Re-innervation of the bladder through end-to-side neurorrhaphy of autonomic nerve and somatic nerve in rats.

End-to-side neurorrhaphy is widely used in the peripheral nervous system for nerve repair; however, the application of this technique has been limited to somatic nerves. The feasibility of nerve regeneration through end-to-side neurorrhaphy between autonomic and somatic nerves with different characteristics in the peripheral nervous system is still undetermined. In this study, rats were divided into three groups for different treatments (n=10 per group). In the end-to-side neurorrhaphy group, left L6 and S1 were transected in the dura, and the distal stump of L6 ventral root was sutured to the lateral face of L4 ventral root through end-to-side coaptation. In the no repair group, the rats did not undergo neurorrhaphy. In the control group, the left L6 dorsal root and S1 roots were transected, respectively, but the L6 ventral root was kept intact. After 16 weeks, the origin and mechanism of nerve regeneration was evaluated by retrograde double labeling technique as well as histological examination and intravesical pressure measurement. Retrograde double labeling indicated that the reconstructed reflex pathway was successfully established and the primary regeneration mechanism involved axon collateral sprouting. Morphological examination and intravesical pressure measurement indicated prominent nerve regeneration and successful re-innervation of the bladder in the neurorrhaphy group, compared with the "no repair" group (p<0.05). No significant changes were observed in the histology of the donor nerve and the bilateral extensor digitorum longus muscles in the neurorrhaphy group. Nerve regeneration may be achievable for nerve repair through end-to-side neurorrhaphy between autonomic and somatic nerves without apparent impairment of donor somatic nerve.