Effects of dietary protein restriction on muscle fiber characteristics and mTORC1 pathway in the skeletal muscle of growing-finishing pigs.
Effects of dietary protein restriction on muscle fiber characteristics and mTORC1 pathway in the skeletal muscle of growing-finishing pigs.
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DOI：
10.1186/s40104-016-0106-8
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发表时间：
2016
影响因子：
7
通讯作者：
Yin Y
中科院分区：
文献类型：
--
作者：
Li Y;Li F;Wu L;Wei H;Liu Y;Li T;Tan B;Kong X;Yao K;Chen S;Wu F;Duan Y;Yin Y
研究日粮粗蛋白限制对生长肥育猪肌纤维特性和骨骼肌蛋白质沉积关键调控因子的影响，（62.30 ± 0.88 kg）分为3组，按推荐的蛋白质水平饲喂（AP，16%CP）、中等限制蛋白质（MP，13%CP）和低蛋白质（LP，10%CP）饮食。对猪不同部位的骨骼肌，包括背最长肌（LDM）、腰大肌（PMM）和股二头肌（BFM）进行了组织学分析。结果表明，与LP组相比，MP组和AP组的日增重和料重比均显著提高（P < 0.01），且MP组有提高LDM体重的趋势（P = 0.09）。不同部位肌肉ATP含量和能荷值存在差异。除肌球蛋白重链（MyHC）Ⅱ b、MyHC Ⅱ x外，其它关键基因的mRNA表达均显著上调（P < 0.05），而泛素连接酶基因的mRNA表达不受日粮CP水平的影响。此外，与饲喂LP饲料的猪相比，饲喂MP或AP饲料的猪骨骼肌中雷帕霉素复合物1（mTORC 1）途径的哺乳动物靶点的激活被刺激（P < 0.05）。结果表明，MP日粮能使生长肥育猪的生长性能和LDM体重达到AP日粮的水平，其机制可能与MP日粮改变了生长肥育猪的能量状态、调节了肌纤维特性、mTORC 1及其下游效应子在不同部位骨骼肌中的激活有关。本文的在线版本（doi：10.1186/s40104-016-0106-8）包含补充材料，可供授权用户使用。
To investigate the effects of dietary crude protein (CP) restriction on muscle fiber characteristics and key regulators related to protein deposition in skeletal muscle, a total of 18 growing-finishing pigs (62.30 ± 0.88 kg) were allotted to 3 groups and fed with the recommended adequate protein (AP, 16 % CP) diet, moderately restricted protein (MP, 13 % CP) diet and low protein (LP, 10 % CP) diet, respectively. The skeletal muscle of different locations in pigs, including longissimus dorsi muscle (LDM), psoas major muscle (PMM) and biceps femoris muscle (BFM) were collected and analyzed. Results showed that growing-finishing pigs fed the MP or AP diet improved (P < 0.01) the average daily gain and feed: gain ratio compared with those fed the LP diet, and the MP diet tended to increase (P = 0.09) the weight of LDM. Moreover, the ATP content and energy charge value were varied among muscle samples from different locations of pigs fed the reduced protein diets. We also observed that pigs fed the MP diet up-regulated (P < 0.05) muscular mRNA expression of all the selected key genes, except that myosin heavy chain (MyHC) IIb, MyHC IIx, while mRNA expression of ubiquitin ligases genes was not affected by dietary CP level. Additionally, the activation of mammalian target of rapamycin complex 1 (mTORC1) pathway was stimulated (P < 0.05) in skeletal muscle of the pigs fed the MP or AP diet compared with those fed the LP diet. The results suggest that the pigs fed the MP diet could catch up to the growth performance and the LDM weight of the pigs fed the AP diet, and the underlying mechanism may be partly due to the alteration in energy status, modulation of muscle fiber characteristics and mTORC1 activation as well as its downstream effectors in skeletal muscle of different locations in growing-finishing pigs. The online version of this article (doi:10.1186/s40104-016-0106-8) contains supplementary material, which is available to authorized users.