title: The effects of estrone, estradiol and estriol on platelet aggregation induced by adrenaline and adenosine diphosphate.
abstract: The impact of estrogens on the cardiovascular system and their ability to regulate platelet functions remains controversial. Changes in platelet functions could contribute to thrombotic risk associated with estrogen treatments. Here, we investigated the effects of various forms of estrogen, including estrone (E1), estradiol (E2) and estriol (E3), on platelet aggregation induced by standard agonists (adrenaline and adenosine diphosphate). Platelet-rich plasma (PRP) was prepared from citrated blood donated by 25 normal volunteers. The study on platelet aggregation was carried out in 96-well flat-bottom microtitre plates and assessed using a microplate reader. For studying the effects of each estrogen, PRP was preincubated with 1, 10 and 100 nM of E1, E2 and E3 at 37 degrees C for 20 min, and then coincubated with normal saline (control untreated PRP), adrenaline (ADR) or adenosine diphosphate (ADP) in the microplate. Platelet aggregation was then measured every minute for 8 min. None of the estrogens (E1, E2 and E3) affected platelet aggregation in untreated PRP. Interestingly, only E1 and E3 can synergize the increased platelet aggregation by either ADR or ADP, while the effects of E2 on the increased platelet aggregation by either ADR or ADP depended on internal factors such as endogenous estradiol and platelet aggregated state. Thus, for the rational use of these internal factors for estrogen use, especially E2, in clinical applications, such as hormone replacement therapy, may need evaluation of thrombotic risk.
authors.affiliation: Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Prannok Rd, Bangkok 10700, Thailand. sipak@mahidol.ac.th
authors.forename: Pravit
authors.initials: P
authors.lastname: Akarasereenont
authors.forename: Pinpat
authors.initials: P
authors.lastname: Tripatara
authors.forename: Sirikul
authors.initials: S
authors.lastname: Chotewuttakorn
authors.forename: Titchaporn
authors.initials: T
authors.lastname: Palo
authors.forename: Athiwat
authors.initials: A
authors.lastname: Thaworn
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000328:Adult; D000368:Aged; D001792:Blood Platelets / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D045166:Estradiol Congeners / Q000494:pharmacology*; D004964:Estriol / Q000494:pharmacology; D004970:Estrone / Q000494:pharmacology; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*
chemical_list: D045166:Estradiol Congeners; D004970:Estrone; D004958:Estradiol; D000244:Adenosine Diphosphate; D004964:Estriol; D004837:Epinephrine