Changes in neuronal structure after auditory deprivation in rat cochlea.

大鼠在出生后立即给予卡那霉素两周，剥夺其听觉功能。出生2周后评估听觉脑干反应，无反应。i)免疫组化研究证实耳蜗内未见毛细胞。内耳及耳蜗核神经元细胞减少。ii)通过免疫组织化学和定量PCR技术检测谷氨酸受体的表达。在对照动物的螺旋神经节细胞和耳蜗核神经元中发现了谷氨酸受体Glu-R 2-5 （Kainic酸受体）和nr1和NMDA受体2 （NMDA受体）。在失聪动物中，glu - r4和NR - 1减少，但glu - r2 /3和NR - 2显著增加。耳聋大鼠中Glu-R 2/3和NR 2的上调反映了耳蜗功能和结构的改变。iii)在耳聋大鼠慢性埋置微型浮剂中给予神经营养因子（HGF），观察其保护作用。结果表明，HGF对螺旋神经节细胞数量和谷氨酸受体表达均有积极影响。强调了神经营养刺激对聋大鼠听觉系统的重要性。

Rats were deprivated the auditory function by administrating the Kanamycin for two weeks, which started immediately after the birth. Auditory brainstem response evaluated after 2 weeks of birth, showed no response. i) Immunohistochemical study confirmed no hair cells in the cochlea., decrease of neuronal cells in the inner ear and cochlear nucleus. ii) Expression of glutamate receptors were examined by both immunohistochemical study and by quantitative PCR technique. In control animals, glutamate receptors of Glu-R 2-5 (Kainic acid receptors) and NR 1 and 2 (NMDA receptors) were found in spiral ganglion cells and cochlear nucleus neurons. In deaf animals, there was a decrease in Glu-R 4 and NR 1, but a significant increase was found in Glu-R 2/3 and NR 2. The fact that the up-regulation of Glu-R 2/3 and NR 2 occurred in deafned rats reflected functional and structual changes in the cochlea. iii) Neurotrophic factor (HGF) was administered with chronocally embedded miniature pomp in deafned rats, and its protective effects was examined. The reslut showed that HGF had positive effects upon the number of spiral ganglion cells and expression in glutamate receptors. The importance of neurotrophic stimulation upon auditory system of deafned rats was stressed.