Efeito da dieta hipoproteica, hiperglicídica no metabolismo de lipídeos e na termogênese do tecido adiposo marrom de ratos

Abstract

To evaluate glucose uptake and the contribution of glucose to fatty acid (FA) synthesis and the glycerol-3-phosphate (G3P) of triacylglycerol synthesis by interscapular brown adipose tissue (IBAT) of low-protein, high-carbohydrate (LPHC) diet-fed rats. Methods: LPHC (6% protein; 74% carbohydrate) or control (C; 17% protein; 63% carbohydrate) diets were administered to rats (~100g body weight) for 15 days. Total FA and G3P synthesis and the synthesis of FA and G3P from glucose were evaluated in vivo by 3H2O and 14C-glucose. Sympathetic neural contribution for FA synthesis was evaluated by comparing the synthesis in denervated (7 days before) IBAT to that of the contralateral innervated side. The insulin signaling and β3 adrenergic receptor (β3-AR) contents, as well as others, were determined by Western blot (Student's t test or ANOVA, P≤ 0.05). Results: Total FA synthesis in IBAT was 133% higher in the LPHC group and was reduced 85% and 70% by denervation for the LPHC and C groups, respectively. Glucose uptake was 3.5-fold higher in the IBAT of LPHC rats than in that of the C rats, and the contribution of glucose to the total FA synthesis increased by 12% in C rats compared to 18% in LPHC rats. The LPHC diet increased the G3P generation from glucose by 270% and the insulin receptor content and the p-AKT insulin stimulation in IBAT by 120% and reduced the β3-AR content by 50%. Conclusions: The LPHC diet stimulated glucose uptake, both the total rates and the rates derived from glucose-dependent FA and G3P synthesis, by increasing the insulin sensitivity and the sympathetic flux, despite a reduction in the β3-AR content.