Noise exposure alters cyclooxygenase 1 (COX-1) and 5-lipoxygenase (5-LO) expression in the guinea pig cochlea.

AbstractConclusion: Changes in the metabolism of arachidonic acid (AA) might be part of a noise-induced compensatory mechanism with regional specificity. Objectives: The released imbalance of prostaglandins and leukotrienes, both AA metabolites, might result in altered blood flow regulation in the inner ear and probably contributes to noise-induced hearing loss. The aim of this study was to gain further information about noise-dependent changes in AA metabolism in the mammalian cochlea. Methods: In this prospective animal study, 10 male guinea pigs were exposed to tone bursts for 1 h at 70 dB sound pressure level (SPL) (n = 5) or 90 dB SPL (n = 5). Five animals were used as controls. Alterations in cyclooxygenase 1 (COX-1) and 5-lipoxygenase (5-LO) expression were determined by quantitative immunohistochemical analysis in 11 cochlear regions. Results: COX-1 expression was decreased after both 70 dB SPL and 90 dB SPL exposure in most cell types of the organ of Corti and increased in the nerve fibers of the...