PLASMA LEVELS OF C-TYPE NATRIURETIC PEPTIDE IN NORMAL, OVERWEIGHT AND OBESE YOUNG POPULATION

Background: Recent evidence suggested C-type NP (CNP) as an important, natural regulator of adipogenesis. Aim of the study was to evaluate plasma levels of CNP in normal (N), overweight (OW) and obese (O) young population. Methods: CNP plasma levels were measured in 82 subjects (age: 13.0±2.3; BMI-N=20.3±0.5; BMI-OW=25.3±0.0.5 BMI-O=30.3±0.6) by a specific radioimmunoassay (Phoenix Pharmaceuticals, c/o Pantec, Italy). NT-proBNP (Roche Diagnostics GmbH, Mannheim), MRproANP (KRIPTOR: BRAHMS AG) and biochemical parameters were also measured in the same samples. Advanced glycated endproducts (AGEs) dependent skin autofluorescence was measured by the AGE reader apparatus. Results: CNP plasma levels resulted progressively reduced in OW=8.8±3.5, n=10 and O=6.7±0.9, n=43 with respect to normal (N=10.4±1.6 pg/mL, n=25; p=0.04 N vs.O) while NT-proBNP (N=36.2±5.9; OW=62.1±30.9 O=54.4±6.4 pg/mL) and MRproANP (N=29.1±1.7; OW=31.8±5.4 O=30.5±1.7 pmol/L) resulted similar in all groups. Insulin (p <0.0001), cholesterol (p=0.003), triglycerides (p=ns) and LDL (p=0.0005) were progressively higher in O and OW in comparison with N subjects. Higher amounts of AGEs were observed in OW (1.74±0.4) and O (1.45±0.06) in comparison with normal (1.28±0.04 AF, p=0.02 N vs. OW). Visceral trunk fat was also measured and resulted significantly higher in OW (36.1±2.39) and O (39.4±0.69) with respect to N (23.3±1.6, p <0.0001 respectively). CNP correlated significantly with age (p=0.001), fat mass (p=0.007), insulin (p=0.01), cholesterol (p <0.0001), LDL (p=0.0006), NT-proBNP (p=0.01) and MRproANP (p=0.01). Circulating CNP values were similar in males and females. A significant correlation (r=0.313, p=0.006) was observed between AGEs and trunk fat. Conclusion: In the population studied we observed lower plasma CNP levels confirming previous data. The correlations observed suggested that these alterations might be in part due to endocrine-metabolic deregulation. The direct relationship between visceral trunk fat and skin AGEs confirms the increased risk of vascular disease due to accumulation of abdominal fat in our population, while the relationship between skin AGEs and circulating levels of total cholesterol and LDL reflects an incorrect food eating.