大剂量甲基强的松龙对大鼠脊髓损伤后神经细胞凋亡的影响

目的:探讨大剂量甲基强的松龙(Methylprednisolone,MP)对大鼠脊髓损伤后神经细胞凋亡的影响。方法:60只Wistar成年大鼠分为MP治疗组与对照组。Allen氏重物坠击法制作T8脊髓损伤模型,治疗组经尾静脉注射大剂量MP,对照组注入等量生理盐水。术后1、3、7、14、28 d取脊髓组织分别进行HE染色、TUNEL法检测凋亡细胞、SABC法检测bcl-2和bax的含量,并对大鼠神经功能评分。结果:大鼠脊髓损伤后神经细胞发生凋亡,1 d后出现,3 d达高峰,28 d下降明显。MP组凋亡率较对照组明显降低,其bcl-2/bax比例增加,大鼠双下肢运动功能改善明显。结论:大剂量MP通过增强大鼠脊髓损伤后bcl-2/bax比例,抑制神经细胞凋亡,从而减轻损伤后的继发性损害。

The Effect of Large dose Methylprednisolone on Neural cell Apoptosis after Spinal Cord injury

Objective To explore the effect of large dose methylprednisolone on neural cell apoptosis in the rat after spinal cord injury(SCI).Methods Sixty wistar rats were divided randomly into MP treated-group and saline solution-treated group as control.The rats were subjected to spinal cord injury at the T8 level respectively by Allen weight-drop.For the MP-treated group,the rats were treated by the intravenous injection of large dose methylprednisolone.The equal volume of normal saline solution was given to the rats in control group.The rats were sacrificed at 1d,3d,7d,14d,28d after injury(n=6).Spinal cord tissue in the injured area were harvested and examined by hematoxylin and eosin(HE) staining and terminal deoxynucleotidyl transferase(TdT)-mediated deoxyuridine triphosphate-biotin nick end labeling(TUNEL) staining method and immmunohistochemical method.The neurological function of rats were evaluted by inclined plane test and BBB(Basso,Beattie and Bresnahan,BBB)scales.Results The existence of apoptosis of neuocytes after SCI was confirmed.The apoptosis phenomena occurred at 1 d,reached the peak at 3 d after injury and declined at 28 d.For the MP-treated group,the apoptosis index declined very significantly and the ratio of bcl-2 to bax was increased strikingly and a much better neurological restoration was observed compared with control group at all time points.Conclusion Large dose methylprednisolone could inhibit effectively the apoptosis of neurocytes with the increase of the ratio of bcl-2 to bax after SCI and thereby reduce the secondary injury.