title: Immunohistochemical localization of cyclooxygenase isoforms in the organ of Corti and the spiral ganglion cells of guinea pig cochlea.
abstract: Prostaglandins have been used in experimental models and clinical studies for the therapy of sudden hearing loss and tinnitus with conflicting results. However, little is known about the rate-limiting enzymes of prostaglandin synthesis in the inner ear, the generally constitutively expressed cyclooxygenase 1 (COX-1) and the distress-inducible cyclooxygenase 2 (COX-2). To extend our knowledge concerning the physiological expression and localization of these two enzymes, immunohistochemical stainings of the guinea pig cochlea were performed. Light microscopical analysis revealed a homogenous distribution of COX-1 within nearly all cell types of the organ of Corti, but no COX-1 expression in the cuticular plates of pillar cells. COX-2 was found to be expressed in all cell types, with much stronger expression in Hensen cells, neighboring Deiters cells and cuticular plates of outer hair cells. Both COX-1 and COX-2 immunoreactions were also found in the spiral ganglion. We conclude that both COX subtypes are expressed in the guinea pig cochlea under physiological conditions. The prominent expression of the distress-inducible COX-2 isoform in cell types under mechanical stress during noise reception might support the hypothesis of a cytoprotective function of COX products in hearing and in cellular stress situations like intense noise exposure.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Johannes Gutenberg University Medical School, Mainz, Germany.
authors.forename: E A
authors.initials: EA
authors.lastname: Ziegler
authors.forename: J
authors.initials: J
authors.lastname: Brieger
authors.forename: U R
authors.initials: UR
authors.lastname: Heinrich
authors.forename: W J
authors.initials: WJ
authors.lastname: Mann
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D004195:Disease Models, Animal; D006168:Guinea Pigs; D003639:Hearing Loss, Sudden / Q000188:drug therapy / Q000201:enzymology; D007150:Immunohistochemistry / Q000379:methods*; D009925:Organ of Corti / Q000187:drug effects / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis*; D011465:Prostaglandins, Synthetic / Q000378:metabolism / Q000627:therapeutic use; D013136:Spiral Ganglion / Q000187:drug effects / Q000201:enzymology*; D014012:Tinnitus / Q000188:drug therapy / Q000201:enzymology
chemical_list: D011465:Prostaglandins, Synthetic; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases