Ikeda I, Cha J Y, Yanagita T, Nakatani N, Oogami K, Imaizumi K, Yazawa K
Laboratory of Nutrition Chemistry, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Biosci Biotechnol Biochem. 1998 Apr;62(4):675-80. doi: 10.1271/bbb.62.675.
The effects of dietary alpha-linolenic, eicosapentaenoic and docosahexaenoic acids on the enzyme activities related to hepatic lipogenesis and beta-oxidation were compared under constant polyunsaturated/monounsaturated/saturated fatty acids and n-6/n-3 ratios of dietary fats in rats. Dietary fat containing linoleic acid as the sole polyunsaturated fatty acid (PUFA) was also given as a control. The concentration of serum triglyceride and phospholipid in the three n-3 PUFA groups was lower than in the linoleic acid group. The hepatic triglyceride concentration was lower and the phospholipid concentration was higher in the three n-3 PUFA groups than in the linoleic acid group. Cytosolic fatty acid synthase (FAS) activity was lower in the n-3 PUFA groups than in the linoleic acid group, the reduction being more predominant in the eicosapentaenoic acid and docosahexaenoic acid groups than in the alpha-linolenic acid group. The cytosolic activities of the NADPH-generating enzymes, glucose-6-phosphate dehydrogenase (G6PDH) and the malic enzyme, were lower in the three n-3 PUFA groups. The activity of carnitine palmitoyltransferase (CPT) in mitochondria was higher only in the eicosapentaenoic acid group than in the other groups. The activity of Mg(2+)-dependent phosphatidate phosphohydrolase (PAP) in microsomes and cytosol was lower in the eicosapentaenoic and docosahexaenoic acid groups than in the linoleic acid group, while there was no effect of dietary fats on the activities of diacylglycerol acyltransferase (DGAT) and glycerol-3-phosphate acyltransferase (G3PAT) in microsomes. The CTP: phosphocholine cytidylyltransferase (CT) activity in the homogenate was lower in the n-3 PUFA groups, the reduction being more prominent in the eicosapentaenoic and docosahexaenoic acid groups than in the alpha-linolenic acid group. The choline kinase (CK) activity in cytosol was lower in the eicosapentaenoic acid group than in the linoleic acid group. These results showed that dietary alpha-linolenic, eicosapentaenoic and docosahexaenoic acids differently influenced hepatic lipogenesis and the partition of fatty acid into oxidation or glycerolipid synthesis.
在大鼠饮食中脂肪的多不饱和/单不饱和/饱和脂肪酸以及n-6/n-3比例恒定的情况下，比较了膳食α-亚麻酸、二十碳五烯酸和二十二碳六烯酸对与肝脏脂肪生成和β-氧化相关的酶活性的影响。还给予了以亚油酸作为唯一多不饱和脂肪酸（PUFA）的膳食脂肪作为对照。三个n-3 PUFA组的血清甘油三酯和磷脂浓度低于亚油酸组。三个n-3 PUFA组的肝脏甘油三酯浓度较低，而磷脂浓度高于亚油酸组。n-3 PUFA组的胞质脂肪酸合酶（FAS）活性低于亚油酸组，二十碳五烯酸和二十二碳六烯酸组的降低比α-亚麻酸组更显著。三个n-3 PUFA组中产生NADPH的酶、葡萄糖-6-磷酸脱氢酶（G6PDH）和苹果酸酶的胞质活性较低。仅二十碳五烯酸组线粒体中的肉碱棕榈酰转移酶（CPT）活性高于其他组。二十碳五烯酸和二十二碳六烯酸组微粒体和胞质中Mg(2+)依赖性磷脂酸磷酸水解酶（PAP）的活性低于亚油酸组，而膳食脂肪对微粒体中二酰甘油酰基转移酶（DGAT）和甘油-3-磷酸酰基转移酶（G3PAT）的活性没有影响。n-3 PUFA组匀浆中CTP：磷酸胆碱胞苷转移酶（CT）活性较低，二十碳五烯酸和二十二碳六烯酸组的降低比α-亚麻酸组更明显。二十碳五烯酸组胞质中的胆碱激酶（CK）活性低于亚油酸组。这些结果表明，膳食α-亚麻酸、二十碳五烯酸和二十二碳六烯酸对肝脏脂肪生成以及脂肪酸向氧化或甘油脂质合成的分配有不同影响。
