Formononetin upregulates nitric oxide synthase in arterial endothelium through estrogen receptors and MAPK pathways

• Published in: Journal of pharmacy and pharmacology 2016-03, Vol.68 (3), p.342-351
• Main Authors: Sun, Tao, Cao, Lei, Ping, Na-Na, Wu, Yue, Liu, Dong-Zheng, Cao, Yong-Xiao
• Format: Article
• Language: English
• Subjects: Acetylcholine - pharmacology; Animals; endothelial nitric oxide synthase; Endothelium; Endothelium, Vascular - drug effects; Endothelium, Vascular - metabolism; Enzyme Inhibitors - pharmacology; estrogen receptor; Estrogens; formononetin; Isoflavones - pharmacology; Male; Mesenteric Arteries - drug effects; Mesenteric Arteries - metabolism; mesenteric artery; mitogen-activated protein kinase pathway; Mitogen-Activated Protein Kinases - metabolism; Nitric oxide; Nitric Oxide Synthase Type III - metabolism; Protein expression; rat; Rats; Rats, Sprague-Dawley; Receptors, Estrogen - metabolism; Rodents; Serotonin - pharmacology; Signal Transduction - drug effects; Up-Regulation - drug effects; Vasodilation - drug effects; Veins & arteries
• ISSN: 0022-3573; 2042-7158
• DOI: 10.1111/jphp.12519

Objectives Formononetin, a phytoestrogen, can improve arterial endothelial cell function by upregulating endothelial nitric oxide synthase (eNOS). The estrogen receptor plays an important role in the regulation of eNOS. This study investigated the hypothesis that formononetin upregulates eNOS through estrogen receptors and MAPK pathways. Methods The rat superior mesenteric arteries were cultured with formononetin or formononetin plus inhibitors for 24 h. The isometric tension of the arteries was measured using a myograph system. The mRNA and protein expression levels of eNOS were determined by real‐time PCR and immunohistochemistry, respectively. Key findings Acetylcholine (ACh) relaxed the mesenteric arteries precontracted with 5‐hydroxytryptamine. This relaxation could be enhanced by formononetin. The removal of endothelium or incubation with l‐NAME (a NOS inhibitor) completely abolished the formononetin‐enhanced relaxation induced by ACh, suggesting that the formononetin‐enhanced vasodilatation is dependent on endothelium and NO pathway. The estrogen receptor inhibitor ICI 182780 attenuated the formononetin‐enhanced vasodilatation induced by ACh, suggesting that the formononetin‐enhanced arterial relaxation is mediated by the estrogen receptor. Formononetin increased the mRNA and protein expression levels of eNOS. ICI 182780, U0126 (an ERK1/2 inhibitor) and SP600125 (a JNK inhibitor) prevented the increases in arterial relaxation and eNOS levels. Conclusions Formononetin upregulates eNOS expression in mesenteric arteries via estrogen receptors, ERK1/2 and JNK pathways.