Axonal and cellular alterations in the inner ear of rats treated with chlorphentermine or iprindole.

An electron-microscopic study was carried out on the inner ear of rats, which had been treated with the anorectic drug chlorphentermine and the antidepressant drug iprindole, two cationic amphiphilic compounds known to induce a generalized lipidosis. After chronic drug treatment the following vestibular and cochlear alterations were observed: a) numerous lamellated and crystalloid cytoplasmic inclusion bodies in various cell types, typical of drug-induced lipidosis; b) axonal balloonings predominantly affecting preterminal sensory endings which were filled with masses of coarse osmiophilic inclusions and autophagic vacuoles. With prolonged treatment degeneration of nerve fibers below the sensory epithelium was observed in increased numbers. Axonal changes are tentatively interpreted to result from drug-induced interference with certain catabolic processes involved in the normal degradation of axoplasmic constituents.