Effects Of Electroacupuncture On Peripheral Facial Nerve Regeneration In Rats And Its Relationship With VEGF/MAPK/ERK Signaling Pathway

Objective: A model of peripheral facial nerve compression injury in SD rats were established.The purpose of this study was to observe the therapeutic effect of electroacupuncture on peripheral facial paralysis induced by buccal branch of facial nerve in rats,and further to elucidate the role of VEGF-mediated MAPK/ERK signaling pathway in the above process and the effect of electroacupuncture on this signaling pathway.Methods:A total of 56 adult male Sprague-Dawley rats were randomly divided into three groups:the normal group(8 rats),model group(24 rats)and electroacupuncture group(EA group 24 rats).Model rats and EA group rats were used to make right facial nerve upper cheeks.After the successful establishment of the model,the rats in the EA group were treated with electroacupuncture 1 hour after the anesthesia was awakened,once a day,each treatment time was 30minutes;the model group was not treated with electroacupuncture.The model group and EA group were divided into three groupsaccording to the time points of the postoperative materials(4,14,and 28 days).To observe the influence of the "Jia che" and "Di cang" on the right side of the electroacupuncture rats on their behavior.In the model group and EA group,four rats in each group were selected after 4,14 and 28 days postoperatively,after hearts were perfused,the facial nerve nucleus was taken to make paraffin blocks.After sectioning,immunohistochemical method was used to detect the expression of VEGF in facial nerve tissue.The expression of VEGF also were detected in the normal group.At the same time,the remaining 4 rats in the model group and the EA group were taken from the lower brain tissue of the fresh pons.Western blot analysis was used to analyze the quantitative expressions of VEGF,ERK and P-ERK protein in facial neurons at each time point in the experimental group and normal group and statistical analysis was performed.Results:1.Observation of facial paralysis in SD rats: rats in the normal group had no symptoms of peripheral facial paralysis.On the 4th day after the facial nerve injury,there was no significant difference between the model group and the EA group in the facial paralysis of the rats.All rats showed symptoms of eyelid insufficiency,nasal tip askewness,and weakened tentacles on the affected side.On the14 th and 28 th days after surgery,the nasal tip deviation of rats inEA group was improved,and the tentacle floatation was increased,while the facial paralysis symptoms such as the tentacle floatation and nasal tip deviation in the model group were not improved as significantly as those in the EA group.Western blot results: the expression of VEGF protein in the normal group was low.However,the expression of VEGF in the EA group and the model group was higher than that in the normal group at all time points.Besides,the expression of VEGF in the EA group was higher than that in the model group(P<0.001).ERK protein expression in normal group,model group and EA group showed no statistical significance(P>0.05).The level of P-ERK protein in the model group and the EA group showed a trend of first decrease,then increase and then decrease on the 4th,14 th and28th days after operation,and the EA group was higher than the model group,showing a statistically significant difference(P<0.001).Immunohistochemical results: positive VEGF staining was brown-yellow,and was expressed in the cytoplasm of facial neurons.The VEGF of the normal group was weakly expressed.The average optical density of VEGF in the EA group and the model group were higher than that in the normal group at 3 time points,and the average optical density of VEGF in the EA group was higher than that in the model group(P<0.001).Conclusion: 1.Electroacupuncture can promote the recovery of peripheral facial paralysis symptoms caused by facial nerve compression injury in SD rats.2.After facial nerve injury,the expression of VEGF protein in rat facial neurons increased,and the expression of P-ERK protein changed with time,indicating that VEGF/MAPK/ERK signaling pathway may participate in the repair process after facial nerve injury.3.Electroacupuncture can promote the expression of VEGF in facial neurons,activating MAPK/ERK signaling pathway,and playing a protective role in facial nerve.