熊果酸调控TLR4/MyD88/NF-κB通路改善GDM大鼠糖脂代谢及炎症反应和氧化应激

Improving effect of ursolic acid on glycolipid metabolism, inflammatory reaction and oxidative stress in pregnant GDM rats by regulating TLR4/MyD88/NF-κB pathway

摘要

目的 探讨熊果酸(UA)基于Toll样受体4(TLR4)/髓样分化因子88(MyD88)/核因子-κB(NF-κB)通路对于妊娠期糖尿病(GDM)大鼠糖脂代谢、炎症反应和氧化应激的作用。方法 建立妊娠期糖尿病大鼠模型,随机分为模型组(GDM组)、UA低剂量组(UA-L组)、UA中剂量组(UA-M组)、UA高剂量组(UA-H组)和二甲双胍组,另设置普通饲料喂养的正常组(NC组),每组10只.收集样本测定空腹血糖(FBG)、空腹胰岛素(FINS)、甘油三酯(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、肝酯酶(HL)、脂蛋白酯酶(LPL)、肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、白细胞介素-2(IL-2)、白细胞介素-4(IL-4)、丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)水平和过氧化物酶体增殖物激活受体γ(PPARγ)及TLR4/MyD88/NF-κB通路蛋白水平。结果 与NC组比较,GDM组FBG、TG、TC、LDL-C、TNF-α、IL-2、IL-1β和MDA水平和TLR4、MyD88和p-NF-κBp65/NF-κBp65蛋白表达水平显著升高,FINS、HL、LPL、IL-4、CAT、SOD、GSH-Px水平和PPARγ蛋白表达显著下降,差异具有统计学意义(P<0.05);与GDM组比较,UA各组及二甲双胍组FBG、TG、TC、LDL-C、TNF-α、IL-2、IL-1β、MDA水平和TLR4、MyD88、p-NF-κBp65/NF-κBp65蛋白表达水平显著下降,FINS、HL、LPL、IL-4、CAT、SOD、GSH-Px水平和PPARγ蛋白表达显著上升,差异具有统计学意义(P<0.05);各组HDL-C水平无显著差异(P>0.05);二甲双胍组与UA-H组上述指标均无显著差异(P>0.05)。结论 UA可能通过下调TLR4/MyD88/NF-κB通路蛋白表达,改善GDM大鼠糖脂代谢、炎症反应和氧化应激.

Abstract

Objective To investigate improving effect of ursolic acid (UA) on glycometabolism and lipid metabolism, inflammatory reaction and oxidative stress in pregnant rats with gestational diabetes mellitus (GDM) by regulating Toll like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88)/nuclear factor-κB (NF-κB) pathway. Methods The rats model of GDM was established. The rats with GDM were divided into six groups: GDM group, low dose UA group (UA-L group), medium dose UA group (UA-M group), high dose UA group (UA-H group), metformin group and normal control group of rats fed with regular feed (NC group), with 10 rats in each group. The fasting blood glucose (FBG) level was tested by blood glucose meter, fasting insulin (FINS) was tested by radioimmunoassay, the levels of blood lipids profile as triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) were tested by automatic biochemical analyzer. Enzyme-linked immunosorbent assay (ELISA) was used to detect lipid metabolism related enzymes as hepatic lipase (HL) and lipoprotein lipase (LPL) levels, and serum inflammatory factors including serum tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-2 (IL-2) and interleukin-4 (IL-4) levels. The levels of oxidative stress factors as malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were detected by micromethod. Western blot method was used to detect peroxisome proliferator activated receptor γ (PPARγ) and TLR4/MyD88/NF-κB pathway protein of the rats. Results Compared with the NC group, the levels of FBG, TG, TC, LDL-C, TNF-α, IL-2, IL-1β, and MDA, and expression levels of TLR4, MyD88, p-NF-κBp65/NF-κBp65 proteins of the rats in the GDM group were significantly higher, while their levels of FINS, HL, LPL, IL-4, CAT, SOD and GSH-Px, and expression of PPARγ protein were significantly lower, the differences were significant (all P<0.05). Compared with the GDM group, the levels of FBG, TG, TC, LDL-C, TNF-α, IL-2, IL-1β, MDA, expressions of TLR4, MyD88, p-NF-κBp65/NF-κBp65 proteins of the rats in the metformin group and different UA doses groups were significantly lower, while their levels of FINS, HL, LPL, IL-4, CAT, SOD, GSH-Px, and expression of PPARγ protein were significantly higher, and the differences were significant (all P<0.05). There was no significant difference in HDL-C level among all groups (P>0.05), and also there were no significant differences in the above indexes between the metformin group and UA-H group (all P>0.05). Conclusion UA could improve glucose metabolism and lipid metabolism, inflammatory reaction and oxidative stress in the GDM rats by down-regulating expression of TLR4/MyD88/NF-κB pathway proteins.

关键词

熊果酸 / 糖脂代谢 / 炎症反应 / 氧化应激

Key words

ursolic acid / glycolipid metabolism / inflammation / oxidative stress

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基金资助

湖北省卫生计生委2018年度第二批联合基金立项项目(IEC(LW066))