Effects of Lithium on Endolymph Homeostasis and Experimentally Induced Endolymphatic Hydrops
| Autor: | Hiroshi Azuma, Setsuko Takeda, Kei Fukushima, T Taguchi, Akinobu Kakigi, Shoichi Sawada, Taizo Takeda, Rie Nishioka |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Vasopressin
medicine.medical_specialty Vasopressins Endolymph Guinea Pigs Gene Expression Lithium urologic and male genital diseases Polymerase Chain Reaction Endolymphatic sac Internal medicine otorhinolaryngologic diseases medicine Animals Homeostasis Endolymphatic Hydrops Inner ear RNA Messenger Endolymphatic hydrops Cochlea Aquaporin 2 Microscopy Confocal Dose-Response Relationship Drug urogenital system Chemistry medicine.disease Immunohistochemistry Rats medicine.anatomical_structure Endocrinology Otorhinolaryngology sense organs Meniere's disease |
| Zdroj: | ORL. 67:282-288 |
| ISSN: | 1423-0275 0301-1569 |
| Popis: | There is evidence to suggest that water homeostasis in the inner ear is regulated via the vasopressin (VP)-aquaporin 2 (AQP2) system in the same fashion as in the kidney. The VP-AQP2 system in the kidney is well known to be inhibited by lithium, resulting in polyuria due to a decrease in reabsorption of water in the collecting duct of the kidney. Therefore, lithium is also likely to inhibit the VP-AQP2 system in the inner ear, and consequently exert some influence on inner ear fluid homeostasis. In this study, we investigated the effects of lithium on AQP2 expression in the rat inner ear, and on the cochlear fluid volume in hydropic ears of guinea pigs. A quantitative PCR study revealed that lithium reduced AQP2 mRNA expression in the cochlea and endolymphatic sac. Lithium application also decreased the immunoreactivity of AQP2 in the cochlea and endolymphatic sac. In a morphological study, lithium intake significantly reduced endolymphatic hydrops dose-dependently. These results indicate that lithium acts on the VP-AQP2 system in the inner ear, consequently producing a dehydratic effect on the endolymphatic compartment. |
| Databáze: | OpenAIRE |
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