摘要
目的探讨肾上腺髓质素(adrenomedullin, ADM)对局灶性脑缺血再灌注大鼠神经元凋亡、梗死体积及早期生长反应基因Egr-1 mRNA表达的影响,进一步研究ADM在局灶性缺血再灌注脑损伤中的作用。方法采用线栓法制成大鼠大脑中动脉缺血再灌注(MCAO)模型,阻断血流2 小时后进行再灌注。TTC染色法测定梗死体积,TUNEL法检测神经元凋亡,原位杂交法检测Egr-1 mRNA阳性细胞表达。结果大鼠局灶性脑缺血再灌注后脑梗死体积为269 ± 20 mm3,股静脉、颈动脉、侧脑室注射ADM 后,梗死体积分别缩小为239 ± 17mm3(减少11.2%),214 ± 14 mm3 (减少20.4%),209 ± 13 mm3 (减少22.3%)。颈动脉注射ADM和侧脑室注射ADM在减少脑梗死体积方面明显优于股静脉注射ADM(P < 0.05)。缺血再灌注组大鼠缺血侧大脑皮质、海马CA1区TUNEL染色阳性细胞明显多于假手术组(P < 0.01)。给予ADM后缺血侧大脑皮质、海马CA1区TUNEL染色阳性细胞显著少于缺血再灌注组,以颈动脉给予ADM组和侧脑室给予ADM组更明显(P < 0.01)。假手术组大鼠大脑皮质有少量Egr-1mRNA阳性细胞表达,缺血再灌注后缺血侧大脑皮质、海马Egr-1mRNA阳性细胞表达多于假手术组(P < 0.01),应用ADM后三组大鼠大脑皮质、海马Egr-1 mRNA阳性细胞的表达明显高于缺血再灌注组(P < 0.01),但以颈动脉给予ADM组和侧脑室给予ADM组Egr-1 mRNA阳性细胞表达增高最明显(P < 0.01)。结论股静脉、侧脑室和颈动脉给予外源性ADM能减少神经元凋亡,减少梗死体积,激活Egr-1 mRNA的表达。
Objective To observe the influence of adrenomedullin （ADM） on neuron apoptosis, infarction volume of brain, and the expression of early growth response 1 （Egr-1） mRNA in ischemia-reperfusion rats. Methods The arteria cerebri media was tied for 2 h to construct the ischemia model. Infarction volume was detected by triphenltetrazolium chloride （T＇I＇C） staining, neuronal apoptosis and necrosis was detected with terminal deoxynucleotidyl transferase nick labeling （TUNEL） method, and the Egr-1 mRNA expression was examined by in situ hybridization （ISH）. Results Infarction volume after ischemia-reperfusion is （269 ± 20） mm^3. Infarction volume after injection of ADM through different ways are femoral vein （239 ± 17） mm^3 （decreased by 11.2%）, arteria carotis （214 ± 14） mm^3 （by 20.4%） and lateral cerebral ventricle （209 ± 13） mm^3 （by 22.3%）, respectively. The results indicate that injecting ADM through arteria carotis and lateral cerebral ventricle is much more effective than it through femoral vein （P 〈 0.05）. The TUNEL-positive cells in cerebral cortex or hippocampus are few in the sham operation group, but much more in the ischemia-reperfusion group. After being supplied with ADM, especially through arteria carotis interna or lateral cerebral ventricle way, the TUNEL-positive cells decreased obviously. Expression of Egr- 1 mRNA was low in the cerebral cortex of the sham operation group rats, enhanced in the ischemia and reperfusion group rats, and enhanced markedly after treatment with ADM, especially through arteria carotis interna or lateral cerebral ventricle way （P 〈 0.01）. Conclusion Injection of ADM through different ways could alleviate neural dysfunction, decrease neuron apoptosis and brain infarction volume, and increase the expression of Egr- 1 mRNA.
