Study Of Age-related Degeneration In Cochlea Of DBA/2Mice

Objective: To detect the age-related morphology changes and pathogenesis in the co-chleaof DBA/2mice.Method: DBA/2mice were divided into four groups:3weeks group(n=20);8weeksgroup(n=20);12weeks group(n=20);8months group(n=20).Auditory brainstem response(ABR) was used to detect the hearing threshold of DBA/2mice in different time points. Thefrequency of mtDNA3873bp deletion and COX Ⅲ genesexpress were detected by real-timePCR. Morphological examination was taken to observe hair cells and spiral ganglioncells(SGC) of cochlear. Immunofluorescence method was to test the expression of COXⅢin cochlear of DBA/2mice.Results: With the growth of age, ABR threshold incresed and the difference of ABRthreshold among all groups were significant(P<0.01). With the growth of age, The HC lossincresed and SGC counts decresed. At eight month point, the HC and SGC loss weresignificant compared with other time points(P<0.05). The rate of mtDNA3873bp deletionwas10-4～10-5. The frequency of the3873bp deletion were not detected change with thegrowth of age(P>0.05).The protein of COXⅢ expressed mainly in SGC, the gene expressof COXⅢwere not detected change along with the growing of age (P>0.05).Conclusions: DBA/2mice perform a age-related hearing loss and morphology changes ofcochlear. DBA/2mice could be used as a model of AHL. The mtDNA3873bp deletion andCOXⅢ deletion were detected in the DBA/2mice. But the relationship betweenmtDNA3873bp deletion and COXⅢ gene deletion and presbycusis of DBA/2mice was notnotable.