Facial nucleus up-regulation of brain-derived neurotrophic factor mRNA following electroacupuncture treatment in a rabbit model of facial nerve injury

BACKGROUND: The effect of acupuncture treatment on peripheral facial nerve injury is generally accepted. However, the mechanisms of action remain poorly understood. OBJECTIVE: To validate the effect of acupoint electro-stimulation on brain-derived neurotrophic factor (BDNF) mRNA expression in the facial nucleus of rabbits with facial nerve injury, with the hypothesis that acupuncture treatment efficacy is related to BDNF. DESIGN, TIME AND SETTING: Peripheral facial nerve injury, in situ hybridization, and randomized, controlled, animal trial. The experiment was performed at the Laboratory of Anatomy, Heilongiiang University of Chinese Medicine from March to September 2005. MATERIALS: A total of 120 healthy, adult, Japanese rabbits, with an equal number of males and females were selected. Models of peripheral facial nerve injury were established using the facial nerve pressing method. METHODS: The rabbits were randomly divided into five groups (n = 24): sham operation, an incision to the followed by suture; model, no treatment following facial nerve model establishment; western left facial skin, medicine, 10 mg vitamin B-1, 50 mu g vitamin B-12, and dexamethasone (2 mg/d, reduced to half every 7 days) intramuscular injection starting with the first day following lesion, once per day; traditional acupuncture, acupuncture at Yifeng, Quanliao, Dicang, Jiache, Sibai, and Yangbai acupoints using a acupuncture needle with needle twirling every 10 minutes, followed by needle retention for 30 minutes, for successive 5 days; electroacupuncture, similar to the traditional acupuncture group, the Yifeng (negative electrode), Jiache (positive electrode), Dicang (negative electrode), and Sibai (positive electrode) points were connected to an universal pulse electro-therapeutic apparatus for 30 minutes per day, with disperse-dense waves for successive 5 days, and resting for 2 days. MAIN OUTCOME MEASURES: Left hemisphere brain stem tissues were harvested on post-operative days 7, 14, 21, and 28 under a dissecting microscope. Neuronal appearance in the facial nucleus was observed following Nissl staining. BDNF mRNA expression in the facial nucleus was determined using in situ hybridization. RESULTS: A total of 120 rabbits were included in the final analysis. In the model group, the nucleolus was asymmetric with cell body swelling, and the number of Nissl bodies decreased. With increasing time, there were more Nissl bodies in the western medicine, traditional acupuncture, and electroacupuncture groups, in particular the electroacupuncture group. However, the number of Nissl bodies remained less than in the sham operation group. The number of BDNF-positive neurons in the facial nucleus was significantly greater in the western medicine, traditional acupuncture, and electroacupuncture groups, compared with the model group (P < 0.01). The number of BDNF-positive neurons in the facial nucleus of reached a minimum in the electroacupuncture group on post-surgery day 21, and increased by day 28, but remained less than control levels. CONCLUSION: Electroacupuncture at acupoints increased BDNF expression in the facial nucleus, alleviated neuronal injury in the facial nucleus, and promoted facial nerve regeneration. The effect was superior over traditional acupuncture and western medicine.