title: Effects of intratympanic injection of steroids on changes in rat inner ear aquaporin expression.
abstract: Although steroid treatment is generally administered for patients with inner ear disorders, including Meniere's disease, the mechanism via which steroids exert their effects remains to be clarified. The aquaporins (AQPs) are a family of small transmembrane water transporters, and it has recently been revealed that they play a role in regulating homeostasis in the inner ear fluids. In order to elucidate the action points of steroids in the inner ear, we firstly identified AQPI, 2, 3, 4, 5 and 6 mRNAs in the rat cochlea and AQP1, 3, 4, 5 and 6 in the rat endolymphatic sac by means of reverse transcription-polymerase chain reaction. Subsequently, we found that intratympanic injections of steroids upregulated AQPI mRNA of the rat cochlea in a dose-dependent manner. These results suggest that steroids may affect water homeostasis in the rat inner ear mainly via AQP1.
authors.affiliation: Department of Otolaryngology and Sensory Organ Surgery, Osaka University Graduate School of Medicine, Osaka, Japan. mfukushima@ent.med.osaka-u.ac.jp
authors.forename: Munehisa
authors.initials: M
authors.lastname: Fukushima
authors.forename: Tadashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Uno
authors.forename: Yuka
authors.initials: Y
authors.lastname: Fuse
authors.forename: Katsumi
authors.initials: K
authors.lastname: Doi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D003907:Dexamethasone / Q000008:administration & dosage / Q000494:pharmacology*; D004712:Endolymphatic Sac / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D015870:Gene Expression; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology*; D007267:Injections; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014432:Tympanic Membrane
chemical_list: D020346:Aquaporins; D005938:Glucocorticoids; D012333:RNA, Messenger; D003907:Dexamethasone