Jeong Sung-Wook, Kim Lee-Suk, Hur Daeyoung, Bae Woo-Yong, Kim Jae-Ryong, Lee Jae-Hoon
Department of Otolaryngology-Head and Neck Surgery, College of Medicine, Dong-A University, Busan, Korea.
Acta Otolaryngol. 2010 Jun;130(6):670-8. doi: 10.3109/00016480903428200.
Reactive oxygen species (ROS) and the c-Jun N-terminal kinase (JNK) signaling pathway may be involved in secondary apoptosis of spiral ganglion cells (SGCs) induced by intracochlear gentamicin injection.
The purpose of this study was to ascertain the role of ROS and the JNK signaling pathway in secondary apoptosis of SGCs induced by intracochlear gentamicin treatment.
Gentamicin (40 mg/ml) was injected into the cochlea of guinea pigs (n = 18) to destroy the hair cells and induce secondary apoptosis of SGCs. At 1 (n = 6), 2 (n = 6), and 3 (n = 6) weeks after gentamicin treatment, the cochleas were removed and stained with hematoxylin and eosin, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling to observe the morphologic changes and apoptosis of SGCs. A dihydroethidium (DHE) assay was performed to detect ROS generation, and RT-PCR and Western blot analysis were used to assess the expression of Fas ligand (FasL), JNK, and c-Jun.
After gentamicin was injected into the cochlea, apoptosis and progressive loss of SGCs were observed. RT-PCR and Western blot analysis showed increased expression of FasL after gentamicin treatment. ROS generation detected by DHE fluorescence increased progressively, and the expression of JNK, phospho-JNK, c-Jun, and phospho-c-Jun also increased.
活性氧（ROS）和c-Jun氨基末端激酶（JNK）信号通路可能参与了耳蜗内注射庆大霉素诱导的螺旋神经节细胞（SGCs）继发性凋亡。
本研究旨在确定ROS和JNK信号通路在耳蜗内注射庆大霉素诱导的SGCs继发性凋亡中的作用。
将庆大霉素（40mg/ml）注入豚鼠（n = 18）耳蜗以破坏毛细胞并诱导SGCs继发性凋亡。在庆大霉素治疗后1周（n = 6）、2周（n = 6）和3周（n = 6），取出耳蜗，用苏木精和伊红染色，并用末端脱氧核苷酸转移酶介导的dUTP-生物素缺口末端标记法观察SGCs的形态变化和凋亡情况。采用二氢乙锭（DHE）检测法检测ROS生成，并用逆转录-聚合酶链反应（RT-PCR）和蛋白质免疫印迹法分析评估Fas配体（FasL）、JNK和c-Jun的表达。
向耳蜗内注射庆大霉素后，观察到SGCs凋亡及逐渐减少。RT-PCR和蛋白质免疫印迹分析显示庆大霉素治疗后FasL表达增加。DHE荧光检测到的ROS生成逐渐增加，JNK、磷酸化JNK、c-Jun和磷酸化c-Jun 的表达也增加。
