Nicotinamide riboside protects noise-induced hearing loss by recovering the hair cell ribbon synapses.

OBJECTIVE

Nicotinamide riboside (NR) has been proved to protect the hearing. To achieve animal models of temporary threshold shift (TTS) and permanent threshold shift (PTS) respectively, evaluate the dynamic change of ribbon synapse before and after NR administration.

METHODS

Mice were divided into control group, noise exposure (NE) group and NR group. The noise was exposed to NE and NR group, and NR was injected before noise exposure. Auditory brainstem response (ABR), ribbon synapse count and cochlear morphology were tested, as well as the concentration of hydrogen peroxide (H2O2) and ATP.

RESULTS

Ribbon synapse count decrease with the intensity of noise exposure, and the cochlear morphology remains stable during TTS and was damaged during PTS. NR promotes the oxidation resistance to protect the synapse and the inner ear morphology.

CONCLUSION

Our findings suggest that TTS mice are more vulnerable to noise, and NR can promote the recovery of the synapse count to protect the animals' hearing.