甘露醇对缺血再灌注大鼠脑保护作用的机制研究

目的 观察甘露醇对缺血再灌注大鼠脑组织神经损伤、炎症、氧化应激及神经元凋亡的影响，并探究其潜在的机制与丝裂原活化蛋白激酶（mitogen-activated protein kinase，MAPK）信号通路之间的联系。方法 线栓法建立大鼠缺血再灌注脑损伤模型。60只大鼠随机分为假手术组、模型组、甘露醇组、甘露醇+二甲双胍组。检测大鼠神经缺损、脑组织含水量、中风率及海马组织病理损伤；酶联免疫吸附试验法检测大鼠血清肿瘤坏死因子α（tumor necrosis factor-α，TNF-α）、白细胞介素6（interleukin-6，IL-6）、超氧化物歧化酶（superoxide dismutase，SOD）、丙二醛（malondialdehyde，MDA）；TdT介导的dUTP末端标记法（TdT mediated dUTP terminal labeling，TUNEL）检测脑组织神经元凋亡；蛋白免疫印迹实验检测脑组织磷酸化（phosphorylation，p）-p38蛋白激酶（p38 mitogen-activated protein kinase,p38）、p-细胞外调节蛋白激酶（extracellular regulated protein kinase，ERK1/2）、p38、ERK1/2蛋白。结果 相较于假手术组，模型组大鼠神经功能缺损评分、脑组织含水量、中风率、脑组织神经元凋亡率均升高，神经元病理损伤加重，血清TNF-α、IL-6、MDA升高，SOD降低，脑组织p-p38、p-ERK1/2蛋白表达升高（P＜0.05）。甘露醇给药后，大鼠的上述指标明显反向调控，且甘露醇的这种作用可被二甲双胍削弱。结论 甘露醇可减少缺血再灌注对大鼠脑神经的损伤，抑制脑炎症和氧化应激反应及神经元的凋亡，发挥保护脑作用的机制与抑制MAPK信号通路的活性有关。

Study on the mechanism of protective effect of mannitou on cerebral ischemia-reperfusion in rats

Objective To observe the effects of mannitou on nerve injury, inflammation, oxidative stress and neuronal apoptosis in brain tissue of rats with ischemia-reperfusion, and to explore the relationship between its potential mechanism and mitogen-activated protein kinase (MAPK) signaling pathway.Methods The model of cerebral ischemia-reperfusion injury in rats was established by thread occlusion method. Sixty rats were randomly divided into sham operation group, model group, mannitou group and mannitou+metformin group. The nerve defect, brain water content, cerebral stroke rate and pathological injury of hippocampus were detected. Serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), superoxide dismutase (SOD), and malondialdehyde (MDA) were detected by enzyme-linked immunosorbent assay (ELISA). TdT mediated dUTP nick end labeling (TUNEL) was used to detect neuronal apoptosis in brain tissue, and the phosphorylated (p)-p38 mitogen-activated protein kinase (p38), extracellular regulated protein kinase 1/2 (ERK1/2), p38 and ERK1/2 proteins were detected by Western blot (WB).Results Compared with the sham operation group, the model group had increased neurological deficit score, brain water content, cerebral stroke rate and neuron apoptosis rate, aggravated pathological injury of neurons, and increased serum TNF-α, IL-6 and MDA increased, decreased SOD, and increased expression of p-p38 and p-ERK1/2 protein in brain (P＜0.05). After administration of mannitou, the above indexes of rats were significantly and reversely regulated, and this effect of mannitou could be weakened by metformin.Conclusion Mannitou could reduce the brain nerve injury induced by ischemia-reperfusion in rats, and inhibit brain inflammation, oxidative stress and neuronal apoptosis, thus protecting the brain. The mechanism may be related to the inhibition of the activity of MAPK signaling pathway.