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

RT-PCR和DNA测序显示肝细胞生长因子(HGF)及其高亲和力受体c-met在大鼠耳蜗组织中有表达。抗HGF和c-Met多克隆抗体免疫组织化学显示HGF和c-Met蛋白定位于Corti器官(毛细胞和邻近支持细胞)。正常大鼠螺旋神经节细胞中未检测到HGF和c-met蛋白。卡那霉素致聋大鼠出生后每日腹腔注射卡那霉素造成耳聋。观察全身应用HGF对神经细胞和非神经细胞存活率的影响。8周后，HGF处理组和非HGF处理组大鼠耳蜗内毛细胞全部消失。HGF治疗组大鼠存活的螺旋神经节细胞数略多于非HGF组，但差异无统计学意义。结果表明，HGF及其高亲和力受体c-Met在大鼠耳蜗神经节细胞中具有活性，对耳蜗神经细胞和非神经细胞有一定的保护作用。

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.