Effect Of Tube Moxibustion On Ras/MEK/ERK Signaling Pathway In Rabbits With Facial Nerve Injury

Objective:To investigate the effect of tube moxibustion on Ras/MEK/ERK signaling pathway in rabbit model with facial nerve injury,and to reveal the signaling mechanism of tube moxibustion for promoting repair and regeneration after facial nerve injury.Methods:Animals were randomly divided into sham operation group,model group,tube moxibustion group,and hyperthermia group using random number table method.Each group had 8 experimental rabbits.Except for the sham operation group,the rabbits' facial nerve injury model was made by nerve crush injury in other groups.The tube moxibustion group and the hyperthermia group was started to treat 5 days after the anti-infective treatment,and 6 days were a course of treatment.The interval between courses was 1 day and there were 2 courses in total.The sham and model groups did not receive any treatment after surgery.The ultrastructure of facial nerve fibers in the facial nerve injury model of rabbits was observed by transmission electron microscopy.Immunohistochemistry,ELISA and Western blot were used for detecting the expression of Grb2,Shc,KRas,MEKK3,MEK5,ERK1/2,P-ERK1/2and c-jun protein in rabbit facial nerves.Results:1.General observation: After facial nerve injury,except for the sham operation group,other groups of rabbits showed facial palsy in different degrees;the recovery offfacial motor function in the tube moxibustion group was faster than that in the model group and the hyperthermia group during the treatment;the facial motor function of the rabbits in the tube moxibustion group were approximately returned to normal,and were improved slightly in the hyperthermia group compared with that before.The model group had no significant changes.2.Ultrastructure observation of nerve fibers: there was no abnormal nerve structures in the sham operation group.The myelin sheath was intact and the Schwanncells had no obvious changes.The demyelination was severe in the model group,and the degree of mitochondria swelling was severe.The degree of demyelination and cellular mitochondrial swelling were mild in the tube moxibustion group;The degree of demyelinating lesions and mitochondrial swelling in the hyperthermia group was between the model group and tube moxibustion group.3.Protein expression of signal transduction molecules: Compared with the model group,the protein expression of Shc,Grb2,Kras,MEKK3,MEK5,ERK1/2,P-ERK1/2,c-jun in the facial nerve of the tubal moxibustion group was increased,and the differences were statistically significant(P<0.05 or P<0.01).However,there were no statistical significance in the hyperthermia group(P>0.05);compared with the sham group,the model group showed an upward trend,but there was no statistical significance.Conclusions:1.Tube moxibustion can promote the restoration of ultrastructures in facial nerve fiber and speed up the process of repair and regeneration of damaged facial nerve.2.Ras/MEK/ERK signaling pathway participates in the process of repair and regeneration after facial nerve injury.Tube moxibustion up-regulates protein expressionof signal molecules at all levels of Ras/MEK/ERK signaling pathway(Grb2,Shc,KRas,MEKK3,MEK5,ERK1/2,P-ERK1/2,c-jun),enhances the activity of Ras/MEK/ERK signaling pathway,mediate neurotrophins and their receptors to promote facial nerve injury repair and regeneration.The Ras/MEK/ERK signaling pathway is an important target for the intervention of the tube moxibustion and it may be one of the mechanisms that the tube moxibustion promotes the repair of the facial nerve injury.