RESUMEN
OBJECTIVE: To observe the effect of electroacupuncture (EA) on ultrastructure of facial nerve and Schwann cells in facial nerve injury rabbits so as to explore its mechanism underlying improving facial palsy. METHODS: A total of 60 Japanese white rabbits were randomly assigned to normal control (normal, n = 6), sham-operation (sham, n = 18), model (n = 18) and EA (n = 18) groups. The facial nerve injury model was established by clamping the right facial nerve for 5 min by using a pair of forceps. EA (1.5 V, 3 Hz/60 Hz) was applied to "Yifeng" (TE 17)-"Hegu" (LI 4), and "Dicang" (ST4)-"Jiache" (ST6) on the affected side for 30 min, respectively, once daily for 3 weeks. Morphologic changes of the myelin sheath and Schwann cells of the facial nerve were observed by using electron microscope after 1, 2 and 3 weeks' treatment. RESULTS: Compared with the normal control group, the number of the myelin sheaths and the thickness values of the facial nerve after treatment of 1, 2 and 3 weeks in the model group were decreased significantly (P < 0.01, P < 0.05). While in comparison with the model group, the thickness value of the facial nerve 2 weeks after modeling in EA group was increased considerably (P < 0.01). In the model group, there were many vacuoles in the cytoplasm of Schwann cells instead of organells in the facial nerve. In the sham group, the demyelination was milder than that of the model group, and majority of myelin sheaths showed integral structure after 2 and 3 weeks, being similar to the normal group. Compared with the model group, the extent of demyelination was less distinct, with relatively more abundant organells in the facial nerve of the EA group, especially after 1 week of treatment. Among the three time points in the EA group, demyelination was milder in the 1st week not in the other time points. In contrast, along with the continuous EA treatment, the situation became worse after 3 weeks of treatment in the EA group. CONCLUSION: In the acute stage of facial nerve injury, EA intervention can play a positive effect on the repair of the nerve and Schwann cells. However, continuous 3- weeks' EA intervention may worsen the facial nerve injury.