The analysis of the mechanism of osmoregulation in the inner ear.

内耳渗透压调节机制分析。

基本信息

批准号：
07671879
负责人：
MATSUNAGA Takashi
金额：
$ 1.41万
依托单位：
Nara Medical University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

We investigated the expression of sodium myo-inositol cotransporter (SMIT) mRNA in the inner ear and brain of rats by in situ hybridization method to understand the mechanism of the osmoreguration system mediated by osmolytes.In the cochlea, the most intense SMIT mRNA signals were observed in fibrocytes of the spiral ligament, moderate signals were found in the spiral limbus, inner hair cells and spiral ganglion cells, while the hybridization signals were almost undetectable in the marginal cells of the stria vascularis and outer hair cells. In the vestibular system, moderate hybridization signals were found in the sensory epithelium, fibrocytes and vestibular ganglion cells. These findings suggest that SMIT plays an important role in maintenance of intracellular ionic balance and cell volume in the inner ear, especially in the fibrocytes associated with generation of the ion gradients between the endolymph and perilymph.And we also investigated the changes in expressions of SMIT mRNA in the brain of acute hypernatremic rats by in situ hybridization and Northern blot methods. Under moderate acute hypernatremic conditions, SMIT mRNA level increased markedly at 1h and returned to almost control levels at 3h, in accordance with plasma Na^+ concentrations. Especially, distinct increase in SMIT mRNA expression were observed in the granule cells and glial cells in the cerebellum. The definite increases of SMIT mRNA expression was not seen in the chronic hypernatremic rats. These findings indicate that SMIT plays an important role in osmoregulation, especially in the early stages of acute hypernatremia in the brain.

We investigated the expression of sodium myo-inositol cotransporter (SMIT) mRNA in the inner ear and brain of rats by in situ hybridization method to understand the mechanism of the osmoreguration system mediated by osmolytes.In the cochlea, the most intense SMIT mRNA signals were observed in fibrocytes of the spiral ligament, moderate signals were found in the spiral limbus, inner hair细胞和螺旋神经节细胞，而杂交信号几乎无法检测到Stria Vascularis和外毛细胞的边缘细胞中。在前庭系统中，在感觉上皮，纤维细胞和前庭神经节细胞中发现了中等的杂交信号。这些发现表明，SMIT在维持内耳的细胞内离子平衡和细胞体积中起着重要作用，尤其是在内膜抑制和围膜之间产生离子梯度相关的纤维细胞中。我们还研究了通过急性超鼻孔大鼠大脑中的SMIT mRNA表达的变化，并通过北脂肪性大鼠脑中的脑化和北部的方法进行了研究。在中等急性高钠血症条件下，SMIT mRNA水平在1H时显着升高，并按照血浆Na^+浓度在3H时几乎恢复到3H的控制水平。特别是，在小脑的颗粒细胞和神经胶质细胞中观察到了SMIT mRNA表达的明显增加。在慢性高钠大鼠中未观察到SMIT mRNA表达的明确增加。这些发现表明，SMIT在渗透压调节中起着重要作用，尤其是在大脑急性高钠血症的早期阶段。