Identification of growth factors for neutronal and non-neutronal cells in the rat inner ear

RT-PCR和DNA测序结果显示，肝细胞生长因子（HGF）及其高亲和力受体c-met在大鼠耳蜗中均有表达。免疫组织化学与特定的多克隆抗体提出了对HGF和c-met表明，HGF和c-met蛋白位于Corti器官（毛细胞和邻近的支持细胞）。正常大鼠螺旋神经节细胞内未见HGF和c-met蛋白表达，出生后每天腹腔注射卡那霉素建立卡那霉素致聋大鼠模型。研究了全身应用HGF对神经元和非神经元细胞存活率的影响。8周后，HGF处理组和未处理组耳蜗毛细胞均消失。肝细胞生长因子治疗组的存活螺旋神经节细胞数略高于无肝细胞生长因子组，但两者之间无统计学意义。在HGF处理的耳聋大鼠耳蜗螺旋神经节细胞中检测到c-met蛋白，提示HGF及其高亲和力受体c-met在耳蜗中具有活性，对耳蜗神经元和非神经元细胞具有一定的保护作用。

RT-PCR and DNA sequencing with rat cochlear cDNAs revealed expressions of mRNAs of hepatocyte growth factor (HGF) and its high-affinity receptor c-met in the rat cochlea. Immunohistochemistry with specific polyclonal antibodies raised against HGF and c-met demonstrated that HGF and c-met proteins were located within the organ of Corti (hair cells and neighboring supporting cells). HGF and c-met proteins were never detected in the Spiral ganglion cells of the normal rats.Kanamycin-deaf rats were developed by daily kanamycin intra-peritoneal injections after birth. Effects of systemic application of HGF on the survival rates of neuronal and non-neuronal cells were examined. After eight weeks, all hair cells were disappeared in the cochleae of both the HGF-treated and no-HGF deal rats. The number of surviving spiral ganglion cells of the HGF-treated rats was slightly larger than that of the no-HGF deaf rats, although there was no statistical significance between them. In the HGF-treated deaf rats, c-met proteins were detected in the spiral ganglion cells.These results suggest that HGF and its high affinity receptor c-met are active in the rat cochlea and that they could exert some protective effects on neuronal and non-neuronal cells there.