瞬时受体电位香草酸亚型1激活通过抑制线粒体通透性转换孔开放保护急性心肌梗死小鼠的心肌细胞抗凋亡

瞬时受体电位香草酸亚型1（TRPV1）在心肌缺血激活后可传导心绞痛信号，释放神经肽，减轻心肌梗死后的心肌细胞凋亡。目前，TRPV1激活抑制心肌梗死后细胞凋亡的具体机制尚不清楚。线粒体通透性转换孔（MPTP）的开放与心肌细胞缺血再灌注损伤密切相关，抑制其开放可保护心肌缺血后的心肌细胞抗凋亡。本研究证明，TRPV1激活通过抑制MPTP开放而减少心肌细胞凋亡。首先，本研究利用左冠状动脉前降支结扎术建立了TRPV1基因敲除（TRPV1-/-）和野生型（WT）小鼠心肌梗死模型，辅以环孢素A（CSA）预处理抑制 MPTP开放，比较观察TRPV1、MPTP在心肌梗死中的作用。心肌组织切片氯化三苯基四氮唑（TTC）染色显示，心肌缺血24 h，TRPV1-/-小鼠的心肌梗死面积明显大于WT型小鼠。而经CSA预处理的TRPV1-/-小鼠比TRPV1-/-小鼠梗死面积明显减小。TUNEL检测心肌细胞凋亡指数（AI）揭示，WT型心肌梗死小鼠的AI明显低于TRPV1-/- 心肌梗死小鼠，而CSA预处理明显降低TRPV1-/-小鼠心肌细胞的AI。Western印迹检测胱天蛋白酶3、胱天蛋白酶9、Bcl-2、Bax、p53和细胞色素C（Cyt-C）水平。结果证明，TRPV1的激活可抑制MPTP的开放，减少线粒体Cyt-C的外溢，降低胱天蛋白酶9和胱天蛋白酶3的表达。GENMEN光度法检测MPTP开放实验显示，激活的TRPV1明显抑制了MPTP的开放。本研究证实，急性心肌梗死后的TRPV1激活可能通过抑制MPTP开放而抵抗心肌细胞凋亡，对心肌起保护作用。

Activation of Transient Receptor Potential Vanilloid 1/TRPV1 Protects Cardiomyocytes against Apoptosis in Acute Myocardial Infarct Mice by #br#Closing Mitochondrial Permeability Transition Pore#br#

The activation of transient receptor potential vanilloid 1 (TRPV1) signal stimulates the release of neuropeptide during myocardial ischemia, thereby alleviates myocardial apoptosis after myocardial infarction (MI). However, the mechanisms of TRPV1 activation inhibited apoptosis remain unclear. The open of mitochondrial permeability transition pore (MPTP) is closely related to myocardial ischemia reperfusion injury, and inhibition of its open may play a role in myocardial protection. In this study we demonstrate that the activation of TRPV1 reduces myocardial apoptosis by inhibiting MPTP open. The MI models of wild type (WT) and TRPV1-null (TRPV1-/-) mice were established using ligation of the anterior interventricular branch of left coronary artery, and part of mice was administrated with cyclosporine A (CSA) prior to MI to inhibit MPTP open. Tissue section and tetrazolium chloride (TTC) staining showed that the infarct size of TRPV1-/- mice was larger than that of WT mice after MI, while pretreatment with CSA significantly reduced the infarct size of TRPV1-/- mice. TUNEL assays revealed that the apoptosis index（AI）in MI-WT mice was markedly diminished compared to that in MI-TRPV1-/- mice, and CSA pretreatment significantly decreased the apoptosis index in MI-TRPV1-/- mice. Western blotting for the expression of caspase 3, caspase 9, Bcl-2, Bax, p53, cytochrome C (Cyt-C) demonstrated that TRPV1 activation blocked MPTP open, reduced the out flow of Cyt-C from the mitochondria, and decreased caspase 3 and caspase 9 expression. GENMEN photometric colorimetry assay showed that activated TRPV1 inhibited MPTP open. Therefore, we conclude that TRPV1 activation may protect cardiac muscle from cardiomyocyte apoptosis by inhibiting MPTP open under acute MI.