Department of Pharmacology and Pharmacy, The University of Hong Kong, Hong Kong, China.
Pharmacol Res. 2011 Nov;64(5):509-16. doi: 10.1016/j.phrs.2011.05.010. Epub 2011 May 27.
The aim of the present study was to investigate the signaling mechanisms underlying the non-genomic effects of estrogen in rat superior mesenteric arteries. Isometric tension was recorded in rings with or without endothelium. Changes in cyclic nucleotide levels and protein kinase (PK) activities were measured. Localization of estrogen receptors (ER) and caveolin-1 were visualized by confocal microscopy. 17β-Estradiol elicited a concentration-dependent relaxation. The relaxation was reduced by SQ 22536 (adenylyl cyclase inhibitor) and KT 5823 (PKG inhibitor) while ODQ (guanylyl cyclase inhibitor) and KT 5720 (PKA inhibitor) had no effect. At the physiological concentration of 1 nM, 17β-estradiol had no significant effect on relaxation but enhanced the relaxation to sodium nitroprusside. The enhancement of relaxation by 17β-estradiol was blocked by SQ 22536 and KT 5823. Although 1 nM 17β-estradiol or 10 nM sodium nitroprusside given alone had minimal effects on PKG activity, in their combined presence, a significant increase in PKG activity was observed. Confocal microscopy demonstrated that ERα and ERβ colocalized with caveolin-1 and PKG in vascular smooth muscle cells. The present findings suggest that 17β-estradiol enhances relaxation of vascular smooth muscle of the rat superior mesenteric artery by activating adenylyl cyclase, leading to an increase in cAMP which cross activates PKG in the caveolae. No detectable increase in total cAMP level was detected as these changes occurred in the caveolae. These results are consistent with the notion that 17β-estradiol mediates its effect in the distinct microdomains of the caveolae of the plasma membrane with colocalization of adenylyl cyclase and PKG.
本研究旨在探讨雌激素在大鼠肠系膜上动脉非基因组效应的信号转导机制。在有或无内皮的环中记录等长张力。测量环核苷酸水平和蛋白激酶 (PK) 活性的变化。通过共聚焦显微镜观察雌激素受体 (ER) 和 caveolin-1 的定位。17β-雌二醇引起浓度依赖性松弛。松弛作用被 SQ 22536（腺苷酸环化酶抑制剂）和 KT 5823（PKG 抑制剂）减弱，而 ODQ（鸟苷酸环化酶抑制剂）和 KT 5720（PKA 抑制剂）没有作用。在生理浓度 1 nM 时，17β-雌二醇对松弛无明显影响，但增强了对硝普钠的松弛作用。17β-雌二醇对松弛的增强作用被 SQ 22536 和 KT 5823 阻断。尽管单独给予 1 nM 17β-雌二醇或 10 nM 硝普钠对 PKG 活性的影响很小，但在它们共同存在的情况下，观察到 PKG 活性显著增加。共聚焦显微镜显示 ERα 和 ERβ 与 caveolin-1 和 PKG 在血管平滑肌细胞中存在共定位。本研究结果表明，17β-雌二醇通过激活腺苷酸环化酶增强大鼠肠系膜上动脉血管平滑肌的松弛作用，导致 cAMP 增加，从而在 caveolae 中交叉激活 PKG。由于这些变化发生在 caveolae 中，因此未检测到总 cAMP 水平的可检测增加。这些结果与以下观点一致，即 17β-雌二醇通过与腺苷酸环化酶和 PKG 共定位，在质膜的 caveolae 独特的微域中介导其作用。
