| Objective: This study was to establish a model of peri-facial nerve injury in rabbits.After being stimulated by electroacupuncture,we observed the effects of electroacupuncture on peripheral paralysis of the facial nerve in rabbits and morphology of facial neurons and the expression of nerve growth factor(NGF)and its receptor to explore the mechanism of electroacupuncture in the treatment of peripheral facial nerve injury.Methods: We divided the New Zealand white rabbits(n=66)into normal group(n = 6),model group(n = 30)and EA group(n = 30)randomly.The EA group and the model group were established the crushing injury model of superior buccal branch of the right facial nerve and with no deal with normal group.Acupuncture at Yifeng,Jiache,Sibai,Yangbai,Quanliao,Decang and Hegu was applied in the EA group,with electrical stimulation of sparse-dense wave,18-20 Hz and 1.5V except Hegu acupoint(once per day,each time for 30 min),model group and normal group would be dealt with no intervention.On the 1st,4th,7th,14 th and 28 th day after the facial nerve injury,3 rabbits in the model group and EA group were sacrificed,we observed the morphological changes of motor neurons by using HE staining and the expression of NGF,TrkA and p75 NTR of facial neurons by using immunohistochemical staining.3 rabbits in the normal group were also treated in the same way.3 rabbits in the model group and the EA group were sacrificed at each time point,we observed the expression of NGF,TrkA and p75 NTR mRNA by quantitative real-time PCR,3 rabbits in the normal group were also treated in the same way.During the experiment,we also need to observe the performance of peripheral facial paralysis in rabbits.Results: 1.The performance of peripheral facial paralysis in rabbits: There was no significant difference between the model group and the EA group on the 1st and 4th day after the facial nerve injury,both with eyelid insufficiency and skewed mouth,and no whisker flicking.EA group rabbit mouth angle skew gradually improved and had more flicking tentacles,while the model group still had no obvious whisker flicker and the mouth angle askew improvement was not as obvious as EA group on the 7th,14 th,28th day after surgery.2.Morphological changes of neurons were observed by H-E staining: normal neurons showed polygonal shape and deeply stained Nissl bodies,the nucleolus were located in the center of the nucleus.There was no significant difference between the two groups of neurons on the 1st day after surgery;The neurons in the model group showed swollen and Nissl bodies decreased,and the nucleolus migrated to the periphery on the 4th,7th day,the neurons in EA group also had similar changes,but the pathological changes were lighter than the model group;The morphology of neurons gradually recovered in EA group on the 14 th and 28 th day after surgery and no swelling neurons were found on the 28 th day after surgery,but the model group showed swelling neurons and Nissl body was not dense,neuronal body structure do not completely recover.The results of immunohistochemical staining: The expression of NGF in model group and EA group undergo a process of decreasing and increasing gradually and then maintaining at a high level.The mean OD value of NGF in the model group were lower than normal group on 1st,4th,7th day after surgery(P <0.05),but the value was higher than normal group on the 14 th day after surgery(P <0.05),the value in EA group was higher than model group at every time point(P <0.05).The expression of TrkA in the model group and the EA group increased firstly and then decreased and increased finally.The mean OD value of TrkA in the model group was higher than that in normal group on the 1st and 4th day after surgery(P < 0.05),and the value was higher than normal group on the 14 th and 28 th day after surgery(P <0.05).The average OD of TrkA in EA group was higher than model group on the 7th,14 th,28th day after surgery(P <0.05).The expression of p75 NTR in model group and EA group appeared a decline and gradually increased and maintained at a high level;The The mean OD of p75 NTR in the model group was lower than that of normal group on the 1st day after surgery(P < 0.05).The average OD of p75 NTR in model group was higher than that in normal group on the 28 th day after surgery(P < 0.05).The average OD of p75 NTR in EA group was higher than model group on the 7th,14 th,28th day after surgery(P < 0.05).3.Real-time PCR results: The relative expression of NGF mRNA increased after decreased and then decreased,and then increased in the model group and EA group after the facial nerve injury.The relative expression of NGF mRNA in EA group was higher than that in model group on the 14 th and 28 th day after the surgery(P <0.05).The relative expression of TrkA mRNA in the model group and EA group gradually increased and then decreased after the surgery.The TrkA mRNA in the EA group was higher than model group on the 7th,14 th,28th day after the surgery(P <0.05).The relative expression of p75 NTR mRNA increased after decreased and then decreased,and then increased in the model group and EA group after the surgery.The p75 NTR mRNA in EA group was higher than model group on the 14 th,28th day after surgery(P <0.05).Conclusion: 1.EA can promote the recovery of facial paralysis after peripheral facial nerve injury in rabbits.2.EA can alleviate the morphological changes of neurons and promote the recovery of neuronal morphology after facial nerve injury.3.The expression of NGF and p75 NTR in the facial nucleus decreased after the facial nerve injury and increased during the progress of the nerve repair,TrkA continued to be highly expressed.NGF may play an active neuron protective role not only through binding to TrkA,but also promote p75 NTR mediated cell body survival through binding with p75 NTR.4.EA can improve the expression of NGF,TrkA,p75 NTR in facial nucleus,and may promote the binding between NGF with TrkA and p75 NTR,which may be the mechanism of EA playing an active role in the repair of facial nerve injury. |
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