环境高温对通城猪血清氧化应激因子及空肠黏膜机械屏障功能的影响

试验旨在研究高温环境对通城猪血清氧化应激指标及空肠黏膜机械屏障功能的影响。选取遗传背景相似、100日龄、体重（45±5）kg的通城猪30头（母猪）,随机分为6组,每组5头,分别为对照组和高温2、4、6、8、10 d处理组。试验猪自由采食、自由饮水,（28±1）℃下适应性饲养7 d。从第8天开始,对照组仍于（28±1）℃饲养,高温组猪舍悬挂保温灯,迅速升温至（38±1）℃,饲养至相应天数屠宰采集样品,测定血清氧化应激指标和空肠黏膜机械屏障和炎性因子相关mRNA表达水平,并对空肠组织进行HE切片和免疫组化染色观察。结果表明：①与对照组相比,在高温第2天,血清丙二醛（MDA）含量和谷胱甘肽过氧化物酶（GSH-Px）活性显著降低（P<0.05）,随后趋于稳定;高温各组血清总超氧化物歧化酶（SOD）活性无显著变化（P>0.05）;血清T-AOC在高温第2、8天显著升高（P<0.05）;②与对照组相比,高温组（2 d）空肠紧密连接蛋白ZO-1、OCLN、CLDN5和CLDN7 mRNA表达量显著降低（P<0.05）;细胞骨架蛋白IQGAP1无显著变化（P>0.05）;IQGAP2和IQGAP3 mRNA表达量显著降低（P<0.05）;Rac1 mRNA表达量显著降低（P<0.05）,Rac2和Rac3 mRNA表达量无显著变化（P>0.05）。与对照组相比,高温组（2 d）空肠黏膜HSP70表达量增高,黏膜结构破损并有炎症产生。综上,通城猪在高温环境下具有较好的抗氧化应激调节能力,但高温环境会使其空肠屏障功能减弱。

Effects of High Environmental Temperature on Serum Oxidative Stress Factors and Jejunal Mucosal Mechanical Barrier Function in Tongcheng Pigs

The study was aimed to investigate the effects of high temperature on serum oxidative stress indexes and jejunal mucosal mechanical barrier function in Tongcheng pigs.Thirty 100-day-old female Tongcheng pigs with similar genetic backgrounds and average initial body weight of 45 kg±5 kg were randomly divided into six groups.All pigs were firstly raised under (28±1) ℃ with ad libitum feeding for 7 d.Then the control group was still raised under (28±1) ℃,the high temperature groups were treated with heat preservation lamps,and the temperature was rapidly raised to (38±1) ℃.Pigs were slaughtered and samples were collected at 2,4,6,8,and 10 days,respectively.Serum oxidative stress indexes and the expression levels of mechanical barrier and inflammatory factor-related mRNA in jejunum mucosa were detected.HE sections and immunohistochemical staining were performed on jejunum tissues.The results showed that ①Compared with the control group,the content of serum MDA and GSH-Px activity decreased significantly on the 2nd day of high temperature (P<0.05),and then stabilized.There was no significant change in serum SOD in high temperature groups (P>0.05).Serum T-AOC increased significantly on the 2nd and 8th day of heat treatment (P<0.05).②Compared with the control group,the expression of tight junction proteins ZO-1,OCLN,CLDN5 and CLDN7 mRNA decreased significantly (P<0.05),while the expression of cytoskeleton proteins IQGAP1,IQGAP2 and IQGAP3 mRNA decreased significantly (P<0.05),and the expression of Rac1 mRNA decreased significantly (P<0.05),the expression of Rac2 and Rac3 mRNA did not change significantly (P>0.05) in the heat stress group (2 days).Compared with the control group,the expression of HSP70 in jejunal mucosa increased,mucosal structure was damaged and inflammation occurred in heat stress group.In conclusion,Tongcheng pigs had good antioxidant stress regulation ability under high temperature environment,but high temperature would weaken jejunal barrier function.