Vetter D E, Liberman M C, Mann J, Barhanin J, Boulter J, Brown M C, Saffiote-Kolman J, Heinemann S F, Elgoyhen A B
The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
Neuron. 1999 May;23(1):93-103. doi: 10.1016/s0896-6273(00)80756-4.
Cochlear outer hair cells (OHCs) express alpha9 nACh receptors and are contacted by descending, predominately cholinergic, efferent fibers originating in the CNS. Mice carrying a null mutation for the nACh alpha9 gene were produced to investigate its role(s) in auditory processing and development of hair cell innervation. In alpha9 knockout mice, most OHCs were innervated by one large terminal instead of multiple smaller terminals as in wild types, suggesting a role for the nACh alpha9 subunit in development of mature synaptic connections. Alpha9 knockout mice also failed to show suppression of cochlear responses (compound action potentials, distortion product otoacoustic emissions) during efferent fiber activation, demonstrating the key role alpha9 receptors play in mediating the only known effects of the olivocochlear system.
耳蜗外毛细胞（OHCs）表达α9烟碱型乙酰胆碱受体，并与起源于中枢神经系统的下行传出纤维接触，这些纤维主要是胆碱能的。为了研究nAChα9基因在听觉处理和毛细胞神经支配发育中的作用，制备了携带该基因无效突变的小鼠。在α9基因敲除小鼠中，大多数OHCs由一个大的终末支配，而不是像野生型那样由多个较小的终末支配，这表明nAChα9亚基在成熟突触连接的发育中发挥作用。α9基因敲除小鼠在传出纤维激活期间也未能表现出耳蜗反应（复合动作电位、畸变产物耳声发射）的抑制，这证明了α9受体在介导橄榄耳蜗系统唯一已知效应中所起的关键作用。
