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

Introduction: Testosterone plays an important role in the blood pressure regulation. However, information with regard to the effect of this hormone on blood pressure in normotensive and hypertensive conditions is limited. Therefore, in this study, the relationship between plasma testosterone level and mean arterial pressure (MAP) was investigated under these conditions. Methods: Normotensive Wistar-Kyoto (WKY) and hypertensive Spontaneous Hypertensive (SHR) male and female rats were gonadectomized with female rats treated with testosterone. Estrous cycle stages of intact female rats of both strains were identified by vaginal smear. Pressure in the carotid artery of anesthetized rats was measured via direct cannulation technique. The blood was withdrawn for plasma testosterone level measurement by enzyme-linked immunosorbent assay. Results: Treatment of ovariectomized female WKY and SHR rats with testosterone for 6-week duration has resulted in MAP to increase (P < 0.05). In male WKY and SHR rats, MAP and plasma testosterone levels decreased by orchidectomy (P < 0.05). No significant differences in MAP and plasma testosterone levels were observed in intact female WKY and SHR rats between stages of the estrous cycle. Conclusions: The effects seen in testosterone-treated ovariectomized female rats and in orchidectomized male rats suggested that testosterone could play an important role in causing the blood pressure to increase.