The Feasibility Study Of Nerve Regeneration And Bladder Reinnervation Through End-to-side Neurorrhaphy Of Autonomic Nerve And Somatic Nerve In Rats

Objective:To investigate the feasibility of nerve regeneration and bladder rehabilitation through end-to-side neurorrhaphy of autonomic nerve and somatic nerve in rats.Methods:Thirty healthy, mature and male Sprague-Dawley rats were randomly divided into three groups (n=10 per group):end-to-side neurorrhaphy group (GroupⅠ), no repair group (GroupⅡ) and control group (GroupⅢ). In group I, the left lumbar 6 and sacral 1 spinal nerves were transected in dura and the distal stump of lumbar 6 ventral root (L6VR) was sutured to lateral face of nearby and intact lumbar 4 ventral root (L4VR) through end-to-side coaptation. In groupⅡ, the same procedure as above was performed without coaptation of L6VR and L4VR. In groupⅢ, the same operation as group I was performed but kept L6VR intact. After 4 months, Fluorogold (FG) and Fast Blue (FB) were injected into the left major pelvic ganglion and sciatic nerve for each group respectively for retrograde nerve tracing. Morphological examination of the recipient nerve (L6VR) and donor nerve (L4VR) to evaluate the effect of nerve regeneration and the impact of end-to-side neurorrhaphy on donor nerve. Intravesical pressure measured of rats in groupⅠto evaluate the bladder function. Wet weight and histological examination of bilateral extensor digitorum longus (EDL) muscles of rats in groupⅠwere performed to evaluate the function of target organ of donor nerve.Results:FG and FB single labeled neurons and FG-FB double neurons were observed in the left ventral horn of L4 of rats in groupⅠby retrograde nerve tracing, and the number of FG-FB double labeled neurons (7.8±1.8) more than FG-labeled neurons (1.1±0.9) (p< 0.05) indicated that the reconstructed neural pathway was established and the main regeneration mechanism was axons collateral sprouting of donor nerve. Morphological examination of the recipient nerve indicated apparent nerve regeneration and the number of myelinated axons in preganglionic pelvic parasympathetic nerve in groupsⅠ,ⅡandⅢwere 326.5±57.2,2.1±1.6 and 533.6±80.0 respectively (p< 0.05). Intravesical pressure measurement of rats in groupⅠindicated intracesical pressure increased apparently when the donor nerve was stimulated and the mean amplitude of intravesical pressure could reach 53% of that in groupⅢ. The intravesical pressure had no obvious change when the same L4VR was stimulated of rats in groupⅡ. The number myelinated axons of L4VR of rats in groupⅠdistal and proximal to coaptation site were 870.1±18.1 and 872.9±14.8, respectively, and there was no statistical differences between the two segments (p> 0.05). The wet weights of bilateral EDL muscles in rats of groupⅠwere 0.1682±0.0036 (left) and 0.1691±0.0036 (right) respectively. There were no statistical differences in the wet weights and histomorphology properties of the bilateral EDL muscles in rats of group I (p> 0.05).Conclusion:Our results indicated that nerve regeneration and reinnervation for bladder could be achieved through end-to-side neurorrhaphy of autonomic nerve and somatic nerve without apparent impairment of donor somatic nerve in rats.