Expression Of α₁、α₂-Na,K-ATPase In The C57BL/6J Mice Cochlea And Its Relationship With The Age-Related Hearing Loss

Objective To investigate the age-related expression of α₁﹑α₂-Na,K-ATPaseisoforms in the C57BL/6J mice cochlea, and to study the relationship between the twoisoforms and age-related hearing loss （AHL）.Methods C57BL/6J mice were divided into four groups according to age（4weeks,14weeks,26weeks and48weeks）. The location of α₁﹑α₂-Na,K-ATPase wasdetected by immunohistochemistry. Real time-polymerase chain reaction （RT-PCR）was used to detect the leave of α₁﹑α₂-Na,K-ATPase mRNA in the inner ear ofC57BL/6J mice at various ages.Results α₁﹑α₂-Na,K-ATPase protein was observed at stria vascularis﹑type Ⅱfibrocytes of spiral ligament﹑corti’s organ and spiral ganglion cells byimmunohistochemistry. The fluorescence intensity decreased rapidly with increasingage. The level of α₁﹑α₂-Na,K-ATPase mRNA also showed a age-related decreasingtrend. There was a significant decrease of α₁﹑α₂-Na,K-ATPase at mRNA levelbetween48and4weeks old in C57BL/6J mice （P <0.05）.Conclusion The expression of α₁﹑α₂-Na,K-ATPase is mainly in the striavascularis﹑type Ⅱ fibrocytes of spiral ligament﹑corti’s organ and spiral ganglioncells in the inner ear of C57BL/6J mice. The expression of the two isoforms transporters are reduced with age at protein and mRNA levels. They play an importantrole in the regulation of K+cycling and normal hearing. The age-related decreasedexpression of α₁﹑α₂-Na,K-ATPase in inner ear may be related to age-related hearingloss.