Expression of connexin 26 in the lateral wall of the rat cochlea after acoustic trauma.

Objective: Although the mutation in the Gap Junction Beta 2-encoding gap junction protein connexin 26 (Cx26) has been related to hereditary non-syndromic deafness and maturation of cochlear development, the physiological role of Cx26 in the cochlear lateral wall remains unclear. It has been suggested to be responsible for the recycling of K+ in the endolymph and for maintenance of the endocochlear potential (EP). In noise-induced hearing loss, alterations in the EP and the K+ concentration in endolymph have been observed. Thus Cx26, which is widely expressed in the cochlear lateral wall, may play a role in the mechanism of acoustic trauma.
Material and Methods: We used a rat model of noise-induced hearing impairment to detect changes in Cx26 expression in the cochlear lateral wall. By means of immunofluorescent staining and Western blotting, we investigated whether Cx26 was involved in the pathophysiological mechanism of acoustic trauma.
Results: The results indicated that abundant Cx26 protein was found on fibrocytes of the spiral ligament in the cochlear lateral wall. Protein extract of cochlear lateral wall expressed Cx26 with a molecular weight of approximately 21 kDa. After noise exposure, with an increasing threshold of the auditory brainstem response (ABR) of approximately 54.2 +/- 21.8 dB SPL, the expression of Cx26 protein increased significantly (p < 0.05) as revealed by semi-quantitative analysis from Western blotting.
Conclusion: Cx26 protein was present in the cochlear lateral wall of rats and was upregulated when the ABR threshold shifted after intense noise exposure. Cx26 protein was involved in the pathogenesis of acoustic trauma.