FIGURE 4.

Reduced duration time of erection by castration. (A–C) Analysis of the relaxation/contraction in vitro. RECs and CECs treatments were performed to induce relaxation/contraction. From sequential images (interval time is 10 s), the edges of the CC are defined and the time of completing the movement of contraction of the CC was calculated after CECs treatment by ImageJ software. We compared the area of sinusoids at each time point (the time point for before treatment, RECs treatment, and CECstreatment). Relaxation was represented as a ratio to the area of sinusoids treated by RECs and before treatment. Contraction was represented as a ratio of the treated area of sinusoid RECs to that of CECs. The contracted/relaxed CC was not significantly altered in its sinusoidal size compared with that of the control mice. We compared each time point of the area of the CC (control and castrated mice). The time to complete contraction in CECs treatment was defined as the contraction time, which was evaluated as the ratio of the contraction time of CC in control and castrated mice. The time to contraction after treatment with CECs was shortened in castrated mice compared to control mice. (D) Schema shows that the androgen reduction prevents sustained erections. It is suggested that castration results in the absence of significant structural changes, stressing again the androgen-independent responses for erection. The current shortened erectile duration time suggests a reduced functional erectile capacity. Thus, the current system provides unique information to further investigate the novel regulations of erectile function and a new evaluation approach to ED.