红外线激光兴奋耳蜗螺旋神经元的机制研究

Limited speech recognition and frequency resolution was performed in patients with cochlear implants (CIs), especially in noise background. It would be much better when infrared laser was applied to the CIs. Our previous research has demonstrated that ABR could be evoked in guinea pigs stimulated by infrared laser, and the spiral ganglion neurons (SGNs) were the direct targets of stimulation. Previous studies suggested that infrared laser could evoke action potentials through opening the TRP channels anchor to the cytomembrane by optothermal effect, infrared laser stimulation could also evoked mitochondrial calcium release. However, the mechanism of the infrared neural stimulation is still open to debate. We proposed hypothesis that mitochondrial calcium release induced by infrared laser activated the TRP channels on the SGNs membrane, results in a quantities of cation influxion dominated by calcium, which triggering the sodium channel to generate an action potential. This study will investigate the effects of infrared laser stimulation on the status of membrane ion channels and the mitochondrial related responses of cytoplastic calcium ions in the intracellular of SGNs by real-time imaging of laser confocal and patch clamp technique, and, demonstrate the co-relations between TRP channels, including their cascading signal pathway and mitochondrial calcium ion responses during the infrared neural stimulation. The mechanism of the infrared neural stimulation on SGNs would be illuminated by our research, which would help us to choose the optimal infrared parameters with more effectiveness and safety, and finally, improving the transformation and application of laser stimulation in the cochlear implants design.

人工耳蜗植入的患者在噪声环境中的频率和空间分辨率有限，如将红外线激光应用于人工耳蜗被认为可助患者获得更高的频率和空间分辨率。我们已证实红外线激光刺激豚鼠能诱发ABR，其作用靶点为螺旋神经元。研究表明红外线可通过光热效应激活细胞膜上的TRP通道使细胞兴奋；也可诱发线粒体释放钙离子。然而，其作用机制尚不明确。我们假设红外线诱发螺旋神经元线粒体释放钙离子导致胞膜上的TRP通道开放，以钙离子为主的阳离子进入胞内，触发细胞膜钠通道开放，产生动作电位。本研究将通过膜片钳和激光共聚焦实时成像探讨红外线激光刺激对螺旋神经元胞膜离子通道活动状态及胞内线粒体钙离子相关反应的作用，分析红外线激光刺激时TRP离子通道及其信号通路与线粒体钙离子相关反应的内在联系，探讨红外线激光兴奋螺旋神经元的作用机制，为更好地选择高效安全的激光参数提供理论依据，为最终将激光刺激应用于人工耳蜗在理论上向前推进。

人工电子耳蜗在噪声环境中的时间和空间分辨率有限，如将光刺激应用于人工耳蜗将有助患者获得更高的时间和空间分辨率。研究表明红外线可通过光热效应激活细胞膜上的TRP通道使细胞兴奋；也可诱发线粒体释放钙离子。我们前期研究已证实红外线激光刺激豚鼠能诱发ABR，其作用靶点为螺旋神经元。然而，红外线神经刺激的作用机制尚不明确。本项目成功建立红外线刺激螺旋神经元全细胞膜片钳实验平台，旨在探讨红外线刺激对螺旋神经元胞膜离子通道活动状态及胞内钙离子相关反应的作用，分析红外线刺激时TRP离子通道及其信号通路与胞内钙离子相关反应的内在联系，探讨红外线激光兴奋螺旋神经元的作用机制。我们的研究结果证实红外线刺激可诱发螺旋神经元产生动作电位；红外线刺激致细胞兴奋可能与光热效应相关，细胞膜上的TRPV1和TRPV4在诱发动作电位过程中起重要作用；且刺激可直接触发胞内钙离子瞬变反应；研究结果为最终将激光刺激应用于人工耳蜗在理论上向前推进。