A pattern of otoferlin expression interrupted by gentamicin exposure in ribbon synapse of inner hair cell in C57BL/6J mice.

Despite ototoxic effect of aminoglycosides on auditory sensory system has been well documented, the mechanism of ototoxic damage on synaptic connection (ribbon synapse) between inner hair cells (IHCs) and spiral ganglion neurons (SGNs) is still largely unknown. Otoferlin is essential for a late step in exocytosis of neurotransmitter at ribbon synapses. In this study, C57BL/6J mice were intraperitoneally injected with gentamicin (100 mg/kg) once a day, the apical coils of organ of Corti were obtained at the 4th day, the 7th day and the 10th day respectively (n = 10/per group), the normal mice without a Gentamicin exposure were set for control (n = 10/per group). Otoferlin was detected by both immunofluorescence and western blotting. The hearing thresholds were measured by auditory brainstem responses (ABR). The expression of Otoferlin was up-regulated during the period of first 7days with a Gentamicin exposure. The down-regulation of Otoferlin expression was found after the 7th day with a gentamicin exposure. The hearing thresholds showed a linear increase. Gentamicin exposure may enhance transiently the expression of Otoferlin in ribbon synapse in C57BL/6J mice. This property might correlate with the ribbon synaptic plasticity in C57BL/6J mice. It may provide us a new insight for a further detailed study of the ribbon synaptic plasticity under the condition of aminoglycosides application.