15 The influence of androgen deprivation therapy on cavernous nerve grafts

Abstract

Introduction: Postradical prostatectomy erectile dysfunction is thought to be neurogenic in origin, and some attempts to improve potency have focussed on regenerating the cavernous nerves. Testosterone has profound positive effects on nerve regeneration. The present study aims to evaluate whether testosterone has any effect on the regeneration of cavernous nerves.Materials and Methods: Forty‐five male Sprague–Dawley rats underwent bilateral cavernous nerve neurotomy followed by unilateral nerve graft using genitofemoral nerve. Animals were then randomised to castrate, intact and testosterone treated arms. At 3 months electrostimulation was performed measuring intracavernosal pressure responses. Grafted nerve segments were then harvested for histological analysis.Results: Significant difference in maximal intracavernosal pressure (MICP) response between groups – mean MICPs were 24, 47 and 59 for castrate, intact and testosterone treated groups respectively (P = 0.003, anova). Total axon counts within grafted segments did not differ significantly between treatment groups, but concentration of nNOS‐containing axons was significantly decreased in castrate animals.Conclusions: Castration resulted in a significant reduction in erectile response to electrostimulation following interpositional nerve grafting. These effects appear to be due to changes in axonal regeneration in differing androgen environments, especially in the regeneration of nNOS containing axons. Clinically, this implies that nerve grafts will be of little functional use in the face of androgen ablation.