title: Aquaporin-2 regulation by vasopressin in the rat inner ear.
abstract: Our previous studies have suggested a close relationship between vasopressin and endolymphatic hydrops, or the increased volume of endolymph in the inner ear. Endolymphatic hydrops is also thought to occur in Ménière's disease patients. In the kidney collecting duct, vasopressin induces the expression of aquaporin-2 (AQP2), resulting in increased water reabsorption. We explored the possibility, using a quantitative PCR method, that vasopressin regulates the expression of AQP2 mRNA in the rat inner ear, as it does in the kidney. The levels of AQP2 mRNA in the cochlea and endolymphatic sac were significantly higher in rats treated with vasopressin than the levels in control animals. We speculate that over-expression of AQP2 may be involved in the formation of endolymphatic hydrops.
authors.affiliation: Department of Otolaryngology, Kochi Medical School, Nankoku, Japan.
authors.forename: Shoichi
authors.initials: S
authors.lastname: Sawada
authors.forename: Taizo
authors.initials: T
authors.lastname: Takeda
authors.forename: Hiroya
authors.initials: H
authors.lastname: Kitano
authors.forename: Shunji
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Akinobu
authors.initials: A
authors.lastname: Kakigi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Azuma
mesh_terms: D000818:Animals; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins / Q000235:genetics*; D001127:Arginine Vasopressin / Q000378:metabolism* / Q000494:pharmacology; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D007758:Ear, Inner / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D004710:Endolymph / Q000378:metabolism*; D004711:Endolymphatic Duct / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D018159:Endolymphatic Hydrops / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D007685:Kidney Tubules, Collecting / Q000166:cytology / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: C496025:Aqp2 protein, rat; D051399:Aquaporin 2; D051403:Aquaporin 6; D020346:Aquaporins; D012333:RNA, Messenger; D001127:Arginine Vasopressin