胱硫醚-β-合成酶在脑缺血-再灌注大鼠模型中表达变化的研究

Dynamic change of cystathionine β-synthase during cerebral ischemia-reperfusion and its effect in rats

目的:观察缺血-再灌注(Ischemia-reperfusion,IR)大鼠模型脑组织中胱硫醚-β-合酶(Cystathionineβ-synthase,CBS)表达的变化及意义。方法:采用改良线栓法制备大鼠大脑中动脉栓塞(Middle cerebral artery occlusion,MCAO)模型。分别应用RT-PCR及Western blot法检测SHAM组大鼠、I组大鼠以及IR组3 h、6 h、12 h和24 h大鼠脑内CBS mRNA和CBS蛋白的表达变化;采用ELISA法检测大鼠血中同型半胱氨酸含量变化;采用CBS抑制剂羟胺抑制CBS活性后,Western blot法检测氧化应激相关蛋白HO-1的表达,并用光镜观察脑组织的病理学变化。结果:IR大鼠脑组织CBS mRNA和蛋白表达水平显著高于假手术组(P<0.01),于再灌注12 h表达至峰值。和假手术组相比,血中同型半胱氨酸含量在再灌注12 h时水平最低(5.73±1.17 vs 2.88±0.93,F=25.56,P=0.001)。应用HA抑制CBS活性后,CBS及氧化应激相关蛋白HO-1表达显著减少,光镜下神经元损伤进一步加重。结论:缺血-再灌注后,脑组织中CBS表达上调可能对神经元产生保护效应。

Objective： To observe the dynamic change of cystathionine β-synthase during cerebral ischemia-reperfusion and its effect in rats. Methods： The ischemic model was established with line embolism to block the middle cerebral artery. The reverse transcription-polymerase chain reaction（ RT-PCR） and Western blot assay were used to assess the expression of cystathionine β-synthase（ CBS） in SHAM group,I group,and IR group. ELISA assay was performed to detected the homocysteine（ HCY） level in plasma. After treating with the inhibitor of cystathionine β-synthase called hydroxyla mine（ HA）,the expression of hemeoxygenase 1（ HO-1） and the pathologic change of the brain was evaluated. Results： As compared to sham group,the expression of CBS was significantly up-regulated in ischemia-reperfusion group at 12 h post-reperfusion. Meanwhile,it existed the lowest level of HCY at 12 h post-reperfusion,comparing to sham grouzp（ 5. 73 ± 1. 17 vs 2. 88 ± 0. 93,F = 25. 56,P = 0. 001）. When inhibited the activity of CBS via using HA,the down-regulation of HO-1 protein and further damage in neuron were observed. Conclusion： Cystathionine β-synthase serves as an protective factor during cerebral ischemia-reperfusion.