Li Sisi, Wang Haichao, Wang Xinxia, Wang Yizhen, Feng Jie
Key Laboratory of Animal Nutrition & Feed, Zhejiang Province, College of Animal Science, Zhejiang University, Hangzhou, China.
J Anim Sci Biotechnol. 2017 Sep 1;8:72. doi: 10.1186/s40104-017-0200-6. eCollection 2017.
Betaine affects fat metabolism in animals, but the specific mechanism is still not clear. The purpose of this study was to investigate possible mechanisms of betaine in altering lipid metabolism in muscle tissue in finishing pigs.
A total of 120 crossbred gilts (Landrace × Yorkshire × Duroc) with an average initial body weight of 70.1 kg were randomly allotted to three dietary treatments. The treatments included a corn-soybean meal basal diet supplemented with 0, 1250 or 2500 mg/kg betaine. The feeding experiment lasted 42 d.
Betaine addition to the diet significantly increased the concentration of free fatty acids (FFA) in muscle ( < 0.05). Furthermore, the levels of serum cholesterol and high-density lipoprotein cholesterol were decreased ( < 0.05) and total cholesterol content was increased in muscle ( < 0.05) of betaine fed pigs. Experiments on genes involved in fatty acid transport showed that betaine increased expression of , (), () and () ( < 0.05). The abundance of fatty acid transport protein and fatty acid binding protein were also increased by betaine ( < 0.05). As for the key factors involved in fatty acid oxidation, although betaine supplementation didn't affect the level of carnitine and malonyl-CoA, betaine increased mRNA and protein abundance of carnitine palmitransferase-1(CPT1) and phosphorylated-AMPK ( < 0.05).
The results suggested that betaine may promoted muscle fatty acid uptake via up-regulating the genes related to fatty acid transporter including , and . On the other hand, betaine activated AMPK and up-regulated genes related to fatty acid oxidation including and . The underlying mechanism regulating fatty acid metabolism in pigs supplemented with betaine is associated with the up-regulation of genes involved in fatty acid transport and fatty acid oxidation.
甜菜碱影响动物脂肪代谢，但具体机制仍不清楚。本研究旨在探讨甜菜碱改变育肥猪肌肉组织脂质代谢的可能机制。
选取120头平均初始体重为70.1 kg的杂交后备母猪（长白猪×大白猪×杜洛克猪），随机分为三种日粮处理组。处理组包括在玉米-豆粕基础日粮中分别添加0、1250或2500 mg/kg甜菜碱。饲养试验持续42天。
日粮中添加甜菜碱显著提高了肌肉中游离脂肪酸（FFA）的浓度（P<0.05）。此外，甜菜碱组猪的血清胆固醇和高密度脂蛋白胆固醇水平降低（P<0.05），肌肉中总胆固醇含量增加（P<0.05）。对参与脂肪酸转运的基因进行实验表明，甜菜碱增加了脂肪酸转运蛋白1（FATP1）、脂肪酸转运蛋白2（FATP2）、脂肪酸转运蛋白4（FATP4）和脂肪酸转运蛋白5（FATP5）的表达（P<0.05）。甜菜碱还增加了脂肪酸转运蛋白（FATP）和脂肪酸结合蛋白（FABP）的丰度（P<0.05）。至于参与脂肪酸氧化的关键因子，虽然添加甜菜碱不影响肉碱和丙二酰辅酶A的水平，但甜菜碱增加了肉碱棕榈酰转移酶-1（CPT1）和磷酸化-AMPK的mRNA和蛋白丰度（P<0.05）。
结果表明，甜菜碱可能通过上调与脂肪酸转运相关的基因，包括脂肪酸转运蛋白1、脂肪酸转运蛋白2和脂肪酸转运蛋白4，促进肌肉脂肪酸摄取；另一方面，甜菜碱激活AMPK并上调与脂肪酸氧化相关的基因，包括肉碱棕榈酰转移酶-1和脂肪酸转运蛋白5。甜菜碱调控猪脂肪酸代谢的潜在机制与脂肪酸转运和脂肪酸氧化相关基因的上调有关。
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