Effects Of Vasopressin On Gene Expression In Rat Inner Ear

Vasopressin is a hormone secreted from the posterior pituitary and regulates water excretion from the kidney by increasing water permeability of the collecting duct. A clinical study reported that plasma levels of arginine vasopressin were significantly higher in patients suffering from Meniere's disease. It was confirmed histologically that chronic administration of vasopressin induced endolymphatic hydrops in guinea pigs. However, the mechanism of endolymphatic hydrops induced by vasopressin is still unclear. A series of work showed vasopressin probably affected fluid balance in inner ear via VP-V2R-AC-cAMP-AQP2, VP-AQPs and or VP-cAMP-IC involving complex multiple sites and ways. Therefore, we investigate the effects of vasopressin on gene expression profiles and aquaporins in rat inner ear using cDNA microarray and RT-PCR technique.Objective1. To study the effects of vasopressin on gene expression profiles in rat inner ear to elucidate the possible mechanism of hydrolabyrinth induced by vasopressin.2. To study the regulation of vasopressin on aquaporins mRNA expression in rat inner ear to reveal the possible role of aquaporins in the formation of endolymphatic hydrops induced by vasopressin.Method1. Wistar rats were intraperitoneally injected with 50 μ g/kg arginine vasopressin once a day for one week. Then both bullae were immediately dissected out for total RNA extraction.2. cDNA microarray technique: cDNA were synthesized from the inner ear mRNA by reverse transcription and labeled with Cy3 or Cy5. The BiostarR-40s cDNA microarray was hybridized with the above cDNA. The changes of mRNA expression intensity in rat inner ear induced by vasopressin injection were showed by data analysis.3. RT-PCR technique: The changes of mRNA expression levels of AQP2 and AQP7 in inner ear of rats treated with vasopressin injection were measured.