Reconstruction of erectile reflex circuit by autologous vein graft combined with use of insulin-like growth factor

Abstract

To explore the feasibility of erectile reflex circuit reconstruction by autologous vein graft combined with the use of insulin-like growth factor-I (IGF-I). 48 male adult Sprague-Dawley rats were randomized into 4 groups of 12 rats: group I (sham-operation group), undergoing operation to identify the bilateral cavernous nerves (CNs) only; group II (bilateral CN ablation group) in which the bilateral CNs of the length of at least 5 mm were ablated; group III (vein graft plus IGF-I group) in which the ablated CNs were repaired by autologous vein graft and IGF-I was injected into the venous cavity; and group IV (vein graft plus normal saline group), in which the ablated CNs were repaired and normal saline was injected instead. Four months later, apomorphine test was performed on each rat, and the erection times during the following half hour were recorded. After that, 4% fluoro-gold was injected into the bilateral corpus cavernosum of penis for each rat after anesthesia. Five days later, the rats were sacrificed and their bilateral major pelvic ganglia were obtained for detection of fluoro-gold by fluorescent microscopy. Apomorphine test showed an erection rate of 92% in group III, significantly higher than those of the group II (0%) and group IV (50%, both P < 0.01), and close to that of the sham-operation group (100%, P > 0.05). The average erection times of the group III was (1.5 +/- 0.8) times, significantly more than those of the group II and group IV [(0.0 +/- 0.0) times and (0.6 +/- 0.7) times respectively, both P < 0.05], but significantly less than that of the sham-operation group [(2.7 +/- 0.9) times, P < 0.05]. Five days after injection of fluoro-gold solution, the number of fluoro-god positively stained neural cells of the group III was 86 +/- 14, significantly more than those of the group II (14 +/- 6) and group IV (46 +/- 14, both P < 0.05), but significantly less than that of the sham-operation group (152 +/- 36, P < 0.05). And the fluoro-gold stained neural cells of the group III was brighter than those of the group II and group IV, but not so bright as those of the sham operation group. Reparation of ablated CNs by autologous vein graft combined with local injection of IGF-I is a new effective method to treat ED following CN injury.