title: Ginkgolide B inhibits platelet release by blocking Syk and p38 MAPK phosphorylation in thrombin-stimulated platelets.
abstract: BACKGROUND
  Atherosclerosis is a chronic vascular inflammatory disease. Platelets play a critic role in the initiation of vascular inflammation in atherosclerosis. In the present study, we investigated the effects of ginkgolide B on the inhibition of platelet release and the potential mechanisms.
  
  
  METHODS
  Experiments were performed in freshly human platelets. Platelet aggregation and ATP release were measured with a Lumi-aggregometer. Thrombin (0.5 U/ml) was used to induce platelet activation. Protein expression and phosphorylation was examined by Western blotting.
  
  
  RESULTS
  The results showed that ginkgolide B significantly suppressed ATP release by 50.8% in thrombin-activated platelets. Ginkgolide B completely abolished the expression of platelet factor 4 (PF4) and CD40 Ligand (CD40L). Moreover, ginkgolide B fully attenuated the phosphorylation of Syk and p38MAPK. Similarly, R788 (a syk inhibitor) and SB203580 (a p38 MAPK inhibitor) inhibited the expression PF4 and CD40L, respectively. Furthermore, the combination of low concentrations of ginkgolide B and R788 or SB203580 has synergistic inhibition on the expression of PF4 and CD40L. Ginkgolide B partially reduced calcium efflux by 52.7% in thrombin-stimulated platelets.
  
  
  CONCLUSIONS
  Ginkgolide B potently inhibited the expression of PF4 and CD40L in thrombin-activated platelets. Ginkgolide B partially decreased ATP release and Ca(2+) efflux. The mechanism might be associated with the inhibition of Syk and p38 MAPK phosphorylation. These results demonstrated that ginkgolide B might be a promising drug on inhibiting platelet function and reducing inflammation in atherosclerosis.
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
authors.forename: Xueqing
authors.initials: X
authors.lastname: Liu
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
authors.forename: Li
authors.initials: L
authors.lastname: Bao
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
authors.forename: Beidong
authors.initials: B
authors.lastname: Chen
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China.
authors.forename: Yanyang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: The Key Laboratory of Geriatrics, Beijing Hospital & Beijing Institute of Geriatrics, Ministry of Health, Beijing 100730, China. Electronic address: ruomeiqi@163.com.
authors.forename: Ruomei
authors.initials: R
authors.lastname: Qi
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001792:Blood Platelets / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D023201:CD40 Ligand / Q000378:metabolism; D046934:Ginkgolides / Q000494:pharmacology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D007783:Lactones / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D000072377:Syk Kinase; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D046934:Ginkgolides; D047908:Intracellular Signaling Peptides and Proteins; D007783:Lactones; D010972:Platelet Activating Factor; D023201:CD40 Ligand; D000255:Adenosine Triphosphate; C045856:ginkgolide B; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D048051:p38 Mitogen-Activated Protein Kinases
keywords: CD40L; Ginkgolide B; PF4; Platelets; Syk; p38MAPK