黄芪甲苷Ⅳ预防肥胖性高血压的作用机制研究

Research on mechanism of action of astragalosideⅣin preventing obesity-induced hypertension

目的探讨黄芪甲苷Ⅳ(AsⅣ)预防肥胖性高血压的作用机制。方法将35只雄性Wistar大鼠分为正常脂肪饲料组(NC组,n=10)和高脂肪饲料组(n=25)。16周后,将18只肥胖大鼠随机分为对照组(n=6)、AsⅣ组(n=6)和AsⅣ+α-bungaratoxin(α-BGT)组(n=6)。测量各组干预前后体质量、血压,血浆和肾组织去甲肾上腺素(NE)水平。采用Western blot或实时荧光定量逆转录聚合酶链反应(RT-qPCR)检测各组下丘脑组织中瘦素受体(LepRb)、磷酸化信号转换器和转录激活因子-3(p-STAT3)、磷酸化磷脂酰肌醇3-激酶(p-PI3K)、细胞因子信号抑制因子(SOCS3)、酪氨酸磷酸酶(PTP1B)、皮质素原(POMC)、神经肽Y(NPY)水平。检测各组下丘脑和脂肪组织中α7烟碱乙酰胆碱受体(α7nAChR)、核因子κB激酶亚单位β/核因子κB抑制剂(IKKβ/NF-KB)和促炎细胞因子[白细胞介素-1β(IL-1β)和肿瘤坏死因子-α(TNF-α)]的水平。结果与对照组相比,AsⅣ组干预后葡萄糖不耐受和胰岛素抵抗指数(HOMA-IR)改善,甘油三酯(TG)、总胆固醇(TC)水平降低,差异有统计学意义(P<0.05);连续干预6周后,对照组收缩压(SBP)、舒张压(DBP)、血浆和肾脏组织中NE水平升高,AsⅣ组SBP、DBP和NE水平降低,差异有统计学意义(P<0.05);与NC组相比,对照组大鼠血浆瘦素水平升高,LepRb mRAN表达降低,瘦素信号分子p-STAT3的表达下降,p-PI3K、SOCS3 mRNA和PTP1B mRNA的表达增加,差异有统计学意义(P<0.05)。而AsⅣ组p-STAT3、LepRb mRNA和POMC mRNA表达增加,p-PI3K、SOCS3 mRNA和PTP1B mRNA水平降低。与对照组比较,AsⅣ组α7nAChR蛋白和mRNA表达升高,p-IKKβ、NF-KB蛋白及其mRNA表达降低,差异有统计学意义(P<0.05)。与AsⅣ组比较,AsⅣ+α-BGT组α7nAChR阻断剂α-BGT降低了α7nAChR mRNA和蛋白表达水平,IKKβmRNA、NF-KB mRNA、p-IKKβ、NF-KB、IL-1β和TNF-α蛋白水平均升高,差异有统计学意义(P<0.05)。与对照组和AsⅣ+α-BGT组比较,AsⅣ组α7nAChR mRNA表达升高,p-IKKβ、NF-KB、IL-1β、TNF-α表达降低,差异有统计学意义(P<0.05)。结论AsⅣ可通过抑制炎症反应和改善瘦素抵抗有效预防肥胖相关高血压,AsⅣ的改善作用与α7nAchR表达增加密切相关。

Objective To investigate the mechanism of astragalosideⅣ(AsⅣ)in preventing obesity-induced hypertension by improving inflammatory response and leptin resistance.Methods A total of 35 male Wistar rats were divided into normal fat feed group(NC group,n=10)and high fat feed group(n=25).After 16 weeks,the obese rats were randomly divided into control group(n=6),AsⅣgroup(n=6),and AsⅣ+α-bungaratoxin(AsⅣ+α-BGT,n=6).Weight,blood pressure,plasma and renal norepinephrine(NE)levels were measured before and after intervention in each group.The levels of leptin receptor(LepRb),phosphorylation signal converter and transcription activator-3(p-STAT3),phosphorylated phosphatidylinositol 3-kinase(p-PI3K),cytokine signal suppressor(SOCS3),tyrosine phosphatase(PTP1B),corticotropin(POMC)and neuropeptide Y(NPY)in the hypothalamus of each group were detected by Western blot or Quantitative real-time polymerase chain reaction(RT-qPCR).Levels ofα7 nicotinic acetylcholine receptor(α7nAChR),inhibitor of nuclear factorκB kinase subunitβ/nuclear factorκB(IKKβ/NF-KB)and pro-inflammatory cytokines[interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)]were detected in hypothalamus and adipose tissue in each group.Results Compared with the control group,glucose intolerance and homeostasis model assessment of insulin resistance(HOMA-IR)were improved,triglyceride(TG)and total cholesterol(TC)levels were decreased in the AsⅣgroup after intervention(P<0.05).After 6 weeks of continuous intervention,the levels of systolic blood pressure(SBP),diastolic blood pressure(DBP)and NE in plasma and kidney tissue were increased in the control group,while the levels of SBP,DBP and NE were decreased in the AsⅣgroup(P<0.05).Compared with the NC group,plasma leptin level in control group increased,LepRb mRAN expression decreased,leptin signaling molecule p-STAT3 expression decreased,p-PI3K,SOCS3 mRNA and PTP1B mRNA expression increased(P<0.05).However,the mRNA expressions of p-STAT3,LepRb and POMC increased in the AsⅣgroup,while the mRNA levels of p-PI3K,SOCS3 and PTP1B decreased.Compared with the control group,the expression ofα7nAChR protein and mRNA in the AsⅣgroup increased,while the expression of p-IKKβand NF-KB protein and their mRNA decreased(P<0.05).Compared with the AsⅣgroup,α7nAChR blockerα-BGT in the AsⅣ+α-BGT group decreased the expression levels ofα7nAChR mRNA and protein expression,and the protein levels of IKKβmRNA,NF-KB mRNA,p-IKKβ,NF-KB,IL-1βand TNF-αwere increased(P<0.05).Compared with the control group and AsⅣ+α-BGT group,α7nAChR mRNA expression was increased and p-IKKβ,NF-KB,IL-1βand TNF-αexpression were decreased in the AsⅣgroup(P<0.05).Conclusion AsⅣcan effectively prevent obesity-related hypertension by inhibiting inflammatory response and improving leptin resistance,and the improvement of AsⅣis closely related to the increased expression ofα7nAChR.