葛根素对豚鼠耳蜗缺血再灌注损伤时听功能和IκBα的影响

Protective effect of Puerarin in on the auditory function and the expressive activity of IκBα following vertebrobasilar artery ischemia-reperfusion injury in the cochlea of guinea pigs

目的探讨葛根素在豚鼠椎基底动脉缺血/再灌注耳蜗损伤中的保护作用及分子机制,为葛根素治疗耳蜗缺血再灌注损伤提供理论依据。方法纯白雄性豚鼠32只,随机分为4组;正常对照组、缺血再灌注7d组、生理盐水组(即缺血再灌注7d加生理盐水对照组)和用药组(即缺血再灌注7d加葛根素保护组)。除正常对照组外,所有豚鼠均进行手术造模。用药组在缺血再灌注开始时即腹腔注射葛根素150mg·kg-1·d-1,每天1次,连用6天,于再灌注7天时处死。生理盐水组操作同用药组,但以等容量生理盐水代替葛根素。应用听觉脑干反应评价听功能。采取石蜡包埋免疫组织化学技术,对各组耳蜗近中轴位切片行IκBα免疫组织化学染色以观察葛根素IκBα的影响。结果用药组动物ABR各波潜伏期、Ⅰ～Ⅲ波间期明显缩短,阈值降低。各组各波潜伏期、Ⅰ～Ⅲ波间期和阈值比较差异均有统计学意义(P<0.01)。正常对照组与用药组比较,Ⅲ、Ⅳ波潜伏期、Ⅰ～Ⅲ波间期和阈值差异无统计学意义(P>0.05)。用药组IκBα表达与缺血再灌注7d组比较活性明显上调,差异有统计学意义(P<0.01)。结论葛根素具有保护耳蜗缺血再灌注损伤的作用,其作用机制可能与上调IκBα表达活性有关。

Objective To investigate the protective effect of Puerarin on vertebrobasilar artery ischemia-reperfusion injury in the cochlea of guinea pigs and the molecular mechanisms of such a protective effect based on an experimental study. Methods Thirty- two healthy white male guinea pigs with normal Preyer＇s reflex, weighed from 200 to 250g, were randomly divided into four groups, i.e. normal controlling group （NCG）, modeling group （MG）, Puerarin treating group （PTG） and normal saline controlling group （NSCG）. The animal models of vertebrobasilar artery ischemia-reperfusion injury were operatively established via the skull base approach among all these animals other than those in NCG. Among the animals of PTG, puerarin was given in an intra-abdominally injected way from the beginning of ischemia-reperfusion injury at a dosage of 150 mg.kg^-1.d^-1 for six days, and then, these animals were put into death at the 7th day. For those in NSCG, all the experimental procedures were the same as in PTG but with normal saline in the same volume in stead of puerarin. Furthermore, the auditory function of these experimental animals was evaluated by evoked auditory brainstem responses （ABR）, and the changes in the expressive activity of IκBα were determined in the cochlear tissues embedded in paraffin by the procedures of immunohistochemistry. Results It was shown from the results of ABR that the latencies of all the waves and the inter-peak duration from waves 1 to It were prevented from delaying, as induced by ischemia-reperfusion injury, following puerarin used among the animals of PTG, with decreasing in the level of auditory threshold. When compared among all these groups, statistically significant differences （P〈 0.01） could be found in their latencies of all the waves, the inter-peak duration from waves Ⅰ to Ⅲ, and the levels of auditory threshold, but not when compared those between PTG and NCG （P〉 0.05）. Moreover, the expressive activity of IκBα, determined at the 7th day following reperfusion in PTG, was shown significantly up-regulated as compared with that of NSCG and MG （P〈0.05）. Conclusions It is significant as shown in this study that puerarin can protect the cochlea from the ischemia-reperfusion injury. Such a protective effect ofpuerarin against ischemia-reperfusion injury taken place in cochlea may be related with the increased activation of IκBα.