GFAP aggregates in the cochlear nerve increase the noise vulnerability of sensory cells in the organ of Corti in the murine model of Alexander disease.

[alexander disease]

Outer hair cell (OHC ) loss in the auditory sensory epithelium is a primary cause of noise-induced sensory -neural hearing loss (SNHL ). To clarify the participation of glial cells in SNHL , we used an Alexander disease (AxD ) mouse model . These transgenic mice harbor the AxD causal mutant of the human glial fibrillary acidic protein (GFAP ) under the control of the mouse GFAP promoter . It is thought that GFAP aggregates compromise the function of astrocytes . In the auditory pathway , the formation of GFAP aggregates was observed only in GFAP -positive cells of the cochlear nerve . The presence of GFAP aggregates did not change auditory function at the threshold level . To assess the change in vulnerability to auditory excitotoxicity , both transgenic and control mice were treated with intense noise exposure . Auditory threshold shifts were assessed by auditory brainstem responses (ABR ) at 1 and 4 weeks after noise exposure , and OHC damage was analyzed by quantitative histology at 4 weeks after exposure . Transgenic mice showed more severe ABR deficits and OHC damage , suggesting that cochlear nerve glial cells with GFAP aggregates play a role in noise susceptibility . Thus , we should focus more on the roles of cochlear nerve glial cells in SNHL .