Cardiovascular effects of dihydrotestosterone in rats

We conducted a study to evaluate the cardiovascular effects of 5 alpha-dihydrotestosterone (DHT), including the supplementary respiratory effects, using normal and obese groups of Wistar castrated male rats, and the association of the hormonal effect with sudden unexplained nocturnal death syndrome (SUNDS). The hormone-treated normal rats had a significantly greater weight of the right ventricular wall and atria and body weight ratio when compared with the controls. Cardiac function estimated from the parametric value multiplied heart rate by carotid maximum systolic pressure was significantly lowered in the hormone-treated rats, However, no difference in the right ventricular action between the hormone-treated and control rats was found. In respiratory parameters, expired CO(2) gas decreased significantly in the hormone-treated rats. On the other hand, the hormone-treated obese rats showed a significantly greater weight of the heart and body weight ratio. This was due to the significant gain of the ventricular septum weight, in addition to the weight gains of the right ventricular wall and atria. Cardiac function of the hormone-treated obese rats was significantly lower than that of the controls and lower than that of normal rats. Significant increase in respiratory rate and decrease in expired CO(2) gas were seen in the hormone-treated rats. Therefore, these results demonstrate that the hormone had hypertrophic effects mainly on the right ventricle or atria and suppressive effects on cardiovascular function or promotive effects on respiratory ventilation, with both of the latter effects enhanced comparatively in obese rats. These cardiac hypertrophic and ventilatory characteristics according to DHT do not seem to apply to the victims of SUNDS.