银杏叶提取物通过Nrf2/HO-1信号通路减轻老年性聋大鼠耳蜗氧化应激损伤的机制

The mechanism of Ginkgo biloba extract in alleviating oxidative stress damage to the cochlea of presbycusis rats by the Nrf2/HO-1 signal pathway

目的观察银杏叶提取物对老年性聋大鼠耳蜗核因子红系相关因子2(Nrf2)/血红素加氧酶1(HO-1)信号通路的影响,探讨银杏叶提取物对老年性聋的保护机制。方法将45只SD大鼠随机分为对照组、模型组和银杏叶提取物低、中、高剂量组,每组9只。采用听性脑干诱发电位(ABR)检测听功能;ELISA法检测血清丙二醛(MDA)和总-超氧化物歧化酶(T-SOD)的含量;透射电镜观察螺旋神经节细胞超微结构;免疫荧光染色观察顶、中、底回毛细胞结构和数量变化;免疫组织化学法及蛋白印迹法检测大鼠耳蜗Nrf2和HO-1蛋白的表达水平。结果与对照组相比,模型组ABR阈值明显升高,血清中MDA含量升高,T-SOD含量降低,螺旋神经节细胞超微结构明显破坏,内、外毛细胞形态紊乱,数量大量丢失,Nrf2和HO-1蛋白表达均下调。经不同剂量银杏叶提取物治疗后,与模型组比较,ABR阈值明显降低,MDA含量降低,T-SOD含量升高,螺旋神经节超微结构明显改善,内、外毛细胞形态清晰,数量逐渐增多,Nrf2和HO-1蛋白表达均上调。结论银杏叶提取物可减轻老年性聋大鼠耳蜗的氧化应激损伤,其机制可能与调控Nrf2/HO-1信号通路有关。

Objective To observe the effect of Ginkgo biloba extract on nuclear factor erythroid related factor 2(Nrf2)/heme oxygenase 1(HO-1)signaling pathway in the cochlea of presbycusis rats,and to explore the mechanism of Ginkgo biloba extract in protection of presbycusis.Methods 45 SD rats were randomly divided into a control group,model group,Ginkgo biloba extract low-dose group,medium-dose group and high-dose group,9 for each group.Auditory function was detected by auditory brainstem response(ABR).The serum contents of malondialdehyde(MDA)and total superoxide dismutase(T-SOD)were detected by ELISA.Ultrastructure of spiral ganglion cells was observed under a transmission electron microscope.Changes in the structure and quantity of hair cells in the Apical,Middle,or Basal turn were observed by immunofluorescence staining.Expression levels of Nrf2 and HO-1 proteins in the cochlea were detected by immunohistochemistry and Western blotting.Results As compared with those in the control group,the ABR threshold in the model group was significantly increased,the serum content of MDA was increased,whereas that of T-SOD was decreased;the ultrastructure of spiral ganglion cells was obviously destroyed,the morphology of the inner and outer hair cells were disordered,the number of hair cells was greatly reduced,and the expression levels of Nrf2 and HO-1 proteins were down-regulated.After treatment with different doses of Ginkgo biloba extract,as compared with those in the model group,the ABR threshold was significantly reduced,the content of MDA was reduced,the content of T-SOD was increased,the ultrastructure of spiral ganglia cells was significantly improved,the morphology of inner and outer hair cells were clear and the cell number gradually increased,and the expression levels of Nrf2 and HO-1 proteins were up-regulated.Conclusions Ginkgo biloba extract can alleviate oxidative stress damage in the cochlea of presbycusis rats,and its mechanism may be related to the regulation of Nrf2/HO-1 signaling pathway.