L-精氨酸对脂多糖应激下大鼠抗氧化能力、免疫功能和肠道健康的影响

Effects of L-Arginine on Antioxidant Capacity,Immune Function and Intestinal Health of Rats under Lipopolysaccharide Stress

本试验旨在研究L-精氨酸(L-Arg)对脂多糖应激下大鼠抗氧化能力、免疫功能和肠道健康的影响。选取24只健康且体型相近的雄性SD大鼠,随机分为2组,分别为空白对照组(CON组)和L-Arg处理组(L-Arg组),每组6个重复,每个重复2只。L-Arg组每日灌胃2 mL L-Arg溶液(0.2 g/kg BW L-Arg),CON组每日灌胃等量生理盐水。试验期共18 d,其中预试期3 d,正试期15 d。正式试验第14天,每个重复随机挑选1只大鼠腹腔注射2 mL LPS溶液(2 mg/kg BW LPS),其余大鼠腹腔注射等量无菌生理盐水。注射LPS后禁食12 h,之后进行屠宰采样。结果显示:1)与CON组相比,L-Arg组大鼠的第10天体重、末重和平均日采食量均显著升高(P<0.05);大鼠肝脏、胸腺和脾脏指数各组间无显著差异(P>0.05)。2)LPS应激导致大鼠血清谷丙转氨酶(ALT)和谷草转氨酶(AST)活性显著升高(P<0.05),白蛋白(ALB)和总蛋白(TP)含量显著下降(P<0.05);而LPS应激条件下L-Arg显著降低大鼠血清ALT和AST活性(P<0.05),显著升高ALB和TP含量(P<0.05)。3)LPS应激显著增加大鼠血清免疫球蛋白[免疫球蛋白A(IgA)、免疫球蛋白G(IgG)、免疫球蛋白M(IgM)]以及炎性细胞因子[白细胞介素-1β(IL-1β)、白细胞介素-6(IL-6)、白细胞介素-8(IL-8)、肿瘤坏死因子-α(TNF-α)]含量(P<0.05);而LPS应激条件下L-Arg显著降低大鼠上述血清免疫球蛋白及炎性细胞因子含量(P<0.05)。4)LPS应激导致大鼠血清及回肠黏膜中过氧化氢酶(CAT)活性和总抗氧化能力(T-AOC)显著下降(P<0.05),丙二醛(MDA)含量显著上升(P<0.05);而LPS应激条件下L-Arg可显著提高大鼠血清和回肠黏膜T-AOC及回肠黏膜CAT活性(P<0.05)。5)LPS应激对大鼠回肠绒毛高度和隐窝深度无显著影响(P>0.05),而L-Arg处理后大鼠回肠绒毛高度以及绒毛高度与隐窝深度的比值均显著提高(P<0.05)。综上可知,LPS应激可诱导大鼠肝脏损伤、氧化应激和免疫系统过度活化及炎症;L-Arg能够促进大鼠生长,并可通过提高机体抗氧化能力、免疫功能以及改善回肠形态而在一定程度上预防和缓解LPS攻毒对大鼠造成的负面影响。

The purpose of this study was to investigate the effects of L-arginine(L-Arg)on growth performance,antioxidant capacity,immune function and intestinal health of rats under lipopolysaccharide(LPS)stress.Twenty-four healthy male SD rats with similar body size were randomly divided into two groups(control group and L-Arg group),with six replicates per group and two rats per replicate.Rats in the L-Arg group were administered 2 mL L-Arg solution(0.2 g/kg BW L-Arg)daily by gavage,while those in the control group were administered the same amount of normal saline.The experimental period was 18 days,with a pre-feeding period of 3 days and a formal trial period of 15 days.On the 14th day of the formal trial,one rat was randomly selected for each replicate to be intraperitoneally injected with 2 mL LPS solution(2 mg/kg BW LPS),the remaining rats were intraperitoneally injected with the same amount of sterile normal saline.Fasting for 12 h after injection of LPS was followed by slaughter sampling.The results showed as follows:1)compared with the control group,the body weight on day 10,final weight and average daily feed intake of rats in L-Arg group increased significantly(P<0.05),but there were no significant differences in liver,thymus and spleen indexes between control group and L-Arg group(P>0.05).2)LPS stress significantly increased the activities of serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)(P<0.05),while significantly decreased the contents of albumin(ALB)and total protein(TP)(P<0.05).Under LPS stress condition,L-Arg significantly decreased the activities of serum ALT and AST(P<0.05),and significantly increased the contents of ALB and TP(P<0.05).3)LPS stress also significantly increased the contents of serum immunoglobulins[immunoglobulin A(IgA),immunoglobulin G(IgG),immunoglobulin M(IgM)]and inflammatory cytokines[interleukin-1β(IL-1β),interleukin-6(IL-6),interleukin-8(IL-8)and tumour necrosis factor-α(TNF-α)],while L-Arg significantly decreased the contents of these immunoglobulins and inflammatory cytokines under LPS stress condition(P<0.05).4)LPS stress significantly decreased CAT activity and T-AOC and significantly increased MDA content in serum and ileal mucosa(P<0.05),while L-Arg significantly increased T-AOC in serum and ileal mucosa and CAT activity in ileal mucosa under LPS stress condition(P<0.05).5)LPS stress had no significant effects on ileal villus height and crypt depth(P>0.05),but ileal villus height and villus height/crypt depth ratio increased significantly after L-Arg treatment(P<0.05).In conclusion,LPS stress induces liver injury,oxidative stress,overactivation of immune system and inflammation in rats.L-Arg can promote the growth of rats,prevent and alleviate the negative effects of LPS challenge on rats to some extent by improving antioxidant capacity,immune function and ileal morphology.