SIRT1 expression in the cochlea and auditory cortex of a mouse model of age-related hearing loss.

SIRT1 is a highly conserved NAD(+)-dependent protein deacetylase known to have protective effects against a variety of age-related diseases. However, there is a lack of information concerning SIRT1 expression in the cochlea and auditory cortex of C57BL/6 mice, a mouse model of age-related hearing loss. Using RT-PCR and immunohistochemistry, we show that SIRT1 is abundantly expressed in the inner hair cells, strial marginal cells, strial intermediate cells, type I and type IV fibrocytes of the spiral ligament and spiral ganglion neurons. In addition, moderate SIRT1 is also detected in the outer hair cells and neurons of the auditory cortex. Associated with elevated hearing thresholds and hair cells loss during aging, there is also a significant reduction of SIRT1 expression in the cochlea and auditory cortex. The expression pattern of SIRT1 in the peripheral and central auditory system suggests that SIRT1 may play an important role in auditory function and therefore may serve as a protective molecule against age-related hearing loss.