title: Inhibitory effect of melatonin on platelet activation induced by collagen and arachidonic acid.
abstract: Melatonin, an indolamine synthesized in the pineal gland, is known to have antiprostanoid activity. The inhibition of platelet aggregation induced by melatonin has been proposed to take place through the cyclooxygenase pathway. In the present study, we found that melatonin has a marked inhibitory effect on collagen, arachidonic acid (AA), adenosine diphosphate (ADP), epinephrine, and A23187-induced aggregation in platelet-rich plasma. On the other hand, using metrizamide-filtered platelets resuspended in Tyrode's buffer, melatonin fails to suppress AA-induced platelet aggregation and 14C-5-HT release. Under the same conditions, melatonin inhibits collagen-induced platelet activation; however, the addition of threshold doses of AA (0.3 mM) abrogates this effect. These studies suggest that melatonin also inhibits platelet function at a stage preceding the cyclooxygenase-dependent pathway.
authors.affiliation: Instituto de Investigaciones Medicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
authors.forename: L I
authors.initials: LI
authors.lastname: Kornblihtt
authors.forename: L
authors.initials: L
authors.lastname: Finocchiaro
authors.forename: F C
authors.initials: FC
authors.lastname: Molinas
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D016718:Arachidonic Acid / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D001792:Blood Platelets / Q000378:metabolism; D001798:Blood Proteins / Q000378:metabolism; D003094:Collagen / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006801:Humans; D008550:Melatonin / Q000494:pharmacology*; D010766:Phosphorylation; D015539:Platelet Activation / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D001798:Blood Proteins; D010975:Platelet Aggregation Inhibitors; D014841:von Willebrand Factor; D016718:Arachidonic Acid; D012701:Serotonin; D000255:Adenosine Triphosphate; D003094:Collagen; D008550:Melatonin