Physiology Department, Xuzhou Medical University, Xuzhou, 221004, Jiangsu, China.
Institute of Cardiovascular Disease Research, Xuzhou Medical University, Xuzhou, 221002, China.
Cell Commun Signal. 2019 Apr 15;17(1):34. doi: 10.1186/s12964-019-0346-2.
BACKGROUNDS/AIM: Male and female hearts have many structural and functional differences. Here, we investigated the role of estrogen (E2) in the mechanisms of sex differences in contraction through the cAMP-L-type Cachannel pathway in adult mice left ventricular (LV) apical myocytes at basal and stress state.
Isolated LV apical myocytes from male, female (Sham) and ovariectomised mice (OVX) were used to investigate contractility, Ca transients and L-type Ca channel (LTCC) function. The levels of βAR, intracellular cAMP, phosphodiesterase (PDE 3 and PDE 4), RyR2, PLB, SLN, and SERCA2a were compared among the experimental groups.
We found that (1) intracellular cAMP, I density, contraction and Ca transient amplitudes were larger in Sham and OVX + E2 myocytes compared to male and OVX. (2) The mRNA expression of PDE 3 and 4 were lower in Sham and OVX + E2 groups compared with male and OVX groups. Treatment of myocytes with IBMX (100 μM) increased contraction and Ca transient amplitude in both sexes and canceled differences between them. (3) βAR-mediated stress decreased cAMP concentration and peak contraction and Ca transient amplitude only in male and OVX groups but not in Sham or OVX + E2 groups suggesting a cardioprotective role of E2 in female mice. (4) Pretreatment of OVX myocytes with GPR30 antagonist G15 (100 nM) abolished the effects of E2, but ERα and ERβ antagonist ICI 182,780 (1 μM) did not. Moreover, activation of GPR30 with G1 (100 nM) replicated the effects of E2 on cAMP, contraction and Ca transient amplitudes suggesting that the acute effects of E2 were mediated by GPR30 via non-genomic signaling. (5) mRNA expression of RyR2 was higher in myocytes from Sham than those of male while PLB and SLN were higher in male than Sham but no sex differences were observed in the mRNA of SERCA2a.
Collectively, these results demonstrate that E2 modulates the expression of genes related to the cAMP-LTCC pathway and contributes to sex differences in cardiac contraction and responses to stress. We also show that estrogen confers cardioprotection against cardiac stress by non-genomic acute signaling via GPR30.
背景/目的：男性和女性的心脏在结构和功能上存在许多差异。在这里，我们通过研究 cAMP-L 型钙通道途径在成年雄性和雌性（假手术）以及去卵巢雌性（OVX）小鼠左心室（LV）心尖细胞收缩中的作用，来探究雌激素（E2）在收缩的性别差异机制中的作用。
从雄性、雌性（假手术）和去卵巢雌性（OVX）小鼠中分离 LV 心尖细胞，以研究收缩、Ca 瞬变和 L 型钙通道（LTCC）功能。比较各组间βAR、细胞内 cAMP、磷酸二酯酶（PDE3 和 PDE4）、RyR2、PLB、SLN 和 SERCA2a 的水平。
我们发现，（1）与雄性和 OVX 相比，假手术和 OVX+E2 雌性小鼠的细胞内 cAMP、I 密度、收缩和 Ca 瞬变幅度更大。（2）与雄性和 OVX 组相比，假手术和 OVX+E2 组的 PDE3 和 4mRNA 表达水平较低。用 IBMX（100μM）处理细胞可增加两性细胞的收缩和 Ca 瞬变幅度，并消除它们之间的差异。（3）βAR 介导的应激仅在雄性和 OVX 组中降低 cAMP 浓度和峰值收缩及 Ca 瞬变幅度，而在假手术或 OVX+E2 组中则不降低，提示 E2 在雌性小鼠中具有心脏保护作用。（4）GPR30 拮抗剂 G15（100nM）预处理 OVX 细胞可消除 E2 的作用，但 ERα 和 ERβ 拮抗剂 ICI 182,780（1μM）则不能。此外，用 G1（100nM）激活 GPR30 可复制 E2 对 cAMP、收缩和 Ca 瞬变幅度的作用，提示 E2 的急性作用是通过非基因组信号通过 GPR30 介导的。（5）与雄性相比，假手术小鼠的 RyR2mRNA 表达更高，而 PLB 和 SLN 则在雄性中更高，但 SERCA2a 的 mRNA 无性别差异。
总之，这些结果表明，E2 调节与 cAMP-LTCC 途径相关的基因表达，并有助于心脏收缩和应激反应的性别差异。我们还表明，雌激素通过非基因组急性信号通过 GPR30 发挥心脏保护作用，从而对抗心脏应激。
