熊果酸对全脑缺血再灌注模型大鼠的保护作用

Protection of ursolic acid on global cerebral ischemia-reperfusion injury in rats

目的：观察熊果酸对全脑缺血再灌注模型大鼠的保护作用。方法将大鼠按随机数字表法分为假手术组，模型组，熊果酸低、中、高剂量组，每组20只。除假手术组外，其余各组大鼠采用四动脉结扎法制备全脑缺血再灌注大鼠模型。熊果酸低、中、高剂量组大鼠于插入栓线后立即尾静脉注射熊果酸混悬液40、80、120 mg/kg，模型组和假手术组给予等体积生理盐水。再灌注后6 h，记录各组大鼠翻正反射和脑电恢复时间，测定各组大鼠脑组织含水量及脑组织中MDA、SOD、乳酸脱氢酶、过氧化氢酶水平；ELISA法测定脑组织中炎症因子TNF-α、IL-1β、IL-6水平。结果与模型组比较，熊果酸中、高剂量组翻正反射恢复时间[（20.6±7.2）min、（18.2±6.9）min 比（27.3±8.8）min]、脑电恢复时间[（16.2±5.8）min、（14.9±5.6）min比（24.1±7.2）min]缩短（P＜0.05或P＜0.01）；脑组织含水量[（79.0±0.7）%、（78.6±0.5）%比（80.7±0.9）%]降低（P＜0.05或 P＜0.01）；脑组织 SOD[（158.5±8.4）U/mg、（165.4±9.0）U/mg 比（143.0±7.1）U/mg]、过氧化氢酶[（3.3±1.4）U/mg、（3.9±1.5）U/mg 比（2.4±0.9）U/mg]、乳酸脱氢酶[（16.0±2.6）mmol/g、（18.4±2.8）mmol/g 比（12.4±1.9）mmol/g]水平升高， MDA[（18.6±2.8）μmol/g、（17.2±2.4）μmol/g比（24.9±3.4）μmol/g]、TNF-α[（45.8±6.3）nmol/L、（40.1±5.6）nmol/L比（56.3±7.2）nmol/L]、IL-6[（187.2±18.5）nmol/L、（136.8±15.7）nmol/L比（238.4±22.9）nmol/L]水平降低。熊果酸高剂量组大鼠脑组织 IL-1β[（713.6±56.3）nmol/L 比（915.7±70.5）nmol/L]水平较模型组降低（P＜0.05或P＜0.01）。结论熊果酸可促进全脑缺血再灌注模型大鼠翻正反射和脑电的恢复、降低脑组织含水量，其作用机制可能与其改善抗氧化酶系统活性、减轻自由基损伤，抑制炎症反应有关。

Objective To investigate the protective effects of ursolic acid （UA） on global cerebral ischemic-reperfusion injury in rats.MethodsThe experimental rats were divided into the sham operation group, the model group, the UA low, medium and high dose groups, 20 in each group. Except the rats in the sham operation group, the rats in other groups were dealed by four arteries occlusion to made global cerebral ischemia-reperfusion model. The rats in the UA low, medium, high dose groups were given UA as 40, 80, 120 mg/kg immediately after the occlusion line was inserted; the rats in the sham operation group and the model group were given equal-volume saline. And 6 hours later, the recovery time of righting reflex and electrical activity of brain were recorded, water content of the brain were evaluated, and the activity of LDH, MDA, SOD, CAT in brain tissue were determined; the inflammatory cytokines content of TNF-α, IL-1β, IL-6 were determined by ELISA. Results Compared with the model group, the recovery time of righting reflex （20.6 ± 7.2 min, 18.2 ± 6.9 min vs. 27.3 ± 8.8 min） and electrical activity of brain （16.2 ± 5.8 min, 14.9 ± 5.6 min vs.24.1 ± 7.2 min） of the UA medium and high dose groups were shortened （P〈0.05 orP〈0.01）; the water content were significantly decreased （79.0% ± 0.7%, 78.6% ± 0.5%vs. 80.7% ± 0.9%;P〈0.05 orP〈0.01）; the activity of SOD （158.5 ± 8.4 U/mg, 165.4 ± 9.0 U/mgvs. 143.0 ± 7.1 U/mg）, CAT （3.3 ± 1.4 U/mg, 3.9 ± 1.5 U/mgvs. 2.4 ± 0.9 U/mg） in brain tissue of the UA medium and the high dose groups were significantly improved; the content of LDH （16.0 ± 2.6 mmol/g, 18.4 ± 2.8 mmol/gvs. 12.4 ± 1.9 mmol/g） were significantly increased; the content of MDA （18.6 ± 2.8μmol/g, 17.2 ± 2.4μmol/gvs. 24.9 ± 3.4μmol/g）, TNF-α （45.8 ± 6.3 nmol/L, 40.1 ± 5.6 nmol/Lvs. 56.3 ± 7.2 nmol/L）, IL-6 （187.2 ± 18.5 nmol/L, 136.8 ± 15.7 nmol/Lvs. 238.4 ± 22.9 nmol/L） were significantly decreased, and the content of IL-1β in UA 120 mg/kg treated group was significantly decreased （713.6 ± 56.3 nmol/L vs. 915.7 ± 70.5 nmol/L;P〈0.05 orP〈0.01）.Conclusion UA can effectively promote righting reflex and EEG recovery, reduce brain water content, which perhaps related with its pharmacological effects of enhanceing the activity of antioxidant enzymes, lower oxidative stress, and inhibit inflammation.