Effect of aldosterone on cochlear Af9 expression and hearing in guinea pig

Abstract

Conclusions: Af9 protein in cochlea may be closely related to endolymph regulation by aldosterone and thus may be involved in pathogenesis of endolymphatic hydrops (EH).

Objectives: EH is the pathological characteristic of Ménière’s disease (MD). Aldosterone could induce EH, but its relationship with MD is still controversial. The aim of the present study is to investigate the 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 treatment group was intraperitoneally injected with aldosterone 0.1 mg/kg/d for 5 days, while the control group was done with saline. Hearing and histomorphology of cochlea were examined. In addition, expression of Af9 protein was studied.

Results: The hearing threshold of the treatment group was increased. EH was induced in 73% of guinea pigs in the treatment group, and no EH was found in the control group. Af9 protein was found in spiral limbus, stria vascularis, Reissner’s membrane, organ of Corti and spiral ganglion in both groups. Af9 expression in cochlea decreased significantly at protein level after treatment by aldosterone.

Chinese abstract

结论: 耳蜗中的Af9蛋白可能与醛固酮调节内淋巴密切相关, 因此可能是内淋巴水肿 (EH) 的发病机制的一部分。

目的: EH是梅尼埃病 (MD) 的病理特征。醛固酮可诱导EH, 但它与MD的关系仍有争议。本研究的目的是调查豚鼠耳蜗的Af9基因表达, 醛固酮调节Af9的表达和人工耳蜗功能。讨论了Af9对于EH发病机制的作用。

方法: 将30只豚鼠随机分为两组。治疗组腹腔注射醛固酮, 每天每公斤体重注射0.1 mg, 共5天；对照组注射盐水。检查听力和耳蜗的组织形态学。另外, 研究了Af9蛋白的表达。

结果: 治疗组听力阈值增加。治疗组中73%的豚鼠有EH的诱导, 对照组未发现EH。 Af9蛋白发现于两组的螺旋角膜缘、血管纹、Reissner膜、Corti器官和螺旋神经节。在醛固酮治疗之后, 耳蜗的Af9表达在蛋白质水平显着降低。

Keywords:

• Endolymphatic hydrops
• aldosterone
• Af9 protein
• hearing

Disclosure statement

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Additional information

Funding

This work was supported by Chongqing Research Program of Basic Research and Frontier Technology (grant number cstc2013jcyjA10034) and National Key Clinical Specialties Construction Program of China([2012]649).