Effects of ginkgo biloba extract on the expression of inducible nitric oxide synthase and platelet-activating factor after local cerebral ischemia/reperfusion in rats

Abstract

Objective To explore the protective effect and mechanism of ginkgo biloba extract (GBE) on brain tissue after local cerebral ischemia and reperfusion in rats.Methods Eight male SpragueDawley rats were randomly divided into two groups:control group ( group A,normal saline injected,n =40),GBE intervention group (group B,GBE injected,n =40),which were then divided into 4 subgrouops,namely,1 h,3 h,6 h and 24 h after reperfusion,10 in each sub-group.The model of right middle cerebral artery occlusion (MCAO) and reperfusion was made.Pathological changes in brain morphology were observed by Hematoxylin and Eosin (HE) staining; immunohitochemical method was used to detect the inducible nitric oxide synthase (iNOS) changes; platelet activating factor (PAF) was detected by enzyme linked immunosorbent assay (ELISA).Results Nerve cell necrosis,apoptosis and cytoplasmic vacuolatin were observed,neuronal shape was difficult to identify,and most of the cell structures disappeared in group A.The injury was relieved at the same time points in group B compared with that in group A.Immunohitochemical results showed that there were a few iNOS expression positive cells 1 h after reperfusion,which increased at 3 h after referfusion and had nucler translocation.Analysis by Image-pro plus 5.0 showed that iNOS expression levels in group B ( 1851.38 ±242.12,2005.41 ±290.52,2625.28 ±385.21,3142.50 ± 425.72) were significantly lower than those in group A ( 1950.25 ± 298.26,2232.45 ± 305.28,3251.22 ± 425.26,3965.36 ± 521.62) (P ＜ 0.05 ),respectively.ELISA results showed that serum PAF levels were increased after ischemia-reperfusion,peaked at 6 h,and decreased at 24 h.Serum PAF level were significantly lower in group B ( 15.36 ± 2.12,18.56 ± 3.28,28.21 ± 4.26,22.48 ± 4.21 ) μg/L than in group A (20.52 ± 4.26,28.25 ± 6.18,36.08 ± 7.45,30.26 ± 6.02) μg/L ( P ＜ 0.05).Conclusion iNOS,and PAF change significantly after the cerebral ischemia-reperfusion in rats,which may be involved in cerebral ischemia-reperfusion injury mechanism.GBE can significantly alleviate the cerebral injury by regulating the expression of iNOS and PAF,suggesting GBE can effectively protect the ischemic cerebral tissues. Key words: Ginkgo biloba extract; Cerebral ischemia; Reperfusion injury; Inducible nitric oxide synthase