Experimental Research Of Extract Of Ginkgo Biloba EGB₅₀ On Facial Nerve After Being Crushed

Objective: To investigate the effect of EGB₅₀ on facial nerve crush injuries, the Japan giant ear white rabbit were suffered with grade III squeezing facial nerve crush injuries and treated with EGB₅₀ and methylcobalamin in order to study the therapeutic feasibility of treating facial nerve injuries in clinical application as a fast and effective medicine.Methods: 40 healthy Japan giant ear rabbits, 6 months old, were randomly devided into4 groups, namely EGB₅₀ experimental group, normal control group, Mecobalamin control group and non-administered control group. Each group contained 10 rabbits. Set up the III grade lateral buccal branch of facial nerve cursh injuried models for EGB₅₀ experimental group, the Mecobalamin control group and the non-administered control group, while setting up facial incision model without crush injuries for the normal control group. Then those 4 groups of rabbits were fed with 1ml liquid medicine twice a day in different ingredients. The EGB₅₀ experimental group of rabbits were given 37 mg/kg EGB₅₀ dissolved in 1 ml of normal saline every time; the Mecobalamin control group of rabbits were given 0.02 mg/kg Mecobalamin dissolved in 1 ml of normal saline every time; while the normal control group and the non-administered group of rabbits were only given 1 ml of normal saline every time. After the operation, those animals' facial injured beard and muscle movements were observed when they were chewing. In 14,and 28 days after being treated with 5 rabbits were picked from each of four groups for surgery, and observed shapes of facial nerves on original wounds and doing neuroelectrophysiology EMG tests.Then those animals were killed and the facial nerve tissues on wounds were taken out to stain with hematoxylin-eosin and warthin-starry staining. After that, the histologic observation under a microscope was conducted and the amount of facial nerve regenration was measured according to an image analyzer. Thereby the situation of the facial nerve regeneration and functional recovery were evaluated.Results: The beard and upper lip orbicular muscle movement of rabbits in the non-administered control group and Mecobalamin group were weaker than that of in EGB₅₀ experimental group, furthermore, it was the worst in the saline group After surgery14 days, the incubation period in. Treatment for 14 days and 28 days after surgery, EGB₅₀ experimental group incubation period were 2.35 ± 0.56 ms and 1.11 ± 0.54 ms;Mecobalamine control group incubation period were 3.06±0.32 ms and 1.70±0.20 ms;non-administered control group incubation period were 3.85±0.67 ms and 3.43±0.57 ms.The orbicularis muscle action potential in the EGB₅₀ experimental group is lower than Mecobalamin control group, and obviously lower than non-administered control group,and the 28 days were lower than the 14 days? P<0.05?; EGB₅₀ experimental group amplitude were 3.48±0.28 m V and 28 days 4.55±0.43 m V; Mecobalamin control group incubation period were 2.87 ± 0.50 m V and 3.59 ± 0.30 m V; non-administered control group incubation period were 2.57±0.88 m V and 3.43±0.57 m V. The amplitude of action potential amplitude?M wave? of compound nerve muscle was higher than that of Mecobalamin control group and obviously higher than the non-administered control group,and the 28 days was higher than the 14 days?P<0.05?. In the EGB₅₀ experimental group, the nerve growth was good, with more uniform thickness of myelin sheath, many axon regeneration, the neurite alignment is regular, and the collagen fibers increased more than in the other two groups, in the Mecobalamin control group and non-administered control group, the axons arranged irregular, myelin thickness was uneven, myelin dissolved liquefaction is obviously, and the non-administered control group was the most obviously. EGB₅₀ experimental group the axon number were 2011±270 and 2596±212;Mecobalamin control group the axon number were 1880 ± 188 and 2258 ± 98;non-administered control group the axon number were 1091±311 and 1423±328. EGB₅₀ experimental group the axon area were 4.03±0.25 ?m2 and 5.07±0.13 ?m2; Mecobalamin control group axon area after surgery were 3.15 ± 0.46 ?m2 and 3.59 ± 0.30 ?m2;non-administered control group axon area were 2.06±0.31 ?m2 and 1.94±0.23 ?m2. In the EGB₅₀ experimental group and Mecobalamin control group, the number, diameter and area of nerve axon were all obviously better than those of non-administered control group, in the EGB₅₀ experimental group, and in the 28 days was better than in the 14 days, there were significant differences between the groups?P<0.05?.Conclusion: EGB₅₀ not only has the facial nerve injury repair function the same as Methylcobalamin, but also accelerates the regeneration speed after facial nerve injury,which is significant for facial injuries treatment. Therefore, EGB₅₀ is expected to become one of the fastest and effective medicines to treat facial nerve injuries in clinical application.