Nagase H, Bray G A, York D A
Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
Am J Physiol. 1996 Mar;270(3 Pt 2):R489-95. doi: 10.1152/ajpregu.1996.270.3.R489.
This study compared the effects of exogenous pyruvate and lactate on the serum levels of pyruvate, lactate, glucose, alanine, and insulin, as well as the activity of hepatic pyruvate dehydrogenase (PDH) in strains of rat that were either sensitive [Osborne-Mendel (OM)] or resistant (S5B/Pl) to high-fat diet-induced obesity. Serum pyruvate and lactate were significantly higher and glucose lower in ad libitum-fed OM rats, but these differences disappeared after an 18-h fast. The increase in pyruvate and lactate after exogenous pyruvate administration was significantly greater in S5B/Pl rats than OM rats. There were no differences in serum alanine with strain or diet. The total PDH activity was similar across strains and diets but the proportion of PDH in its activated form (PDHa) was decreased in ad libitum-fed S5B/Pl rats. Pyruvate injection increased insulin and hepatic PDHa activity in OM rats fed both high- and low-fat diets, but these responses were greatly attenuated or absent in S5B/Pl rats. The data are consistent with the hypothesis that modulation of carbohydrate oxidation by PDH may be related to susceptibility to obesity when rats are fed a high-fat diet.
本研究比较了外源性丙酮酸和乳酸对易患[奥斯本-孟德尔（OM）]或抵抗（S5B/Pl）高脂饮食诱导肥胖的大鼠品系血清中丙酮酸、乳酸、葡萄糖、丙氨酸和胰岛素水平，以及肝脏丙酮酸脱氢酶（PDH）活性的影响。随意进食的OM大鼠血清丙酮酸和乳酸显著升高，葡萄糖降低，但禁食18小时后这些差异消失。外源性丙酮酸给药后，S5B/Pl大鼠丙酮酸和乳酸的增加显著大于OM大鼠。血清丙氨酸在品系或饮食方面没有差异。总PDH活性在各品系和饮食之间相似，但随意进食的S5B/Pl大鼠中活性形式（PDHa）的PDH比例降低。丙酮酸注射增加了高脂和低脂饮食喂养的OM大鼠的胰岛素和肝脏PDHa活性，但这些反应在S5B/Pl大鼠中大大减弱或不存在。这些数据与以下假设一致，即当大鼠喂食高脂饮食时，PDH对碳水化合物氧化的调节可能与肥胖易感性有关。
