Botion L M, Kettelhut I C, Migliorini R H
Department of Biochemistry and Physiology, School of Medicine, University of São Paulo, Ribeirão Preto, Brazil.
Horm Metab Res. 1995 Jul;27(7):310-3. doi: 10.1055/s-2007-979967.
Glyceroneogenesis was assessed in epididymal adipose tissue from rats adapted to a high protein, carbohydrate-free (HP) diet. All experiments were performed in the fed state. Adaptation to the HP diet induced a two-fold increase in the activity of adipose tissue phosphoenolpyruvate carboxykinase (PEPCK). In the absence of glucose, the conversion of 14C-pyruvate (0.2, 1.0 or 5.0 mM) to glyceride-glycerol was significantly higher in adipose tissue from HP-fed rats than in controls. In the presence of glucose, rates of glycerol synthesis in tissues from HP-fed rats did not differ significantly from those in controls. Incorporation of 14C-pyruvate into fatty acids, both in the presence and absence of glucose, was not affected by the diet. The conversion of 14C-glucose (5 mM) into either glyceride-glycerol or fatty acids did not differ in HP-fed and control rats at any of the concentrations of pyruvate utilized. The data provide further evidence for the adaptative nature of adipose tissue PEPCK and suggest that in situations of reduced availability of glucose in the diet, glyceroneogenesis may be important to maintain an adequate supply of alpha-glycerophosphate for esterification of diet-derived fatty acids.
在适应高蛋白、无碳水化合物（HP）饮食的大鼠附睾脂肪组织中评估甘油异生作用。所有实验均在喂食状态下进行。适应HP饮食可使脂肪组织磷酸烯醇式丙酮酸羧激酶（PEPCK）的活性增加两倍。在无葡萄糖的情况下，HP喂养大鼠的脂肪组织中14C-丙酮酸（0.2、1.0或5.0 mM）向甘油甘油酯的转化明显高于对照组。在有葡萄糖存在的情况下，HP喂养大鼠组织中的甘油合成速率与对照组相比无显著差异。无论有无葡萄糖，饮食均不影响14C-丙酮酸掺入脂肪酸。在所用的任何丙酮酸浓度下，HP喂养大鼠和对照大鼠中14C-葡萄糖（5 mM）向甘油甘油酯或脂肪酸的转化均无差异。这些数据为脂肪组织PEPCK的适应性提供了进一步的证据，并表明在饮食中葡萄糖可用性降低的情况下，甘油异生作用对于维持足够的α-甘油磷酸供应以用于饮食来源脂肪酸的酯化可能很重要。
