Downregulation of Cav1.3 calcium channel expression in the cochlea is associated with age-related hearing loss in C57BL/6J mice

Age-related hearing loss (ARHL) is the most common human morbidity. However, the molecular mechanisms underlying ARHL are little known. In the present study, the expression of Ca(v)1.3 calcium channels in the C57BL/6J ARHL mouse cochlea was investigated. The hearing threshold was assessed by auditory brainstem response and the expressions of Ca(v)1.3.3 calcium channels at the protein and mRNA levels were detected by immunohistochemistry, western blot, and real-time RT-PCR. Associated with the auditory brainstem response threshold increased with age, the Ca(v)1.3.3 expression was gradually decreased. In comparison with 4-week-old mice, Ca(v)1.3.3 expressions in the cochlea at 14, 24, and 48 weeks of age were significantly and gradually decreased at both the protein and the mRNA levels. Immunohistochemistry showed that the expression of Ca(v)1.3.3 was apparently reduced at the inner hair cells, outer hair cells, and stria vascularis in the cochlear lateral wall in the aged mice. Our findings indicate that Ca(v)1.3.3 calcium channel expression in the cochlea is reduced in the ARHL mice and is associated with ARHL. The data also support a view that Ca(v)1.3.3 calcium channel is a good target for prevention and therapy of ARHL.