Direct effects of reactive oxygen species on cochlear outer hair cell shape in vitro

• Published in: Hearing research Vol. 84; no. 1; pp. 30 - 40
• Main Authors: Clerici, William J., DiMartino, Debra L., Prasad, M.Renuka
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-04-1995; Elsevier
• Subjects: Animals; Auditory; Biological and medical sciences; Catalase - pharmacology; Cell Size - drug effects; Cochlea - cytology; Cochlea - drug effects; Colorimetry; Cytoplasmic bleb; Deferoxamine - pharmacology; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Female; Free radical; Free Radical Scavengers - pharmacology; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Hair Cells, Auditory, Outer - cytology; Hair Cells, Auditory, Outer - drug effects; Hydrogen peroxide; Hydrogen Peroxide - toxicity; Hydroxyl radical; Hydroxyl Radical - toxicity; Male; Perilymph - physiology; Superoxide anion; Superoxide Dismutase - pharmacology; Superoxides - toxicity; Vertebrates: nervous system and sense organs; Superoxide anion; Cytoplasmic bleb; Auditory; Hydrogen peroxide; Free radical; Hydroxyl radical; Vertebrata; Oxygen; Mammalia; Guinea pig; Toxicity; Rodentia; Cochlea; Ciliated cell; Inner ear; Organ of hearing
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(95)00010-2

Reactive oxygen species (ROS) have been implicated in the ototoxicity of various agents. This study examines the effects of superoxide anion (O
2
.), hydroxyl radical (OH
.) and hydrogen peroxide (H
2O
2), on isolated cochlear outer hair cell (OHC) morphology. OHCs were superfused with artificial perilymph (AP) or AP containing a specific ROS scavenger, and then with AP, ROS system or scavenger plus ROS system for 90 min. The generation of ROS as well sa the scavenging properties of other agents were confirmed by specific biochemical assays. Control cells decreased 4.8% in mean length, and showed no obvious membrane damage. Generation of O
2
. or OH
. resulted in high rates (85.7 and 42.9%, respectively) of bleb formation at the synaptic pole, and decreased (O
2
., 15.2%; OH
., 17.3%) mean cell length. Length change and bleb formation rate were H
2O
2 concentration-dependent. 20 mM H
2O
2 led to 33.3% decreased mean cell length, and only 20% bleb formation; 0.1 mM H
2O
2 led to 83.3% bleb formation, with no length decrease. Superoxide dismutase, deferoxamine and catalase protected against O
2
., OH
. and H
2O
2 effects, respectively. Bleb formation and diminished cell length likely represent differential lipid peroxidative outcomes at supra- and infranuclear membranes, and are consistent with effects of certain ototoxicants.