Kornblihtt L I, Finocchiaro L, Molinas F C
Instituto de Investigaciones Medicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
J Pineal Res. 1993 May;14(4):184-91. doi: 10.1111/j.1600-079x.1993.tb00501.x.
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.
褪黑素是一种在松果体中合成的吲哚胺，已知具有抗前列腺素活性。有人提出，褪黑素对血小板聚集的抑制作用是通过环氧合酶途径实现的。在本研究中，我们发现褪黑素对富含血小板血浆中胶原、花生四烯酸（AA）、二磷酸腺苷（ADP）、肾上腺素和A23187诱导的聚集有显著抑制作用。另一方面，使用悬浮在台氏缓冲液中的经甲泛葡胺过滤的血小板，褪黑素无法抑制AA诱导的血小板聚集和14C-5-羟色胺释放。在相同条件下，褪黑素可抑制胶原诱导的血小板活化；然而，添加阈值剂量的AA（0.3 mM）可消除这种作用。这些研究表明，褪黑素在环氧合酶依赖性途径之前的阶段也能抑制血小板功能。
