糖皮质激素通过下调水通道蛋白2缓解精氨酸加压素诱导的膜迷路积水

Glucocorticoids alleviate endolymphatic hydrops induced by arginine vasopressin by downregulating aquaporin-2

摘要

目的 探讨糖皮质激素对精氨酸加压素诱导的膜迷路积水大鼠的治疗作用及其与水通道蛋白2(aquaporin-2, AQP2)表达调控的关联。方法 将Wistar大鼠随机分为4组:对照组(生理盐水)、造模组(醋酸去氨加压素)、地塞米松干预组(DXM组)及地塞米松联合米非司酮干预组(DXM+RU486组)。采用HE染色观察耳蜗组织膜迷路积水程度,计算中阶面积与中阶、前庭阶面积之和的比值(R值)进行量化;免疫组化检测AQP2蛋白在耳蜗中的分布与表达;qRT-PCR检测AQP2 mRNA表达水平。结果 造模组较对照组出现明显膜迷路积水(P<0.01),耳蜗AQP2 mRNA及蛋白表达水平均显著升高(P<0.05)。DXM组积水程度较造模组减轻(P<0.05),AQP2表达水平下降(P<0.05)。DXM+RU486组积水程度及AQP2表达均较DXM组显著增加(P<0.001)。免疫组化显示AQP2广泛表达于血管纹(stria vascularis, SV)、螺旋韧带(spiral ligament, SL)、螺旋器(organ of Corti, OC)、前庭膜及螺旋神经节,且定位于细胞膜。SV与SL中AQP2表达变化与积水程度一致;OC中DXM组AQP2表达虽下降但差异无统计学意义。结论 糖皮质激素可能通过下调耳蜗中AQP2的表达缓解精氨酸加压素诱导的膜迷路积水,其作用与SV、SL等部位AQP2的调控密切相关,该效应可被糖皮质激素受体拮抗剂米非司酮部分逆转。

Abstract

Objective To investigate the therapeutic effect of glucocorticoids on arginine vasopressin (AVP)-induced endolymphatic hydrops (ELH) in rats and its association with the regulation of aquaporin-2 (AQP2) expression. Methods Wistar rats were randomly divided into four groups: control (normal saline), model (desmopressin acetate), dexamethasone (DXM) intervention, and DXM + mifepristone (RU486) intervention groups. Cochlear tissues were collected for hematoxylin-eosin staining to assess the degree of ELH, quantified by the ratio (R value) of the scala media area to the sum of scala media and scala vestibuli areas. Immunohistochemistry was performed to analyze the distribution and expression of AQP2 protein in the cochlea, and qRT-PCR was used to detect AQP2 mRNA expression levels. Results Compared with the control group, the model group showed significant ELH (P<0.01) and markedly increased AQP2 mRNA and protein expression (P<0.05). The DXM group exhibited reduced ELH (P<0.05) and decreased AQP2 expression (P<0.05) compared with the model group. In the DXM+RU486 group, both ELH severity and AQP2 expression were significantly higher than those in the DXM group (P<0.001). Immunohistochemistry revealed widespread AQP2 expression in the stria vascularis (SV), spiral ligament (SL), organ of Corti (OC), Reissner's membrane, and spiral ganglion neurons, with predominant localization to the cell membrane. Changes in AQP2 expression in the SV and SL were consistent with the degree of hydrops. In the OC, although AQP2 expression decreased in the DXM group, the difference was not statistically significant. Conclusion Glucocorticoids may alleviate AVP-induced ELH by downregulating AQP2 expression in the cochlea, particularly in the SV and SL. This effect can be partially reversed by the glucocorticoid receptor antagonist mifepristone.

关键词

糖皮质激素 / 膜迷路积水 / 水通道蛋白2

Key words

Glucocorticoid / Endolymphatic Hydrops / Aquaporin-2

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基金资助

国家自然科学基金项目(82371153)

山东省自然科学基金项目(ZR2021MH378)

烟台毓璜顶医院基金项目(FZ202401)