietary fat intake. In boys, the presence of the LIPC C-514T polymorphism was associated with significantly higher HDL-C among children within the highest tertiles of total, saturated, monounsaturated, or polyunsaturated fat intake. Apo A-I levels were significantly higher in carriers of the LIPC C-514T polymorphism, but only among boys who consumed high total as well as monounsaturated fat and among girls who consumed high total, saturated, monounsaturated, and polyunsaturated fat. Our data show that dietary fat intake modifies the effect of the LIPC C-514T polymorphism on plasma HDL-C and apo A-I levels in prepubescent children, being associated with higher levels of HDL-C and apo A-I only when fat intake is high. This significant gene-nutrient interaction could help to explain inter-individual variations in the plasma lipid response to fat intake.

Influence of the interaction between the adiponectin G276T polymorphism and body mass index on lipid levels in healthy children

Adiponectin is an adipose tissue-specific hormone which is inversely associated with metabolic alterations related to atherosclerosis. Polymorphisms in the adiponectin gene (AdipoQ) have been related to low adiponectin levels as well as several cardiovascular risk factors, but this association remains controversial. In our study we investigated the relationship between the AdipoQ T45G (rs: 2241766) and G276T (rs: 1501299) polymorphisms and adiponectin concentrations, blood pressure, and lipid and insulin levels, in a population-based sample of 12- to 16-year-old children. The study included 815 healthy Spanish children (388 boys and 427 girls). Plasma glucose and lipid levels were determined by standard methods. Insulin concentrations were measured by RIA, and serum adiponectin levels were determined by ELISA. The AdipoQ T45G and AdipoQ G276T polymorphisms were determined by TaqMan® allelic discrimination assays. ANOVA or t test allowed for comparison of the studied parameters across genotypes or genotype groups, respectively. A linear regression analysis was performed to examine the independent relationships of the lipid variables with BMI (body mass index), AdipoQ G276T polymorphism and the interaction between the two. When independently comparing the effect of these polymorphisms in normal-weight and overweight children, we observed that overweight boys carriers of the minor allele T had significantly lower TC, LDL-C and apo A-I levels than non-carriers, but these differences were not apparent in normal-weight boys. Furthermore, linear regression analysis demonstrated that interaction between the BMI and the AdipoQ G276T polymorphism is a significant factor explaining the variations of TC and LDL-C levels. To our knowledge, this is the first study to report an association between the AdipoQ G276T polymorphism and lipid levels in overweight boys alone, thereby suggesting that the influence of the AdipoQ polymorphisms on cardiovascular risk factors may be dependent on BMI.

Genetic determinants of plasma HDL-cholesterol levels in prepubertal children

INTRODUCTION Genetic determinants have been related to variation of high-density lipoprotein cholesterol (HDL-C) levels, but the extension of this association remains controversial. In our study, we analyzed the contribution of several polymorphisms on HDL-C-related genes to variation of plasma HDL-C in prepubertal children. METHODS We studied 1269 (641 males and 628 females) 6-8 years old healthy children, who participated in a cross-sectional study examining cardiovascular risk factors in Spain. Common genetic variants in the apolipoprotein AI, apolipoprotein AII, cholesteryl ester transfer protein (CETP), hepatic lipase, ATP-binding cassette transporter A1, and paraoxonase genes were determined by PCR. RESULTS CETP TaqI B2 carrier girls had significantly higher HDL-C levels than B1B1 girls. B2B2 boys had significantly higher (p<0.001) HDL-C than B1B1and B1B2 boys. In linear regression analysis, CETP TaqIB appears as the main predictor of HDL-C plasma levels, accounting for 4.5% and 1.8% of HDL-C variation in girls and boys respectively. CONCLUSIONS Our data showed that among the studied polymorphisms only the CETP TaqIB polymorphism contributes to the variation in HDL-C levels in prepubertal children, particularly in girls, but overall these polymorphisms explain a small part of the variation of HDL-C plasma levels at this age.