Female sex hormones are considered to reduce the risk of ischemic stroke. As a part of the renin–angiotensin system, angiotensin-(1–7) [Ang-(1–7)] has recently been reported to play a role in protecting neuronal tissues from ischemic stroke. Thus, we examined the effects
of female sex hormones on the levels of Ang-(1–7) and its downstream pathways in the brain. Female rats were ovariectomized and 17β-estradiol (17β-EST), progesterone (PGR), or a combination of 17β-EST plus PGR were administered. Our data demonstrated that lack of female
sex hormones significantly decreased the levels of Ang-(1–7) in the cerebral cortex and hippocampal CA1 area. Also, we observed a linear relationship between cortex levels of Ang-(1–7) and plasma brain natriuretic peptide levels (as an indicator for risk of ischemic stroke). We
further showed that lack of female sex hormones decreased the expression of Ang-(1–7), Mas-receptor (Mas-R), and neuronal nitric oxide synthase (nNOS). Overall, our findings show for the first time that Ang-(1–7) and Mas-R/nNOS in the cortex are influenced by circulating 17β-EST
and (or) PGR, whereas Ang-(1–7) and its pathways in the hippocampal CA1 area are primarily altered by 17β-EST. This suggests that female sex hormones play a role in regulating the expression of Ang-(1–7) and its pathways during ischemic brain injuries.
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