Chaves Valéria E, Frasson Danúbia, Garófalo Maria A R, Navegantes Luiz C C, Migliorini Renato H, Kettelhut Isis C
Laboratory of Physiology and Pharmacology, Federal University of São João del-Rei, Avenida Sebastião Gonçalves Coelho 400, Chanadour, Divinópolis, Minas Gerais, Brazil.
Lipids. 2012 Aug;47(8):773-80. doi: 10.1007/s11745-012-3683-0. Epub 2012 Jun 10.
We have previously shown that a high-protein, carbohydrate-free diet can decrease the production of glycerol-3-phosphate (G3P) from glucose and increase glyceroneogenesis in both brown (BAT) and epididymal (EAT) adipose tissue. Here, we utilized an in-vivo approach to examine the hypothesis that there is reciprocal regulation in the G3P synthesis from glucose (via glycolysis) and glyceroneogenesis in BAT, EAT and liver of fasted rats and cafeteria diet-fed rats. Glyceroneogenesis played a prominent role in the generation of G3P in the liver (70 %) as well as in BAT and EAT (80 %) in controls rats. The cafeteria diet induced an increase in the total glyceride-glycerol synthesis and G3P synthesis from glucose and a decrease in glyceroneogenesis in BAT; this diet did not affect either the total glyceride-glycerol synthesis or G3P generation from glyceroneogenesis or glycolysis in the liver or EAT. Fasting induced an increase in total glyceride-glycerol synthesis and glyceroneogenesis and a decrease in G3P synthesis from glucose in the liver but did not affect either the total glyceride-glycerol synthesis or G3P synthesis from glyceroneogenesis in BAT and EAT, despite a reduction in glycolysis in these tissues. These data demonstrate that reciprocal changes in the G3P generation from glucose and from glyceroneogenesis in the rat liver and BAT occur only when the synthesis of glycerides-glycerol is increased. Further, our data suggest that this increase may be essential for the systemic recycling of fatty acids by the liver from fasted rats and for the maintenance of the thermogenic capacity of BAT from cafeteria diet-fed rats.
我们之前已经表明，高蛋白、无碳水化合物饮食可减少葡萄糖生成3-磷酸甘油（G3P），并增加棕色脂肪组织（BAT）和附睾脂肪组织（EAT）中的甘油生成。在此，我们采用体内研究方法来检验以下假设：在禁食大鼠和喂食自助餐厅饮食的大鼠的BAT、EAT和肝脏中，葡萄糖（通过糖酵解）生成G3P的过程与甘油生成之间存在相互调节。在对照大鼠中，甘油生成在肝脏中G3P的生成中起主要作用（约70%），在BAT和EAT中也起主要作用（约80%）。自助餐厅饮食导致BAT中甘油三酯-甘油的总合成以及葡萄糖生成G3P增加，而甘油生成减少；这种饮食对肝脏或EAT中甘油三酯-甘油的总合成或甘油生成或糖酵解生成G3P均无影响。禁食导致肝脏中甘油三酯-甘油的总合成和甘油生成增加，葡萄糖生成G3P减少，但尽管这些组织中的糖酵解减少，对BAT和EAT中甘油三酯-甘油的总合成或甘油生成生成G3P均无影响。这些数据表明，仅当甘油三酯-甘油的合成增加时，大鼠肝脏和BAT中葡萄糖生成G3P和甘油生成之间才会发生相互变化。此外，我们的数据表明，这种增加对于禁食大鼠肝脏中脂肪酸的全身循环以及喂食自助餐厅饮食的大鼠BAT产热能力的维持可能至关重要。
