Echinacoside‑induced nitric oxide production in endothelial cells: Roles of androgen receptor and the PI3K‑Akt pathway.

Echinacoside (ECH) is a natural compound with an endotheliumdependent vasodilatory effect. Nitric oxide (NO) is an important vasorelaxant released from endothelial cells. In order to examine the molecular mechanism of ECHinduced NO production in endothelial cells, the present study investigated the involvement of androgen receptor (AR) and the phosphatidylinositol 3kinase (PI3K)/protein kinase B (Akt) pathway in the phosphorylation of endothelial nitric oxide synthase (eNOS) in human umbilical vein endothelial cells (HUVECs). Using the fluorescent probe DAFFM, the production of NO was found to be significantly increased, and eNOS was phosphorylated at Ser1177 in a concentrationdependent manner under 0.0110 microM ECH treatment in HUVECs. In addition, NO production and eNOS phosphorylation induced by ECH were diminished when pretreated with the AR antagonist nilutamide, or when transfected with AR small interfering RNAs. Furthermore, the ECHinduced phosphorylation of the Akt at Ser473 was abrogated by 5 microM wortmannin (a PI3K inhibitor). These data indicated that ECH stimulated NO production via the ARdependent activation of eNOS in HUVECs, and that the PI3K/Akt pathway may be involved in eNOS phosphorylation induced by ECH.