McLean Will J, Smith K Anne, Glowatzki Elisabeth, Pyott Sonja J
Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA.
J Assoc Res Otolaryngol. 2009 Mar;10(1):37-49. doi: 10.1007/s10162-008-0152-9. Epub 2008 Dec 12.
Processing of sound in the cochlea involves both afferent and efferent innervation. The Na,K-ATPase (NKA) is essential for cells that maintain hyperpolarized membrane potentials and sodium and potassium concentration gradients. Heterogeneity of NKA subunit expression is one mechanism that tailors physiology to particular cellular demands. Therefore, to provide insight into molecular differences that distinguish the various innervation pathways in the cochlea, we performed a variety of double labeling experiments with antibodies against three of the alpha isoforms of the NKA (NKA alpha 1-3) and markers identifying particular subsets of neurons or supporting cells in whole mount preparations of the organ of Corti and spiral ganglion. We found that the NKA alpha 3 is abundantly expressed within the membranes of the spiral ganglion somata, the type I afferent terminals contacting the inner hair cells, and the medial efferent terminals contacting the outer hair cells. We also found expression of the NKA alpha 1 in the supporting cells that neighbor the inner hair cells and express the glutamate transporter GLAST. These findings suggest that both the NKA alpha 1 and NKA alpha 3 are poised to play an essential role in the regulation of the type I afferent synapses, the medial efferent synapses, and also glutamate transport from the afferent-inner hair cell synapse.
耳蜗中的声音处理涉及传入和传出神经支配。钠钾ATP酶（NKA）对于维持超极化膜电位以及钠和钾浓度梯度的细胞至关重要。NKA亚基表达的异质性是一种根据特定细胞需求调整生理功能的机制。因此，为了深入了解区分耳蜗中各种神经支配途径的分子差异，我们使用针对NKA的三种α亚型（NKA α1 - 3）的抗体以及识别柯蒂氏器和螺旋神经节整装标本中特定神经元或支持细胞亚群的标记物进行了多种双重标记实验。我们发现，NKA α3在螺旋神经节细胞体的膜内、与内毛细胞接触的I型传入终末以及与外毛细胞接触的内侧传出终末中大量表达。我们还在与内毛细胞相邻并表达谷氨酸转运体GLAST的支持细胞中发现了NKA α1的表达。这些发现表明，NKA α1和NKA α3都可能在I型传入突触、内侧传出突触以及从传入 - 内毛细胞突触的谷氨酸转运调节中发挥重要作用。
