Cryptotanshinone and wogonin up-regulate eNOS in vascular endothelial cells via ERα and down-regulate iNOS in LPS stimulated vascular smooth muscle cells via ERβ

Phytoestrogens were widely used as natural alternatives to estrogen for treating cardiovascular diseases. They have been reported to have cardioprotective and anti-inflammatory response, but the mechanisms remain unclear. In this study, we found cryptotanshinone and wogonin exhibited phytoestrogenic property in an estrogen-responsive reporter assay. In EA.hy926 cells, treatment of cryptotanshinone and wogonin led to significant increase in NO production levels, which were inhibited by co-incubation of estrogen receptor (ER)alpha antagonist methyl-piperidino-pyrazole (MPP). The expression of endothelial NO synthase (eNOS) and ER alpha were up-regulated with the same treatment, indicating they stimulate NO and eNOS expression via ER alpha-dependent pathway in endothelial cells. While in lipopolysaccharide activated vascular smooth muscle cell line A7r5, cryptotanshinone and wogonin exerted anti-inflammatory effects by inhibiting NO and inducible NO synthase expression via ER beta-dependent pathway. The reduction of NO synthesis was not affected by MPP, and was abrogated by ER beta antagonist R,R-tetrahydrochrysene. Our findings provide the potential molecular mechanism of cryptotanshinone and wogonin as phytoestrogens for their cardioprotective effects, which exerted regulatory effects on NO synthesis through differential regulation of estrogen receptors. It can be employed as a basis for evaluating the beneficial effects of phytoestrogens in the treatment of patients at risk of cardiovascular disease.