Objectives: Testosterone is an important hormone for the physical and mental health of men. However, testosterone administration has also been suggested to adversely affect the cardiovascular system. We investigated the effects of excessive testosterone administration on vascular endothelial and erectile function in rats.
Methods: 12-week-old rats were divided into the following groups: Sham, castrated (Cast), castrated with subcutaneous administration of 100 mg/kg/month testosterone (Cast+T1), and castrated with subcutaneous administration of 100 mg/kg/week testosterone (Cast+T4). To observe the changes in testosterone level after the administration, rats were further divided into the following groups: control; T(6.25); T(25); and T(100), wherein the rats were subcutaneously injected with 6.25, 25 or 100 mg/kg testosterone per week. Erectile and endothelial functions were measured using intracavernosal pressure (ICP) and isometric tension.
Results: The ICP/MAP ratio in the Cast group (0.42 ± 0.04) was significantly lower than that in the Sham group (0.79 ± 0.07). The ICP/MAP ratio in the Cast+T1 group (0.73 ± 0.06) was significantly higher than that in the Cast group (P <0.01) and that of the Cast+T4 (0.38 ± 0.01) group was unchanged (P >0.05). The T(25) and T(100) groups exhibited significantly lower responses to ACh than the control group at four weeks (P < 0.01). Meanwhile, the ICP/MAP ratios in the T(25) group (0.44 ± 0.07) and T(100) group (0.47 ± 0.03) were significantly lower than that in the control group (0.67 ± 0.05) at stimulation frequencies of 16 Hz (P < 0.05).
Conclusion: Excessive testosterone may cause endothelial dysfunction in the aorta and erectile dysfunction in rats and that the blood concentration should be monitored after testosterone administration.