ABSTRACT
BACKGROUND: Because androgen replacement therapy (ART) is not performed immediately after the onset of androgen deficiency, the treatment is considered to be late. AIM: To investigate the effects of late ART, starting 4 weeks after castration of rats, on erectile function and structural changes in the corpus cavernosum. METHODS: Rats were subjected to ART for 4 (Late-ART [4w]) or 8 (Late-ART [8w]) weeks. In either case, rats were assigned to the following groups: castrated (Cast), castrated with subcutaneous administration of testosterone (3 mg/kg/day; Cast+T), and sham (Sham). Cast + T rats received daily subcutaneous doses of testosterone starting 4 weeks after castration for 4 or 8 weeks whereas Sham and Cast rats received only the vehicle. OUTCOMES: Erectile function was assessed by evaluating intracavernosal pressure (ICP) and mean arterial pressure (MAP) after electrical stimulation of the cavernous nerve, corporal veno-occlusive function using dynamic infusion cavernosometry, and histology using Masson's trichrome staining. RESULTS: No increase in the ICP was observed in Cast+T rats in the Late-ART (4w) group (0.47 ± 0.02, P > .05), whereas, in Cast+T rats in the Late-ART (8w) group, there was a significant increase in the ICP/MAP ratio (0.60 ± 0.02, P < .05), drop rate, and smooth muscle/collagen ratio. CLINICAL TRANSLATION: The present study provides scientific evidence for the effect of late ART on erectile function. STRENGTHS AND LIMITATIONS: This study provides insights into the influence of late ART on erectile function through improvements in the structure of corpus cavernosum. The major limitation of this study is the difference in the time required for healing between the humans and rats, which might have a bearing on the translational relevenace of the results. CONCLUSIONS: Late ART could improve erectile function. However, as improvement requires a considerable time period, it is necessary to persist with therapy patiently for optimal results. Kataoka T, Hotta Y, Yamamoto Y, et al. Effect of Late Androgen Replacement Therapy on Erectile Function Through Structural Changes in Castrated Rats. Sex Med 2021;XX:XX-XXX.
ABSTRACT
Corporal veno-occlusive function is the essential part in the hemodynamic process of penile erection. Parameters for evaluation of the quality of the veno-occlusive mechanism are end diastolic flow velocity (EDV) and its derivative resistance index (RI) as measured by pharmacopenile duplex ultrasound which is considered as an initial screening test for the patients with vasculogenic impotence. We compared the accuracy of these parameters by investigating the correlation between the result of duplex sonographic study and some other studies, pharmacoerection test and dynamic infusion cavernosometry (DIC) in 45 patients who received all of these studies and were proved to have normal arterial inflow of the penis. EDV and RI values were well correlated with maintenance flow rate values of DIC at various levels of intracavernosal pressures (50, 100 and 150 mmHg) (R=0.418-0.701 and R=0.454-0.620 respectively). Diagnostic result of duplex scanning was identical to cavernosometric result in 80% and pharmacoerection response in 82%. We conclude that EDV and RI appeared to be used as good indices evaluating corporal veno-occlusive function.