大鼠脊髓损伤后神经型一氧化氮合酶羧基末端PDZ结合配体mRNA的表达

Expression of CAPON mRNA after spinal cord injury in rats

目的 探讨大鼠脊髓损伤后神经型一氧化氮合酶（nNOS）羧基末端PDZ结合配体（carboxy-terminal PDZ ligand of nNOS，CAPON）mRNA的表达变化及其意义。方法采用脊髓横断模型，用实时荧光定量聚合酶链式反应（realtime-PCR）及原位杂交与免疫荧光技术结合的方法检测正常成年大鼠脊髓内以及脊髓损伤后不同时间点损伤段脊髓组织中CAPONmRNA的表达，采用cresylviolet染色计数脊髓组织内存活神经元。结果 CAPON mRNA在对照组大鼠脊髓内呈低水平表达于前角神经元，脊髓损伤后表达于灰质各部分神经元及白质。在损伤早期2h表达开始升高，于8h达到高峰，随后1d有下降趋势，3d时稍有上升，损伤后14d恢复至正常水平。而nNOSmRNA在损伤后2h迅速上调，于8h达高峰，随即下降至正常水平。在此过程中，有神经元凋亡现象的发生。损伤后2h存活神经元的数量即减少，随后稍有增多，但仍少于对照组，3d后存活神经元再度减少，持续至14d。结论 大鼠脊髓损伤后CAPONmRNA表达发生变化，提示CAPON可能通过调节nNOS的活性及亚细胞定位而影响神经元的凋亡，在脊髓损伤病理过程中发挥积极的调节作用。

Objective To study the expression of carboxy-terminal PDZ ligand of nNOS （CAPON） mRNA in the spinal cord of rats after spinal cord injury （SCI）. Methods After the spinal cord transection rat model was established, the expression of CAPON-encoding mRNA in normal rat spinal cord and at various time points after SCI was detected by Real-time PCR and in situ hybridization （ISH） combined with immunohistochemistry. Living neurons in the spinal cord were counted by cresyl violet stai- ning. Results The low expression of CAPON mRNA was present in the anterior horn neuron of spinal cord before SCI and in the neuron of various parts of the gray substance and white substance after SCI. Expression of CAPON mRNA was increased at the 2nd hour, reached the peak at the 8th hour and then began to decrease at day 1, but was increased slightly at day 3 and returned to normal at day 14 after SCI. The expression of nNOS mRNA increased immediately at the 2nd hour and reached peak at the 8th hour after SCI and then decreased to normal level, when neuron apoptosis occurred. The number of living neurons began to decrease at the 2nd hour after SCI and thereafter increased slightly but still lower than control group. The living neurons tended to reduce gradually at days 3-14. Conclusions High level expression of CAPON mRNA in rats after SCI indicates that CAPON may play an active regulatory role in the pathological progression after SCI by stabilizing nNOS and subcellular localization to prevent neuron apoptosis.