敌草快和硫辛酸对育肥猪肠道结构及消化功能的影响

本文旨在研究敌草快和硫辛酸(LA)对育肥猪肠道结构及消化功能的影响,以探究LA对敌草快引起的应激是否有缓解作用。选取24头(70.64±3.61)kg的健康大白阉公猪,按照2×2因子设计,随机分为对照组、LA组、敌草快组和LA+敌草快组,每个组设6个重复,每个重复1头猪。试验期29 d。LA添加剂量为800 mg/kg饲粮,饲喂贯穿试验全程,而一次性腹腔滴注敌草快于试验第15天进行,无腹腔滴注敌草快试验猪滴注等量的生理盐水。于试验第29天对所有试验猪前腔静脉采血后屠宰取样,运用试剂盒检测血浆和肠道氧化损伤标志物的含量以及空肠食糜消化酶的活性,苏木精-伊红(HE)染色后运用图像分析软件观察肠道形态结构并测定绒毛高度、隐窝深度,并计算绒毛高度/隐窝深度(V/C),荧光定量PCR法检测闭合蛋白(occludin)和紧密结合蛋白(ZO-1)的相对表达量。结果表明:1)敌草快极显著升高了试验猪血浆和肠道丙二醛(MDA)、蛋白质羰基(PCO)和8-羟基鸟苷(8-OHd G)的含量(P0.01),极显著降低了十二指肠、空肠及回肠绒毛高度、隐窝深度(P0.01),极显著增大了十二指肠和空肠V/C(P0.01),显著增大了回肠V/C(P0.05),极显著降低了空肠occludin和ZO-1 m RNA相对表达量(P0.01),极显著降低了空肠食糜中淀粉酶、胰蛋白酶以及脂肪酶的活性(P0.01)。2)饲粮中添加LA对试验猪血浆和肠道MDA、PCO和8-OHd G含量的影响均不显著(P0.05),对十二指肠、空肠和回肠的绒毛高度、隐窝深度以及V/C的影响均不显著(P0.05),对空肠occludin和ZO-1 m RNA相对表达量的影响也不显著(P0.05),对空肠食糜中淀粉酶、胰蛋白酶以及脂肪酶活性的影响差异也均不显著(P0.05)。3)在应激状态下,饲粮中添加LA使猪血浆8-OHd G含量显著降低(P0.05),十二指肠绒毛高度、空肠绒毛高度以及回肠隐窝深度显著升高(P0.05),空肠V/C显著降低(P0.05),回肠V/C极显著降低(P0.01),空肠occludin和ZO-1 m RNA相对表达量显著升高(P0.05),空肠食糜淀粉酶和胰蛋白酶的活性显著提升(P0.05)。由此可见,敌草快引起了育肥猪强烈的氧化应激,导致了肠道结构的严重损伤并减弱了肠道的消化功能;在敌草快引起的应激状态下,饲粮中添加800 mg/kg LA能够减缓肠道结构的损伤并能一定程度地提高肠道的消化功能。

Effects of Diquat and Lipoic Acid on Intestinal Morphology and Digestive Function of Finishing Pigs

This study was to investigate the effects of diquat and lipoic acid ( LA ) on intestinal morphology and digestive function of finishing pigs, in order to explore whether diquat induced stress on the LA had a role in alleviating. Twenty-four healthy finishing pigs (Yorkshire) with the body weight of (70.64±3.61) kg were randomly allocated to control, LA, diquat, LA+diquat groups with 6 replicates per group and 1 pig per repli-cate by a 2×2 factorial arrangement. The trial period was 29 days. LA was given all in the trial (800 mg/kg di-et) . Diquat challenged pigs were given a single intraperitoneal injection of diquat at the 15th days and non-chal-lenged pigs were injected intraperitoneally with the equal physiological saline amount at the same time. All the pigs were slaughtered after the vena cava blood was sampledon the 29th day. Using kits to detected the contents of plasma and intestine oxidative damage markers and the activities of digestive enzymes in jejunum chyme. Af-ter hematoxylin and eosin ( HE ) staining, using image analysis software to observed intestinal morphology structure and determined villus height, crypt depth, and calculated the value of the villus height to crypt depth ( V/C) . Using fluorescence quantitative PCR to detected the relative expression abundance of occludin and zonula occludens protein-1 ( ZO-1) mRNA in jejunum. The results showed as follows:1) diquat significantly increased the contents of malondialdehyde ( MDA) , protein carbonyl ( PCO) and 8-hydroxy deoxyguanosine ( 8-OHdG) in plasma and intestine ( P<0.01) , significantly reduced the villus height and crypt depth in duode-num and jejunum and ileum ( P<0.01) , while significantly increased the V/C in duodenum and jejunum ( P<0.01) , and significantly increased the V/C of the ileum ( P<0.05) , significantly reduced the relative expres-sion abundance of occludin and ZO-1 mRNA in jejunum ( P<0.01) , and significantly reduced the activities of amylase, trypsase and lipase in jejunum chyme ( P<0.01) . 2) There were no significant difference on the con-tents of MDA, PCO and 8-OHdG in plasma and intestine when dietary supplementation of LA ( P>0.05) , as same as the villus height, crypt depth and V/C in duodenum, jejunum and ileum, the relative expression abun-dance of occludin and ZO-1 mRNA in jejunum, the activities of amylase, trypsase and lipase in jejunum chyme ( P>0.05) . 3) Under the oxidative stress, dietary supplementation of LA significantly reduced the content of 8-OHdG in plasma ( P<0.05) , while significantly improved the villus height in duodenum and jejunum ( P<0.05) , and significantly improved crypt depth in ileum ( P<0.05) , significantly reduced V/C in jejunum ( P<0.05) and ileum (P<0.01), significantly increased the relative expression abundance of occludin and ZO-1 mRNA in jejunum (P<0.05), significantly improved the activity of amylase and trypsase in jejunum chyme ( P<0.05) . In conclusion, diquat caused oxidative stress in pigs is strong, leading to serious injury of intestinal structure and weakened intestinal digestive function. Dietary supplementation of 800 mg/kg of LA can suppress the oxidative stress caused by diquat injection on intestinal injury of finishing pigs, and may improve digestive function.