Progestogens reduce thromboxane production by cultured human endothelial cells

Abstract

Objectives Progestogens have been poorly studied concerning their roles in endothelial physiology. Prostanoids are vasoactive compounds, such as thromboxane A2, a potent vasoconstrictor, and prostacyclin, a vasodilator. We examined the effects of two progestogens used clinically, progesterone and medroxyprogesterone acetate, on thromboxane A2 production by cultured human umbilical vein endothelial cells (HUVEC) and investigated the role of progesterone receptors and the enzymes involved in production of thromboxane A2 and prostacyclin.

Methods Cells were exposed to 1–100 nmol/l of either progesterone or medroxyprogesterone acetate, and thromboxane A2 production was measured in culture medium by enzyme immunoassay. Gene expression of prostacyclin synthase and thromboxane synthase was analyzed by quantitative real-time polymerase chain reaction. Expression of prostacyclin synthase protein was analyzed by Western blot.

Results Both progestogens decreased thromboxane A2 release after 24 h. Protein and gene expression of prostacyclin synthase were increased after exposure to both progestogens, without changes in thromboxane synthase expression. These effects induced by progestogens were mediated through progesterone receptors, since they were decreased in the presence of the progesterone receptor antagonist RU486. The cyclo-oxygenase-1 selective inhibitor reduced thromboxane release.

Conclusion Progesterone and medroxyprogesterone acetate decreased HUVEC thromboxane release in a progesterone receptor-dependent manner, without changes in thromboxane synthase expression and enhanced prostacyclin synthase gene and protein expression.

Key words:

• THROMBOXANE
• ENDOTHELIUM
• PROGESTOGENS
• PROSTAGLANDINS

Acknowledgements

The authors are indebted to Mrs Rosa Aliaga and Mrs Elvira Calap for their excellent technical assistance.

Conflict of interest  The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

Source of funding  This study was supported by Spanish Ministerio de Ciencia e Innovación, Instituto de Salud Carlos III (grants FIS 06/0589 and Red HERACLES RD06/0009), Consellería de Sanidad, Generalitat Valenciana (grants AP 010/2007 and AP 121/2008) and Consellería de Educación, Generalitat Valenciana (grant GVPRE/2008/276). P.J. Oviedo holds a post-doc position, and A. Sobrino is a fellowship recipient from the FPI program (BFPI 06/145), both from Consellería de Educación, Generalitat Valenciana, Spain.