Vanilloid receptors in hearing: altered cochlear sensitivity by vanilloids and expression of TRPV1 in the organ of corti.
Vanilloid receptors in hearing: altered cochlear sensitivity by vanilloids and expression of TRPV1 in the organ of corti.
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DOI：
10.1152/jn.00919.2002
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发表时间：
2003-07
影响因子：
2.5
通讯作者：
Jiefu Zheng;C. Dai;P. Steyger;Youngki Kim;Z. Vass;T. Ren;A. Nuttall
中科院分区：
文献类型：
--
作者：
Jiefu Zheng;C. Dai;P. Steyger;Youngki Kim;Z. Vass;T. Ren;A. Nuttall
辣椒素是一种香草素，它可以选择性地激活感觉神经元上的香草素受体（VRs），以进行有害感知，据报道，辣椒素可以增加耳蜗血流量（CBF）。在内耳中也发现了vr相关受体。本研究旨在解决VRs是否存在于Corti器官中并在耳蜗生理中发挥作用的问题。将辣椒素或更有效的VR激动剂树脂干扰素（RTX）注入豚鼠耳蜗鼓膜，观察其对耳蜗敏感性的影响。辣椒素（20 μ m）提高了听神经复合动作电位的阈值，降低了耳蜗传声器和电诱发耳声发射的强度。这些作用是可逆的，可以被一种竞争性拮抗剂，辣椒素阻断。应用2微米RTX引起的耳蜗敏感性改变与辣椒素类似，也可被辣椒平阻断。在辣椒素或RTX长时间灌注的情况下，观察到脱敏现象。辣椒素可使脑血流短暂增加，但未使耳蜗电位降低。辣椒素改变了基底膜速度（BM）在最佳频率附近的生长函数和基底膜速度的调节。免疫组化研究发现，瞬时受体电位通道家族的1型香草酸受体存在于耳蜗的毛细胞、支持细胞和螺旋神经节细胞中。结果表明辣椒素主要作用于外毛细胞，提示耳蜗内VRs在耳蜗内稳态中起作用。
Capsaicin, the vanilloid that selectively activates vanilloid receptors (VRs) on sensory neurons for noxious perception, has been reported to increase cochlear blood flow (CBF). VR-related receptors have also been found in the inner ear. This study aims to address the question as to whether VRs exist in the organ of Corti and play a role in cochlear physiology. Capsaicin or the more potent VR agonist, resiniferatoxin (RTX), was infused into the scala tympani of guinea pig cochlea, and their effects on cochlear sensitivity were investigated. Capsaicin (20 microM) elevated the threshold of auditory nerve compound action potential and reduced the magnitude of cochlear microphonic and electrically evoked otoacoustic emissions. These effects were reversible and could be blocked by a competitive antagonist, capsazepine. Application of 2 microM RTX resulted in cochlear sensitivity alterations similar to that by capsaicin, which could also be blocked by capsazepine. A desensitization phenomenon was observed in the case of prolonged perfusion with either capsaicin or RTX. Brief increase of CBF by capsaicin was confirmed, and the endocochlear potential was not decreased. Basilar membrane velocity (BM) growth functions near the best frequency and BM tuning were altered by capsaicin. Immunohistochemistry study revealed the presence of vanilloid receptor type 1 of the transient receptor potential channel family in the hair cells and supporting cells of the organ of Corti and the spiral ganglion cells of the cochlea. The results indicate that the main action of capsaicin is on outer hair cells and suggest that VRs in the cochlea play a role in cochlear homeostasis.