The Effect Of Capsaicin Receptor On The Axonal Regeneration After Sciatic Crush Injury In Rats

Objective:To observe the effect of the transient receptor potential vanilloid 1(TRPV1) on neuronal regeneration after crush injury to the rat’s sciatic nerve.Methods:48 Sprague-Dawly(SD)healthy female rats were randomly divided into 4 groups.The right sciatic nerve of each rats were crushed.Two groups of the rats received a subcutaneous injection of AMG-517,a highly potent and selective TRPV1 antagonist,into the right hind paw 1h before the crush at a standard of 300μg/kg while the other two received a injection of normal saline at the same standard.At the crush zone,proximal zone and distal zone,the numbers of nerve fibers on the transverse section were counted after a surviving time of 7 or 14 days.The expression of TRPV1 in bilateral sciatic nerves,bilateral L3-L5 DRG,and lumbar spinal cords were detected by immunofluorescence.The co-localization of TRPV1 and CGRP,TRPV1 and Trk A in bilateral sciatic nerves,bilateral L3-L5 DRG,and lumbar spinal cords were detected by double immunofluorescent staining.Results:(1) After a surviving time of 14 days,the number of nerve fibers at the proximal zone,the crush zone or the distal zone.was higher than the number of which appeared after a surviving time of one week;with the injection of AMG517 before the crush,the number of nerve fibers at the proximal zone,the crush zone or the distal zone which appeared after a surviving time of 7 days or 14 days was higher than the number of which appeared without the injection of AMG517 before the crush.(2)The average integrated optical density of TRPV1 expression at the injured site,ipsilateral DRG, ipsilatera dorsal horn were increased after crush. The average integrated optical density were lower with the application of AMG517. TRPV1 and CGRP, TRPV1 and Trk A were partially colocalized in the sciatic nerve,patent DRG and dorsal horn and the average integrated optical densitywere higher with the application of AMG517.Conclusion:TRPV1 interfere the regenerative process after nerve injury by its functional alterations and the inhibition of TRPV1 by its antagonists might accelerate or stimulate the regenerative process after injury.