Effects of ginkgo biloba extract on intercellular adhesion molecule-1 and interleukin-6 in acute ischemic myocardium of Rats

Objective To study the expressiou of intercellular adhesion molecule-1 (ICAM-1) and interleukin (IL)-6 in myocardium with acute myocardial infarction in rats and the influence of ginkgo biloba extract on them,and to explore the mechanism of protective effects of ginkgo biloba extract on acute infarcted myocardium.Methods One hundred and nine healthy female SD rats were selected to make acute myocardial infartion model by ligation of the left anterior descending (LAD) coronary artery,and then they were randomly divided into model group ( group A,n =38 ),ginkgo biloba treatment group ( group B,n =39 ),and sham operation group ( group C,n =32).In goup A,the left anterior descending (LAD) coronary artery was ligated solely; in group B,Ginkgo biloba extract (2 mg/kg body weight) was intravenously injected 30 min before ligation of LAD coronary artery; in group C,a loose knol was made around the first descending branch of LAD coronary arterv,witbout ligation.Each group was then randomly divided into 4 subgroups,which were observed 2 h,6 h,48 h,and 7 days after operation,respectively.Blood and heart samples were collected at every time point.Morphological changes were observed by HE staining method under the light microscopy,and ICAM-1 and IL-6 expression was detected by using immunohistochemistry.Results By using HE staining,in group A,the number of myocardial cells was decreased,and myocardial interstitial congestion,edema,myocardial fiber dissolution,flaky necrosis and infiltration of inflammatory cells were observed.Range of myocardial infarction was more than 1/2 of cardiac wall,and large number of viable myocardial cells still could be seen in the other side of cardiac wall; In group B,myocardial injuries were significantly milder than those in group A ; In group C,there were myocardial interstitial scattered congestion,edema in subepicardium of left ventricular anterior wall,but without myocardial necrosis.Immunohistochemistry revealed that at 2nd h,6th h,48th h,and 7th day,the protein levels of ICAM-1 (493.02 ± 86.32,550.05 ±87.36,695.05 ± 117.35,807.56 ± 132.05 ) and IL-6 ( 153.02 ± 26.32,179.05 ± 28.36,185.35 ±37.05,161.18 ±31.05) in group A,and those [(ICAM-1:434.83 ±75.63,508.45 ±96.21,596.28 ±105.36,679.25 ± 129.54 ) and ( IL-6:137.83 ± 33.63,155.42 ± 26.21,157.28 ± 25.36,135.25 ±26.54)] in group B were significantly higher than those in group C ( ICAM-1:310.59 ± 82.31,330.27 ±80.32,320.95 ± 81.36,341.84 ± 82.35 ; IL-6:87.59 ± 22.31,97.27 26.32,93.95 ± 19.36,91.84 ±24.35),respectively (P＜0 05).ICAM-1 and IL-6 protein levels in group A were significantly higher than those in group B at each time point,respectively ( P ＜ 0.05).Conclusion ( 1 ) The expression of ICAM-1 and IL-6 was upregulated in acute infracted myocardium; (2) The application of ginkgo biloba extract can downregulate the expression of ICAM-1 and IL-6,and reduce the extent of myocardial injury,suggesting the protective effect of gnkgo biloba extract on ischemic myocardium. Key words: Myocardial infarction; Ginkgo biloba extract; Myocardial protection; Adhesion molecule; Interleukin-6