Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological 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, Hunan, China; Guangdong Provincial Key Laboratory of Animal Nutrition Regulation, Guangdong, China.
Laboratory of Animal Nutritional Physiology and Metabolic Process, Key Laboratory of Agro-ecological 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, Hunan, China; Department of Animal Science, University of California, Davis, California, USA.
Nutrition. 2018 Oct;54:173-181. doi: 10.1016/j.nut.2018.03.057. Epub 2018 Apr 24.
The aim of this study was to investigate the effects of different branched-chain amino acid (BCAA) ratios on intestinal cell proliferation and protein metabolism.
This in vivo study was conducted in growing pigs (average initial body weight = 9.85 ± 0.35 kg) exposed to different leucine, isoleucine, and valine (Leu:Ile:Val) ratios (1:1:1, 1:0.75:0.75, 1:0.51:0.63, and 1:0.25:0.25) in 17% crude protein (CP) diets for 45 d to determine intestinal morphology, cell proliferation, and amino acid transporter mRNA expression. This in vitro study was performed in porcine jejunal epithelial cell line to investigate the effects of different BCAA ratios (0, 1:0.25:0.25, 1:0.5:0.5, and 1:1:1) on cell proliferation, AA transporter expression. and protein turnover.
Relative to the positive control (Leu:Ile:Val = 1:0.51:0.63, 20% CP), the 1:0.75:0.75 group (17% CP) significantly increased the jejunal villus height, the percentage of proliferating cell nuclear antigen-positive cells and decreased the ileal crypt depth (P <0.05). Moreover, most AA concentrations and AA transporter expression in the jejunal and ileal mucosa in 17% CP diets were increased to the levels similar to those in the positive control. Additionally, this in vitro study showed that the BCAA ratio of 1:0.25:0.25 significantly increased intestinal cell proliferation, mRNA expression of AA transporters, AA concentrations, and protein turnover (P <0.05).
These findings suggest that optimal BCAA ratio (in vivo = 1:0.75:0.75; in vitro = 1:0.25:0.25) would improve intestinal morphology and cell proliferation, increase intestinal AA absorption through mediating expression of intestinal AA transporters, and promote intestinal protein turnover. The findings yield new insights into the use of BCAAs in humans and animals.
本研究旨在探讨不同支链氨基酸（BCAA）比例对肠道细胞增殖和蛋白质代谢的影响。
本体内研究在生长猪（平均初始体重=9.85±0.35kg）中进行，这些猪暴露于不同亮氨酸、异亮氨酸和缬氨酸（Leu：Ile：Val）比例（1：1：1、1：0.75：0.75、1：0.51：0.63 和 1：0.25：0.25）的 17%粗蛋白（CP）饮食中 45 天，以确定肠道形态、细胞增殖和氨基酸转运体 mRNA 表达。本体外研究在猪空肠上皮细胞系中进行，以研究不同 BCAA 比例（0、1：0.25：0.25、1：0.5：0.5 和 1：1：1）对细胞增殖、AA 转运体表达和蛋白质周转的影响。
与阳性对照（Leu：Ile：Val=1：0.51：0.63，20%CP）相比，1：0.75：0.75 组（17%CP）显著增加了空肠绒毛高度、增殖细胞核抗原阳性细胞的百分比，并降低了回肠隐窝深度（P<0.05）。此外，17%CP 饮食中大多数 AA 浓度和空肠和回肠黏膜中的 AA 转运体表达均增加至与阳性对照相似的水平。此外，本体外研究表明，BCAA 比例为 1：0.25：0.25 可显著增加肠道细胞增殖、AA 转运体 mRNA 表达、AA 浓度和蛋白质周转（P<0.05）。
这些发现表明，最佳的 BCAA 比例（体内=1：0.75：0.75；体外=1：0.25：0.25）可改善肠道形态和细胞增殖，通过调节肠道 AA 转运体的表达增加肠道 AA 吸收，并促进肠道蛋白质周转。这些发现为 BCAA 在人类和动物中的应用提供了新的见解。
