Whether the effect of miR-181a is sexually dimorphic in stroke is unknown. Prior work showed protection of male mice with miR-181a inhibition. Estrogen receptor-α (ERα) is an identified target of miR181 in endometrium. Therefore we investigated the separate and joint effects of miR-181a inhibition and 17β-estradiol (E2) replacement after ovariectomy. Adult female mice were ovariectomized and implanted with an E2- or vehicle-containing capsule for 14d prior to 1h middle cerebral artery occlusion (MCAO). Each group received either miR-181a antagomir or mismatch control by intracerebroventricular injection 24h before MCAO. After MCAO neurologic deficit and infarct volume were assessed. Primary male and female astrocyte cultures were subjected to glucose deprivation with miR-181a inhibitor or transfection control, and E2 or vehicle control, with/without ESRα knockdown with small interfering RNA. Cell death was assessed by propidium iodide staining, and lactate dehydrogenase assay. A miR-181a/ERα target site blocker (TSB), with/without miR-181a mimic, was used to confirm targeting of ERα by miR-181a in astrocytes. Individually, miR-181a inhibition or E2 decreased infarct volume and improved neurologic score in female mice, and protected male and female astrocyte cultures. Combined miR-181a inhibition plus E2 afforded greater protection of female mice and female astrocyte cultures, but not in male astrocyte cultures. MiR-181a inhibition only increased ERα levels in vivo and in female cultures, while ERα knockdown with siRNA increased cell death in both sexes. Treatment with ERα TSB was strongly protective in both sexes. In conclusion, the results of the present study suggest miR-181a inhibition enhances E2-mediated stroke protection in females in part by augmenting ERα production, a mechanism detected in female mice and female astrocytes. Sex differences were observed with combined miR-181a inhibition/E2 treatment, and miR-181a targeting of ERα.

中文翻译：

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通过靶向星形胶质细胞雌激素受体-α，抑制miR-181a可保护雌性小鼠免受短暂性局灶性脑缺血的影响。

尚不清楚miR-181a在卒中中是否具有性二态性。先前的研究表明，miR-181a抑制作用可以保护雄性小鼠。雌激素受体-α（ERα）是子宫内膜中miR181的靶标。因此，我们研究了卵巢切除术后miR-181a抑制和17β-雌二醇（E2）替代的单独和联合作用。将成年雌性小鼠切除卵巢，并在大脑中动脉闭塞1h（MCAO）之前植入含E2或载剂的胶囊14天。每组在MCAO前24h接受脑室内注射miR-181a antagomir或错配对照。MCAO后评估神经功能缺损和梗塞体积。使用miR-181a抑制剂或转染对照，以及E2或溶媒对照对原代雄性和雌性星形胶质细胞进行葡萄糖剥夺，有/无ESRα基因敲低的小干扰RNA。通过碘化丙啶染色和乳酸脱氢酶测定评估细胞死亡。具有/不具有miR-181a模拟物的miR-181a /ERα靶位阻滞剂（TSB）用于确认星形胶质细胞中miR-181a对ERα的靶向作用。单独地，miR-181a抑制或E2减少了雌性小鼠的梗塞体积并改善了神经系统评分，并保护了雄性和雌性星形胶质细胞培养物。组合的miR-181a抑制作用加上E2可以为雌性小鼠和雌性星形胶质细胞培养物提供更大的保护，但在雄性星形胶质细胞培养物中则没有。对MiR-181a的抑制只会增加体内和女性培养物中的ERα水平，而用siRNA抑制ERα则可增加男女的细胞死亡。ERαTSB的治疗对男女都有强烈的保护作用。综上所述，本研究的结果表明，miR-181a抑制作用部分地通过增强ERα的产生而增强了雌性E2介导的中风保护，这是在雌性小鼠和雌性星形胶质细胞中发现的一种机制。联合miR-181a抑制/ E2处理和miR-181a靶向ERα观察到性别差异。