部分背根神经切断对脊髓Ⅱ板层GDNF表达的影响

The Effect of Partial Dorsal Root Rhizotomy on the Expression of GDNF in Spinal Lamina Ⅱ

目的 :为探讨胶质源性神经营养因子 (GDNF)与脊髓Ⅱ板层可塑性的关系 .方法 :将成年雄猫 5只行单侧部分背根切断术 (切除一侧的L1～L5,L7～S2 DRG ,保留L6DRG为备用根 ) .术后动物存活 10d .取L3 脊髓制作 2 0 μm厚冰冻切片 .用GDNF抗体 (1∶15 0 0 )按常规ABC法染色 ,观察GDNF样免疫反应在脊髓的分布 ,计数Ⅱ板层GDNF阳性神经膨体密度 .测定Ⅱ板层GDNF的平均灰度值以间接反映其相对含量 .结果 :正常侧 ,GDNF的免疫阳性反应物主要分布在脊髓灰质神经元 ,胞浆染色 ,Ⅱ板层亦见少量GDNF阳性神经膨体 ,白质胶质细胞亦有GDNF阳性反应 .部分去背根后 10d ,L3 平面手术侧Ⅱ板层GDNF含量及神经膨体密度均明显较非手术侧减少 .结论 :部分背根切断后 ,手术侧Ⅱ板层GDNF的含量减少提示GDNF不仅与脊髓的生理功能有关 。

Objective: Investigating the relationship between glial cell line-derived neurotrophic factor(GDNF) and plasticity of the spinal lamina Ⅱ. Methods: 5 adult male cats were performed unilateral spared root rhizotomy (L 1-L 5, L 7-S 2 was transected, L 6 DRG was spared). On the 10th day after the operation, the animals were sacrificed and L 3 segments were taken and made into frozen section 20?μm on the thickness. The sections were stained using specific GDNF antibody (1∶1?500) by ABC method. The distribution of GDNF-like immunoreactivity products in the spinal cord was observed and the density of GDNF positive varicosities in the spinal lamina Ⅱ was also counted. Furthermore, the gray degree of GDNF in the spinal lamina Ⅱ were also determined to know its content. Results: In the intact side, GDNF positive immunoreactive products mainly distributed in neurons of gray matter. GDNF positive varicosities appeared in the lamina Ⅱ and some glial cells. On 10d after the operation, density of GDNF positive varicosities in lamina Ⅱ of the operated side decreased apparently compared to that of the opposite side, while gray degree increased prominently. Conclusion: The level of GDNF in lamina Ⅱ of the operated side after partial dorsal rhizotomy was downregulated. It indicates that GDNF not only participates in the physiological function of the spinal cord, but also plays an important role in the plasticity of the spinal lamina Ⅱ.