Evaluation of Kisspeptin levels in prepubertal obese and overweight children: sexual dimorphism and modulation of antioxidant levels.

OBJECTIVE: Kisspeptin, neuropeptide involved in puberty beginning and regulation of pituitary-gonadal axis, has been shown to stimulate antioxidant defenses in murine models. Its levels are greater in females than males and also in obese prepubertal girls. Therefore, our aim was to evaluate sex-related differences in prepubertal obese patients and the relationships of Kisspeptin with metabolic/hormonal parameters. PATIENTS AND METHODS: We studied Kisspeptin concentrations in 54 children (22 males and 32 females, Tanner stage 1), 5-12 ys, classified according to Cole's criteria into 17 overweight and 37 obese; 25 normal-weight children, aged 6-12 years, were studied as controls. We evaluated metabolic (glucose and insulin levels after oral glucose load, total- LDL- HDL-cholesterol, triglycerides, uric acid) and hormonal (fT3, fT4, TSH, IGF-1, leptin) parameters. Moreover, total antioxidant capacity (TAC) was evaluated by spectrophotometric method, using the system H202-metmyoglobin-ABTS. Kisspeptin levels were measured by RIA. RESULTS: We did not find significant differences between obese and normal-weight children, but obese males presented significantly lower levels than females. Kisspeptin did not correlate with BMI, HOMA-IR, Insulin peak levels and TAC; a significant correlation was found between Kisspeptin and fT3 (r2=0.25; p=0.003) in the obese group; leptin levels, significantly greater in obese vs. overweight and control children, significantly correlated with TAC (r2=0.39; p=0.03). CONCLUSIONS: These data suggest that both hormones could modulate antioxidants, Kisspeptin indirectly via influence on thyroid hormones, and Leptin by a direct effect. This mechanism seems to be sex-related, not attributable to peripheral steroid levels. Further studies can clarify the complex interrelationship between central and peripheral Kisspeptin secretion and oxidative stress in children obesity.

Frailty of Obese Children: Evaluation of Plasma Antioxidant Capacity in Pediatric Obesity.

Background: Obese children are subject to the same chronic oxidative and inflammatory stress, responsible for the onset of all the complications typical of adult age, such as insulin resistance, type 2 diabetes, dyslipidemia and cardiovascular disease. Objectives: Since few studies are reported in prepubertal obese children, we investigated the relationship between oxidative stress, body composition and metabolic pattern in childhood obesity in comparison with adult obese patients. Methods: We enrolled 25 prepubertal children (12 males and 13 females) aged 5-12 years with a mean value of standard deviation of BMI (SDS-BMI)±SEM of 1.96±0.09. We performed oral glucose tolerance test, hormonal and metabolic evaluation, bioimpedentiometry, evaluation of total antioxidant capacity using spectroscopical method using a radical cation, 2,2I- azinobis(3-ethylbenzothiazoline-6 sulphonate) (ABTS), as indicator of radical formation, with a latency time (LAG) proportional to antioxidant in the sample. Results: LAG values significantly correlate with % fat mass, waist circumference and waist/hip ratio. However mean LAG values were significantly lower than in obese adults. Conclusions: We suggest that children are more susceptible to oxidative stress than adults, possibly to incomplete development of antioxidant system. Prognostic and therapeutical implications need to be further investigated.