Effect of extract of Ginkgo biloba leaves on expression of inducible nitric oxide synthase after sciatic nerve injury: Experimental with rats

Objective: To investigate the effect of extract of Ginkgo biloba leaves (EGb5O) on the expression of inducible nitric oxide synthase (iNOS) after sciatic nerve injury. Methods: 156 male SD rats were randomly divided into 3 groups: experiment group (n = 72), undergoing section and anastomosis of sciatic nerve and then gastric perfusion of EGb5O 200 mg · kg^-1 · d^-1; injury control group (n = 72), undergoing section and anastomosis of sciatic nerve and then gastric perfusion of normal saline daily; and sham operation group (n = 12), undergoing sham operation and gastric perfusion of normal saline daily. The rats were killed at different time points: 1, 3, 7, 14, 21, and 28 days after the operation. The sciatic nerve distant to the anastomotic sites with a length of 0.5 cm was cut out to undergo immunohostochemistry and RT-PCR to detect the protein and mRNA expression of iNOS. Results: No obvious iNOS protein and mRNA expression was seen in the sham operation group. 3, 7, 14, and 21 days after operation the mean values of absorbance of iNOS in the sciatic nerve specimens of the experiment group were all significantly lower than those of the injury control group (P < 0.05, P < 0.01). High mRNA expression of iNOS began to be shown in the sciatic nerve specimens since 1 day after the operation and remained at a high level till 7 days after and then began to decrease in the injury control group. The levels of mRNA expression of iNOS in the sciatic nerve specimens 1, 3, and 7 days after the operation of the experiment group were all significantly lower than those of the injury control group (all P < 0.01), and there was no significant difference in the levels mRNA expression of iNOS 14, 21, and 28 days after the operation between the experiment group and injury control group (all P > 0.05). Conclusion: The extract of Gingko biloba promotes the regeneration of nervous tissues, probably by inhibiting the expression of iNOS.