α-硫辛酸对顺铂诱导小鼠耳毒性的保护作用

Protective effect of alpha-lipoic acid on cisplatin-induced ototoxicity in mice

目的研究α-硫辛酸对顺铂诱导的小鼠耳毒性的保护效果,并推测其可能机制。方法使用前瞻性随机对照实验,小鼠随机分为以下四组:对照组、顺铂组、硫辛酸+顺铂组、硫辛酸组,每组各10例,分别给予相应药物处理,药物干预前、后行听性脑干反应(ABR)的检查。第6天处死小鼠取耳蜗,切片及染色后共聚焦显微镜及电镜下观察耳蜗毛细胞形态改变,免疫组化检查8-羟基脱氧鸟苷阳性表达,Western blot分析GSH-Px、Bax、Bal-2蛋白的表达。结果顺铂组的ABR阈值偏移较对照组显著上升,硫辛酸+顺铂组阈值偏移明显小于顺铂组。共聚焦显微镜下及电镜下发现顺铂组外毛细胞数量减少、静纤毛见缺失、倒伏和融合,硫辛酸+顺铂组外毛细胞数量较顺铂组明显恢复,外毛细胞静纤毛大体正常。免疫组化显示顺铂组的外毛细胞中8-OHdG免疫阳性,在硫辛酸+顺铂组仅少量的8-OHdG阳性。顺铂组上调Bax表达、下调Bcl-2的表达,硫辛酸+顺铂组与之相反且上调GSH-Px表达。结论硫辛酸对顺铂诱导的耳毒性显示出强烈的缓解作用,8-OHdG染色从免疫组化的角度揭示氧化性DNA损伤是顺铂导致耳毒性的机制之一。

Objective To study the protective effect ofα-lipoic acid on cisplatin-induced ototoxicity in mice and speculate its possible mechanism.Methods Using a prospective randomized controlled trials,mice were divided into the following four groups:control group,cisplatin group,lipoic acid+cisplatin group,and lipoic acid group(n=10),and were treated with corresponding drugs.Examination of auditory brainstem response(ABR)was conducted before and after drug intervention.The mice were sacrificed on the 6th day.The cochlea was removed,and the morphological changes of the cochlea hair cells were observed under a confocal microscope and an electron microscope after sectioning and staining.The positive expression of 8-OHdG was examined by immunohistochemistry.We used western blot to analyze the expression of GSH-Px,Bax,and Bal-2 proteins.Results The ABR threshold shift of the cisplatin group was significantly higher than that of the control group,and the threshold shift of the lipoic acid+cisplatin group was significantly smaller than that of the cisplatin group.The number of outer hair cells in the cisplatin group was reduced under confocal microscopy and electron microscopy.The number of outer hair cells in the lipoic acid+cisplatin group was significantly higher than that in the cisplatin group.Immunohistochemistry showed that 8-OHdG was positive in outer hair cells of the cisplatin group,and only a small amount of 8-OHdG was positive in the lipoic acid+cisplatin group.Cisplatin group up-regulateed Bax expression and down-regulated Bcl-2 expression,lipoic acid+cisplatin group was the opposite and up-regulated GSH-Px expression.Conclusion Lipoic acid showed a strong palliative effect on cisplatin-induced ototoxicity.8-OHdG staining revealed that oxidative DNA damage is one of the mechanisms of cisplatin-induced ototoxicity from the perspective of immunohistochemistry.