A Study Of Electroacupuncture On Schwann Cell Morphology And CNTF Expression In Facial Nerve Injury

Objective:Acupuncture therapy for facial nerve injury has been proven to be effective. To investigate the influence of electro-acupuncture on the morphology of injured facial nerves, Schwann cells and the content of CNTF in order to provide strong theory foundation to the clinical application of electro-acupuncture.Methods:A total of60Japanese big-eared rabbits were randomly assigned to four groups: control (n=6), model (n=18), sham-operated (n=18), electroacupuncture (EA; n=18) groups. We established the model by clamping the facial nerve. The animals received electroacupuncture treatment at dicang (ST4), jiache (ST6), yifeng (TE17) and hegu (LI4) on the injured side, retaining the needle for30minutes, once a day, five treatments made a course and there was two days break between two courses. We examined the morphology of the injured facial nerves and schwann cells, as well as the expression of ciliary neurotrophic factor and mRNA by electron microscopy, light microscopy, immunohistochemistry and in situ hybridization after each course.Results:1. The morphological changes:In normal group, facial nerve bundles and the myelin sheaths were intact, with the smooth capsule enveloping bundles of nerve fibers. Schwann cells were normal with abundant organelles. In model group, the structural integrity of the facial nerve bundles was destroyed. Different degrees of edema, a great deal of vacuolation and inflammatory cells infiltration were observed with disaggregated myelin sheaths. Compared with the model group, the histopathological changes in the sham and EA group were milder. In sham group, the repair completed after three courses. In EA group, the extent of demyelination was milder with more organelles.2. Quantitative myelin sheaths analysis:In model group, it was extremely severe without intact myelin sheaths after one course. After the second and third course, irregular myelin sheaths formed in model group. There were differences in the number and thickness of the myelin sheaths between the control and model group(P<0.01, P<0.01). In sham group, the number and thickness of the myelin sheaths were different from those in the control group, which was close to normal after the third course (P>0.05). After one course, the number and thickness of the myelin sheaths between the control and EA groups was similar (P>0.05), which were different between the model and EA groups were significant after the second course (P<0.01). With continued of EA treatment, they dwindled gradually and the number of the myelin sheaths was less after the third course (P<0.05), while the thickness of myelin sheaths was not different (P＞0.05).3. The results of CNTF protein expression:There was low CNTF protein expression in control group. In model group, the content of CNTF protein was significantly higher than that of control group(P<0.01). Five days after EA treatment, the levels of them were lower than in model group (P<0.05), Subsequently, which increased in EA group, and the CNTF level was significantly different from the model group after the third course (P<0.01).4. The results of CNTFmRNA expression:In control group, there was low level of CNTFmRNA expression. The content of CNTFmRNA in model group was significantly higher than that of control group(P<0.01). Five days after EA treatment, the levels of them were lower than in model group (P＜0.01), Subsequently, which increased in EA group, and the CNTFmRNA level was not different from the model group after the third course (P>0.05).Conclusions:1. EA could significantly speed up the process of the repair of injured facial nerves, and quickly promote the myelin sheath and Schwann cells to normal structure in acute stage of facial nerve injury.2. The expression of CNTF protein and mRNA were positively related with the degree of injured facial nerves. EA could rapidly regulate the level of CNTF protein and mRNA expression to normal level.3. The effect of EA was not positively correlated with the quantity of stimulus. With the same quantity of stimulus, it may not be beneficial for facial nerve fibers and Schwann cell recovery. We should follow the principle of "the disease lasts" in the application of EA treatment.