姜黄素对断奶仔猪肠粘膜屏障的保护作用及其机制研究

In modern pig production，piglet early weaning is a bottleneck problem which restrict the industrial pig farm. It can lead to "Piglet early weaning syndrome", such as low appetite, dyspepsia, diarrhea and lower immune function. The main reason was impairment of intestinal mucosal barrier caused by weanling stress. Curcumin is a kind of plant extract. The anti-inflammatory, anti-oxidant, and free radical scavenging effects of curcumin have been demonstrated by numerous experimental studies. The objectives of this study was to grasp systematically the protective effects and mechanism of curcumin on intestinal mucosal barrier, and thus find a kind of non-pollution and green feed additive which can effectively solve the piglet early weaning syndrome. The present study use animal nutrition, immunobiology and molecular biotechnology, and was designed to study the effects of curcumin on intestinal mucosal barrier function of weaned pigs, and to feel furtherly a suitable adding proportion by constructing stress model challenged by rotavirus. In order to reveal the mechanism of curcumin on intestinal mucosal barrier function, the further animal experiments is conducted to study the effects of curcumin on NF-κB and MAPK signal pathway in inintestinal mucosal of weaned pigs. The results of the study can provide theoretical basis for development and application of green feed additive. It has important theoretical and practical significance for healthy and sustainable development of livestock husbandry.

在现代养猪生产中，仔猪早期断奶是制约规模化养猪的瓶颈问题，往往造成仔猪断奶后食欲差、消化不良、腹泻、免疫功能下降等所谓"仔猪早期断奶综合症"。产生这一后果的主要原因之一是由于断奶应激而使仔猪肠道屏障受损。姜黄素(Curcumin，CUR)是一种植物提取物，具有抗感染、抗炎、抗氧化、清除自由基等作用。本课题希望通过姜黄素对断奶仔猪肠道屏障功能的影响及其机制研究，从而探索出一种能有效解决断奶仔猪综合症的无公害、无污染的绿色饲料添加剂。项目采用动物营养、免疫学及分子生物学技术，通过轮状病毒攻毒断奶仔猪，构建应激模型，研究姜黄素对断奶仔猪肠道粘膜屏障功能的影响，并摸索合适的添加量，在此基础上进一步通过动物实验研究姜黄素对轮状病毒诱导的断奶仔猪肠粘膜NF-κB和MAPK信号通路的影响，揭示其对肠粘膜屏障作用的分子机制，为猪绿色饲料添加剂的开发应用提供科学依据，对畜牧业健康、可持续发展具有重要意义。

为探讨日粮中添加姜黄素对断奶仔猪生长性能和肠粘膜屏障功能的影响，并探索适合的添加量。本试验选取胎次、体重相近的21日龄健康早期断奶“杜×长×大”仔猪50头，公母各半，随机分为5个处理，每个处理10个重复，每个重复1头猪，对照组饲喂基础饲粮，试验组饲喂分别添加50 mg/kg喹烯酮、200 mg/kg、300 mg/kg 和400mg/kg姜黄素。预试期7 d，于第4 d接种大肠杆菌，正试期21d。结果表明1）日粮中添加300或400 mg/kg姜黄素可有效地促进仔猪生长，提高机体抗氧化性；改善空肠和回肠粘膜形态结构和紧密连接性，降低肠粘膜通透性；增加空肠和回肠粘膜杯状细胞数量，降低空肠粘膜Calprotectin、TLR4蛋白和空肠、回肠粘膜炎性因子表达，提高空肠粘膜sIgA蛋白及空肠、回肠粘膜IL-10 mRNA表达；Illumina-MiSeq高通量测序结果表明，日粮添加300mg/kg姜黄素能够改善肠道微生物菌落组成结构，可能是通过增加回肠链球菌属和拟杆菌属物种丰度，进而增强肠道免疫机能，需要进一步验证。2）日粮中添加50mg/kg喹烯酮可降低料重比，提高提高抗氧化能力，改善空肠和回肠粘膜形态结构，降低空肠和回肠粘膜TLR4表达。3）日粮添加300mg/kg姜黄素可降低p65 NF-κB和p38 MAPK mRNA表达。.为进一步探讨姜黄素对肠粘膜NF-κB和MAPK信号通路的影响，选取胎次、体重相近的21日龄健康断奶仔猪30头，随机分成5组，每组6头，分别为对照组(A组)、姜黄素组(B组)、p38抑制剂组(C组)、JNK 抑制剂组(D组)和ERK1/2抑制剂组(E组)，实验期为5d，各组于试验第2 d经口服感染大肠杆菌，结果表明，B、C、D组可显著降低IL-1β、TNF-α 和 IL-6 mRNA相对表达，提高IL-10 mRNA表达。.综上所述，日粮中添加300mg/kg或400mg/kg姜黄素可以促进仔猪生长和提高肠粘膜屏障功能，其作用效果优于喹烯酮，因此得出结论，姜黄素作为绿色饲料添加剂具有替代抗生素的潜力，其发挥对肠粘膜屏障的保护作用可能是通过抑制NF-κB和MAPK信号通路实现的，还需进一步验证。