中国人民解放军联勤保障部队第九八〇医院耳鼻咽喉头颈外科
河北省医学科学研究课题计划项目(20231311)
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【】目的:研究橄榄苦苷调节脯氨酸蛋白激酶底物蛋白(PRAS40)/哺乳动物雷帕霉素靶蛋白复合物1(mTORC1)信号通路对噪声性耳聋(NIHL)大鼠耳蜗组织损伤的影响。方法:总共选取48只大鼠,随机选出12只大鼠作为NC组,剩余大鼠采用白噪声来构建NIHL大鼠模型。随后将NIHL模型大鼠随机分为Model组、橄榄苦苷组(50 mg/kg)、橄榄苦苷+NV-5138组(50 mg/kg+160 mg/kg mTORC1激活剂)。观察各组大鼠的情况,评估各组大鼠的听性脑干反应(ABR)阈值；苏木精-伊红(HE)染色检测大鼠耳蜗组织的病理损伤；TUNEL观察大鼠耳蜗组织凋亡情况；共聚焦显微镜(DAPI染色)观察耳蜗基底膜毛细胞序列变化；Western blot检测大鼠耳蜗组织PRAS40、磷酸化PRAS40(p-PRAS40)、磷酸化mTORC1(p-mTORC1)、mTORC1、Bax蛋白表达。结果:与NC组比较,Model组大鼠ABR阈值与细胞凋亡数目增加、耳蜗组织病理损伤加重、p-mTORC1/mTORC1、Bax蛋白表达升高,基底膜毛细胞序列损坏、p-PRAS40/PRAS40蛋白表达降低(P<0.05)；与Model组比较,橄榄苦苷组大鼠ABR阈值与细胞凋亡数目减少、耳蜗组织病理损伤减轻、p-mTORC1/mTORC1、Bax蛋白表达降低,基底膜毛细胞序列整齐、p-PRAS40/PRAS40蛋白表达升高(P<0.05)；而橄榄苦苷+NV-5138组中相应实验检测结果与橄榄苦苷组相反,大鼠损伤加重。在NV-5138干预后减弱了橄榄苦苷对NIHL大鼠耳蜗组织损伤的改善作用(P<0.05)。结论:橄榄苦苷可能通过促进PRAS40/mTORC1信号通路减轻噪声性耳聋大鼠耳蜗组织的损伤。
Objective: To investigate the effect of oleuropein on cochlear tissue damage in noise-induced hearing loss (NIHL) rats by regulating the proline-rich Akt substrate of 40 kDa (PRAS40)/mammalian rapamycin target protein complex 1 (mTORC1) signaling pathway. Methods: A total of 48 rats were selected, and 12 rats were randomly regarded as the NC group. The remaining rats were used to construct a NIHL rat model using white noise. Subsequently, NIHL model rats were randomly grouped into a Model group, an oleuropein group (50 mg/kg), and an oleuropein+NV-5138 group (50 mg/kg+160 mg/kg mTORC1 activator). The condition of rats in each group was observed, and the auditory brainstem response (ABR) threshold of rats in each group was evaluated; hematoxylin-eosin (HE) staining was applied to detect pathological damage in cochlear tissue; TUNEL was applied to observe the apoptosis of cochlear tissue; Confocal microscopy (DAPI staining) was applied to observe changes in the sequence of hair cells in the cochlear basement membrane; Western blot was applied to detect the expression of PRAS40, phosphorylated PRAS40 (p-PRAS40), phosphorylated mTORC1 (p-mTORC1), mTORC1, and Bax proteins in rat cochlear tissue. Results: Compared with the NC group, the ABR threshold and apoptosis number of rats in the Model group increased, the pathological damage to cochlear tissue increased, the expression of p-mTORC1/mTORC1 and Bax proteins increased, basal membrane hair cell sequence was damaged, the expression of p-RAS40/PRAS40 protein decreased (P<0.05); compared with the Model group, the ABR threshold and apoptosis number of rats in the oleuropein group decreased, the pathological damage of cochlear tissue alleviated, the expression of p-mTORC1/mTORC1 and Bax proteins decreased, basal membrane hair cell sequence was neat, the expression of p-PRAS40/PRAS40 protein increased (P<0.05); the corresponding experimental detection results in the oleuropein+NV-5138 group were opposite to those in the oleuropein group, and the damage in the rats worsened. The intervention of NV-5138 weakened the improvement effect of oleuropein on cochlear tissue damage in NIHL rats (P<0.05). Conclusion: Oleuropein may alleviate cochlear tissue damage in noise-induced hearing loss rats by promoting the PRAS40/mTORC1 signaling pathway.
