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Introduction Cavernous nerve injury (CNI) in rats and radical prostatectomy (RP) in men result in loss of nitrergic function and increased adrenergic-neurogenic contractions of cavernosal tissue. Aim To evaluate the modulation of the α-adrenergic system as a strategy to relieve erectile dysfunction (ED) and functional cavernosal alterations induced by CNI. Methods A non-selective α-blocker (phentolamine 1 mg/kg daily), a selective α 1A -blocker (silodosin [SILOD] 0.1 mg/kg daily), or vehicle was orally administered for 4 weeks after bilateral crush CNI (BCNI). Erectile and neurogenic responses of the corpus cavernosum (CC) were evaluated. The acute effects of SILOD also were evaluated in vivo (0.03 mg/kg intravenously) and ex vivo (10 nmol/L). The effects of SILOD and tadalafil (TAD) on nitrergic relaxations were determined in human CC from patients with ED with a vascular etiology or ED secondary to RP. Main Outcome Measures Erectile responses in vivo in rats and neurogenic contractions and relaxations of rat and human CC. Results Long-term treatment with SILOD significantly improved erectile responses and allowed for the potentiation of erectile responses by acute treatment with TAD (0.3 mg/kg intravenously) in rats with BCNI. SILOD partly recovered nitrergic relaxations and normalized neurogenic contractions in CC from rats with BCNI. Long-term treatment with SILOD partly prevented BCNI-induced decreases in neuronal nitric oxide synthase expression. Acute administration of SILOD (0.03 mg/kg intravenously) improved erectile responses in vivo and potentiated nitrergic relaxation and decreased neurogenic contractions ex vivo in CC from rats with BCNI. In human CC from patients with ED with a vascular etiology, TAD (30 nmol/L), SILOD (10 nmol/L), or their combination increased nitrergic relaxations. Potentiation by TAD was lost in human CC from patients with ED after RP but was recovered after co-treatment with SILOD. Conclusion α-Adrenergic modulation, especially selective α 1A -blockade, improves erectile and cavernosal functions after BCNI. Modulation of the adrenergic system, mainly in combination strategies, could have a role in the management of ED after RP. [ABSTRACT FROM AUTHOR]

Introduction: Novel effective therapeutic strategies are necessary for treating erectile dysfunction secondary to cavernous nerve injury (CNI). Aim: To functionally evaluate the benefits of long-term oral treatment with a phosphodiesterase type 5 inhibitor on the potential capacity of intracavernosal cell therapy to recover erectile function after CNI. Methods: Bilateral crush CNI (BCNI) was produced in anesthetized male rats. After BCNI, rats were treated with the phosphodiesterase type 5 inhibitor tadalafil (TAD; 5 mg/kg/d orally; BCNI + TAD), a single intracavernosal injection of bone marrowederived mesenchymal stem cells (BMSCs; BCNI + BMSC), or dual therapy (BCNI + BMSC + TAD). Ex vivo function of the corpus cavernosum (CC) and in vivo intracavernosal pressure responses to CN electrical stimulation were evaluated 4 weeks after BCNI. Trichrome staining and terminal 20-deoxyuridine- 50-triphosphate nick-end labeling assay were used for fibrosis and apoptosis determination, respectively, in the CC. Main Outcome Measures: In vivo erectile responses in anesthetized rats, ex vivo evaluation of endothelium-dependent relaxation, neurogenic relaxation and neurogenic contraction in CC strips, and histologic evaluation of fibrosis and apoptosis in cavernosal tissue. Results: BCNI resulted in amarked decrease of erectile responses that were partly recovered in the BCNI+TAD and BCNI + BMSC groups. Complete recovery of erectile function was achieved only in the BCNI + BMSC + TAD group. Endothelium-dependent and nitric oxide donor-induced relaxations of the CC were not altered by BCNI or the treatments. BCNI resulted in enhanced neurogenic adrenergic contractions and impaired nitrergic relaxations of the CC.TheBCNI+TADgroup displayed diminished neurogenic contractions,whereas theBCNI+TADand BCNI+ BMSC groups showed partly recovered nitrergic responses. In the BCNI + BMSC + TAD group, neurogenic contractions were decreased and nitrergic relaxations were normalized. Cavernosal apoptosis and fibrosis were similarly prevented in the BCNI + TAD, BCNI + BMSC, and BCNI + BMSC + TAD groups. Conclusion: A dual strategy combining the intracavernosal injection of BMSCs and oral administration of TAD was superior to individual approaches in normalizing neurogenic control of cavernosal tone and preserving erectile function after CNI, suggesting the potential of this dual strategy in the future management of erectile dysfunction after radical prostatectomy. [ABSTRACT FROM AUTHOR]