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The effects of melatonin in human platelets
D P Cardinali1, M M Del Zar, M I Vacas
1Department of Physiology, Faculty of Medicine, University of Buenos Aires, Argentina.
Acta Physiologica, Pharmacologica Et Therapeutica Latinoamericana : Organo De La Asociacion Latinoamericana De Ciencias Fisiologicas Y [De] La Asociacion Latinoamericana De Farmacologia
|January 1, 1993
Summary
Human platelets are sensitive to melatonin, a hormone that regulates circadian rhythms. This study found that melatonin affects platelet function, suggesting platelets can be used to monitor melatonin
Area of Science:
- Neuroscience
- Endocrinology
- Hematology
Background:
- Pineal melatonin influences circadian rhythms and seasonal breeding in mammals.
- Melatonin's role in human physiology, particularly in peripheral organs, is not fully understood.
- Platelets are potential peripheral targets for melatonin action.
Purpose of the Study:
- To investigate the sensitivity of human platelets to melatonin.
- To explore the potential of platelets as peripheral indicators of central melatonin activity.
- To characterize the effects of melatonin on platelet function.
Main Methods:
- In vitro and in vivo experiments assessing melatonin's effects on platelet aggregation, ATP and serotonin release, and thromboxane B2 production.
- Analysis of dose-dependent and time-of-day variations in melatonin's effects.
- Radioligand binding studies using 3H-melatonin to detect binding sites on human platelet membranes.
Main Results:
- Human platelets exhibit sensitivity to melatonin, with nanomolar concentrations inhibiting aggregation, ATP/serotonin release, and thromboxane B2 production.
- Melatonin's inhibitory effects on platelet function were generally greater and dose-dependent in the evening compared to the morning.
- Platelet melatonin activity peaked before circulating melatonin levels, indicating a dissociation between hormone concentration and platelet sensitivity.
- Specific melatonin binding sites were identified in human platelet membranes with a dissociation constant (Kd) in the nanomolar range.
Conclusions:
- Human platelets are peripheral cells responsive to melatonin.
- Melatonin significantly impacts key platelet functions, including aggregation and secretion.
- Platelets may serve as accessible peripheral markers for assessing central melatonin activity in clinical settings.