吡咯喹啉醌改善断奶仔猪小肠上皮跨细胞转运与养分吸收的作用机制

It is great loss for swine nutrition and feed industry that weaned piglets are often challenged by post-weaning stress of grain feed, which can result in poor performance and increased incidence of diarrhea. Our former studies showed that dietary pyrroloquinoline quinone (PQQ) can improve average daily gain, feed conversion ratio and decrease the occurrence of diarrhea. This research intends to explore the effect and mechanism of PQQ on the absorption and transmembrane transportation of small intestine, intestinal mucosal injury and repair, intestinal epithelial development, activation of MAPK pathway regulates the expression of amino acids and glucose transporters, induction of CREB-PGC1ɑ pathway upregulates of mitochondrial biogenesis based on principles of morphology, physiology, biochemistry, cell biology, molecular biology and methods of terminal ileum fistula, intestinal arterial hepatic portal vein catheter, Ussing chamber, Western blot and RT-PCR technology. We try to evaluate the role of PQQ as a new functional feed additive and provide theoretical basis for improved absorptive and transport capacity of weaned piglets.

减缓仔猪断奶不可避免的谷物饲粮应激损征是饲料和营养学科直面的科学难题，迫切需要不断创新研究。项目组前期试验结果证实，饲粮添加吡咯喹啉醌（PQQ）改善断奶仔猪的饲料转化效率和生长性能。本项目围绕断奶仔猪小肠消化吸收功能紊乱难题，以改善小肠养分吸收和粘膜上皮跨细胞转运为切入点，依据营养学、组织学、消化道生理学、细胞生物学和分子生物学原理与方法，采用回肠末端瘘管、肠动静脉血插管、尤斯灌流室、蛋白质印记和实时定量PCR等关键技术，从仔猪个体营养平衡、肠膜吸收、上皮跨细胞转运和上皮线粒体供能等维系养分吸收的主干层面，纵深研究PQQ刺激小肠上皮生长与吸收、激活MAPK信号通路上游调节氨基酸等载体表达、诱导CREB-PGC1ɑ通路上调线粒体生物合成的影响，揭示PQQ改善小肠吸收能力与上皮跨细胞转运吸收的分子机制。为PQQ成为功能性新饲料添加剂的应用技术及改善小肠吸收功效的作用机理，提供应用基础理论支撑。

首先通过共计 522 头断奶仔猪的 3 次重复饲养试验研究证实，饲粮添加 PQQ 改善断奶仔猪的饲料转化效率、降低仔猪腹泻频次，提高仔猪的生长性能。对小肠粘膜上皮组织形态和结构的研究证实，饲粮添加 PQQ 提高了断奶仔猪空肠和回肠的绒毛膜高度，降低了隐窝深度，绒毛高度与隐窝深度比值增高。这进一步说明，在采食量不变的前提下，PQQ 是通过改善断奶仔猪小肠上皮的吸收功能，增加了养分的绝对利用量，进而提高了断奶仔猪的饲料转化效率并同时降低了腹泻频次。证实 PQQ 改善断奶仔猪的饲料转化效率和生长性能具有剂量依赖效应，PQQ适宜添加水平在该试验条件下为 3.0 mg/kg饲粮。其次，通过两次安全性试验分别证明了饲粮添加30mg/kg 和75mg/kg PQQ·Na2对仔猪生长性能和血液指标无负面影响，并且可以提高断奶仔猪的抗氧化能力。最后，通过攻毒试验证明，饲用添加PQQ的日粮能显著改善断奶仔猪的饲料转化率。特别是在K88 攻毒的条件下，日粮中添加PQQ能显著降低仔猪空肠粘膜中炎症因子水平，这表明日粮中添加PQQ缓解了病原性大肠杆菌侵袭对断奶仔猪的危害作用，其作用机制可能是通过抑制NF-κB这一信号通路发挥作用的。