Abstract
Objective
To investigate the effect of early chronic tadalafil administration on erectile dysfunction after cavernous nerve (CN) injury in the rat model.
Methods
Using the CN crush injury model, animals were divided into four groups: no CN injury (sham), bilateral CN injury exposed to either no tadalafil (control) or tadalafil at a dose (2 mg/kg) daily postoperation for 4 weeks, and normal group. At the time point, we assessed erectile function by apomorphine test, measurement of maximum intracavernosal pressure (ICP)/mean arterial pressure (MAP) ratio with major pelvic ganglion (MPG) electrical stimulation. For the histological analyses, the mid-shaft of penis were harvested. Immunohistochemical antibody staining was performed for nNOS and the numbers of nNOS-positive nerve fibers were recorded.
Results
Penile erection was observed in 50% (6/12) of the rats for (1.13±0.92) times within 30 min in control group, as compared with 0% (0/11) of the rats for (0.00±0.00) times in CN crush group (P<0.05), and 100% (10/10) of the rats for (2.03±0.97) times in sham group (P<0.05), and 100% (10/10) of the rats for (2.36±1.02) times in normal group (P<0.05). No significant differences in ICP/MAP ratio before MPG electrical stimulation in 4 groups (P>0.05), while ICP/MAP ratio after MPG electrical stimulation of control group was significantly higher than that of CN crush group (P<0.05), but significantly lower than that of sham group (P<0.05) and normal group (P<0.05). The numbers of nNOS-positive nerve fibers was significantly larger in control group than in CN crush group (54.11±5.02 vs. 21.34±3.17, P<0.05), but was significantly smaller than that of sham group (76.48±8.24, P<0.05) and normal group (81.09±7.25, P<0.05).
Conclusions
Early chronic low-dose tadalafil administration on erectile dysfunction after CN injury contributes to restoration of erectile function.
Keywords: Erectile dysfunction, cavernous nerve (CN), radical prostatectomy, tadalafil