Jiang L-J, Zhang S-M, Li C-W, Tang J-Y, Che F-Y, Lu Y-C
Department of Neurology, Linyi People's Hospital Affiliated to Shandong University, Linyi City, Shandong Province, China.
Eur Rev Med Pharmacol Sci. 2017 Apr;21(7):1532-1540.
The aim of this study was to investigate the roles of the Nrf2/HO-1 pathway in the responses to the oxidative stress created by ischemia-reperfusion brain injury in rats.
54 healthy, adult, male SD rats were included in the study. Eighteen (18) rats were placed in the sham group. The ischemia-reperfusion model was created in the other 36 rats, among which 18 received injections of Nrf2 agonist before the surgery. The suture method was used to create artery occlusions in the right brain of the rats; and reperfusion was done after 90-minute ischemia (MCAO); while no suture was inserted in the sham group. At 3, 6, 12, 24, 48 and 72 hours after the modeling, their neurological functions were evaluated. Also, at different time points, rats were decapitated, and their fresh brain tissues were used to detect the infarct volume percentages by TTC staining and the brain water contents by the dry-wet weight method. The SOD contents in the brain tissue were measured by Xanthine oxidase assay. RT-PCR was used to detect the mRNA expression of HO-1 in the brain tissues, and western blot method was used to detect the expression level of HO-1 and Nrf-2.
The rats in the sham group had no obvious neurological defects; while those in the MCAO group showed significant neurological defects at all time points. The MCAO group had higher neurological evaluation scores than the sham group. TTC staining showed that infarct in the MCAO group kept increasing over time and peaked at 24h. Measurements of SOD found that the sham group had the highest SOD among the three groups, and showed no significant fluctuation over time. The MCAO group had much lower SOD activities than the sham group at all the time points. The higher the level of HO-1mRNA and protein expression in the brain tissue of rats in each group, the higher the degree of brain injury, but the lower the level of Nrf2 protein expression and the lower degree of brain injury. Nrf2 agonist markedly improved all these indicators in the rats which underwent the MCAO surgery.
The expression of HO-1 after ischemia-reperfusion brain injury may contribute to the increased infarct volume. Activation of Nrf2 could improve the prognosis of ischemia-reperfusion brain injury.
本研究旨在探讨Nrf2/HO-1信号通路在大鼠缺血再灌注脑损伤所致氧化应激反应中的作用。
本研究纳入54只健康成年雄性SD大鼠。18只大鼠置于假手术组。对其余36只大鼠建立缺血再灌注模型，其中18只在手术前注射Nrf2激动剂。采用结扎法对大鼠右脑进行动脉闭塞；缺血90分钟（大脑中动脉闭塞，MCAO）后进行再灌注；假手术组不插入结扎线。建模后3、6、12、24、48和72小时，评估其神经功能。此外，在不同时间点，将大鼠断头，取新鲜脑组织，通过TTC染色检测梗死体积百分比，采用干湿重法检测脑含水量。用黄嘌呤氧化酶法测定脑组织中SOD含量。采用RT-PCR检测脑组织中HO-1的mRNA表达，用蛋白质免疫印迹法检测HO-1和Nrf-2的表达水平。
假手术组大鼠无明显神经功能缺损；而MCAO组大鼠在所有时间点均表现出明显的神经功能缺损。MCAO组神经功能评分高于假手术组。TTC染色显示，MCAO组梗死面积随时间不断增加，在24小时达到峰值。SOD检测发现，假手术组SOD含量在三组中最高，且随时间无明显波动。MCAO组在所有时间点的SOD活性均远低于假手术组。各组大鼠脑组织中HO-1 mRNA和蛋白表达水平越高，脑损伤程度越高，但Nrf2蛋白表达水平越低，脑损伤程度越低。Nrf2激动剂显著改善了MCAO手术大鼠的所有这些指标。
缺血再灌注脑损伤后HO-1的表达可能导致梗死体积增加。激活Nrf2可改善缺血再灌注脑损伤的预后。
