Martinuzzo M, Del Zar M M, Cardinali D P, Carreras L O, Vacas M I
Departamento de Fisiología, Facultad de Medicina, Hospital de Clínicas José de San Martín, Universidad de Buenos Aires, Argentina.
J Pineal Res. 1991 Oct-Nov;11(3-4):111-5. doi: 10.1111/j.1600-079x.1991.tb00465.x.
The effect of melatonin on thrombin-induced [3H]-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 [3H]-AA to prostaglandin (PG) F2 and thromboxane (Tx) B2, and inhibited slightly the conversion to PGE2 and PGD2. After preincubation of platelets with 1 mM imidazole, the melatonin inhibitory effect was significant for PGF2 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.
在0830时和2030时从正常志愿者获取的血小板中，测定了褪黑素对凝血酶诱导的[3H] - 花生四烯酸（AA）代谢为环氧化酶衍生物的影响。对于所分析的每种环氧化酶衍生物，放射性AA的转化率在2030时通常比在0830时更高。微摩尔或更高浓度的褪黑素显著降低了[3H] - AA向前列腺素（PG）F2和血栓素（Tx）B2的转化，并轻微抑制了向PGE2和PGD2的转化。在用1 mM咪唑预孵育血小板后，褪黑素的抑制作用仅对PGF2显著。褪黑素（10^(-6) M）在2030时对佛波醇-12-肉豆蔻酸酯-13-乙酸酯（PMA）诱导的血小板ATP释放显示出显著的抑制作用，该作用被1 mM阿司匹林抑制。这些结果表明，在药理浓度下，褪黑素抑制人血小板环氧化酶。
