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Melatonin effect on arachidonic acid metabolism to cyclooxygenase derivatives in human platelets
Author(s) -
Martinuzzo Marta,
Zar Maria de las M.,
Cardinali Daniel P.,
Carreras Luis O.,
Vacas Maréa I.
Publication year - 1991
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.1991.tb00465.x
Subject(s) - melatonin , platelet , arachidonic acid , cyclooxygenase , arachidonic acid metabolism , endocrinology , metabolism , medicine , chemistry , platelet aggregation , pharmacology , biochemistry , enzyme
The effect of melatonin on thrombin‐induced [ 3 H]‐arachidonic acid (AA) metabolism to cyclooxygenase derivatives was determined in platelets obtained from normal volunteers at 0830 and 2030 h. Percent conversion of radioactive AA was generally greater at 2030 h than at 0830 h for every cyclooxygenase derivative analyzed. Micromolar or greater concentrations of melatonin decreased significantly the conversion of [ 3 H]‐AA to prostaglandin (PG) F 2 and thromboxane (Tx) B2, and inhibited slightly the conversion to PGE 2 and PGD 2 . After preincubation of platelets with 1 mM imidazole, the melatonin inhibitory effect was significant for PGF 2 only. Melatonin (10 −6 M) showed a significant inhibitory influence on platelet ATP release induced by phorbol‐12 myristate‐13 acetate (PMA) at 2030 h, an effect inhibited by 1 mM aspirin. These results indicate that at pharmacological concentrations melatonin inhibits human platelet cyclooxygenase.