Brito Salete Cipriano, Festuccia William Lara, Kawashita Nair Honda, Moura Maria Ferreira, Xavier Analúcia Rampazzo, Garófalo Maria Antonieta, Kettelhut Isis Carmo, Migliorini Renato Hélios
Department of Biochemistry-Immunology, School of Medicine, University of São Paulo, 14049-900 Ribeirão Preto, São Paulo, Brazil.
Metabolism. 2006 Jan;55(1):84-9. doi: 10.1016/j.metabol.2005.07.010.
We have previously shown in in vivo experiments that adipose tissue glyceroneogenesis is increased in rats adapted to a high-protein, carbohydrate-free (HP) diet. The objectives of the present study were (1) to verify if the increased glyceroneogenic activity is also observed in isolated adipocytes and (2) to investigate the role of preformed fatty acids in the production of the increased adipose tissue glyceroneogenesis. Control rats received a balanced diet, with the same lipid content of the HP diet. Glyceroneogenic activity was found to be higher in adipocytes from HP rats than in controls, as evidenced by increased rates of conversion of pyruvate and lactate to triacylglycerol (TAG)-glycerol. Administration of Triton WR 1339, which blocks the removal of TAG incorporated into circulating lipoproteins, to HP diet-adapted rats caused a significant reduction in the incorporation of 14C-pyruvate into TAG-glycerol by adipose tissue, which was accompanied by a marked inhibition of phosphoenolpyruvate carboxykinase activity, the key enzyme of glyceroneogenesis. The inhibitory effect of Triton on TAG-glycerol synthesis by adipose tissue was also observed in vivo, after administration of 3H2O. Adaptation to the HP diet induced a marked increase in the activity of retroperitoneal and epididymal fat LPL, which was restored to control values 24 hours after replacement of the HP diet by the balanced diet. The data suggest that in rats adapted to a carbohydrate-free diet, adipose tissue glyceroneogenesis is activated by an increased use of diet-derived fatty acids.
我们之前在体内实验中表明，适应高蛋白、无碳水化合物（HP）饮食的大鼠脂肪组织甘油生成增加。本研究的目的是：（1）验证在分离的脂肪细胞中是否也观察到甘油生成活性增加；（2）研究预先形成的脂肪酸在脂肪组织甘油生成增加中的作用。对照大鼠接受平衡饮食，其脂质含量与HP饮食相同。发现HP大鼠脂肪细胞中的甘油生成活性高于对照组，丙酮酸和乳酸转化为三酰甘油（TAG）-甘油的速率增加证明了这一点。给适应HP饮食的大鼠施用Triton WR 1339（它会阻止纳入循环脂蛋白的TAG的清除），导致脂肪组织将14C-丙酮酸掺入TAG-甘油的量显著减少，同时磷酸烯醇丙酮酸羧激酶活性受到明显抑制，磷酸烯醇丙酮酸羧激酶是甘油生成的关键酶。在施用3H2O后，在体内也观察到Triton对脂肪组织TAG-甘油合成的抑制作用。适应HP饮食会导致腹膜后和附睾脂肪脂蛋白脂肪酶（LPL）活性显著增加，在用平衡饮食替代HP饮食24小时后，该活性恢复到对照值。数据表明，在适应无碳水化合物饮食的大鼠中，脂肪组织甘油生成通过增加使用饮食来源的脂肪酸而被激活。
