Deng Yuankun, Cheng Hao, Li Junyao, Han Hui, Qi Ming, Wang Nan, Tan Bi'e, Li Jianjun, Wang Jing
College of Animal Science and Technology, Hunan Agricultural University, Changsha, Hunan, China.
Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agroecological Processes in Subtropical Region, National Engineering Laboratory for Pollution Control and Waste Utilization in Livestock and Poultry Production, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China.
Front Vet Sci. 2023 Jul 27;10:1202369. doi: 10.3389/fvets.2023.1202369. eCollection 2023.
Aspartate (asp), glutamate (glu), and glutamine (gln) are the major energy fuels for the small intestine, and it had been indicated in our previous study that the mix of these three amino acid supplementations could maintain intestinal energy homeostasis. This study aimed to further investigate whether the treatment of gln, glu, and asp in low energy diet affects the intestinal barrier integrity and amino acid pool in weaning piglets. A total of 198 weaned piglets were assigned to 3 treatments: control (basal diet + 1.59% L-Ala); T1 (basal diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp); and T2 (low energy diet + 1% L-Gln + 0.5% L-Glu + 0.1% L-Asp). The blood, jejunum, and ileum were obtained on day 5 or on day 21 post-weaning, respectively. Our results showed that T1 and T2 treatments increased the abundances of occludin, claudin-1, and claudin-3 in the small intestine while decreasing the serum diamine oxidase (DAO) and D-lactate levels in weaning piglets. Meanwhile, T1 and T2 treatments significantly increased the positive rate of proliferating cell nuclear antigen (PCNA) of the small intestine, promoting intestinal cell proliferation. We also found that supplementation with glu, gln, and asp improved the serum amino acid pool and promoted ileal amino acid transporter gene expression of , and in weaned piglets. Additionally, on day 21 post-weaning, T1 and T2 treatments stimulated the phosphorylation of the mTOR-S6K1-4EBP1 signaling pathway in the small intestine, which may implicate the enhanced protein synthesis rate. In summary, dietary supplementation of gln, glu, and asp was beneficial to the intestinal barrier function and amino acid pool regulation, while the benefits of gln, glu, and asp treatment might be diminished by the low-energy diet. The results demonstrated that the supplementation of gln, glu, and asp under low energy levels was preferentially supplied as the energy fuel to restore the gut barrier function in piglets on day 5 post-weaning. With the increase in age and intestinal maturation (on day 21 post-weaning), gln, glu, and asp supplementation could also show an effect on the regulation of the amino acid pool and protein synthesis.
天冬氨酸（asp）、谷氨酸（glu）和谷氨酰胺（gln）是小肠的主要能量燃料，我们之前的研究表明，这三种氨基酸补充剂的组合可以维持肠道能量稳态。本研究旨在进一步探讨在低能量日粮中添加gln、glu和asp是否会影响断奶仔猪的肠道屏障完整性和氨基酸池。总共198头断奶仔猪被分为3组处理：对照组（基础日粮+1.59%L-丙氨酸）；T1组（基础日粮+1%L-谷氨酰胺+0.5%L-谷氨酸+0.1%L-天冬氨酸）；T2组（低能量日粮+1%L-谷氨酰胺+0.5%L-谷氨酸+0.1%L-天冬氨酸）。分别在断奶后第5天或第21天采集血液、空肠和回肠样本。我们的结果表明，T1组和T2组处理增加了断奶仔猪小肠中闭合蛋白、紧密连接蛋白-1和紧密连接蛋白-3的丰度，同时降低了血清二胺氧化酶（DAO）和D-乳酸水平。同时，T1组和T2组处理显著提高了小肠增殖细胞核抗原（PCNA）的阳性率，促进了肠道细胞增殖。我们还发现，添加glu、gln和asp改善了断奶仔猪的血清氨基酸池，并促进了回肠氨基酸转运体基因的表达。此外，在断奶后第21天，T1组和T2组处理刺激了小肠中mTOR-S6K1-4EBP1信号通路的磷酸化，这可能意味着蛋白质合成速率提高。综上所述，日粮中添加gln、glu和asp有利于肠道屏障功能和氨基酸池的调节，而低能量日粮可能会削弱gln、glu和asp处理的益处。结果表明，在低能量水平下添加gln、glu和asp优先作为能量燃料供应，以恢复断奶后第5天仔猪的肠道屏障功能。随着年龄的增长和肠道成熟（断奶后第21天），添加gln、glu和asp也可能对氨基酸池的调节和蛋白质合成产生影响。
