Effect of Estrogen and Progesterone Hormones on the Expression of Angiotensin II Receptors in the Heart and Aorta of Male Rats

Abstract

Background: Activation of the Angiotensin II type 1 receptor (AT1R) has been implicated in the pathogenesis of the cardiovascular disease, while activation of Angiotensin II type 2 receptor (AT2R) leads to effects that are opposite to those mediated by AT1R. The interaction between female sex hormones and the renin-angiotensin system was proven to play an essential role in the pathological changes in the cardiovascular system. Objectives: To investigate the direct effect of estrogen and progesterone on arterial and cardiac AT1R and AT2R expression in vivo in male. Method: Male adult rats were assigned into four groups: Group 1 (control), group 2 (progesterone treated group; 10mg/kg), group 3 (estrogen treated group; 20μg/kg) and group 4 (progesterone; 10mg/kg + estrogen; 20μg/kg treated group). All treatments were administrated subcutaneously every second day for 21days. Results: Estrogen treatments increase the left ventricle (LV) protein expression of AT1R, and progesterone treatment decreased the LV protein expression of AT2R. In the aorta, estrogen treatment increased the mRNA expression levels of AT1R, while progesterone treatment increased the AT2R mRNA expression levels. Estrogen treatment decreases the LV and aortic endothelial nitric-oxide synthase (eNOS) mRNA levels while progesterone treatments decrease the LV eNOS mRNA levels but increase the aortic eNOS mRNA levels. The serum angiotensin II levels were increased by estrogen treatment only. Conclusion: Both estrogen and progesterone treatments appear to have a harmful effect on the male rat hearts, possibly by increasing the protein expression of AT1R (for estrogen), decrease the protein and mRNA expression of AT2R (for progesterone), and decrease the eNOS mRNA levels (for both). However, it seems that progesterone but not estrogen exerts a vascular protective effect in males.