一氧化氮对大鼠局灶性脑缺血再灌注损伤的影响

目的观察L-精氨酸(L-Arg)和氨基胍(AG)对大鼠局灶性脑缺血组织中一氧化氮(NO)含量的影响,探讨NO对脑缺血再灌注损伤的作用及机制。方法将60只大鼠随机分为假手术组、模型组、L-Arg组和AG组,每组15只。L-Arg组、AG组、模型组和假手术组用线栓法建立大鼠局灶性脑缺血(MCAO)模型后,L-Arg组按500mg·kg-1腹腔注射1mLL-Arg注射液;AG组按100mg·kg-1术后腹腔注射1mLAG注射液;模型组和假手术组术后腹腔注射1mL灭菌生理盐水。观察缺血再灌注后12、24、72h大鼠行为学改变,血清中NO浓度和脑内一氧化氮合酶(NOS)分布的变化。结果与模型组相比,L-Arg组在缺血再灌注12h行为学评分显著降低(P<0.05),AG组在缺血再灌注24h行为学评分显著降低(P<0.05);AG组在缺血再灌注12h行为学评分高于L-Arg组(P<0.05)。与假手术组相比,模型组、L-Arg组和AG组缺血再灌注12、24、72h的NO含量均显著增加(P<0.05);与模型组相比,L-Arg组缺血再灌注12h的N0含量显著升高(P<0.05),AG组缺血再灌注24h的NO含量显著降低(P<0.05)。缺血再灌注12和24h,AG组的NO含量均显著低于L-Arg组(P<0.05);与假手术组相比,缺血再灌注12、24、72h的模型组、L-Arg组和AG组的iNOS阳性细胞均显著增加(P<0.05);与模型组相比,缺血再灌注12、24、72h的L-Arg组iNOS阳性细胞数差别无统计学意义(P>0.05);但AG组在3个时间点的iNOS阳性细胞数均显著低于模型组(P<0.05);AG组在3个时间点的iNOS阳性细胞数均低于L-Arg组(P<0.05)。结论脑缺血再灌注损伤后脑组织内NO和NOS的表达随时间动态变化,且NO在参与缺血性脑损伤过程中可能具有双重作用。L-Arg、AG通过不同的作用机制对大鼠局灶性脑缺血再灌注损伤具有保护作用。

Effects of nitric oxide on focal cerebral ischemia-reperfusion injury of rats

Objective To evaluate the effects of L-arginine( L-Arg) and aminoguanidine( AG) on the contents of the nitric oxide( NO) in the focal cerebral ischemia tissue of rats,and to investigate the effects and mechanism of NO on cerebral ischemiareperfusion injury. Methods Sixty rats were randomly divided into sham operation group,model group,L-Arg group and AG group,15 rats in each group. After the middle cerebral artery occlusion( MCAO) model of rat was established with line bolt method in four groups,1 mL of L-Arg ( 500 mg · kg -1 ) was given intraperioneally injection in L-Arg group; 1 mL of AG ( 100 mg·kg-1) was given intraperioneally injection in AG group;1 mL sterile saline was received intraperitoneal injection in sham operation group and model group. To observe the neurobehavioral score changes of the rat model with 12,24 and 72 hours reperfusion. The contents of NO in serum and nitric oxide synthase ( NOS) in the focal ischemic cerebral tissues at the scheduled time were assayed respectively. Results Compared with model group,the neurobehavioral scores at 12 hours of reperfusion following ischemia significantly decreased in L-Arg group( P < 0. 05) ,and at 24 hours of reperfusion following ischemia significantly decreased in AG group( P < 0. 05) ; The neurobehavioral score at 12 hours reperfusion following ischemia in AG group was higher than that in L-Arg group( P < 0. 05). Compared with sham operation group,the content of NO significantly increased in model group,L-Arg group and AG group at 12,24 and 72 hours reperfusion following ischemia ( P < 0. 05 ) ; Compared with model group,the content of NO significantly increased at 12 hours reperfusion following ischemia in L-Arg group ( P < 0. 05) ,and significantly decreased at 24 hours reperfusion following ischemia in AG group( P < 0. 05). The contents of NO at 12 and 24 hours reperfusion following ischemia in AG group were lower than those in L-Arg group( P < 0. 05). Compared with sham operation group,the positive cells expression of iNOS protein at 12,24 and 72 hours reperfusion following ischemia increased significantly in L-Arg group and AG group( P < 0. 05). There were no statistically significance in positive cells expression of iNOS protein at 12,24 and 72 hours reperfusion following ischemia between L-Arg group and model group( P > 0. 05) ,but in AG group were low-er than those in model group( P < 0. 05) ,and in AG group were lower than those in L-Arg group( P < 0. 05). Conclusion The expressions of NO and NOS in the tissue of focal cerebral ischemia-reperfusion injury were dynamic changes over time,and NO involved in ischemic brain injury may have a dual role. L-Arg and AG has beneficial protective effects on the focal cerebral ischemia-reperfusion injury of rats through the different mechanisms.