藻蓝蛋白在脑缺血再灌注损伤过程中的抗氧化作用

The antioxidative effect of phycocyanin in the course of cerebral ischemia-reperfusion injury in rats

目的研究脑缺血再灌注神经细胞一氧化氮合酶（NOS）的表达以及藻蓝蛋白的抗氧化作用机制。方法随机将52只Wistar大鼠分为假手术组（4只）、对照组（24只）和治疗组（24只）；后两组再分为脑缺血1h再灌注6、12h，1、3、7及14天组，每组4只。应用线栓法制作大鼠大脑中动脉阻塞再灌注（MCAO／R）模型，藻蓝蛋白进行干预，采用免疫组织化学方法分别观察神经元型NOS（nNOS）、内皮型NOS（eNOS）、诱导型NOS（iNOS）的表达以及藻蓝蛋白的干预作用。结果假手术组脑组织中nNOS、iNOS和eNOS有微弱表达，脑缺血再灌注后6h，皮质区和纹状体区nNOS、iNOS和eNOS逐渐表达增强，于24h达高峰，之后逐渐减弱，至7～14d仍高于假手术组。治疗组NOS变化趋势与对照组相似，与对照组同一时间点比较，nNOS和iNOS表达明显低，eNOS表达明显增强。结论脑缺血再灌注损伤后，藻蓝蛋白可能通过降低脑组织中nNOS和iNOS表达，上调eNOS的表达，而发挥其抗氧化作用。

Objective To study the expression of nNOS, eNOS and iNOS after focal cerebral ischemia-reperfusion in rats and the protective effect of phycocyanin on the neurons. Methods Fifty-two adult male Wistar rats were divided into three groups： sham operation group （n =4）, model control group （ n = 24） and phycocyanin group （ n = 24）. The model, of middle cerebral artery occlusion-reperfusion （MCAO/R） was established using the intraluminal filament occlusion and phycocyanin was used for intervention. The apoptosis and the expression of NOS were determined by immunohistochemical staining to evaluate the effects of phycocyanin. Results The expression of nNOS, iNOS and eNOS in brain tissue was weak in sham operation group, and increased in model control group after reperfusion for 6 h after ischemia, reached a maximum at 24 h, then decreased gradually, but still higher than that in sham operation group. In phycocyanin group, the tendency of changes in expression of nNOS, iNOS and eNOS was similar to that in the control group, but the expression of nNOS and iNOS was significantly lower and eNOS was higher than those in control group. Conclusions Phycocyanin might have protective effect against cerebral ischemia-reperfusion injury through its antioxidative effect by down-regulating expression of nNOS and iNOS and upregulating eNOS.