| Objective:Brucea javanica oil exists in the fruits of Brucea javanica oil,and its main active ingredients are oleic acid and linoleic acid which have the efficacy of antineoplastic activity.Brucea javanica oil effusion has been used as the assistant medicine in the therapy of many types of tumors.Use of Brucea javanica oil effusion can activate blood coagulation system,and has promoting effect on platelet activation and thrombosis,but Brucea javanica oil is also able to decrease levels of blood lipids and increase the local concentration of endogenous prostaglandin E2(PGE2),and indirectly inhibits or enhances platelet activation and thrombosis.So it is worth exploring whether Brucea javanica oil really has inhibitory effect on platelet activation or not and what the mechanisms are.There are a lot of agonist receptors on external membrane of platelet.When the receptor is bound to its ligand,platelet-activating signals are transduced and platelet is activated,the platelet aggregation occurs and platelet secrets the contents of its storage organelles.In this study,effects of Brucea javanica oil on the activated platelets induced by 5 different agonists were compared to observe the protective efficacy of Brucea javanica oil in washed platelet activation, and the possible mechanisms are explored.Materials and methods:Healthy blood donors(age ranging from 25-40 years old) without use of any medicines 10 days prior to blood collection were randomly divided into 3 groups:acetone control(0%,g/g,A0),low-dose Brucea javanica oil group(9%, A1) and high-dose Brucea javanica oil group(22.5%,A2).Blood,collected from the cubital veins,was treated with ACD anti-coagulant(whole blood:ACD=9:1,v/v) and fabricated into washed platelet suspension of 4.5×10~8 platelets per milliliter by centrifugation.Platelet aggregation test induced by adrenaline,ADP,arachidonic acid (AA),collagen and thrombin,respectively,was measured by turbidimetric method and the inhibition rate of Brucea javanica oil on platelet aggregation was calculated, respectively,too.The dose-dependent platelet aggregation test was assayed,the correlation between platelet aggregation level and Brucea javanica oil concentration was observed and analyzed.The expressions of p-selectin(CD62p) and fibrinogen receptor(CD41/CD61) on external membrane of activated platelet induced by the 5 agonists were determinated with flow cytometry,inhibition rate of fibrinogen receptor expression was calculated.And the F-actin changes of cytoskeletal structure in activated platelet induced by ADP and thrombin were detected with SDS-PAGE.Results and conclusions:(1)In either group A1 or A2,Brucea javanica oil significantly decreased platelet aggregation level and inhibited the platelet aggregation induced by the 5 different agonists,but there was a more marked decreasing and inhibitory effect for groups A2.There was a more significant inhibitory effect in group A2 than that in group A1 on platelet aggregation.(2)There was marked negative correlation between platelet aggregation level induced by the 5 agonists and Brucea javanica oil concentration:Higher the concentration was,lower the aggregation level was and larger extent of inhibition was.(3)There was no statistical effect of Brucea javanica oil on changes of F-actin and p-selectin expression on external membrane of activated platelet induced by the 5 agonists in the 3 groups.But Brucea javanica oil significantly decreased the expression level of fibrinogen receptor on external membrane of platelet indcued by 5 gaonists in both group A1 and group A2,and this efficacy was in accordance with that in platelet aggregation level.Therefore, conclusions of this study are drawn as follows: (1)Brucea javanica oil has dose-dependent inhibitory effect on platelet aggregation induced by different agonists.(2)Brucea javanica oil has no effects on the changes of F-actin and contraction system of activated platelet.(3)Brucea javanica oil has no inhibitory effects on secretion reaction of activated platelet.(4)Brucea javanica oil decreases the expression level of fibrinogen receptor on external membrane of activated platelet and inhibits,in a dose-dependent manner, platelet aggregation.(5)Brucea javanica oil has special inhibitory effect on activated platelet and thrombosis. |
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