However, the basis for the higher baseline values of CPP in intact sham rats and whether this elevation can exert a cardioprotective role remains unclear. Nevertheless, consistent with our hypothesis, physical training decreased the ANG II-induced vasoconstriction in ovariectomized rats to similar levels of trained or sedentary rats with normal estrogen levels. The vasoactive response to ANG II depends directly on the receptor that it binds to, with AT2 or AT1 promoting vasodilation or vasoconstriction, respectively. Estrogen has been shown to decrease the expression of the AT1
receptor in various organs [14], [37] and [53]. Conversely, Baiardi et al. have shown that estrogen causes an upregulation of both receptors in the kidneys of female rats [4]. Moreover, the treatment of ovariectomized rats with estrogen decreased see more the constriction induced by ANG II in aortic rings [6] and [53]. Physical exercise attenuates ANG II-induced vasoconstriction by modulating the expression of the AT1 and AT2 receptors. ANG II binding to the AT1 receptor can activate gp91phox (Nox2), an enzyme subunit that generates reactive oxygen species (ROS), which decreases the bioavailability of nitric oxide (NO) [1] and [45]. In the mammary artery of patients with coronary arterial disease, physical
exercise promoted an increase in AT2 mRNA and a decrease in AT1 mRNA and protein, gp91phox mRNA, Nox4 mRNA (another homologue of gp91phox present in endothelial and vascular smooth muscle cells) and p22phox33 mRNA [1]. These molecular changes learn more are followed by reduced ROS production, which results in the attenuation of the maximum vasoconstrictor response to ANG II [27]. Moreover, physical exercise decreases
the expression of Pyruvate dehydrogenase ACE and AT1 receptor in the heart [58] and plasma ANG II levels [60], changes that are associated with lower cardiac fibrosis [58] and a decrease in systemic blood pressure [60], respectively. In addition to the vascular mechanism, adiposity is another important factor that can enhance the risk of CVD in the post-menopausal period. During the training protocol, the SO group exhibited a significant increase in BW. A previous study analyzed the possible causes involved in the fat gain caused by E2 deficiency, the authors observed that after OVX, the animals exhibited hyperphagic behavior and reduced locomotor activity and were more prone to accumulating fat because of these changes in behavior [57]. In addition, lipoprotein metabolism was altered (the rate of lipolysis was decreased and the activity of lipoprotein lipase in adipose tissue was augmented) in post-menopausal women [17]. In mice, estradiol supplementation also protected against adipocyte hypertrophy and adipose tissue oxidative stress and inflammation [51]. The fact that central fat accumulation is a consequence of estrogen deficiency is also supported by studies of aromatase gene knockout (ArKO) mice (who cannot synthesize endogenous estrogens).