Abstract:
This study was undertaken to determine the role of adenosine signalling in the development of age-related hearing loss (ARHL). Weand others have shown previously that adenosine signalling via A1 receptors is involved in cochlear protection from noise-induced cochlear injury. Here we demonstrate that enhanced adenosine signalling in the cochlea provides partial protection fromARHL in C57BL/6Jmice. We targeted adenosine kinase (ADK), the key enzymein adenosinemetabolism, using a treatment regimewith the selective ADK inhibitor ABT- 702 (1.5mg/kg intraperitoneally twice a week) commencing at the age of three months or six months. This treatment, intended to increase free adenosine levels in the ochlea,was maintained until the age of nine months and hearing thresholds were evaluated monthly using auditory brainstem responses (ABR). At nine months, when C57BL/6J mice normally exhibit significant ARHL, both groups treated with ABT-702 showed lower ABR threshold shifts at 10 and 16 kHz compared to control animals receiving the vehicle solution. The better thresholds of the ABT-702-treated mice at these frequencies were supported by increased survival of hair cells in the apical region of the cochlea. This study provides the first evidence that ARHL can bemitigated by enhancing adenosine signalling in the cochlea.