title: Prolactin does not affect human platelet aggregation or secretion.
abstract: Platelets play an important role in the development of plaque formation and in the events after rupture of the atherosclerotic plaque, leading to atherothrombosis. Multiple hormones, either in excess or when deficient, are involved in the development of atherothrombotic disease, but, to which extent such hormones affect platelet function, is still controversial. It was the objective of this study to assess the ability of the pituitary hormone prolactin to affect platelet functions. Venous blood was collected from six healthy males. Platelet activation was studied by (i) flow cytometry in whole blood (exposure of P-selectin as a measure of platelet secretion, and binding of PAC-1 as a measure of ligand-binding conformation of alpha(IIb)beta(3)), and by (ii) optical aggregation and whole blood aggregation. All studies were performed without and with exposure to several concentrations of ADP (0.1, 0.5 and 1.0 microM) and prolactin (50 and 1,000 microg/l). The presence of the prolactin receptor was investigated by Western blot and flow cytometry. In response to either 50 or 1,000 microg/l prolactin, no evidence of platelet activation or aggregation was found. In addition, ADP-induced platelet activation or aggregation was not enhanced by prolactin. Finally, prolactin receptors could not be detected on the surface of platelets. The present data indicate that prolactin does not directly modulate platelet function.
authors.affiliation: Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands. a.q.reuwer@amc.uva.nl
authors.forename: Anne Q
authors.initials: AQ
authors.lastname: Reuwer
authors.forename: Rienk
authors.initials: R
authors.lastname: Nieuwland
authors.forename: Isabelle
authors.initials: I
authors.lastname: Fernandez
authors.forename: Vincent
authors.initials: V
authors.lastname: Goffin
authors.forename: Claudia M
authors.initials: CM
authors.lastname: van Tiel
authors.forename: Marianne C L
authors.initials: MC
authors.lastname: Schaap
authors.forename: René J
authors.initials: RJ
authors.lastname: Berckmans
authors.forename: John J P
authors.initials: JJ
authors.lastname: Kastelein
authors.forename: Marcel Th B
authors.initials: MT
authors.lastname: Twickler
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000494:Allosteric Regulation; D001792:Blood Platelets / Q000378:metabolism* / Q000473:pathology; D002460:Cell Line; D002469:Cell Separation; D054641:Dual Specificity Phosphatase 2 / Q000378:metabolism; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D019007:P-Selectin / Q000378:metabolism; D010974:Platelet Aggregation / Q000235:genetics; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D011485:Protein Binding; D011981:Receptors, Prolactin / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D019007:P-Selectin; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D011981:Receptors, Prolactin; D000244:Adenosine Diphosphate; D011388:Prolactin; D054641:Dual Specificity Phosphatase 2