The Quantitative Analysis Of Hair Cells And Efferents In Guinea Pigs With Chronic Gentamicin Ototoxicity

Objective To detect the importance of the medial olivochlear efferents (MOC) in chronic aminoglycoside ototoxicity, the morphological changes and quantitative analysis of the MOC efferents in the cochlea of guinea pig and their correlations with the impairment of the outer hair cells (OHC) were observed. Methods The guinea pigs were injected gentamicin ten days. The MOC efferents were examined using the histochemical stain for acetylcholinesterase(AchE) and the numbers of OHC were numerateding with silver nitrate staining on the surface preparation. The guinea pigs were perfomed the inspection of distortion production otoacoustic emissions and auditory brainstem response audiometry. Results The outer hair cells were damaged after two weeks and inner hair cells were not abnormed. The MOC fibers and terminals lesion were lesion after four weeks, especially in those animals ten weeks after the gentaminic administration. The numeric value of distortion production otoacoustic emissions decreased. The latencies of ABR lengthened and thresholds decreased. Conculsion The results suggested that the OHC lesion was earlier than MOC efferents impairment and the character of lesion were similar. The lesion of MOC played important rolls in aminoglycoside ototoxicity...