Orchidectomy reduces blood pressure, but testosterone increases it in intact and orchidectomized normotensive rats

Background: The cardioprotective effect of estrogen has been well documented, and the effect of testosterone on blood pressure (BP) is controversial and remains inconclusive. Aim: The present study is aimed at investigating the effect of testosterone on BP in normotensive rats. Materials and Methods: In a blind study, 30 male albino rats (200-250 g) were divided into 5 oral treatment groups (n = 6 rats each) as follows: Groups I and II were intact rats that received 1 ml/kg normal saline (vehicle) and 25 mg/kg testosterone subcutaneously for 24 days. Group III was sham-operated and received normal saline for 24 days. Groups IV and V were bilaterally orchidectomized and received normal saline and 25 mg/kg testosterone subcutaneously for 24 days. Results: The systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), and mean arterial pressure (MAP) of the sham-operated rats that received normal saline were not significantly different from the intact (control) rats that received normal saline (P > 0.05). Testosterone treatment in control rats caused a sustainably higher SBP (P < 0.001), DBP (P < 0.001), PP (P < 0.001), and MAP (P < 0.001) when compared to control that received normal saline. The SBP (P < 0.01), DBP (P < 0.001), MAP (P < 0.001), but not PP (P > 0.05) was significantly reduced in orchidectomized rats that received normal saline when compared to control. However, administration of testosterone in orchidectomized rats abolished orchidectomy-induced reduction in SBP, DBP, MAP, but not PP and further increased them above the control level (P < 0.05). Conclusion: This study shows that testosterone is prohypertensive in normotensive rats.