Effects of Lithium on Endolymph Homeostasis and Experimentally Induced Endolymphatic Hydrops
Effects of Lithium on Endolymph Homeostasis and Experimentally Induced Endolymphatic Hydrops
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DOI：
10.1159/000089409
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发表时间：
2005-12
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影响因子：
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通讯作者：
Kei Fukushima;T. Takeda;A. Kakigi;S. Takeda;S. Sawada;R. Nishioka;Hiroshi Azuma;T. Taguchi
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文献类型：
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作者：
Kei Fukushima;T. Takeda;A. Kakigi;S. Takeda;S. Sawada;R. Nishioka;Hiroshi Azuma;T. Taguchi
有证据表明，内耳中的水稳态通过血管加压素（VP）-水通道蛋白2（AQP 2）系统以与肾脏中相同的方式调节。众所周知，肾脏中的VP-AQP 2系统被锂抑制，由于肾脏集合管中水的重吸收减少而导致多尿。因此，锂也可能抑制内耳中的VP-AQP 2系统，从而对内耳流体稳态产生一定影响。在这项研究中，我们研究了锂对大鼠内耳AQP 2表达的影响，以及对豚鼠积水耳耳蜗液量的影响。定量PCR研究显示，锂减少耳蜗和内淋巴囊中的AQP 2 mRNA表达。锂的应用也降低了耳蜗和内淋巴囊中AQP 2的免疫反应性。在一项形态学研究中，锂摄入量显著降低了内淋巴积水的剂量依赖性。这些结果表明，锂作用于内耳中的VP-AQP 2系统，从而在内淋巴室产生脱水作用。
There is evidence to suggest that water homeostasis in the inner ear is regulated via the vasopressin (VP)-aquaporin 2 (AQP2) system in the same fashion as in the kidney. The VP-AQP2 system in the kidney is well known to be inhibited by lithium, resulting in polyuria due to a decrease in reabsorption of water in the collecting duct of the kidney. Therefore, lithium is also likely to inhibit the VP-AQP2 system in the inner ear, and consequently exert some influence on inner ear fluid homeostasis. In this study, we investigated the effects of lithium on AQP2 expression in the rat inner ear, and on the cochlear fluid volume in hydropic ears of guinea pigs. A quantitative PCR study revealed that lithium reduced AQP2 mRNA expression in the cochlea and endolymphatic sac. Lithium application also decreased the immunoreactivity of AQP2 in the cochlea and endolymphatic sac. In a morphological study, lithium intake significantly reduced endolymphatic hydrops dose-dependently. These results indicate that lithium acts on the VP-AQP2 system in the inner ear, consequently producing a dehydratic effect on the endolymphatic compartment.