Effect of the NF-κB/iNOS Signaling Pathway on Spiral Ganglion in Mouse Model of Sensorineural Hearing Loss

  Objective  To explore the effect of changes in the expression level of necorsis factor (NF)-κB/inducible nitric oxide synthase (iNOS) signaling pathway on hearing loss in a mouse model of sensorineural hearing loss (SNHL) induced by 3-nitropropionic acid (3-NP).

  Methods  The animal model was established by tympanic injection. C57BL/6 male mice were divided into three groups, 3-NP group receiving tympanic injection of 3-NP solution, 3-NP+EVP4593 group receiving tympanic injection of 3-NP solution and intraperitoneal injection of EVP4593 solution, and a control group receiving tympanic injection of phosphate buffered saline (PBS). Auditory brainstem response (ABR) was tested before and after injection. After 4 weeks, the cochlea was harvested and immunohistochemistry and qRT-PCR of NF-κB p65, RelB, iNOS, and Caspase-3 were conducted accordingly.

  Results  The hearing thresholds of the 3-NP group were higher than those of the control group and the 3-NP+EVP4593 group (P<0.05), and the hearing thresholds of the 3-NP+EVP4593 group were also higher than those of the control group (P<0.05). Immunofluorescence staining and qRT-PCR results showed that 3-NP exposure caused an increase in the expressions of NF-κB p65, RelB, and iNOS in the spiral ganglion in comparison with those of the control group (P<0.05), and their expressions decreased with the administration of EVP4593 (P<0.05). The expression of Caspase-3 in the spiral ganglion cells in the 3-NP group was higher than that in the control group, while in the 3-NP+EVP4593 group, it was lower than that in the 3-NP group (P<0.05).

  Conclusion  This study found that, by activating the NF-κB/iNOS signaling pathway, 3-NP may cause inflammation in the spiral ganglion of the cochlear in the SNHL model mice, which may play an important role in the pathogenesis of SNHL.