大鼠脊髓发育及损伤后NIDD mRNA表达的实验研究

Expression of NIDD mRNA in spinal cord during the development and after spinal cord injury

目的：探讨在大鼠发育过程中及急性脊髓损伤后脊髓组织中NIDD （nNOS-interacting DHHC domain-containing protein with dendritic mRNA）mRNA的表达变化及意义。方法：采用改良Allen＇s打击法，咬除T8-10椎板后，造成大鼠脊髓损伤模型，致伤量为10×10g·cm；借助实时荧光定量PCR、原位杂交与免疫荧光结合的方法，定量、定位研究发育过程中及脊髓损伤后早期大鼠脊髓组织中NIDD mRNA与nNOS mRNA表达的时间和空间分布特征。结果：大鼠发育过程中，胚胎16d的大鼠脊髓中可见NIDD mRNA的高表达，在生后1d，与nNOS共表达于尚未分化成熟的前角，在白质也见NIDD的阳性信号。成年后呈低表达；nNOS mRNA于生后1～3d出现表达高峰；脊髓损伤后NIDD mRNA表达明显增多，在8h到达高峰，分布于脊髓前角、中间带、中央管周围及后角nNOS阳性的神经元，7d恢复至正常水平；nNOS mRNA在损伤后8h达到高峰，1d降低至正常水平。而且，在脊髓损伤后NIDD mRNA与nNOS mRNA二者表达呈正相关。结论：胎鼠脊髓中，NIDD高表达于nNOS阳性细胞，提示其在脊髓组织的发育成熟过程中的作用可能与nNOS相关。脊髓损伤后脊髓组织中NIDD与nNOS表达增多，提示在脊髓损伤的病理过程中，NIDD可能通过调节nNOS的细胞亚定位及活性而发挥一定的生物学作用。

Objective： To study NIDD mRNA expression during the development and after spinal cord injury（SCI）. Methods： The thoracic spinal cord （T8-T10） of rats were injured according to the method of modified Allen＇s by 10×10 g·cm. By means of Real time polymerase chain reaction （Real time-PCR） and in situ hybridization （ISH）, the spatial and time distribution features of the early expression ofNIDD mRNA in develop ing and injured spinal cord tissues of rats were measured. Results： During the development of spinal cord, NIDD mRNA was highly expressed at embryo 16d and at postnatal ld, and co-localized with nNOS in the undifferenti ated ventral horn, as well in white matter. And then it decreased significantly till postnatal 12w, nNOS mRNA was highly expressed from postnatal ld to 3d. The high expression ofNIDD mRNA appeared at the 8 hour after spinal cord injury, and co-localized with nNOS in neurons of ventral horn, intermedial zone, the area around central canal and dorsal horn, and recovered to the normal at the 7 day after SCI. The expression of nNOS mR NA reached the peak at the 8 hour after SCI and immediately decreased to normal level. Conclusions： High co-expression of NIDD mRNA and nNOS during embryo and early postnatal period suggests that a probable role of NIDD and nNOS in the development of central nervous system. After spinal cord injury, the phenomenon of the increase of NIDD and nNOS mRNA indicates that NIDD may interact with nNOS during the pathological process.