IBIMOL   23987
INSTITUTO DE BIOQUIMICA Y MEDICINA MOLECULAR PROFESOR ALBERTO BOVERIS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
FRUCTOSE OVERLOAD IN RATS WOULD INCREASE CORTICOSTERONE PRODUCTION MODIFYING NADPH METABOLISM IN EPIDIDYMAL WHITE ADIPOSE TISSUE
Autor/es:
CARRANZA A; HOCHT C; GEREZ E; POLIZIO AH; MAYER M; TAIRA CA; PUYÓ AM; FRAGA CG; GALLEANO M
Lugar:
Buenos Aires
Reunión:
Congreso; The 2nd International Congress on Abdominal Obesity; 2011
Institución organizadora:
International Chair on Cardiometabolic Risk
Resumen:
Fructose-overload (FO) in rats resembles the human metabolic syndrome characterized by insulin resistance (IR), dislypidemia and hypertension. NAPDH metabolism links the pentose phosphate pathway with the antioxidant enzymes network and glucocorticoids synthesis. Altered glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PD) activities have been associated to IR and lipid dysregulation. Moreover, corticosterone (Cort) administration produces increased adiposity, IR, and elevated plasma leptin, insulin and triglycerides (TG). Objectives: Characterize metabolic parameters and enzymatic activities involved in NADPH metabolization in epididymal white adipose tissue (EWAT) from rats subjected to FO. Methods: Male Sprague-Dawley rats received fructose (F, 10% w/v tap water, n=8) by 7 weeks or tap water as control group (C, water, n=8). Plasma TG and glucose were determined by enzymatic assay and Cort by HPLC-UV. Enzymatic activities were measured spectrophotometrically in homogenates of EWAT: GPx by the GR-coupled method, GR monitoring NADPH loss in the presence of GSSG, CAT following H2O2 loss, SOD by cytochrome C method, and G6PD by monitoring NADPH production in the presence of G6P. Results: FO produced hypertriglyceridemia (mg/dl: 173±4 vs. 79±16; p<0.01) without significant changes in glucemia. CAT, SOD and GR activities were unchanged by the treatment. GPx activity decreased in FO (nmoles/min. mg prot: 52±5 vs. 87±10; p<0.05). On the contrary, G6PD activity increased in FO (nmoles of reduced NADP/min.mg prot: 4.7±0.5 vs. 3.0±0.2; p<0.03). The endogenous content of NADPH in EWAT remained unchanged by FO treatment, while plasma Cort was significantly increased in FO rats (pg/ml: 190±22 vs. 90±12; p<0.01). Conclusion: As a result of the increase in G6PD and the decrease in GPx activities there should be a higher NADPH supply for Cort production by 11b-HSD1 in FO rats. In this way, EWAT could be one of the sources of the higher Cort levels detected in FO plasma respect to C rats.