Persistent Erectile Dysfunction after Discontinuation of 5-Alpha Reductase Inhibitor Therapy in Rats Depending on the Duration of Treatment.

PURPOSE

The current study is aimed to assess whether a longer duration of 5α-reductase inhibitor (5α-RI) exposure was associated with higher rate of permanent erectile dysfunction (ED) in a rat model.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n=76) were assigned to five groups: (i) normal control group; (ii) dutasteride (0.5 mg/rat/d) for 4-weeks group; (iii) dutasteride for 4-weeks plus 2-weeks of resting group; (iv) dutasteride for 8-weeks group; and (v) dutasteride for 8-weeks plus 2-weeks of resting group. In vivo erectile responses to electrical stimulation, and changes of fibrotic factors and smooth muscle/collagen contents in the corpus cavernosum were evaluated in each group.

RESULTS

Dutasteride administration for 4 and 8 weeks significantly decreased erectile parameters compared with the control group. Reduced erectile responses were recovered during 2 weeks of drug-free time in the 4-week treatment group, but were not in the 8-week group. Protein levels of fibrosis-related factors transforming growth factor (TGF)-β1, TGF-β2, and p-Smad/Smad (Smad 2/3) in the corpus cavernosum showed no significant change after 4 weeks of dutasteride oral administration, but were enhanced after 8 weeks. Dutasteride markedly decreased smooth muscle content and increased collagen after 4 and 8 weeks of use, but no nuclear size changes; however, neither group showed significant improvement in the smooth muscle to collagen ratio after the rest period.

CONCLUSIONS

Our study showed that recovery from ED depended on the duration of medication, and administration of dutasteride for more than 8-weeks in rats could result in irreversible ED even after discontinuation of medication.