Abstract
Studies have presented conflicting findings regarding the association between both fluctuation and deprivation of ovarian hormones and cardiovascular autonomic modulation and oxidative stress and their potential impact on resting arterial pressure (AP) and cardiovascular risk. This study aimed to assess cardiovascular autonomic modulation, baroreflex sensitivity (BRS), and oxidative stress in male rats (M) and in female rats during ovulatory (FOV) and non-ovulatory phases (FNOV) of the estrous cycle and after deprivation of ovarian hormones (FO). Direct AP was recorded, and BRS was assessed by using increasing doses of phenylephrine and sodium nitroprusside. AP and heart rate variability were assessed by spectral analysis. Oxidative stress profile was evaluated in cardiac, renal, and muscle tissues. In females, the ovulatory phase and ovarian hormone deprivation induced an increase in AP (FOV and FO ~ 9 mmHg) when compared to the non-ovulatory phase. Ovariectomy promoted increased cardiac sympathovagal balance (~ 17–37%) when compared to other groups. Both FOV and FO groups presented impaired BRS, associated with higher AP variability. In general, antioxidant capacity was higher in the FNOV than in the M group. Ovarian hormone deprivation induced a decrease in catalase activity in cardiac and renal tissues and an increase in lipid peroxidation in all tissues analyzed. Positive correlations (p < 0.05) were found between vascular sympathetic modulation and lipid peroxidation in cardiac (r = 0.60), renal (r = 0.60), and muscle (r = 0.57) tissues. In conclusion, both oscillation and deprivation of ovarian hormones play an important role in cardiovascular autonomic control and oxidative stress profile in target organs, which is reflected in AP changes.
Highlights
In males and females, the prevalence of cardiovascular diseases (CVD) increases with age [1], regardless of sex
We aimed to evaluate the effects of ovarian hormones in female rats on cardiovascular autonomic modulation and baroreflex sensitivity, as well as on the profile of target organ oxidative stress when compared to male rats
Cardiovascular and autonomic assessment The hemodynamic assessment found higher values of arterial pressure (AP) in the female rats during ovulatory (FOV) when compared to the FNOV group (p < 0.05, Table 1)
Summary
The prevalence of cardiovascular diseases (CVD) increases with age [1], regardless of sex. Women in reproductive age have been found to be less affected by cardiovascular events than men [1]. Ovarian hormone concentrations fluctuate during the menstrual cycle in order to fulfill their biological functions. In this context, it is suggested that estrogen and progesterone fluctuations change arterial pressure (AP) [4]. Several studies have shown that the hormonal oscillations during the menstrual cycle modulate AP and baroreflex control. Minson et al [5] have observed increased sympathetic baroreflex
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