MORPHOLOGICAL EVIDENCE OF OTOTOXICITY OF THE IRON CHELATOR DEFEROXAMINE

Recent reports of the role of iron-catalyzed free radical formation in gentamicin ototoxicity and the successful attenuation of gentamicin o totoxicity by iron chelators led us to re-examine experimental materia l from a previously unpublished study of deferoxamine. Deferoxamine wa s injected i.m. into adult Japanese quail at either 300 or 750 mg/kg b ody weight for 30 days. Examination of sections from the basilar papil la at the light microscope level indicated that supporting cells were damaged after the lower drug dose, and that both supporting cells and hair cells were damaged after the higher drug dose. High, prolonged ex posure to deferoxamine produced pathological changes similar to those seen in the basilar papilla after much lower, shorter doses of gentami cin. These results demonstrate that deferoxamine damages the quail inn er ear and are consistent with the idea that the ototoxic actions of g entamicin may be mediated by iron chelation.