Pégorier J P, Duée P H, Herbin C, Laulan P Y, Bladé C, Peret J, Girard J
Centre de Recherches sur la Nutrition du CNRS, Meudon-Bellevue, France.
Biochem J. 1988 Feb 1;249(3):801-6. doi: 10.1042/bj2490801.
Fatty acid oxidation and synthesis were studied in isolated hepatocytes from adult rats adapted for 44 days on low-fat, high-carbohydrate (LF), diet or high-fat diets, composed of long-chain (LCT) or medium-chain (MCT) triacylglycerols. The rates of [1-14C]octanoate oxidation were almost similar in each group studied, whereas the oxidation of [1-14C]oleate was 50% lower in the LF group than in animals adapted to high-fat diets. The rates of oleate oxidation are inversely correlated with the rates of lipogenesis. However, it seems unlikely that [malonyl-CoA] itself represents the sole mechanism involved in the regulation of oleate oxidation during long-term LCT or MCT feeding, since: (1) despite a 3-fold higher concentration of malonyl-CoA in MCT-fed rats than in LCT-fed ones, the rates of oleate oxidation are similar; (2) when malonyl-CoA concentration is increased after stimulation of lipogenesis (by adding lactate + pyruvate) in MCT-fed rats, to a level comparable with that of the LF group, the rate of oleate oxidation remains 55% higher than that measured under similar conditions in the LF-fed rats; (3) in the LF group, the 90% decrease in malonyl-CoA concentration [by 5-(tetradecyloxy)-2-furoic acid] is not associated with a stimulation of oleate oxidation. By contrast, the sensitivity of carnitine palmitoyltransferase I (CPT I) to malonyl-CoA is markedly decreased in the LCT- and MCT-fed rats, by 90% and 70% respectively. The relevance of this decrease in the sensitivity of CPT I is discussed.
对成年大鼠分离的肝细胞进行了脂肪酸氧化和合成的研究，这些大鼠分别以低脂高碳水化合物（LF）饮食或由长链（LCT）或中链（MCT）三酰甘油组成的高脂饮食适应44天。在所研究的每组中，[1-¹⁴C]辛酸氧化速率几乎相似，而LF组中[1-¹⁴C]油酸的氧化速率比适应高脂饮食的动物低50%。油酸氧化速率与脂肪生成速率呈负相关。然而，[丙二酰辅酶A]本身似乎不太可能是长期LCT或MCT喂养期间油酸氧化调节的唯一机制，因为：（1）尽管MCT喂养的大鼠中丙二酰辅酶A的浓度比LCT喂养的大鼠高3倍，但油酸氧化速率相似；（2）当通过在MCT喂养的大鼠中刺激脂肪生成（添加乳酸+丙酮酸）使丙二酰辅酶A浓度增加到与LF组相当的水平时，油酸氧化速率仍比在类似条件下LF喂养的大鼠中测得的速率高55%；（3）在LF组中，丙二酰辅酶A浓度[通过5-（十四烷氧基）-2-糠酸]降低90%与油酸氧化的刺激无关。相比之下，LCT和MCT喂养的大鼠中肉碱棕榈酰转移酶I（CPT I）对丙二酰辅酶A的敏感性分别显著降低了90%和70%。讨论了CPT I敏感性降低的相关性。
