GPR81激动剂对非酒精性脂肪肝病大鼠胰岛素抵抗的影响

doi:10.12047/j.cjap.6055.2021.033

摘要/Abstract

摘要： 目的: 探讨NOD样受体蛋白3(NLRP3)信号通路对非酒精性脂肪肝病(NAFLD)大鼠胰岛素抵抗的影响及乳酸受体G蛋白偶联受体81(GPR81)激动剂的干预作用。方法: 选择清洁级SD雄性大鼠30只,随机分为3组,对照组、NAFLD组、GPR81激动剂组,每组10只。用高脂饮食建立大鼠非酒精性脂肪肝模型;GPR81激动剂组:在非酒精性脂肪肝模型基础上腹腔注射GPR81特异性乳酸激动剂(50 nmol/L),每周1次,其余两组注射等量的生理盐水,共12周。测定肝生化指标、空腹血糖及胰岛素和肝匀浆中炎症因子的含量,观察各组肝组织病理学形态;Western blot检测肝组织中NLRP3、含CARD结构域的凋亡相关斑点蛋白(ASC)、天冬氨酸特异性半胱氨酸蛋白酶1(caspase-1)、胰岛素受体底物-1(IRS-1)、胰岛素受体底物酪氨酸磷酸化(Tyr⁴⁶⁵-IRS-1)、胰岛素受体底物丝氨酸磷酸化(Ser⁶³⁶-IRS-1)、葡萄糖转运蛋白4(GLUT4)的蛋白表达;qRT-PCR法检测肝组织NLRP3、ASC、caspase-1、IRS-1、GLUT4 mRNA表达水平。结果: 与对照组相比,NAFLD组大鼠血清肝生化指标甘油三酯(TG)、丙氨酸转氨酶(ALT)、天门冬氨酸氨基转移酶(AST)、空腹血糖(FPG)、空腹胰岛素(FINS)和胰岛素抵抗指数(HOMA-IR)值均显著升高(P＜0.05);肝组织病理学形态结果表明,NAFLD组大鼠肝组织可见明显的肝脂肪变性,肝细胞有脂肪滴,存在明显的炎性细胞浸润,且NAFLD组肝组织NLRP3、ASC、caspase-1的mRNA和蛋白表达及Ser⁶³⁶-IRS-1的蛋白表达均显著升高,且肝组织及血清中白细胞介素-1β(IL-1β)和白细胞介素-18(IL-18)的含量升高;而IRS-1、GLUT4 的mRNA和蛋白表达Tyr⁴⁶⁵-IRS-1的蛋白表达显著降低(P＜0.05);与NAFLD组相比,GPR81激动剂组上述指标均得到明显改善。结论: NLRP3信号通路活化介导炎症因子产生促进了NAFLD的发生发展,GPR81激动剂可能成为NAFLD潜在的治疗手段。

关键词: GPR81, NLRP3信号通路, 非酒精性脂肪肝, 胰岛素抵抗, 大鼠

Abstract: Objective: To investigate the effects of NOD-like receptor protein 3 (NLRP3) signaling pathway on insulin resistance and the intervention of lactic acid receptor G protein-coupled receptor 81 (GPR81) agonist in nonalcoholic fatty liver disease (NAFLD) rats. Methods: Thirty SD male rats were randomly divided into three groups: control group, NAFLD group and GPR81 agonist group, with 10 rats in each group. Nonalcoholic fatty liver rat model was established by high fat diet. The rats in GPR81 agonist group were injected intraperitoneally with GPR81 specific agonist lactate (50 nmol/L) on the basis of nonalcoholic fatty liver model once a week, and the other two groups were injected with the same amount of normal saline for 12 weeks. The levels of liver biochemical indexes, fasting blood glucose, insulin and inflammatory factors in liver homogenate were measured, and the histopathological morphology of liver in each group was observed. The protein expressions of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), cysteinyl aspartate specific proteinase-1 (caspase-1), insulin receptor substrate 1 (IRS-1), Tyr⁴⁶⁵-IRS-1, Ser⁶³⁶-IRS-1, glucose transporter 4 (GLUT4) in liver tissue were detected by Western blot. The mRNA expression levels of NLRP3, ASC, caspase-1, IRS-1 and GLUT4 in liver tissue were detected by qRT-PCR. Results: Compared with the control group, the serum levels of triglyceride (TG), alanine aminotransfease (ALT), aspartate aminotransfease (AST), fasting plasma glucose (FPG), fasting insulin (FINS) and homeostasis model assessment of insulin resistance (HOMA-IR) of NAFLD group were increased significantly (P＜ 0.05). The results of liver histopathology showed that in NAFLD group, there were obvious fatty changes in liver tissue, fat droplets in hepatocytes and inflammatory cell infiltration. And the mRNA and protein expressions of NLRP3, ASC, caspase-1 and the protein expression of Ser⁶³⁶-IRS-1 in NAFLD group were increased significantly, and the contents of interleukin 1β (IL-1β) and interleukin 18 (IL-18) in liver and serum were increased, while the mRNA and protein expressions of IRS-1 and GLUT4 and Tyr⁴⁶⁵-IRS-1 were decreased significantly (P＜0.05). Compared with NAFLD group, the above indexes of GPR81 agonist group were all significantly improved. Conclusion: The activation of NLRP3 signaling pathway mediates the production of inflammatory factors and promotes the development of NAFLD. GPR81 agonist may be a potential treatment for NAFLD.

中图分类号:

R575.5

张瑜, 路青华, 曹海芳, 张生荣, 王虎德. GPR81激动剂对非酒精性脂肪肝病大鼠胰岛素抵抗的影响[J]. 中国应用生理学杂志, 2021, 37(4): 354-358.

ZHANG Yu, LU Qing-hua, CAO Hai-fang, ZHANG Sheng-rong, WANG Hu-de. Effects of GPR81 agonist on insulin resistance in rats with nonalcoholic fatty liver disease[J]. CJAP, 2021, 37(4): 354-358.

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