Effect Of Aldosterone On Cochlear Af9 Expression And Hearing In Guinea Pig

Objective: Endolymphatic hydrops(EH)is the pathological characteristic of M�ni�re's disease(MD).Aldosterone could induce EH,but its relationship with MD is still controversial.The aim of the present study is to investigate Af9 protein expression in guinea pig cochlea,and regulation of Af9 expression and cochlear function by aldosterone.The role of Af9 in pathogenesis of EH is discussed.Methods: Thirty guinea pigs were randomly divided into two groups.The animals in the treatment group were intraperitoneally injected with aldosterone 0.1mg.kg-1.d-1 for 5 days,while those in the control group were done with saline.After one month,cochlea function was tested by auditory brainstem response(ABR),morphology of cochlea was examined by hematoxylin-eosin staining(HE),the location of Af9 protein was detected by immunohistochemistry(IHC)and immunofluorescence(IF),and the expression of Af9 gene was detected by Western blot and fluorescence quantitative PCR at the protein and mRNA level.Results: Compared to the control group(18.33�2.73),The ABR threshold in the treatment group(23.33�2.38)was higher(P <0.05).73% of animals in the treatment group had EH,while the control group no EH.Af9 protein was found in stria vascularis,Reissner's membrane,spiral limbus,organ of Corti and spiral ganglion in both groups.Western blot showed that Af9 protein expression(0.75 � 0.15)in the treatment group was lower than that in the control group(1.06 � 0.08),and the expression of Af9 mRNA(0.36 � 0.07)in the treatment group was also lower than that in the control group(1.00�0.00),which indicated that aldosterone inhibited Af9 gene expression at both the protein and mRNA level.Conclusion: Af9 gene in cochlea may be closely related to endolymph regulation by aldosterone and thus may be involved in pathogenesis of endolymphatic hydrops(EH).