College of Animal Science and Technology, Hunan Agricultural University, Changsha, China.
Food Funct. 2020 Feb 26;11(2):1304-1311. doi: 10.1039/c9fo01757g.
Branched-chain amino acids (BCAAs) are reduced in various protein restricted models, while the detailed role of BCAAs in protein restricted response is still obscure. Thus, the current study mainly investigated the amino acid metabolism in protein restricted piglets and the effects of BCAA balance in a low-protein diet on growth performance, amino acid metabolism, intestinal structure, and gut microbiota with focus on which BCAAs contributed to the protein restricted response. The results showed that protein restriction increased serum Ser, Thr, Ala, Lys, and Trp but reduced His, Cys, Val, and Ile levels. Intestinal amino acid transporters mainly mediated the mechanism of amino acid uptake. The BCAA balance refreshed the serum BCAA pool, which further improved growth performance in protein restricted piglets. Leu, Val, and Ile balances increased serum BCAA concentrations, respectively, and Leu and Val but not Ile enhanced the feed intake and weight gain in protein restricted piglets. In addition, protein restriction impaired the villus structure and increased the number of goblet cells in the ileum. Also, gut microbiota (Spirochaetales, Gammaproteobacteria, Lactobacillales at the order level) were altered in protein restricted pigs, while the BCAA balance markedly improved Gammaproteobacteria, Lactobacillales, and Aeromonadales proliferation, which might mediate growth promotion and amino acid metabolism. In conclusion, protein restriction markedly affected the host amino acid metabolism (i.e., Ser, Thr, Lys, His, BCAAs). The BCAA balance (especially for supplementation with Leu and Val) improved the amino acid metabolism, growth performance, and gut microbiota communities.
支链氨基酸（BCAAs）在各种蛋白质限制模型中减少，而 BCAAs 在蛋白质限制反应中的详细作用仍然不清楚。因此，本研究主要研究了蛋白质限制仔猪的氨基酸代谢以及低蛋白饮食中 BCAA 平衡对生长性能、氨基酸代谢、肠道结构和肠道微生物群的影响，重点研究了哪些 BCAAs 导致了蛋白质限制反应。结果表明，蛋白质限制增加了血清 Ser、Thr、Ala、Lys 和 Trp，但降低了 His、Cys、Val 和 Ile 水平。肠道氨基酸转运体主要介导了氨基酸摄取的机制。BCAA 平衡更新了血清 BCAA 池，进一步提高了蛋白质限制仔猪的生长性能。Leu、Val 和 Ile 的平衡分别增加了血清 BCAA 浓度，而 Leu 和 Val 但不是 Ile 增强了蛋白质限制仔猪的采食量和体重增加。此外，蛋白质限制损害了空肠的绒毛结构并增加了回肠中的杯状细胞数量。此外，蛋白质限制猪的肠道微生物群（螺旋体目、γ-变形菌纲、乳杆菌目）发生了改变，而 BCAA 平衡显著提高了γ-变形菌纲、乳杆菌目和气单胞菌目增殖，这可能介导了生长促进和氨基酸代谢。总之，蛋白质限制显著影响了宿主氨基酸代谢（即 Ser、Thr、Lys、His、BCAAs）。BCAA 平衡（特别是补充 Leu 和 Val）改善了氨基酸代谢、生长性能和肠道微生物群。
