Growth hormone enhances regeneration of cavernous nerves after their transplantation in rats]

OBJECTIVE: To investigate the effect of growth hormone (GH) on penile erection after reconstruction of cavernous nerves using sural nerve as an interposition nerve graft in rats. METHODS: Twenty-four male Sprague-Dawley rats (3-4 ms of age and 300-400 g in weight) were randomly divided into 2 groups: nerve graft group and GH group, each electrostimulated to determine the erectile potency 2 and 4 months after nerve graft (followed by hypodermic GH injection). The nNOS-positive nerve fibers in the corpora cavemosa were examined by streptavidin-peroxidase immunohistochemistry technique (SP method). Image analysis was used to calculate the area stained in pixel. RESULTS: Electrostimulation at 2 months produced 31.25% of erections in the GH group but none in the grafted rats. There was a significant difference in the erection rate produced by electrostimulation between the two groups at 2 months (P < 0.05). The pixel of the expression of nNOS-positive nerve fibers in the GH group (38971 +/- 7692) was also greater than that of the graft group (16538 +/- 3179, P < 0.05). At 4 months, 43.75% of the graft group and 75% of the GH group produced erections upon electrostimulation, with no significant difference between the two groups (P > 0.05). The pixels of the expression of nNOS-positive nerve fibers were 79276 +/- 12,021 and 91348 +/- 18965, respectively (P > 0.05). CONCLUSION: GH can accelerate the regeneration of cavernous nerves after bilateral nerve grafting, and GH administration may present a new physiological approach to the treatment of erectile dysfunction after radical pelvic surgery.