部分去背根猫备用背根节和脊髓Ⅱ板层NT-3及其mRNA的表达变化

采用免疫组化和原位杂交技术探讨了部分去背根猫备用背根节 (L6 )和 L3、L5脊髓 II板层 NT-3及其 m RNA的表达变化。结果发现 ,正常组 NT-3及其 m RNA阳性产物主要分布于背根节的大型神经元和少数中、小型神经元。部分去背根后 ,3 d和10 d两时相 NT-3 m RNA大型神经元阳性数明显减少 ,而 NT-3阳性大型神经元数术后 10 d时方明显减少 (P<0 .0 1) ;NT-3及其 m RNA阳性小型细胞数在术后两时相均较正常组者增多 (P<0 .0 1) ;而在中型神经元只有 NT-3阳性神经元数有增加。相对地 ,在脊髓 板层 ,两时相 NT-3阳性神经元及胶质细胞百分数均较正常者明显增加 (P<0 .0 1) ,且以 3 d组者为最明显 ,但均未见 NT-3 m RNA阳性信号。结果表明 ,部分去背根不仅导致背根节各类神经元中 NT-3的表达发生了变化 ,且对 板层 NT-3阳性神经元及胶质细胞数量也有明显影响。提示 NT-3可能在脊髓 板层可塑性中发挥作用

THE CHANGE OF NT-3 AND ITS mRNA IN SPARED DORSAL ROOT GANGLION AND SPINAL DORSAL HORN LAMINA Ⅱ FOLLOWING PARTIAL DORSAL RHIZOTOMY

In order to explore the change of NT 3 and its mRNA expression in spared dorsal root ganglion and spinal dorsal horn lamina Ⅱ following partial dorsal rhizotomy, fifteen cats were used and divided into three groups. Two group animals were performed unilateral spared rhizotomy and animals were sacrificed at survived 3 and 10 days after operation. The segment L 3, L 5 of spinal cord and L 6 dorsal root ganglion(DRG) from the three group animals were taken and sectioned into 20 μm in thickness. The sections were stained by immunohistochemistry method (antibody for NT 3 1∶1500, Santa Cruz) and in situ hybridization technique (NT 3 cRNA probe, 1∶100). The percentage of neurons for large, medium and small size in DRG and the percentage of neurons and glia cells in spinal lamina Ⅱ in one side of normal animals, operation side of unilateral dorsal rhizotomy were counted and analyzed by statistic method. The results were as follows: The positive product of NT 3 and its mRNA of DRG was mainly distributed in large neurons and in a few medium and small neurons. At 3 and 10 days after partial dorsal rhizotomy, the number of NT 3 mRNA positive neuron decreased apparently than that seen in normal group while the decrease in number of NT 3 positive neuron occurred at 10 days after operation (P<0.01). On the contrary, the number of NT 3 positive neurons in DRG and NT 3 mRNA in small neurons and NT 3 in medium neurons increased greatly than those of normal group (P<0.01). In contrast, in intact spinal lamina Ⅱ, the positive products of NT 3 were distributed not only in neurons but also in glia cells. After partial dorsal root rhizotomy, the number of positive neurons and glia cells in spinal lamina Ⅱ increased greatly than that of intact animal. And the maximum was at 3 days after operation. However, the NT 3 mRNA positive signal was not seen in spinal lamina Ⅱ in each group. Our results suggest that it is different for the reaction of three types of neurons in DRG following partial dorsal root rhizotomy. Especially, the results that the expression of NT 3 decreased in large neurons and increased in small neurons may imply that the partial dorsal rhizotomy may switch the expression of NT 3 from large neuron to small neuron. In addition, our results also suggest that the increase in number of positive neurons and glia cells for NT 3 in spinal lamina Ⅱ result from the partial dorsal rhizotomy. The above results indicate that NT 3 may be involved in the plasticity of spinal lamina Ⅱ.