ABSTRACT
There is increasing evidence that at least one function of both the medial and the lateral olivocochlear efferent systems is to provide adjustment of the set point of activity in their postsynaptic target, the outer hair cells and afferent processes, respectively. New results, summarized in this review, suggest that both efferent systems can provide protection from noise through this mechanism. There are also intracellular pathways that can provide protection from noise-induced cellular damage in the cochlea. This review also summarizes new results on the pathways that regulate and react to levels of reactive oxygen species in the cochlea as well as the role of stress pathways for the heat shock proteins and for neurotrophic factors in protection, recovery and repair.
Subject(s)
Acoustic Stimulation , Action Potentials , Animals , Cochlea/anatomy & histology , Hearing Loss, Noise-Induced/prevention & control , Heat-Shock Proteins/metabolism , Humans , Oxidative Stress/physiology , Reactive Oxygen Species/metabolismABSTRACT
Discovered in the 1940s, the aminoglycoside antibiotics were the long-sought remedy for tuberculosis and other serious bacterial infections. They are still one of the most commonly used antibiotics today, thanks to the combination of their high efficacy with low cost. This review begins by addressing some of the history and the acute side effects of aminoglycosides. It then details their chronic toxicity to the inner ear (ototoxicity). The review concludes with recent advances that have demonstrated free-radical reactions as the underlying mechanism and intervention with antioxidant/chelation therapy to prevent aminoglycoside ototoxicity.