大鼠坐骨神经切断后外源性bcl-2对脊髓运动神经元的保护作用

采用大鼠坐骨神经切断损伤模型,行神经外膜端端对线缝合,术中依不同组别,动物于神经缝合处远端0．5cm处分别注射人的正义和反义bcl-2重组腺病毒(Ad／s-bcl-2、Ad／as-bcl-2),报道基因重组腺病毒(Ad／lacZ)和生理盐水。术后48h,7d,15d和30d常规灌注固定大鼠,取L4-L6脊髓节段,应用X-gal染色、bel-2原位杂交和免疫组化染色、TUNEL染色以及乙酰胆碱酯酶(AChE)组织化学染色方法,观察到外源基因能在脊髓中表达,同时外源性Ad／s-bcl-2能显著减少L4到L6节段脊髓前角运动神经元凋亡的数目,减少脊髓前角运动神经元中因坐骨神经切断导致的AChE活性的降低幅度,并加快其恢复。而Ad／as-bcl-2可显著增加坐骨神经切断诱导的脊髓前角运动神经元凋亡数目以及AChE活性降低幅度,并延缓其恢复。这些观察结果表明,外源性bcl-2能保护周围神经切断后引起的脊髓运动神经元损伤。

Protective effect of exogenous bcl-2 on spinal cord motoneurons following sciatic nerve axotomy in the rat

The aim of this study was to investigate the protective effect of exogenous bcl-2 on spinal cord motoneurons following sciatic nerve axotomy. After epineurium suturing, sense bcl-2 (Ad/s-bcl-2), antisense bcl-2 (Ad/as-bcl-2), or reporter gene lacZ(Ad/lacZ) recombinant adenovirus or NS was injected into the sciatic nerve 0.5 cm distant from the sutured point respectively in different groups. The rats were transcardially perfused with 4% paraformaldehyde on postoperative 48 h, 7d, 15d and 30d respectively and the spinal cords of L4 to L6 were harvested. X-gal staining, bcl-2 in situ hybridization and immunohistochemical staining, TUNEL (terminal deoxynucleotidyl transferase mediated dUTP nick end labeling) staining and AChE (acetyl cholinesterase) histochemical staining were used. We observed that the exogenous lacZ gene was expressed in the spinal cord of Ad/lacZ group, and sense bcl-2 significantly decreased the number of apoptotic motoneurous and the decreasing degree of AChE activity of the motoneurons in the spinal cord induced by sciatic nerve axotomy and accelerate AChE activity recovery. However, antisense bcl-2 increased the number of apoptotic motoneurons and the decreasing degree of AChE activity of the motoneurous in the spinal cord induced by sciatic nerve axotomy and prolonged AChE activity recovery. These results demonstrate that exogenous bcl-2 may protect motor neurons from injury induced by peripheral nerve axotomy.