Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 2799 West Grand Blvd, Detroit, MI 48202-2689, USA.
Hypertension. 2010 May;55(5):1172-8. doi: 10.1161/HYPERTENSIONAHA.110.150839. Epub 2010 Mar 8.
Premenopausal women have less cardiovascular disease and lower cardiovascular morbidity and mortality than men the same age. Our previous studies showed that female mice have lower mortality and better preserved cardiac function after myocardial infarction. However, the precise cellular and molecular mechanisms responsible for such a sex difference are not well established. Using cultured adult mouse cardiomyocytes, we tested the hypothesis that the survival advantage of females stems from activated estrogen receptors and Akt survival signaling pathways. Adult mouse cardiomyocytes were isolated from male and female C57BL/6J mice and treated with hydrogen peroxide (100 micromol/L) for 30 minutes. Cell survival was indicated by rod ratio (rod shaped cells:total cells), cell death by lactate dehydrogenase release, and positive staining of annexin-V (a marker for apoptosis) and propidium iodide (a marker for necrosis). In response to hydrogen peroxide(,) female adult mouse cardiomyocytes exhibited a higher rod ratio, lower lactate dehydrogenase release, and fewer Annexin-V-positive and propidium iodide-positive cells compared with males. Phospho-Akt was greater in females both at baseline and after hydrogen peroxide stimulation. The downstream molecule of Akt, phosphor-GSK-3beta (inactivation), was also higher, whereas caspase 3 activity was lower in females in response to hydrogen peroxide. Bcl-2 did not differ between sexes. Estrogen receptor-alpha was the dominant isoform in females, whereas estrogen receptor-beta was low but similar in both sexes. Our findings demonstrate that female adult mouse cardiomyocytes have a greater survival advantage when challenged with oxidative stress-induced cell death. This may be attributable to activation of Akt and inhibition of GSK-3beta and caspase 3 through an estrogen receptor-alpha-mediated mechanism.
绝经前女性患心血管疾病的风险低于同年龄男性，且心血管发病率和死亡率更低。我们之前的研究表明，雌性小鼠在心肌梗死发生后死亡率更低，心脏功能保存更好。然而，导致这种性别差异的确切细胞和分子机制尚不清楚。本研究使用培养的成年雄性和雌性 C57BL/6J 小鼠心肌细胞，检验了这样一个假说，即雌性的生存优势源于雌激素受体和 Akt 生存信号通路的激活。用 100 微摩尔/升过氧化氢处理成年雄性和雌性 C57BL/6J 小鼠心肌细胞 30 分钟，然后通过杆状细胞与总细胞的比例（杆状细胞：总细胞）评估细胞存活率，通过乳酸脱氢酶释放评估细胞死亡率，并用 Annexin-V（凋亡标志物）和碘化丙啶（坏死标志物）阳性染色评估细胞死亡。与雄性相比，过氧化氢处理后雌性成年小鼠心肌细胞的杆状细胞比例更高，乳酸脱氢酶释放更少， Annexin-V 阳性和碘化丙啶阳性细胞更少。过氧化氢刺激前后，雌性心肌细胞磷酸化 Akt 均高于雄性。Akt 的下游分子磷酸化 GSK-3β（失活）也更高，而过氧化氢刺激后雌性心肌细胞 caspase 3 活性更低。Bcl-2 在两性之间无差异。雌激素受体-α是雌性中的主要亚型，而雌激素受体-β在两性中含量较低但相似。这些发现表明，雌性成年小鼠心肌细胞在受到氧化应激诱导的细胞死亡挑战时具有更大的生存优势。这可能归因于雌激素受体-α介导的 Akt 激活和 GSK-3β及 caspase 3 抑制。
