目的 探讨使用高、中、低剂量硫酸镁(MgSO4)预处理和治疗对脑缺血再灌注损伤的作用及其可能机制.方法 选取120只昆明种小鼠为研究对象,采用单纯随机抽样将其分为假手术组(30只)、缺血再灌注组(30只)、不同剂量MgSO4(20、40、80 mg/kg)预处理组(30只,每一剂量组均为10只)、不同剂量MgSO4(70、140、280 mg/kg)治疗组(30只,每一剂量组均为10只).预处理组小鼠缺血前腹腔注射不同剂量MgSO4,治疗组小鼠于再灌后即刻腹腔注射不同剂量MgSO4.观察各组小鼠组织病理学变化,检测其脑组织一氧化氮(NO)含量和总一氧化氮合酶(total nitric oxide synthase, T-NOS)、诱导型一氧化氮合酶(inducible nitric oxide synthase,iNOS)及ATP酶的活性.于脑缺血再灌注后24小时评估并记录各组小鼠的神经行为学评分.结果 不同剂量预处理组和治疗组小鼠脑组织缺血再灌注损伤病理学改变明显轻于缺血再灌注组,中、高剂量治疗组与预处理组小鼠平均存活时间均显著长于假手术组和缺血再灌注组(P<0.05).缺血再灌注组小鼠脑组织中NO含量和T-NOS、iNOS活性均明显高于假手术组、不同剂量预处理组及不同剂量治疗组(P<0.05或P<0.01).不同剂量治疗组小鼠脑组织中NO含量及T-NOS、iNOS活性均具有显著差异(P<0.05).不同剂量预处理组小鼠脑组织iNOS活性无显著差异(P>0.05).假手术组、不同剂量预处理组及不同剂量治疗组小鼠脑组织中Na+-K+-ATP酶及Ca2+-Mg2+-ATP酶的活性均高于缺血再灌注组(P<0.05).高剂量预处理组小鼠的Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活性均显著高于中、低剂量预处理组、缺血再灌注组及不同剂量治疗组(P<0.05).缺血再灌注组小鼠的神经行为学评分与假手术组、不同剂量预处理组及不同剂量治疗组比较均具有显著差异(P<0.01或P<0.05);高剂量治疗组与假手术组小鼠的神经行为学评分比较无显著差异(P>0.05),高剂量预处理组与假手术组小鼠旷场实验和悬挂实验的神经行为学评分比较均具有显著差异(P<0.01或P<0.05).结论 MgSO4预处理和治疗可能通过降低T-NOS和iNOS活性和减少NO合成而增加ATP酶的活性,减轻神经元损伤,对脑缺血再灌注损伤具有保护作用.%Objective To explore the protective effect and possible mechanism of different doses of magnesium sulfate (MgSO4) pretreatment and treatment for cerebral ischemia-reperfusion injury in mice. Method 120 Kunming mice were selected and divided into sham-operated group by simple random sampling, sham-operated group (30 mice), ischemia-reperfusion group (30 mice) and different doses of MgSO4(20, 40, 80 mg/kg) pretreatment group (30 mice, 10 mice per dose) and different doses MgSO4(70, 140, 280 mg/kg) treatment group (30 mice, 10 mice per dose). Mice in pretreatment group were injected intraperitoneally with different doses of MgSO4before ischemia. Mice in treatment group were injected intraperitoneally ismmediately after reperfusion. The pathologic change was observed. The content of nitric oxide (NO), the activity of total nitric oxide synthase (T-NOS) and inducible nitric oxide synthase (iNOS) and ATPase of cerebral tissue were also detected. Animals were assessed and recorded for neurobehavioral scores at 24 hours after cerebral ischemia and reperfusion. Result The pathological change of ischemic impairment in pretreatment and treatment groups were significantly lighter than that of ischemia-reperfusion group. The average survival time of the middle and high dose treatment group and pretreatment group was significantly higher than that of sham-operated group and the ischemia-reperfusion group. The content of NO and the activities of T-NOS and iNOS of cerebral tissue in sham-operated group, pretreatment group and treatment group were all significantly lower than those of ischemia-reperfusion group (P<0.05, P<0.01). There were significant differences in NO content and T-NOS and iNOS activity among different doses treatment group (P<0.05). There was no significant difference in the activity of iNOS in brain tissue of mice among different dose pretreatment group (P>0.05). The activity of Na+-K+-ATPase and Ca2+-Mg2+-ATPase of cerebral tissue were all higher than those of ischemia-reperfusion group (P < 0.05). The activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase in high-dose pretreatment group were significantly higher than those in low-dose pretreatment group, middle-dose pretreatment group, ischemia-reperfusion group and treatment group (P<0.05). The neurobehavioral scores of ischemia-reperfusion group were significantly different from those in sham-operated group, pretreatment group and treatment group (P<0.05, P<0.01).There was no significant difference in the neurological score between high-dose treatment group and sham-operated group (P>0.05), there was significant difference the neurological score between high-dose pretreatment group and sham-operated group in open-field test and suspension test (P<0.01 or P<0.05). Conclusion MgSO4pretreatment and treatment may reduce the degree of neuron injury and have protective effect on ischemia-reperfusion cerebral injury, which may be associated with the decrease of the content of NO and the activities of NOS, iNOS and the increase of the activity of ATPase.
展开▼
