The risk of myocardial infarction and stroke increases dramatically in women after menopause. Loss of endogenous estrogen associated with menopause contributes to this increased cardiovascular risk. An important, recently established vasoprotective function of estrogen is enhancement of endothelial nitric oxide (NO) secretion which promotes vasodilation and antagonizes thrombosis. NO secreted by the endothelium is regulated through Ca2+ activation of endothelial NO synthase (eNOS). The objective of my research is to elucidate the cellular and molecular mechanisms whereby estrogen and raloxifene, a selective estrogen receptor modulator, enhance release of endothelial vasodilatory factors (EDRF) including NO, prostacyclin (PGI2), and endothelium-dependent hyperpolarizing factors (EDHF). I propose that after estrogen and raloxifene bind to their receptors, they alter gene expression and/or ion transport mechanisms raising [Ca2+]i through enhanced Ca2+ influx and/or decreased Ca2+ extrusion in endothelial cells.
Aims : I will test which combination of the plausible target molecules (e.g., eNOS, EDHF) are affected by estrogen and raloxifene treatment. In addition, I will evaluate whether activation of non-genomic receptors by physiologically relevant concentrations of estrogen modulates calcium-dependent eNOS in endothelial cells. The knowledge gained is expected to provide new insight into the role of estrogen and raloxifene therapy in cardiovascular protection. Experiments will be performed in intact valvular endothelium and aortic rings taken from different groups of rats as well as in endothelial cells derived from human umbilical veins (HUVECs). EDRF release will be measured using Bioassay. Bioassay allows us to identify the nature of EDRF and its cellular action(s) in our preparation. The role of intracellular Ca2+ in stimulation of EDRF secretion will be determined using ratiometric fura- 2 fluorimetry. The extent of altered gene expression will be assessed by RT-PCR, Western blots, and immunohistochemistry. Understanding the mechanisms underlying the cardioprotective action of estrogen is expected to contribute significantly to the development of new therapeutic strategies, whereby the beneficial cardioprotective effects of synthetic estrogen analogues might be separated from the undesirable components of estrogen activity. The enhanced insight into these protective mechanisms is expected to eventually also be beneficial for the male population.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Academic Research Enhancement Awards (AREA) (R15)
Project #
Application #
Study Section
Pharmacology A Study Section (PHRA)
Program Officer
Goldman, Stephen
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of the Pacific-Stockton
Schools of Pharmacy
United States
Zip Code
Chen, Haigang; Zhang, Huizhen; Thor, Der et al. (2012) Novel pH-sensitive cationic lipids with linear ortho ester linkers for gene delivery. Eur J Med Chem 52:159-72
Thor, Der; Uchizono, James A; Lin-Cereghino, Geoff P et al. (2010) The effect of 17 beta-estradiol on intracellular calcium homeostasis in human endothelial cells. Eur J Pharmacol 630:92-9
Thor, Der; Zhang, Rui; Anderson, Leigh et al. (2010) Effects of 17 ?-estradiol on lipopolysacharride-induced intracellular adhesion molecule-1 mRNA expression and Ca²+ homeostasis alteration in human endothelial cells. Vascul Pharmacol 53:230-8
Goel, Aditya; Thor, Der; Anderson, Leigh et al. (2008) Sexual dimorphism in rabbit aortic endothelial function under acute hyperglycemic conditions and gender-specific responses to acute 17beta-estradiol. Am J Physiol Heart Circ Physiol 294:H2411-20
Goel, Aditya; Zhang, Yingmin; Anderson, Leigh et al. (2007) Gender difference in rat aorta vasodilation after acute exposure to high glucose: involvement of protein kinase C beta and superoxide but not of Rho kinase. Cardiovasc Res 76:351-60
Padar, Shanthala; van Breemen, Cornelis; Thomas, David W et al. (2004) Differential regulation of calcium homeostasis in adenocarcinoma cell line A549 and its Taxol-resistant subclone. Br J Pharmacol 142:305-16
Rahimian, Roshanak; Chan, Lally; Goel, Aditya et al. (2004) Estrogen modulation of endothelium-derived relaxing factors by human endothelial cells. Biochem Biophys Res Commun 322:373-9