The Cochlear Ribbon Synaptic Response to Aminogiycoside Ototoxicity in C57BL/6J Mice

ObjectiveTo investigate the early change of cochlear ribbon synapses on inner hair cells in response to aminoglycoside ototoxicity.MethodsC57BL/6J mice received intraperitoneal injection of gentamicin (100 mg/kg/day), and the apical coil organ of Corti was examined on the 4th, 7th and 10th day (n=10). Littermates without gentamicin treatment served as controls (n=10). RIBEYE on the presynaptic membrane and AMPA receptors on the postsynaptic membrane were labeled with CtBP2 or GluR2/3 respectively. Three dimension reconstruction was conducted using the 3DS MAX 8.0 software.ResultsThere were no disruptions of outer or inner hair cells in all groups. However, the number of ribbon synapses on cochlear inner hair cells increased significantly within 7 days after gentamicin exposure (P<0.01), followed by a significant decrease after 7 days.ConclusionDuring the early stage of aminoglycoside ototoxicity, increased population of cochlear ribbon synapses may indicate a significant down-regulation of synaptic function.