大剂量甲基强的松龙对大鼠脊髓损伤后诱导型一氧化氮合酶表达及细胞凋亡的影响

背景:甲基强的松龙(MP)具有多方面的神经保护作用,目前广泛应用于治疗急性颅脑和脊髓损伤,但其作用机制尚不完全清楚。目的:探讨大鼠脊髓损伤后应用大剂量甲基强的松龙(MP)对诱导型一氧化氮合酶(iNOS)表达及细胞凋亡的影响。设计:采用随机分组、安慰剂对照实验研究。单位:大连医科大学第一附属医院骨科。材料:实验在大连医科大学第一附属医院骨科实验室完成。成年雄性SPF级SD大鼠56只,体质量300～350g。由大连医科大学实验动物中心提供。干预:成年大鼠随机分为脊髓损伤后应用大剂量甲基强的松龙组(A组)和应用生理盐水组(B组)。损伤后不同时间点(4,8h,1,3,7,14,21d)按Tarlov标准评价大鼠双后肢神经功能恢复情况,然后处死。用苏木精-伊红(HE)染色观察损伤脊髓组织病理变化,用免疫组化染色检测iNOS阳性细胞,原位末端标记法(TUNEL法)标记凋亡细胞。主要观察指标:两组大鼠各时相点iNOS表达阳性细胞率,凋亡指数和Tarlor平分。结果:HE染色镜检发现脊髓组织病理学改变甲基强的松龙组明显轻于生理盐水组。两组均发现凋亡细胞及iNOS表达,神经细胞凋亡指数及iNOS表达均为生理盐水组大于甲基强的松龙组(P<0.01或P<0.05)。结论:大剂量甲基强的松龙能抑制大鼠脊髓损伤后iNOS表达及细胞凋亡。

Effect of high-dose methylprednisolone on expression of inducible nitric oxide synthase and apoptosis in rats after spinal cord injury

BACKGROUND: Methylprednisolone(MP) has multiple protective effects on neurons, and now has been widely applied for the treatment of clinical craniocerebral injury and spinal cord injury(SCI) . However, its mechanism remains not quite clear.OBJECTIVE: To investigate the effect of high-dose MP on expression of inducible nitric oxide synthase(iNOS) and apoptosis in rats after spinal cord injury(SCI).DESIGN: A randomized grouping and placebo-controlled trial. SETTING: Department of Orthopaedics, the First Affiliated Hospital of Dalian Medical University.MATERIALS: The experiment was completed in the Laboratory of Department cf Orthopaedics, the First Affiliated Hospital of Dalian Medical University. Fifty-six adult male Sprague-Dawley rats (300- 350 g) ranked SPF were provided by Center for Experimental Animals, Dalian Medical University.INTERVENTIONS: After SCI, the adult SD rats were divided randomly into two groups, MP group and normal saline group (NS group). They were observed for Tarlov' s scores on functional recovery of dual behind limbs at 4, 8 hours, 1, 3, 7, 14, 21 days after surgery, and then were sacrificed. The tissue sections were stained with hematoxylin and eosin (HE), immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) method, and the injured spinal cord tissues were evaluated.MAIN OUTCOME MEASURES: Positive expression of iNOS, apoptotic index and Tarlov' s scores were determined at different phases in the two groups.RESULTS: The histopathological changes in the spinal cord tissues observed with HE staining microscopic examination in NS group were worse than those in MP group. Expression of iNOS and apoptotic cells were observed in the two groups, and the apoptotic index and expression of iNOS in NS group were higher than those in MP group( P ＜ 0.01 or P ＜ 0.05).CONCLUSION: High-dose MP can inhibit iNOS expression and apoptosis after SCI in rats.