[Ototoxicity of aminosides: recent results on uptake and clearance of gentamycin by sensory cells of the cochlea]

Abstract

Recent experiments using autoradiographic and immunohistochemical labelling of gentamicin have demonstrated that GM penetrates specifically into the sensory cells of the inner ear, with a good correlation between the intensity of the labelling and the respective degrees and localisations of ototoxic damages. In the sensory hair cells GM ils localised below the cuticular plate, in an area rich in lysosomes during the ototoxic treatment. This penetration precedes the development of ototoxicity and there seems to be a threshold of intracellular concentration of GM for development of intracellular ototoxic processes. Clearance is very slow since GM can still be observed 11 months after the end of a non toxic treatment (60 mg/kg/day for 6 consecutive days). This observation is of clinical interest, in view of the delayed development of ototoxicity often observed clinically, and with respect to other hazards, including new ototoxic treatments, to which the cells can be exposed while loaded with the aminoglycoside molecule.