Immunoreactivity for myeloperoxidase (MPO) in the vestibule after the injection of bacterial lipopolysaccharide into the middle ear

Objective: In this study, the effect of endotoxin on the vestibule of the ear of guinea pigs was immunohistochemically examined. Methods: Bacterial lipopolysaccharide was injected into the middle ear transtympanically. After 48 h, the animals were sacrificed by intracardiac perfusion of fixative; then, the temporal bones were removed and processed for immunohistochemical staining with the anti-myeloperoxidase antibody. Results: Myeloperoxidase could be detected after 48 h in the sensory epithelium and the dark cell area. Conclusion: It is reported that radical oxygen species, which are cytotoxic, are detected under inflammatory conditions. Our results suggest that myeloperoxidase and reactive oxygen species are involved in vestibular dysfunction under inflammation.