OBJECTIVETo investigate the effect of FK506 on the cavernous nerve regeneration after injury and to discuss its possible action mechanisms.

METHODSFifty-four male adult Sprague-Dawley rats were randomized into three groups: Group 1 (sham control), Group 2 (unilateral cavernous nerve ablation), and Group 3 (unilateral cavernous nerve ablation with subsequent injection of FK506). Electrostimulation of the cavernous nerve was performed at 1 and 3 months after surgical injury. The intracavernous pressure was continuously detected and the rats were followed by nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) staining to identify NOS in the penile nerve fibers of the penile shaft.

RESULTSAt 1 month, the number of NOS-positive nerve fibers significantly decreased with no statistical difference among the three groups except the sham controls (P > 0.05). At 3 months, electrostimulation revealed greater maximal intracavernous pressure in Group 3 than in Group 2 (P < 0.01). Furthermore, the number of NOS-positive nerve fibers showed a significant increase (P < 0.01), but not in Group 2 (P > 0.05).

CONCLUSIONFK506 injection enhances the regeneration of cavernous nerves after injury and the recovery of erectile function in rats.