Background

Myocardial ischemia/reperfusion (I/R) injury is closely related to cardiomyocyte apoptosis. Stimulating β2 adrenergic receptor (β2AR) can effectively combat cardiomyocyte apoptosis. Previous studies demonstrate that the gut microbial metabolite phenylacetylglycine (PAGly) can stimulate β2AR. However, the effect of PAGly on myocardial I/R injury remains unknown. Methods: The hypoxia/reoxygenation (H/R) model was established using the neonatal mouse cardiomyocytes (NMCMs). Different doses of PAGly were used to treat NMCMs, and apoptosis was detected by terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) staining. Additionally, the level of cyclic adenosine monophosphate (cAMP) was examined by using a cAMP detection kit. Mouse model of myocardial I/R injury was established in C57BL/6 mice, and different doses of phenylacetic acid were administrated intraperitoneally. Apoptosis of myocardial cells was detected by TUNEL and α-actin staining. The area at risk and the infarct areas were identified by 2,3,5-triphenyltetrazolium chloride (TTC) and Evans blue staining. Western blotting was used to measure the protein expression levels of phosphorylated phosphatidylinositol 3-kinase (p-PI3K), total Akt (t-Akt), phosphorylated Akt (p-AKT), Bcl-2-associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), cleaved caspase-3. Results: PAGly significantly suppressed H/R injury-induced apoptosis in NMCMs and inhibited apoptosis in myocardial I/R injured mice in vivo. We verified that PAGly activated the anti-apoptotic Gαi/PI3K/AKT signaling cascade in NMCMs via stimulating β2AR signaling. Continuous administration of PAGly at an appropriate dose could inhibit apoptosis and reduce the infarct size resulting from I/R injury in mice. However, high-dose PAGly treatment was associated with a higher mortality rate. Moreover, we demonstrated that Aspirin reduced the infarct size and the high mortality caused by high doses of PAGly in I/R injured mice. Conclusions: These findings suggest that treatment with the gut microbial metabolite PAGly could suppress cardiomyocyte apoptosis caused by myocardial I/R injury and reduce the infarct size, which provides a novel therapeutic strategy for patients with myocardial infarction.

中文翻译：

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肠道微生物代谢产物苯乙酰基甘氨酸可通过激活β2AR保护免受缺血/再灌注引起的心脏损伤

背景

心肌缺血/再灌注（I / R）损伤与心肌细胞凋亡密切相关。刺激β2肾上腺素能受体（β2AR）可有效对抗心肌细胞凋亡。先前的研究表明，肠道微生物代谢产物苯乙酰基甘氨酸（PAGly）可以刺激β2AR。但是，PAGly对心肌I / R损伤的作用仍然未知。方法：使用新生小鼠心肌细胞（NMCM）建立了缺氧/复氧（H / R）模型。使用不同剂量的PAGly治疗NMCM，并通过末端脱氧核苷酸转移酶介导的缺口末端标记（TUNEL）染色检测凋亡。此外，使用cAMP检测试剂盒检查了环磷酸一腺苷（cAMP）的水平。在C57BL / 6小鼠中建立心肌I / R损伤的小鼠模型，并腹膜内给予不同剂量的苯乙酸。通过TUNEL和α-肌动蛋白染色检测心肌细胞的凋亡。通过2,3,5-三苯基四唑氯化物（TTC）和伊文思蓝染色确定了危险区域和梗塞区域。Western印迹用于测量磷酸化磷脂酰肌醇3-激酶（p-PI3K）的蛋白质表达水平，结果： PAGly在体内显着抑制了H / R损伤诱导的NMCM细胞凋亡，并抑制了心肌I / R损伤小鼠的细胞凋亡。我们证实，PAGly通过刺激β2AR信号传导激活了NMCM中的抗凋亡Gαi/ PI3K / AKT信号传导级联。以适当的剂量连续施用PAGly可以抑制细胞凋亡并减少小鼠I / R损伤引起的梗塞面积。然而，大剂量PAGly治疗与更高的死亡率相关。此外，我们证明了阿司匹林减少了I / R损伤小鼠中高剂量PAGly引起的梗塞面积和高死亡率。结论： 这些发现表明，用肠道微生物代谢产物PAGly治疗可以抑制由心肌I / R损伤引起的心肌细胞凋亡并减小梗塞面积，这为心肌梗塞患者提供了一种新颖的治疗策略。