二甲胺四环素对大鼠脊髓损伤后Bcl-2及Bax和Bcl-xl表达的影响

背景:中枢神经系统损伤后,神经细胞的凋亡在继发性损伤中发挥重要作用。近年来有研究表明二甲胺四环素抑制凋亡对脑组织缺血有明显的神经保护功能。目的:探讨二甲胺四环素对大鼠脊髓损伤后神经细胞凋亡和相关因子表达的影响及对损伤脊髓神经功能的保护作用。设计:随机对照动物实验。单位:华中科技大学同济医学院附属同济医院。材料:实验于2003-11/2004-12在华中科技大学同济医学院附属同济医院完成。成年雄性SD大鼠36只,随机分成4组:①空白组6只。②损伤组10只。③二甲胺四环素治疗组10只。④甲基强的松龙治疗组10只。方法:建立脊髓损伤模型,空白组只暴露脊髓,不损伤;损伤组损伤脊髓,不治疗;二甲胺四环素治疗组大鼠伤后1h给予腹腔内注射二甲胺四环素(50mg/kg),24h后再次给予50mg/kg剂量注射,然后再给予5d的25mg/kg的剂量治疗。甲基强的松龙治疗组大鼠伤后1h予腹腔内注射甲基强的松龙(100mg/kg)。空白组和损伤组予生理盐水注射,给药方法同二甲胺四环素治疗组。主要观察指标:①各组大鼠神经功能评估结果。②免疫组化法检测损伤脊髓神经细胞凋亡因子(Bcl-2,Bcl-xl,Bax)的表达。③各组大鼠脊髓组织细胞凋亡指数。结果:36只大鼠均进入结果分析。①二甲胺四环素治疗组的神经功能较损伤组提高(P<0.05),与甲基强的松龙组差异无显著性意义(P>0.05)。②二甲胺四环素治疗组Bcl-2阳性表达细胞多于损伤组,差异有显著性(62.53±7.76)%,(35.14±3.70)%,P<0.05,Bcl-xl,Bax表达与损伤组差异无显著性(P>0.05)。③损伤组的凋亡阳性细胞多于二甲胺四环素治疗组和甲基强的松龙治疗组(44.63±5.90)%,(32.71±5.26)%,(34.31±6.84)%,P<0.05。结论:二甲胺四环素能上调Bcl-2的表达,改变Bcl-2/Bax的比值,从而抑制脊髓神经细胞凋亡,对损伤脊髓的神经功能有保护作用。

Effect of minocycline on expression of Bcl-2, Bax and Bcl-xl in rats with spinal cord injury

BACKGROUND: Neuronal apoptosis produced a main effect in secondary injury after injury of central nervous system. Recently, minocycline has been reported to protect neurologic function evidently by decreasing apoptosis.OBJECTIVE:To study the effect of minocycline on apoptosis and expression of related factor, and protective effect of minocycline on neurologic function of injured spine after spinal cord injury (SCI) in rats.DESIGN: A randomized controlled animal study.SETTING: Tongji Hospital Affiliated to Tongji Medical College,Huazhong University of Science and Technology.MATERIALS: The experiment was performed at the Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology between November 2003 and December 2004. A total of 36male SD rats were divided into four groups: ①Blank control group (group A) with 6 rats, ②injured group (group B) with 10 rats, ③minocycline treatment group (group C) with 10 rats, and ④methylprednisolone treatment group (group D) with 10 rats.METHODS: The animal SCI model was established. Spinal cords of rats in the group A were exposed without injury. Spines of rats in the group B were injured without treatment. Rats of group C was treated with minocycline (50 mg/kg) by intraperitoneal injection at 1 hour after injury, and 24 hours later another 50 mg/kg was given, and then another 25 mg/kg was injected for 5 days. Methylprednisolone (100 mg/kg) was intraperitoneally injected 1 hour after injury in the group D. The rats in the group A and the group B were treated with saline, and the method of administration was the same with that of the group C.MAIN OUTCOME MEASURES: ①Neurofunction evaluation of rats in each group. ②Expressions of Bcl-2 family members (Bcl-2, Bcl-xl, and Bax) were tested with immunocytochemical method. ③Apoptosis index of spinal tissue of rats of each group.RESULTS: A total of 36 rats were involved in the result analysis. ①Neurofunction of rats in the group C increased as compared with the group B (P ＜ 0.05), and there was insignificant difference between group C and the group D (P ＞ 0.05). ②Bcl-2 positive expressive cells in the group C was more than that in the group B, and showed obvious difference between the two groups [(62.53±7.76)%, (35.14±3.70)%,P ＜ 0.05]. There was insignificant difference between expressions of Bcl-xl and Bax in group C as compared with the group B (P ＞ 0.05). ③The number of apoptosis positive cells in the group B was more than that in the group C and D [(44.63± 5.90)%, (32.71± 5.26)%, (34.31± 6.84)%,P ＜ 0.05].CONCLUSION: Minocycline can up-regulate the expression of Bcl-2, and raise the ratio of Bcl-2/Bax, so as to inhibit the neural apoptosis of spine,which have protective effect on neurologic function of injured spine.