利拉鲁肽调控高脂诱导的非酒精性脂肪肝病的分子机制

Molecular mechanism on nonalcoholic fatty liver disease by liraglutide regulation

目的探讨大鼠非酒精性脂肪肝病(NAFLD)模型中利拉鲁肽对炎症反应和抗氧化能力的影响及对脂类代谢相关酶的表达调控。方法 SD大鼠70只,25只给予正常饮食,45只采用高糖饮食加高脂灌胃12周,正常组和模型组随机挑取5只大鼠处死。确定NAFLD模型成功建立后,随机分为空白对照组(n=20)、模型对照组(n=20)和利拉鲁肽治疗组(n=20)。利拉鲁肽治疗组给予利拉鲁肽60μg/(kg·d)皮下注射,模型对照组给予生理盐水1ml/(kg·d)皮下注射。利拉鲁肽治疗开始4周和8周后,各组处死大鼠各半,测定各组血浆中炎性因子、氧化因子、抗氧化因子、肝功能和脂类的变化,检测肝脏的形态学改变,采用反转录聚合酶链反应(RT-PCR)检测胆固醇调节元件结合转录因子-1c(SREBF-1c)和乙酰辅酶A羧化酶α(ACCα)的mRNA表达,应用免疫组织化学和Western blotting检测SREBF-1c和ACCα的蛋白质表达。结果与模型对照组比较,利拉鲁肽治疗4周和8周后,血浆中C反应蛋白(CRP)、白细胞介素(IL)-1α、IL-1β、IL-6、肿瘤坏死因子-α(TNF-α)、丙二醛(MDA)、天冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、甘油三酯(TG)、总胆固醇(TC)和低密度脂蛋白胆固醇(LDL-C)含量降低(P<0.05);超氧化物歧化酶(SOD)、谷胱甘肽(GSH)和总抗氧化能力(T-AOC)增加(P<0.05),肝脏组织脂肪颗粒沉积减少;肝脏组织中SREBF-1c和ACCα的mRNA和蛋白表达下调(P<0.05)。利拉鲁肽治疗8周与治疗4周比较,上述指标进一步改善。结论利拉鲁肽可以减轻NAFLD中炎症反应,提高抗氧化能力,改善肝功能;利拉鲁肽可能通过下调肝脏组织中SREBF-1c和ACCα的表达,减少脂质的生成,缓解肝脏组织中的脂肪变性,而且随治疗时间的增加,对NAFLD的防治作用更明显。

Objective To investigate the effect of liraglutide on the reaction of inflammation and antioxidant capacity on the model of nonalcoholic fatty liver disease （NAFLD） rats and study the regulation of liraglutide to the expression of lipid metabolism enzyme. Methods Seventy SD rats, 25 SD rat were given normal clict, the others were induced to produc NAFLD by high glucose and high fat diet by gavage for 12 weeks, five rats were killed randomly from control group and model group respeetly. After the successful establishment of NAFLD model, the rats were randomly divided into the control group （ n = 20）, the model group （ n = 20） and the liraglutide treatment group （ n = 20）. The liraglutide treatment group was given liraglutide 60μg/（ kg·d） by subcutaneous injection, while the model group received normal saline lml/（kg·d）. The rats were killed 4 week or 8 weeks after the liraglutide injection, 50% from each group at each time point, so as to observe the changes of inflammatory factors, oxidant factors, antioxidant factors, liver function and lipids in the plasma, and to detect the liver morphological changes and the mRNA expressions of sterol regulatory element binding transcription factor-1c （SREBF-1c） and acetyl coenzyme A carboxylase alpha （ACCα） by the reverse transcription-PCR（RT-PCR）. The protein expressions of SREBF-1c and ACCα were detected by the immunohistoehemistry and Western blotting. Results Compared with the model group, C-reactive protein ＂（CRP）, interleukin（IL）-1α, IL-1β, IL-6, gumor necrosis facto-or （TNF-α） , malondialdehyde （ MDA ） , aspartateamino trans ferase （AST） , alanineamino transferase （ALT）, triglyceride（ TG）, total cholesterol（TC） and low-density lipoprotein （LDL-C） contents in the plasma of the rats with the liraglutide treatment were reduced after 4 weeks （ P 〈 0.05 ）, with superoxide dismutase （ SOD）, total antioxidant capacity（T-AOC） and glutathione （GSH） being increased （ P 〈 0. 05 ）, liver fat particle deposition reduced and the expressions of mRNA and protein of SREBF-lc and ACC α in the liver tissue regulated downward（ P 〈 0. 05 ）. After the liraglutide treatment for 8 weeks, the above indicators were improved were more obviously. Conclusion Liraglutide can reduce the inflammatory reaction in NAFLD and improve the antioxidant capacity as well as the liver function. It can also reduce the generation of lipid by down-regulating the expressions of SREBF-1c and ACCα in liver tissue possibly, and alleviate the liver fatty degeneration. With the increase of treatment time, the effect of liraglutide on the prevention and treatment of NAFLD becomes more obvious.