Liu W J, Yang J
Xinhua Hospital, Shanghai Jiaotong University, Shanghai Jiaotong University Ear Institute.
Eur J Histochem. 2015 Feb 11;59(1):2464. doi: 10.4081/ejh.2015.2464.
The expression pattern of connexin 43 (Cx43) in the cochlea is not determined and is controversial. Since the presence of Cx43 is essential for hearing, we re-examined its distribution during postnatal development of rat cochlea. Cx43 protein was expressed in spiral ganglion neurons (SGNs) and their neurite terminals innervating the inner and outer hair cells (IHCs and OHCs) as early as birth (post-natal day 0, P0), and persisted until P14. Double immunofluorescence staining, using two antibodies against Cx43 and TUJ1, a marker for all SGNs and afferent terminals, showed that immunoreactivity for Cx43 and TUJ1 was perfectly colocalized in SGNs and afferent terminals associated with the IHCs and OHCs. However, beyond P14, Cx43 immunostaining could no longer be detected in the region of the synaptic terminals at the bases of IHCs and OHCs (P17, adult). In contrast, Cx43 maintained its expression in SGNs into adulthood. We further performed quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) to identify the presence of Cx43 mRNA in the modiolus (mainly containing SGNs). Cx43 mRNA was higher at P8, compared with P1, and subsequently decreased at P14. These results indicated that Cx43 correlated with cochlear synaptogenesis and establishment of auditory neurotransmission.
连接蛋白43（Cx43）在耳蜗中的表达模式尚未明确，且存在争议。由于Cx43的存在对听力至关重要，我们重新研究了其在大鼠耳蜗出生后发育过程中的分布情况。早在出生时（出生后第0天，P0），Cx43蛋白就在螺旋神经节神经元（SGNs）及其支配内、外毛细胞（IHCs和OHCs）的神经突末端表达，并持续至P14。使用针对Cx43和TUJ1（一种标记所有SGNs和传入神经末梢的标志物）的两种抗体进行的双重免疫荧光染色显示，Cx43和TUJ1的免疫反应性在与IHCs和OHCs相关的SGNs和传入神经末梢中完全共定位。然而，在P14之后，在IHCs和OHCs基部的突触末端区域（P
17，成年期）无法再检测到Cx43免疫染色。相比之下，Cx43在SGNs中持续表达直至成年。我们进一步进行了定量实时逆转录聚合酶链反应（qRT-PCR），以确定蜗轴（主要包含SGNs）中Cx43 mRNA的存在情况。与P1相比，P8时Cx43 mRNA水平更高，随后在P14时下降。这些结果表明，Cx43与耳蜗突触发生和听觉神经传递的建立相关。
