Impact of gonadectomy on blood pressure regulation in ageing male and female rats

Abstract

BackgroundSexual dimorphism in blood pressure has been associated with differential expression of the angiotensin II (AII) receptors and with activity of the nervous system. It is generally accepted that ageing affects kidney function as well as autonomic nervous system and hormonal balance. Given that hypertension is more prevalent in men than women until women reach their seventh decade, we hypothesised that females would be relatively protected from adverse effects of ageing compared to males and that this would be mediated by the protective effect of ovarian steroids.MethodsIntact and gonadectomised male and female normotensive Wistar rats aged 6, 12 and 18 months were used to study renal function, blood pressure, heart rate, and blood pressure variability.ResultsWe observed that intact females had lower levels of proteinuria and higher (12.5%) creatinine clearance compared to intact males and that this difference was abolished by castration but not by ovariectomy. Ovariectomy resulted in a change by 9% in heart rate, resulting in similar cardiovascular parameters to those observed in males or gonadectomised males. Spectral analysis of systolic blood pressure revealed that high-frequency power spectra were significantly elevated in the females vs. males and were reduced by ovariectomy.ConclusionsTaken altogether, the results show that females are protected from age-related declining renal function and to a lesser extent from rising blood pressure in comparison to males. Whilst ovariectomy had some deleterious effects in females, the strongest effects were associated with gonadectomy in males, suggesting a damaging effect of male hormones.Electronic supplementary materialThe online version of this article (doi:10.1186/s13293-016-0111-9) contains supplementary material, which is available to authorized users.

Prolonged Exposure to Alcohol Vapor Causes Change in Cardiovascular Function in Female but not in Male Rats

“…Our findings are in line with previous studies in humans and rodents that report higher HR values in females compared to males (Bazett, ; Gowda et al., ; Johnson et al., ; Pijacka et al., ; Ryan et al., ; Tadros et al., ; Vieira et al., ). One explanation could be that the smaller heart in females leads to lower stroke volumes compared to that in males and, when women tend to have a similar cardiac index as men (cardiac output normalized by their body weight), their HR is higher than in males (Johnson et al., ).…”

“…Furthermore, ovariectomized rats exposed to alcohol showed enhanced sympathetic activity as indicated by significant increases in plasma norepinephrine levels (El‐mas and Abdel‐rahman, ). In addition, studies have shown that females/young women with intact ovaries demonstrated increased cardiac vagal tonus compared to males and postmenopausal women (Pijacka et al., ; Ryan et al., ; Virtanen et al., ). The same increase in cardiac parasympathetic activity is observed in female rats after alcohol treatment (El‐mas and Abdel‐rahman, ; Ibrahim et al., ).…”

Influence of testosterone on mean arterial pressure: A physiological study in male and female normotensive WKY and hypertensive SHR rats

“…In this study, a positive correlation between plasma testosterone level and MAP has been identified. MAP was found to be higher in intact male WKY and SHR rats as compared with intact female WKY and SHR rats and these findings were consistent with the reports by others (4,7,30,31,35). In this study, gonadectomies performed prior to pubertal age, that is, 8 weeks were found to decrease the MAP in both male and female normotensive WKY and SHR rats.…”

“…The findings in male WKY and SHR rats in which orchidectomy had also caused a decrease in blood pressure have further strengthened the view that testosterone is involved in increasing the blood pressure, a finding similar to that found by others (23). There were conflicting reports with regard to the effect of ovariectomy on MAP (9,35,42). Ovariectomy has been reported not to cause changes in blood pressure of wild-type mice.…”

Cardiometabolic Changes in Different Gonadal Female States Caused by Mild Hyperuricemia and Exposure to a High-Fructose Diet

“…When a variable was observed over time, such as SBP, a random factor was introduced (hence, the mixed denomination, the presence of fixed factors, treatments and the gonadal condition, and a random factor (time)). In order to analyze the differences of each random variable between the treatments and the gonadal state, the multiple comparisons method of Di Rienzo, Guzman, and Casanoves (DGC) was used, using the multivariate cluster analysis technique [ 13 ].…”