| Objective:Protection and regeneration of injured peripheral nerve is a commonly encountered clinical problem for the doctors. The one reason is lack useful medicine to protection and promoting regeneration of injured peripheral nerve. Extensive investigation toward the development of medicine to protect and regenerate the injured nerve is a imminent task for clinical researchers. Ginkgo Biloba leaves is a traditional Chinese medicine, It's extract has been widely used for the treatment of cerebrovascular and cardiovascular diseases. Recent years some experiment study has proved that the Extract of Ginkgo biloba leaves can protect and regenerate neuron in the injured peripheral nerve, however, the mechanism is not clearly. Calcitonin gene-related peptide(CGRP)that formed by 37 amino acids is widely distributed in central and peripheral nervous system . The expression of CGRP correlated closely to protection and regeneration of injured peripheral nerve. In our study, the sciatic nerve injured animal model have been established first, and then we investigate the effect of Extract of Ginkgo biloba leaves 761(EGB761)on the expression of calcitionin gene-related peptide in anterior horn motor neurons of spinal cord following sciatic nerve injury, to provide a theoretical basis for clinical treatment of peripheral nerve injury using Extract of Ginkgo biloba leaves.Methods: Sciatic nerve injury model was established by transacting the right sciatic nerve in 60 male SD rats, which were randomly divided into two groups. The rats were fed with EGB761(200mg/kg) in the experimental group and with normal saline in the control group. At the same time, other 10 rats were employed as the normal group without any treatments. The spinal cord was harvested at 1,2,4,6,8 week after operation. Immunohistochemical method and image analysis were used to evaluate the expression of CGRP.Results: In the normal group each section has 2 or 3 calcitonin gene-related peptide positive cells in the anterior horn of lumbosacral spinal at most, it's mainly located in the anterolateral horn of the spinal cord. The positive cells with large body is round or polygonal. The positive expression area was yellowish-brown and mainly in the cytoplasm at the same time the nucleus was negative. The optical density of positive expression of CGRP in normal group at 1,2,4,6,8 weeks after operation : ( 160.62±2.86 ),(158.70±3.03),(159.12±2.47),(157.84±3.19),(159.01±2.60).The positive expression of CGRP in anterior horn was remarkably increased in the control group at 1 week after operation . at 2 weeks after operation the positive expression reached the summit and then gradually decreased. at 8 weeks after operation the positive expression was already closed to normal. The optical density of positive expression of CGRP in control group at 1,2,4,6,8 weeks after operation : ( 168.26±4.20 ),( 177.68±4.85 ),( 166.23±5.02 ),(162.76±3.67),(160.50±3.14).the number of positive cells in control group at 1,2,4,6,8 weeks after operation: (8.6±0.5),(10.7±1.2),(7.1±0.8),(5.5±0.6),(3.6±0.7). The CGRP positive expression between experimental and control group have significant difference at 1 week after operation, at 2 weeks after operation the difference is more remarkable. The positive cells with large body is round or ellipse. The positive area was dark-brown and mainly in the cytoplasm at the same time the nucleus was negative. The integrated optical density of positive expression of CGRP in experimental group at 1,2,4,6,8 weeks after operation : (176.35±4.09),(189.84±5.27),(179.26±4.60),(175.69±4.25),(170.15±5.38).the number of positive cells in experimental group at 1,2,4,6,8weeks: (11.4±1.9),(16.8±1.4),(12.0±1.5),(10.2±1.2),(8.3±0.8).The positive expression of CGRP in anterior horn were higher in the experimental group than that in the control group at 1,2,4,6,8 weeks after operation(P<0.05).Conclusions: through the animal model we discovered that EGB761 can increase the positive expression of CGRP in anterior horn motor neurons of spinal cord after sciatic nerve injury. which may be the one way of protection and regeneration of injured peripheral nerve. It provide a theoretical basis for clinical treatment of peripheral nerve injury using ginkgo biloba extract 761.
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