The role of peroxisome proliferator-activated receptor-gamma and estrogen receptors in genistein-induced regulation of vascular tone in female rat aortas

Abstract

Background: Genistein (GST) is a phytoestrogen that binds estrogen receptors (ER) to produce a protective cardiovascular effect. It also has been shown binding peroxisome proliferator-activated receptor-gamma (PPAR-gamma).

Methods: In the present study, we assessed the role of PPAR-gamma and ER in GST-mediated regulation of vascular tone in female rat aortas by in vitro tension measurement, immunohistochemistry, immunofluorescence, immunoprecipitation and Western blot analysis.

Results: In aortas pretreated with GW9662 (inhibitor of PPAR-gamma), ICI182780 (inhibitor of ER) and a combination of GW9662 and ICI182780, the magnitudes of GST-induced dilatation were attenuated. N(G)-nitro-L-arginine methyl ester had a similar effect. ER-beta and PPAR-gamma colocalized in all 3 layers of the aortas, while ER-alpha and PPAR-gamma colocalized only in the vascular endothelium and adventitia. In GST-treated whole-cell protein samples, we demonstrated coimmunoprecipitation of ER-beta (not ER-alpha) and PPAR-gamma. The expression of ER-beta and PPAR-gamma in nuclear protein from GST-treated samples increased, which was partially reversed by either GW9662 or ICI182780 and more efficiently reversed using a combination of GW9662 and ICI182780.

Conclusion: Our findings suggest that GST can relax phenylephrine-induced vascular contraction in female rat aortas, which is mediated by PPAR-gamma and ER-beta.