Sun Yuli, Wu Zhenlong, Li Wei, Zhang Chen, Sun Kaiji, Ji Yun, Wang Bin, Jiao Ning, He Beibei, Wang Weiwei, Dai Zhaolai, Wu Guoyao
State Key Laboratory of Animal Nutrition, Department of Animal Nutrition and Feed Science, China Agricultural University, Beijing, 100193, China.
Amino Acids. 2015 Aug;47(8):1517-25. doi: 10.1007/s00726-015-1985-2. Epub 2015 May 5.
L-Leucine is a signaling amino acid in animal metabolism. It is unknown whether supplementing L-leucine to breast-fed neonates may enhance their small-intestinal development. This hypothesis was tested with a piglet model. Seven-day-old sow-reared pigs with an average birth weight of 1.45 kg were assigned randomly to the control or leucine group (n = 30/group). Piglets in the leucine group were orally administrated with 1.4 g L-leucine/kg body weight, whereas piglets in the control group received isonitrogenous L-alanine, twice daily for 14 days. The supplemental L-leucine amounted to 200 % of L-leucine intake from sow's milk by 7-day-old pigs. At the end of the 2-week experiment, tissue samples were collected for determining intestinal morphology, expression of genes for intestinal leucine transporters (real-time RT-PCR and western blot analysis), and plasma metabolites and hormones. L-leucine administration increased (P < 0.05) villus height in the duodenum, an elevated ratio of villus height to crypt depth in the duodenum and ileum, plasma concentrations of leucine, glutamine and asparagine, as well as body-weight gains. mRNA levels for L-leucine transporters (SLC6A14, SLC6A19 and SLC7A9) and the abundance of the ATB(0,+) protein were increased (P < 0.05) but those for SLC7A7 mRNA and the LAT2 protein were decreased (P < 0.05) in the jejunum of leucine-supplemented piglets, compared with the control. Plasma concentrations of ammonia, urea, triglycerides, and growth-related hormones did not differ between the control and leucine groups. Collectively, these results indicate that L-leucine supplementation improves intestinal development and whole-body growth in suckling piglets with a normal birth weight.
L-亮氨酸是动物新陈代谢中的一种信号氨基酸。给母乳喂养的新生儿补充L-亮氨酸是否能促进其小肠发育尚不清楚。本研究使用仔猪模型对这一假设进行了验证。将平均出生体重为1.45千克、7日龄由母猪饲养的仔猪随机分为对照组和亮氨酸组（每组n = 30）。亮氨酸组的仔猪按每千克体重口服1.4克L-亮氨酸，而对照组的仔猪则每日两次接受等氮的L-丙氨酸，持续14天。补充的L-亮氨酸量相当于7日龄仔猪从母乳中摄入亮氨酸量的200%。在为期2周的实验结束时，采集组织样本以测定肠道形态、肠道亮氨酸转运体基因的表达（实时逆转录聚合酶链反应和蛋白质免疫印迹分析）以及血浆代谢物和激素水平。给予L-亮氨酸可增加（P < 0.05）十二指肠绒毛高度，提高十二指肠和回肠绒毛高度与隐窝深度的比值、血浆亮氨酸、谷氨酰胺和天冬酰胺浓度以及体重增加量。与对照组相比，补充亮氨酸的仔猪空肠中L-亮氨酸转运体（SLC6A14、SLC6A19和SLC7A9）的mRNA水平和ATB(0,+)蛋白丰度增加（P < 0.05），但SLC7A7 mRNA水平和LAT2蛋白水平降低（P < 0.05）。对照组和亮氨酸组之间血浆氨、尿素、甘油三酯和生长相关激素浓度没有差异。总体而言，这些结果表明，补充L-亮氨酸可改善正常出生体重哺乳仔猪的肠道发育和全身生长。
