豚鼠耳毒性耳蜗损伤模型的建立与超声信号末梢编码识别

Establishment of a Cochlear Intoxication Model and Investigation on Peripheral Coding and Recognition of Ultrasonic Signals

摘要: 目的：用一定剂量庆大霉素腹腔注射制作耳蜗损伤模型；用不同频率、不同声强的骨导超声诱发大脑皮层血氧台水平依赖(BLOD)效应的磁共振成像(fMRI)感兴趣区(Region of interest, ROI)，探究庆大霉素耳蜗毛细胞损伤机制及骨导超声耳蜗末梢编码识别。方法：以庆大霉素100 mg/kg的剂量腹腔注射14天制作豚鼠耳蜗中毒损伤模型,分别以20~25 kHz、70~80 kHz骨导超声诱发豚鼠大脑皮层BLOD效应的fMRI ROI，耳蜗中毒模型分别行外马达蛋白(Prestin)及内毛细胞Otofelin免疫荧光检测。结果：庆大霉素中毒可引起全耳蜗外毛细胞Prestin及内毛细胞Otofelin表达明显下降；30~35 Khz骨导超声诱发正常对照组及豚鼠耳蜗中毒模型大脑皮层BLOD效应的fMRI ROI引出率分别为30%、0%，80~90 kHz骨导超声引出率分别为20%、20%。结论：豚鼠庆大霉素中毒可引起全耳蜗外毛细胞的损伤，不同部位耳蜗毛细胞损伤程度有差异；庆大霉素中毒豚鼠耳蜗不能感受较低频率超声，但可感受较高频率超声，提示毛细胞的空间部位对较低频率超声频率具有编码功能，较高频率骨导超声的末梢感受可能不需耳蜗毛细胞的参与，可能直接刺激螺旋神经节或脑干相关神经核感受。

Abstract: Objective: To make a cochlear injury model with a certain dose of gentamycin injection, and to use different frequencies and different intensity of bone-guided ultrasound to induce the cerebral cortex oxygen level dependence (BLOD) effect of magnetic resonance imaging (Region of Interest, ROI), to investigate the damage mechanism of gentamicin of cochlear hair cells and the identifica-tion of bone-guided ultrasound cochlear peripheral coding. Methods: The cochlear intoxication injury model of Guinea pig was made by the dosage of intraperitoneal injection of gentamicin, the ROI of the BLOD effect in the cerebral cortex was induced by 20 - 25 khz and 70 - 80 khz ultrasound, respectively, Immunofluorescence assay of outer hair cell (OHC) Prestin and inner hair cell (IHC) Otofelin was performed to verify the intoxication models. Results: Gentamicin intoxication can cause the injury of prestin and otofelin in the outer hair cells of the whole cochlea. The ROI extraction rate of BLOD effect in normal control group and guinea pig cochlea intoxication model induced by 30 - 35 khz Bone conduction ultrasounds (BCU) was 30% and 0%, 80 - 90 khz BCU was 20% and 20% respectively. Conclusion: Gentamicin intoxication in Guinea pigs can cause the injury of cochlear hair cells and the different injury of cochlear hair cells in different parts. The cochlea of gentamicin poisoned guinea pig can not feel lower frequency ultrasound, but can feel higher frequency ultrasound, suggesting that the space of the hair cell has the encoding function to the lower frequency ultrasound and the peripheral perception of high frequency BCU may not require the participation of cochlear hair cells.