Steroid hormone receptors including estrogen receptors (ER) classically function as ligand-regulated transcription factors. However, estrogens also elicit cellular effects through binding to extra-nuclear ER (ERα, ERβ, and G protein-coupled ER or GPER) that are coupled to kinases. How extra-nuclear ER actions impact cardiac ischemia-reperfusion (I/R) injury is unknown. We treated ovariectomized wild-type female mice with estradiol or an estrogen-dendrimer conjugate (EDC), which selectively activates extra-nuclear ER, or vehicle interventions for two weeks. I/R injury was then evaluated in isolated Langendorff perfused hearts. Two weeks of treatment with estradiol significantly decreased infarct size and improved post-ischemic contractile function. Similarly, EDC treatment significantly decreased infarct size and increased post-ischemic functional recovery compared to vehicle-treated hearts. EDC also caused an increase in myocardial protein S-nitrosylation, consistent with previous studies showing a role for this post-translational modification in cardioprotection. In further support of a role for S-nitrosylation, inhibition of nitric oxide synthase, but not soluble guanylyl cyclase blocked the EDC mediated protection. The administration of ICI182,780, which is an agonist of G-protein coupled estrogen receptor (GPER) and an antagonist of ERα and ERβ, did not result in protection; however, ICI182,780 significantly blocked EDC-mediated cardioprotection, indicating participation of ERα and/or ERβ. In studies determining the specific ER subtype and cellular target involved, EDC decreased infarct size and improved functional recovery in mice lacking ERα in cardiomyocytes. In contrast, protection was lost in mice deficient in endothelial cell ERα. Thus, extra-nuclear ERα activation in endothelium reduces cardiac I/R injury in mice, and this likely entails increased protein S-nitrosylation. Since EDC does not stimulate uterine growth, in the clinical setting EDC-like compounds may provide myocardial protection without undesired uterotrophic and cancer-promoting effects.

中文翻译：

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内皮中的非核雌激素受体α活化减少了小鼠的心脏缺血-再灌注损伤。

包括雌激素受体（ER）在内的类固醇激素受体通常起配体调节的转录因子的作用。但是，雌激素也通过与与激酶偶联的核外ER（ERα，ERβ和G蛋白偶联的ER或GPER）结合而引起细胞作用。核外ER作用如何影响心脏缺血-再灌注（I / R）损伤尚不清楚。我们用雌二醇或雌激素-树状大分子缀合物（EDC）处理了卵巢切除的野生型雌性小鼠，该蛋白可选择性激活核外ER，或接受媒介物干预两周。然后在离体的Langendorff灌注心脏中评估I / R损伤。用雌二醇治疗两周可显着减少梗塞面积并改善缺血后的收缩功能。同样，与媒介物治疗的心脏相比，EDC治疗显着减少了梗塞面积并增加了缺血后功能恢复。EDC还引起心肌蛋白S-亚硝基化的增加，这与以前的研究表明这种翻译后修饰在心脏保护中的作用一致。为进一步支持S-亚硝基化作用，一氧化氮合酶的抑制作用，而不是可溶性鸟苷酸环化酶的阻滞作用，阻断了EDC介导的保护作用。ICI182,780是G蛋白偶联雌激素受体（GPER）的激动剂，也是ERα和ERβ的拮抗剂，因此未给予保护；然而，ICI182,780显着阻断了EDC介导的心脏保护作用，表明ERα和/或ERβ参与。在确定特定的ER亚型和涉及的细胞靶标的研究中，EDC减少了心肌细胞缺少ERα的小鼠的梗塞面积并改善了功能恢复。相反，缺乏内皮细胞ERα的小鼠失去了保护。因此，内皮中的核外ERα激活减少了小鼠的心脏I / R损伤，这可能需要增加蛋白S-亚硝基化。由于EDC不会刺激子宫生长，因此在临床环境中，类似EDC的化合物可提供心肌保护，而不会产生不希望的子宫营养和促癌作用。