Guangdong Provincial Key Laboratory of Animal Nutrition Regulation, South China Agricultural University, Guangzhou, China.
Laboratory of Animal Nutritional Physiology and Metabolic Process, Institute of Subtropical Agriculture Chinese Academy of Sciences, Key Laboratory of Agro-ecological Processes in Subtropical Region, Hunan Provincial Engineering Research Center for Healthy Livestock and Poultry Production, Scientific Observing and Experimental Station of Animal Nutrition and Feed Science in South-Central, Ministry of Agriculture, Changsha, China.
J Anim Physiol Anim Nutr (Berl). 2019 May;103(3):846-857. doi: 10.1111/jpn.13077. Epub 2019 Feb 18.
This study aims to investigate the effects and roles of excess leucine (Leu) versus its metabolites α-ketoisocaproate (KIC) and β-hydroxy-β-methyl butyrate (HMB) on fatty acid composition and lipid metabolism in skeletal muscle of growing pigs.
Thirty-two pigs with a similar initial weight (9.55 ± 0.19 kg) were fed one of the four diets (basal diet, L-Leu, KIC-Ca and HMB-Ca) for 45 days. Results indicated that dietary treatments did not affect the intramuscular fat (IMF) content (p > 0.05), but differently influenced the fatty acid composition of longissimus dorsi muscle (LM) and soleus muscle (SM). In particular, the proportion of N3 PUFA specifically in LM was significantly decreased in the Leu group and increased in both KIC and HMB group relative to the basal diet group (p < 0.05). Furthermore, pigs fed KIC-supplemented diets exhibited decreased expression of FATP-1, ACC, ATGL, C/EBPα, PPARγ and SREBP-1c in LM and increased expression of FATP-1, FAT/CD36, ATGL and M-CPT-1 in SM relative to the basal diet control (p < 0.05).
These findings indicated that doubling dietary Leu content decreased the percentage of N3 PUFA mainly in glycolytic skeletal muscle, whereas KIC and HMB improved muscular fatty acid composition and altered lipid metabolism in skeletal muscle of growing pigs. The mechanism of action of KIC might be related to the TFs, and the mechanism of action of HMB might be associated with the AMPK-mTOR signalling pathway.
本研究旨在探讨过量亮氨酸（Leu）及其代谢产物 α-酮异己酸（KIC）和 β-羟基-β-甲基丁酸（HMB）对生长猪骨骼肌脂肪酸组成和脂代谢的影响和作用。
32 头初始体重（9.55±0.19kg）相似的猪被喂食四种日粮（基础日粮、L-Leu、KIC-Ca 和 HMB-Ca）中的一种，为期 45 天。结果表明，日粮处理对肌内脂肪（IMF）含量没有影响（p＞0.05），但对背最长肌（LM）和比目鱼肌（SM）的脂肪酸组成有不同的影响。特别是，Leu 组 LM 中 N3PUFA 的比例显著降低，而 KIC 和 HMB 组则高于基础日粮组（p＜0.05）。此外，与基础日粮对照组相比，KIC 组猪的 LM 中 FATP-1、ACC、ATGL、C/EBPα、PPARγ 和 SREBP-1c 的表达降低，SM 中 FATP-1、FAT/CD36、ATGL 和 M-CPT-1 的表达增加（p＜0.05）。
这些发现表明，日粮 Leu 含量加倍会降低糖酵解骨骼肌中 N3PUFA 的比例，而 KIC 和 HMB 则改善了生长猪骨骼肌的脂肪酸组成和脂代谢。KIC 的作用机制可能与 TFs 有关，HMB 的作用机制可能与 AMPK-mTOR 信号通路有关。
