顺铂致聋后大鼠耳蜗螺旋神经元NeuroD的表达

目的检测神经分化因子NeuroD在大鼠耳蜗螺旋神经元顺铂损伤后的表达变化。方法通过免疫组织化学及Real-TimePCR技术,观察耳蜗螺旋神经元损伤1d、3d、5d后NeuroD的表达变化。正常成年SD大鼠32只随机分为对照组(生理盐水5ml/kg,1次/d,腹腔注射,连续5d),用药1d组(顺铂5mg/kg,腹腔注射),用药3d组(顺铂5mg/kg,1次/d,腹腔注射,连续3d),用药5d组(顺铂5mg/kg,1次/d,腹腔注射,连续5d),每组8只,建立顺铂耳毒性模型。采用Real-TimePCR、免疫组织化学染色检测不同时间螺旋神经元NeuroD的mRNA及蛋白表达变化。结果成功建立顺铂耳毒性大鼠模型,随着用药时间的延长,神经分化因子NeuroD在耳蜗螺旋神经元中呈动态变化。NeuroD的mRNA和蛋白表达在用药1d及3d组分别为2.17±0.39、1.15±0.20及7.02±0.69、2.42±0.40,与对照组及用药5d组比较具有统计学意义(P值<0.01)。结论 NeuroD在用药1d后开始增加,3d后达到高峰,5d后下降;在用药早期有一过性表达增强,后期表达下降同时听力损失明显。表明NeuroD可能参与顺铂损伤螺旋神经元后的修复过程。

Expression of NeuroD in spiral ganglion neurons following cisplatin-induced ototoxicity in rats

Objective To investigate the effects of neurogenic differentiation(NeuroD)on spiral ganglion cells neurons(SGNs) in cisplatin-induced ototoxicity.Methods Thirty two adult Sprague-Dawley(SD)rats were divided randomly into 4 groups (n=8 in each group) to receive intraperitoneal injection of cisplatin (5mg/kg,qd) for 1,3 or 5 days,or equivalent volume of saline (control group).The mRNA level of NeuroD expression in cochlear tissues was examined by Real-Time PCR.The expressing pattern of NeuroD in damaged cochlea was studied by immunochemistry using antibodies against NeuroD protein.Results This was a successful model of cisplatin ototoxicity,showing dynamic changes in expression of NeuroD in SGNs along with cisplatin administration.At day 1 and day 3 of cisplatin treatment,NeuroD mRNA levels were 2.17±0.39 and 1.15±0.20,and NeuroD protein levels were 7.02±0.69 and 2.42±0.40,respectively,higher the control and 5 day treatment groups (P<0.01).Conclusions Expression of NeuroD seems to increase and peak at days 1-3 after cisplatin treatment,and decrease at day 5.This temporary increase at early stage followed by a later decrease (seemingly parallel to increasing hearing damage) may represent NeuroD’s role in the repair of SGNs following cisplatin-induced damage.