新生大鼠缺氧缺血模型脑组织中肾上腺髓质素含量变化及其对脑细胞凋亡的影响

Content changes of adrenomedullin in brain tissue of newborn rat models of hypoxic-ischemia and its effect on programmed cell death

目的:观察新生大鼠缺氧缺血后脑内肾上腺髓质素含量变化,以及给予外源性肾上腺髓质素对缺氧缺血大鼠脑细胞凋亡的影响。方法:实验于2003-11-01/30在延边大学附属医院儿科疾病研究室进行。①脑组织肾上腺髓质素测定:选用7日龄Wistar大鼠29只单纯随机分为正常组9只、模型组及肾上腺髓质素组各10只,正常组不干预,另外2组大鼠结扎左侧颈总动脉,并吸入含体积分数为0.08氧气制备缺氧缺血性脑病模型,造模后肾上腺髓质素组即刻腹腔注射肾上腺髓质素2.0nmol/kg(浓度为82μmol/L),48h后将大鼠断头处死,取左侧脑组织测肾上腺髓质素含量。②细胞凋亡测试:7日龄Wistar大鼠39只分4组,正常组9只,模型组、肾上腺髓质素组和胰岛素样生长因子1组各10只,正常组不干预,另外3组同前造模,造模后即刻后2组分别腹腔注射肾上腺髓质素2.0nmol/kg、胰岛素样生长因子11.5μg/kg。48h后心脏灌注处死,取脑组织,行TUNEL法及苏木精-伊红染色,测定细胞凋亡数,凋亡百分率,凋亡面密度及数密度。结果:68只大鼠全部进入结果分析。①脑组织肾上腺髓质素含量:肾上腺髓质素组高于正常组和模型组[(1.81±0.43),(0.41±0.02),(1.07±0.27)ng/g,F=34.81,P<0.01],模型组高于正常组(P<0.01)。②凋亡细胞数:正常组显著低于其他3组(P<0.001),肾上腺髓质素组显著低于模型组[(9.20±0.53),(23.43±5.11)个/视野,P<0.001]。③凋亡细胞数密度和面密度:模型组高于正常组(P<0.001),肾上腺髓质素组低于模型组(数密度:0.0016±0.0007比0.0049±0.0009;面密度:0.043±0.018比0.131±0.044,P<0.001),胰岛素样生长因子1组与肾上腺髓质素组差异不显著(P>0.05)。④凋亡细胞百分率:模型组明显高于正常组[(55.5±5.1)%,(7.6±3.6)%,P<0.01],肾上腺髓质素组明显低于模型组[(21.8±1.8)%,P<0.01]。结论:①肾上腺髓质素在缺氧缺血后脑组织内含量明显升高。②肾上腺髓质素可降低缺氧缺血后的脑细胞凋亡,对脑细胞有保护作用,其效果与胰岛素样生长因子1相似。

AIM： To observe the content changes of adrenomedullin （ADM） in brain tissue of newborn rats after hypoxic-ischemic brain damage （HIBD）, and the effect of giving exogenous ADM on programmed cell death （PCD）. METHODS：The experiment was conducted in the Laboratory of Pediatrics Disease of Yanbian University Hospital from First to Thirtieth in November 2003. ①Determination of the content of brain tissue： Twenty-nine 7-day-old Wistar rats were Selected and randomly divided into normal group （n =9）, model group （n=10） and ADM group （n=10）. No intervention was given to normal group; the other groups were subjected to left carotid artery ligation and inhalation of 0.08 volume fraction oxygen to make the HIBD models. Then the ADM group was intraperitoneally injected with 2.0 nmol/kg ADM （82 μmol/L）. Forty-eight hours later, the rats were killed to determine the ADM levels in the left brain tissue. ② PCD detection： Thirty-nine 7-day-old Wistar rats were divided into 4 groups： normal group （n=9）, model group （n=10）,ADM group （n=10） and insulinlike growth factor-1 （IGF-1） group （n=10）. The normal group was no given any intervention; another 3 groups were made animal model as before. After modeling, the rats of the latter two groups were injected immediately 2.0 nmol/kg ADM.and 1.5 ug/kg IGF-1, respectively. Fortyeight hours later, the rats were killed and the brain tissue was taken for TUNEL and HE staining, and the number of apoptotic cells, apoptosis rate, apoptosis dense of rate were detected. RESULTS： Sixty-eight rats were involved in the result analysis. ① Content of ADM in the brain tissue： It was significantly higher in the ADM group than that in the normal group and model group [（1.81±0.43）, （0.41±0.02）, （1.07±0.27） ng/g, F=34.81, P 〈 0.01]; and the model group was higher than the normal group （P 〈 0.01）. ②Number of apoptotic cells： It was significantly lower in the normal group than that in another 3 groups （P 〈 0.001）, and the ADM group was lower than the model group [（9.20±0.53）, （23.43±5.11） cells per field, P 〈 0.001]. ③Numerical and area density of apoptotie cell： It was higher in the model group than that in the normal group （P 〈 0.00）, and the ADM group was lower than that in the model group （numerical density： 0.001 6±0.000 7 vs. 0.004 9±0.000 9; area density： 0.043±0.018 vs. 0.131±0.044, P〈 0.001）. No significant difference was found between the ADM group and IGF-1 group （P 〉 0.05）. ④Apoptosis rate： It was significantly higher in the model group than the normal group [（55.5±5.1）%, （7.6±3.6）%, P 〈 0.01], and the ADM group was lower than the model group [（21.8±1.8）%, P 〈 0.01]. CONCLUSION： ① The ADM level in brain tissue is increased significantly after hypoxic-ischemia. ② ADM may decrease cellular apoptosis and can protect cerebral cells during ischemia period, which is similar with IGF-1.