背景技术中链脂肪酸(MCFA)通常用于提高婴儿配方食品的热量含量。我们先前报道,与饲喂富含等热量长链脂肪酸(LCFA)配方的猪相比,饲喂MCFA的猪发生了肝脂肪变性。
目的:本研究的目的是调查:1)MCFA和LCFA喂养是否影响肝脏脂肪酸氧化,和2)脂肪类型如何改变肝脏脂肪酸代谢基因的表达。
方法:二十六,饲喂7日龄猪:低能量对照(CONT)配方,和两个富含LCFA或MCFA的等热量高能配方,持续22天。收集肝脏进行离体脂肪酸氧化,脂肪酸含量和脂肪酸代谢基因的mRNA表达。
结果:MCFA组猪的肝脏脂肪为20%,而CONT和LCFA组的肝脏脂肪为4.6%和2.9%(P<0.05)。MCFA饲喂的猪有更多的肝月桂酸盐,Myristate,棕榈酸盐,和棕榈油酸酯(14、34、49和9.3mg•g-1)与LCFA和CONT(1.8、1.9、19、1.5mg•g-1)配方相比(P≤0.05)。与饲喂CONT(54mmol·mg-1·h-1)和LCFA(51mmol·mg-1·h-1)的猪相比,饲喂MCFA(29mmol·mg-1·h-1)的猪的肝月桂酸盐和棕榈酸盐氧化降低配方(P<0.05)。脂肪酸合成酶3(FASN-3)的表达,脂肪酸结合蛋白1(FABP-1),与LCFA和CONT组相比,MCFA中的猪的乙酰辅酶A羧化酶1(ACACA-1)分别高8、6和2倍(P<0.05)。
结论:与富含LCFA的等热量配方相比,饲喂MCFA导致肝脏脂肪变性。脂肪变性伴随着脂肪酸氧化的减少,但脂肪酸合成和分解代谢基因的mRNA表达更高。
BACKGROUND: Medium-chain fatty acids (MCFAs) are commonly used to enhance the caloric content of infant formulas. We previously reported that pigs fed MCFA developed hepatic steatosis when compared to those fed isocaloric long-chain fatty acid (LCFA) rich formula.
OBJECTIVE: The objectives of this study were to investigate: 1) whether MCFA and LCFA feeding affect hepatic fatty acid oxidation, and 2) how fat type alters the expression of hepatic fatty acid metabolic genes.
METHODS: Twenty-six, 7-d-old pigs were fed a low-energy control (CONT) formula, or 2 isocaloric high-energy formulas rich in LCFA or MCFA for 22 days. Livers were collected for examining ex vivo fatty acid oxidation, fatty acid content, and mRNA expression of fatty acid metabolic genes.
RESULTS: Liver fat was 20% for pigs in the MCFA compared with 2.9% and 4.6% for those in the CONT and LCFA groups (P < 0.05). MCFA-fed pigs had greater amounts of hepatic laurate, myristate, palmitate, and palmitoleate (14, 34, 49, and 9.3 mg · g-1) than those fed LCFA and CONT (1.8, 1.9, 19, 1.5 mg · g-1) formulas (P ≤ 0.05). Hepatic laurate and palmitate oxidation was reduced for pigs fed MCFA (29 mmol · mg-1 · h-1) compared with those fed CONT (54 mmol · mg-1 · h-1) and LCFA (51 mmol · mg-1 · h-1) formulas (P < 0.05). Expression of fatty acid synthase 3 (FASN-3), fatty acid binding protein 1 (FABP-1), and acetyl-CoA carboxylase 1 (ACACA-1) were 8-, 6-, and 2-fold greater for pigs in the MCFA than those in the LCFA and CONT groups (P < 0.05).
CONCLUSIONS: Feeding MCFA resulted in hepatic steatosis compared with an isocaloric formula rich in LCFA. Steatosis occurred concomitantly with reduced fatty acid oxidation but greater mRNA expression of fatty acid synthetic and catabolic genes.