OBJECTIVETo study the effect of vasopressin on aquaporin 7 (AQP7) expression in rat inner ear and reveal the possible role of aquaporins in the formation of endolymphatic hydrops induced by vasopressin.

METHODSWistar rats were intraperitoneally injected with 50 microg/kg arginine vasopressin once a day for one week. Differentially expressed genes of aquaporins induced by vasopressin injection in rat inner ear were filtered by cDNA microarray. The changes of mRNA expression level of AQP7 in inner ear of rats treated with vasopressin injection were measured by RT-PCR.

RESULTSDifferentially expressed gene AQP7 of aquaporins induced by vasopressin injection was screened out in rat inner ear. The expression level of AQP7 mRNA in inner ear of rats treated with vasopressin injection was significantly lower.

CONCLUSIONVasopressin may down-regulate the expression of AQP7 mRNA in the endolymphatic sac and induce a decreased absorption of endolymph, which decreases the water permeability in the potassium ions recycle pathway in the organ of Corti and disturbs the circulation of endolymph, resulting in endolymphatic hydrops.