Shi Wenying, Zhao Qi, Gao Hongwei, Yang Chao, Tan Zhiyong, Li Na, Jiang Feng, Wang Hongjie, Ji Yonghua, Zhou You
School of Basic Medical Sciences, Hebei University, Baoding, 071000, China.
Shanghai Chongming Xinhua Translational Medical Institute for Cancer Pain, Shanghai, 202150, China.
Mol Neurobiol. 2025 Apr;62(4):4115-4138. doi: 10.1007/s12035-024-04533-6. Epub 2024 Oct 14.
Neural hyperexcitability of the central auditory system is a key pathological characteristic of tinnitus, but its underlying molecular mechanisms remain elusive. The large-conductance Ca-activated K channel (BK) plays a crucial role in down- or upregulating neuronal activity. This study aims to investigate the role of BK channels in mediating tinnitus-associated neural hyperexcitability and elucidate the mechanisms behind it. Immunofluorescent staining revealed extensive expression of the BK channels on neurons within the central auditory system of rats. After long-term systemic administration of salicylate, a stable tinnitus inducer, we observed a significant change in the expression levels of BKα and β4 subunits in the rat central auditory system. In addition, salicylate was found to enhance the outward potassium currents mediated by the BK channel when exogenously expressed in HEK293 cells. Interestingly, this effect could be blocked by ryanodine, a potent inhibitor of ryanodine receptors (RyRs). Molecular docking identified Gln4020 within the central domain of RyR as a key residue in RyR-salicylate interactions. The results indicated that salicylate might directly activate RyRs leading to Ca release from endoplasmic reticulum, and increased BK currents subsequently. Systemic treatment with paxilline, a potent blocker of BK channel, selectively reversed the increased P4/P1 amplitude ratios in the frequency region of tinnitus perception induced by single-dose salicylate administration. These results suggest that BK channels and ryanodine receptors may play a selective role in salicylate-induced tinnitus.
中枢听觉系统的神经兴奋性过高是耳鸣的一个关键病理特征,但其潜在的分子机制仍不清楚。大电导钙激活钾通道(BK)在下调或上调神经元活动中起关键作用。本研究旨在探讨BK通道在介导耳鸣相关神经兴奋性过高中的作用,并阐明其背后的机制。免疫荧光染色显示BK通道在大鼠中枢听觉系统的神经元上广泛表达。在长期全身给予水杨酸(一种稳定的耳鸣诱导剂)后,我们观察到大鼠中枢听觉系统中BKα和β4亚基的表达水平发生了显著变化。此外,当在HEK293细胞中外源表达时,发现水杨酸可增强由BK通道介导的外向钾电流。有趣的是,这种效应可被ryanodine受体(RyRs)的强效抑制剂ryanodine阻断。分子对接确定RyR中心结构域内的Gln4020是RyR-水杨酸相互作用中的关键残基。结果表明,水杨酸可能直接激活RyRs,导致内质网释放钙,随后增加BK电流。用BK通道的强效阻滞剂paxilline进行全身治疗,可选择性逆转单剂量水杨酸给药诱导的耳鸣感知频率区域中增加的P4/P1振幅比。这些结果表明,BK通道和ryanodine受体可能在水杨酸诱导的耳鸣中起选择性作用。