Association of the rs17782313, rs17773430 and rs34114122 Polymorphisms of/near MC4R Gene with Obesity-Related Biomarkers in a Spanish Pediatric Cohort.

Obesity is a multifactorial disease whose onset and development are shaped by the individual genetic background. The melanocortin 4 receptor gene (MC4R) is involved in the regulation of food intake and energy expenditure. Some of the single nucleotide polymorphisms (SNPs) of this gene are related to obesity and metabolic risk factors. The present study was undertaken to assess the relationship between three polymorphism SNPs, namely, rs17782313, rs17773430 and rs34114122, and obesity and metabolic risk factors. One hundred seventy-eight children with obesity aged between 7 and 16 years were studied to determine anthropometric variables and biochemical and inflammatory parameters. Our results highlight that metabolic risk factors, especially alterations in carbohydrate metabolism, were related to rs17782313. The presence of the minor C allele in the three variants (C-C-C) was significantly associated with anthropometric measures indicative of obesity, such as the body mass and fat mass indexes, and increased the values of insulinemia to 21.91 µIU/mL with respect to the wild type values. Our study suggests that the C-C-C haplotype of the SNPs rs17782313, rs17773430 and rs34114122 of the MC4R gene potentiates metabolic risk factors at early ages in children with obesity.

Reduced Free Fatty Acid Receptor 4 Gene Expression is Associated With Extreme Obesity and Insulin Resistance in Children.

OBJECTIVES: Free fatty acid receptor 4 (FFAR4) is a G-protein-coupled membrane receptor highly expressed in macrophages that triggers anti-inflammatory effects and promotes insulin sensitization. We have previously found significant associations between the FFAR4 rs11187533 single nucleotide polymorphism (SNP) and various obesity comorbidity parameters. We aimed to verify the FFAR4 expression levels in children with obesity and the associated comorbidities. METHODS: Thirty-eight children with obesity were studied. Clinical and anthropometric evaluation was performed. A venous sample under fasting conditions was obtained. Biochemical study included parameters of metabolic risk. DNA was extracted and genotyped for the rs11187533 FFAR4 SNP. Real-time PCR technique was performed to investigate the gene expression. Relative FFAR4 mRNA levels were determined according to the 2-ΔΔCt method. RESULTS: Significant differences in FFAR4 expression levels between the CC and CT-TT genotypes of the rs11187533 FFAR4 SNP were observed (P = 0.034). The minor allele T presented higher levels of FFAR4 expression. We found that a loss of FFAR4 expression was associated with extreme obesity (P = 0.032). The lowest FFAR4 expression levels were observed in children who had higher insulin (P = 0.008) and homeostasis model assessment insulin resistance values (P = 0.012) and lower quantitative insulin-sensitivity check index (P = 0.033). CONCLUSIONS: The underexpression of FFAR4 was associated with extreme obesity and parameters indicative of obesity comorbidities in children. This under expression could be partially influenced by the presence of the C allele rs11187533 FFAR4 SNP.

Melatonin Levels in Children with Obesity Are Associated with Metabolic Risk and Inflammatory Parameters.

Melatonin, the hormone of circadian rhythm regulation, is involved in the modulation of mitochondrial activity through its antioxidant and anti-inflammatory properties. Alteration of circadian rhythms such as sleep is related to obesity and metabolic pathogenesis in adulthood, but studies during childhood are scarce. The present study investigated the association of melatonin with metabolic and inflammatory markers in children with (n = 113) and without obesity (n = 117). Melatonin was measured in saliva four and two hours before bedtime, and after one hour of sleep. Cardiometabolic factors, high sensitivity C-reactive protein, immune markers (monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, tumor necrosis α and interferon-γ), leptin and ghrelin were determined. Sleep duration was recorded by a questionnaire. The melatonin level at 1 h after sleep was found to be increased more than twofold in children with obesity (90.16 (57.16-129.16) pg/mL) compared to controls (29.82 (19.05-61.54) pg/mL, p < 0.001) and was related to fat mass (rho = 0.294, p < 0.001); melatonin levels at 1 h after sleep were inversely correlated with high-density lipoprotein cholesterol. Positive correlation was found with apolipoprotein B, adipokines, high sensitivity C-reactive protein, plasminogen activator inhibitor-1 and tumor necrosis factor-α. Shorter sleep duration and earlier waking times were recorded in children with obesity. In conclusion, melatonin in children with obesity appears to be involved in the global metabolic and inflammatory alteration of this condition.

Melatonin Content of Human Milk: The Effect of Mode of Delivery.

Objective: Cesarean section rates are increasing in developed countries and could be performed as an emergency or elective procedure. Our research aim was to determine whether elective cesarean section influences the melatonin content, the main circadian hormone, in human milk. Methods: Twenty-one women after vaginal delivery and 18 women after elective cesarean section were included. Only healthy mothers with normal newborns exclusively breastfed were recruited. Two samples of human milk were collected for each woman at three stages of lactation: colostrum, transitional milk, and mature milk; at each stage, one daytime sample and another nighttime sample were obtained. In total, 228 milk samples were studied. The melatonin content was analyzed by enzyme-linked immunosorbent assay. Results: Melatonin rhythmicity with higher melatonin content at night was maintained at each of the three stages of lactation, regardless of the type of delivery. A higher melatonin content was found in daytime colostrum after cesarean section with respect to colostrum obtained from mothers after vaginal delivery (30.3 pg/mL versus 14.7 pg/mL, p = 0.020). Melatonin content decreased progressively throughout the course of lactation in both groups. This decrease was significant when comparing transitional milk to colostrum in the cesarean group, both in the daytime (p = 0.016) and nighttime samples (p = 0.048). Conclusions: Cesarean section is associated with an increase in daytime colostrum melatonin. No difference was observed in mature milk with respect to vaginal delivery. Melatonin values in human milk decrease during the first month of lactation and circadian rhythmicity was observed irrespective of the mode of delivery.