Original Article Pathological changes of cochlear in deaf mice at different time after mouse cytomegalovirus infection

Abstract: Objective: This study aims to observe the pathological changes of inner ear in deaf mice at different time after mouse cytomegalovirus infection. Methods: A total of 60 BALB/C mice were divided into 2 groups randomly: model group (A) and control group (B). In model group, 10 μl of MCMV was injected into the brain of each mouse while 10 μl of physiological saline was injected in control group. 10 cochlear samples were taken from 5 mice selected from each group randomly after infection for 1, 3, 5, 7, 14 and 21 days respectively. They were detected with PCR and HE staining methods. Auditory brain stem response was determined. The apoptosis of spiral ganglion (SGN) cells was detected by apoptosis assay kit. The levels of Bcl-2 and Bax were detected by RT-PCR and western blotting methods. Results: In group A, PCR results were negative after infection for 1 day, they were positive after infection for 3 days to 21 days. In group B, PCR results were negative in the experimental period. Compared with group B, ABR I wave latency and threshold increased while ABR I wave decreased in group A. There were no obvious hyperemia and inflammatory cells infiltration in group B, In group A, hemorrhage of scala tympani and scala vestibule appeared and reached highest peak after infection for 3 days accompanied by inflammatory cell infiltration; the vestibular membrane thickened after infection for 5 days; cell gap of SGN cells widened, arranged more sparsely with cell edema after infection for 7 days accompanied by infiltration of plasma cells; fibroblast proliferation and fibrosis appeared after infection for 14 days. Conclusions: MCMV infection occurred in cochlear after MCMV infection for 3 days and could sustain, the continues pathological changes of inner will bring difficulties to the treatment of CMV deafness, further studies on the specific mechanism of SGN changes caused by CMV infection will provide an important target for the treatment of CMV deafness