氯氮平对大鼠局灶性脑缺血再灌注损伤的保护作用

Protective effects of clozapine on focal cerebral ischemia-reperfusion injury in rats

目的:观察氯氮平对局灶性脑缺血再灌注损伤的保护作用,并与尼莫地平进行阳性对照。方法:实验于1999年在郑州大学医学院药理教研室实验室进行,取Wistar大鼠240只,单纯随机分成缺血再灌注组,氯氮平24,12,6mg/kg组,尼莫地平组和假手术组6组,每组40只。氯氮平24,12,6mg/kg组腹腔注射相应剂量的氯氮平,尼莫地平组腹腔注射0.2mg/kg尼莫地平,缺血再灌注组和假手术组腹腔注射等体积生理盐水,均为1次/d,连续7d。给药7d后除假手术组外其他5组大鼠栓塞法建立大脑中动脉局灶性缺血再灌注模型。测定再灌注2h缺血侧脑组织含水量、丙二醛含量和超氧化物歧化酶活性;流式细胞仪定量分析细胞凋亡率;Fura-2负载,以荧光分光光度计测定细胞内游离钙的变化。结果:经补充后240只大鼠进入结果分析。①脑组织含水量:缺血再灌注组高于假手术组([81.62±0.15)%,(75.81±0.23)%,P<0.01],其他4组均低于缺血再灌注组(P<0.01)。②丙二醛含量:缺血再灌注组高于假手术组([10.85±0.38),(4.07±0.63)μmol/g,P<0.01],其他4组均低于缺血再灌注组(P<0.01)。③超氧化物歧化酶活性:缺血再灌注组低于假手术组([82.47±10.73),(280.15±10.32)Nu/mg,P<0.01],其他4组均高于缺血再灌注组(P<0.01)。④细胞内游离钙浓度:缺血再灌注组高于假手术组([574.87±14.56),(215.76±10.84)nmol/L,P<0.01],其他4组均低于缺血再灌注组(P<0.01)。⑤细胞凋亡率:假手术组为0,缺血再灌注组为28%,氯氮平6,12,24mg/kg组及尼莫地平组分别为19%,12%,5%,13%。结论:①6～24mg/kg氯氮平可显著降低细胞内游离钙含量,抑制缺血再灌注诱导的神经细胞凋亡,提示氯氮平对缺血再灌注所致神经细胞损伤的保护作用可能与其钙拮抗以及抗脂质过氧化有关。②氯氮平的神经保护作用与尼莫地平相似。

AIM： To investigate the protective effects of clozapine （CLO） on focal cerebral ischemia-reperfusion （IR） injury in rats. METHODS： The experiment was performed at the Department of Pharmacology, School of Medicine, Zhengzhou University in 1999. Totally 240 healthy SD rats were randomly divided into six groups with 40 rats in each. Namely, sham operation group; cerebral IR group; Nimodipine group; three dose groups of CLO （6, 12 and 24 mg/kg respectively）. All the rats were administered with intraperitoneal injections of CLO （6, 12 and 24 mg/kg）, Nimodipine （0.2 mg/kg） and saline in the corresponding groups, once a day and continuously for 7 days. Then the embolization method was used to establish the models of middle cerebral artery occlusion （MCAO） in rats except sham operation group. After 2 hours of IR, rats were executed to measure the contents of H2O and malonic dyadic aldehyde （MDA） along with superoxide dismutase （SOD） activity. Apoptosis was analyzed quantitatively by flow cytometer, and the change of intracellular free calcium was determined by Fura-2 fluorometry. RESULTS： A total of 240 rats were involved in the result analysis after supplement. （1）The contents of H2O and MDA were higher in IR group than in other 5 groups [（81.62±0.15）%, （75.81±0.23）%; （10.85±0.38）, （4.07±0.63） μmol/g, P 〈 0.01].（2）Compared with IR group, SOD activity was increased in other 5 groups [（82.47±10.73）, （280.15±10.32） Nu/mg, P 〈 0.01]. （3）The concentrations of intracellular free calcium were higher in IR group than in sham operation group and other 4 groups [（574.87±14.56）, （215.76±10.84） nmol/L, P 〈 0.01]. （4）The apoptosis was 0 in sham operation group, 28% in IR group, 13% in Nimodipine group, and 19%, 12%, 5% in CLO groups of 6, 12 and 24 mg/kg. CONCLUSION： （1）CLO can markedly reduce the content of intracellular free calcium, inhibit the IR-induced apoptosis, which indicates that the protective effects of CLO on cerebral ischemia-reperfusion injury may be related with calcium channel blockers and anti-lipid peroxidation. （2）CLO has the identical neuroprotective effect as Nimodipine.