大鼠脊髓全横断后脑源性神经营养因子及其高亲和力受体在运动皮质表达的变化

CHANGES OF BDNF AND TrkB EXPRESSION IN RAT MOTOCORTEX FOLLOWING COMPLETE SPINAL CORD TRANSECTION

目的 研究大鼠脊髓全横断后脑源性神经营养因子 (BDNF)及其高亲和力受体 (TrkB)在运动皮质表达的变化 ,为进一步探索脊髓损伤后再生修复机制和神经营养因子治疗脊髓损伤提供实验依据。 方法 雄性SD大鼠 4 2只随机分为 3组 :1 脊髓横断组 :动物脊髓在胸 9节段完全横断 ,按存活时间不同分为术后 3、7、14、2 1及 2 8d组 ;2 假手术组 (只行椎板切除术 ) ;3 正常对照组。动物到达存活时间点后 ,应用免疫组织化学ABC方法和图像分析技术检测TrkB及BDNF在运动皮质的表达和分布。 结果 对照组和实验组运动皮质TrkB和BDNF阳性细胞主要分布在第 5层 ,第 3、4、6层也有少量阳性细胞。脊髓全横断后TrkB和BDNF的表达逐渐增高 ,于术后 2 1d达高峰 ,2 8d回到正常水平 ,且TrkB表达上调早于BDNF。 结论 脊髓全横断后运动皮质对BDNF的需求增加 ,内源性BDNF的增加可能有利于受损的皮质脊髓束神经元的存活与再生 ;在损伤早期给予外源性BDNF可能更有利于受损的皮质脊髓束神经元。

Objective Changes of expression of brain\|derived neurotrophic factor(BDNF) and its high affinity receptor(TrkB) in rat motocortex following complete spinal cord transection have been studied in order to provide the experimental evidences for the mechanisms of regeneration and repair after spinal cord injury and for neurotrophins to treat spinal cord injury. Methods Male Sprague\|Dawley rats weighing 200\|250?g were divided into three groups at random:(1)Spinal cord transection group which was randomly subdivided into five subgroups according to the survival time at the day 3,7,14,21 and 28 postoperative( n =6 for each time point).In this group,the spinal cord of rat was transected completely at thoracic level 9.(2)Sham operation group(laminectomy only, n =6).(3)Normal control group( n =6).The expression of TrkB and BDNF in motocortex was examined by immunocytochemistry and image analysis. Results TrkB and BDNF immunoreactive cells were mainly localized in motocortex layer V in both control and experimental groups,only a few positive cells were found in layers Ⅲ,Ⅳ and Ⅵ.After operation the expression of TrkB and BDNF was increased gradually and reached the peak at the day 21,and then returned to the normal level at the day 28 postoperative.The up\|regulation of TrkB occurred earlier than that of BDNF.Our data first reveal the profile of BDNF and TrkB expression in motocortex after complete spinal cord transection at thoracic level.Conclusions\ The results suggest that the demand of BDNF increases in motocortex after spinal cord injury and the increase of endogenous BDNF may be beneficial for the survival and regeneration of the injured corticospinal neurons and that administration of exogenous BDNF may be more beneficial for the injured neurons at the early stage after injury.\;[