title: "Platelet-associated regulatory system (PARS)" with particular reference to female reproduction.
abstract: BACKGROUND
  Blood platelets play an essential role in hemostasis, thrombosis and coagulation of blood. Beyond these classic functions their involvement in inflammatory, neoplastic and immune processes was also investigated. It is well known, that platelets have an armament of soluble molecules, factors, mediators, chemokines, cytokines and neurotransmitters in their granules, and have multiple adhesion molecules and receptors on their surface.
  
  
  METHODS
  Selected relevant literature and own views and experiences as clinical observations have been used.
  
  
  RESULTS
  Considering that platelets are indispensable in numerous homeostatic endocrine functions, it is reasonable to suppose that a platelet-associated regulatory system (PARS) may exist; internal or external triggers and/or stimuli may complement and connect regulatory pathways aimed towards target tissues and/or cells. The signal (PAF, or other tissue/cell specific factors) comes from the stimulated (by the e.g., hypophyseal hormones, bacteria, external factors, etc.) organs or cells, and activates platelets. Platelet activation means their aggregation, sludge formation, furthermore the release of the for-mentioned biologically very powerful factors, which can locally amplify and deepen the tissue specific cell reactions. If this process is impaired or inhibited for any reason, the specifically stimulated organ shows hypofunction. When PARS is upregulated, organ hyperfunction may occur that culminate in severe diseases.
  
  
  CONCLUSIONS
  Based on clinical and experimental evidences we propose that platelets modulate the function of hypothalamo-hypophyseal-ovarian system. Specifically, hypothalamic GnRH releases FSH from the anterior pituitary, which induces and stimulates follicular and oocyte maturation and steroid hormone secretion in the ovary. At the same time follicular cells enhance PAF production. Through these pathways activated platelets are accumulated in the follicular vessels surrounding the follicle and due to its released soluble molecules (factors, mediators, chemokines, cytokines, neurotransmitters) locally increase oocyte maturation and hormone secretion. Therefore we suggest that platelets are not only a small participant but may be the conductor or active mediator of this complex regulatory system which has several unrevealed mechanisms. In other words platelets are corpuscular messengers, or are more than a member of the family providing hemostasis.
authors.affiliation: Department of Obstetrics and Gynecology, University of Pécs, 7624 Pécs Édesanyák útja 17, Hungary ; HAS-UP Human reproduction scientific research group, 7624 Pécs Édesanyák útja 17, Hungary.
authors.forename: József
authors.initials: J
authors.lastname: Bódis
authors.affiliation: Department of Obstetrics and Gynecology, University of Pécs, 7624 Pécs Édesanyák útja 17, Hungary.
authors.forename: Szilárd
authors.initials: S
authors.lastname: Papp
authors.affiliation: Institiute of Diagnostics, Faculty of Health Sciences, University of Pécs, 7400 Kaposvár, Szent Imre u. 14/b, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Vermes
authors.affiliation: Faculty of Health Sciences, University of Pécs, 7621 Pécs Vörösmarty u. 4, Hungary.
authors.forename: Endre
authors.initials: E
authors.lastname: Sulyok
authors.affiliation: Department of Obstetrics and Gynecology, University of Pécs, 7624 Pécs Édesanyák útja 17, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Tamás
authors.affiliation: Department of Obstetrics and Gynecology, University of Pécs, 7624 Pécs Édesanyák útja 17, Hungary.
authors.forename: Bálint
authors.initials: B
authors.lastname: Farkas
authors.affiliation: Department of Nuclear Medicine, University of Pécs, 7624 Pécs Ifjúság u. 13, Hungary.
authors.forename: Katalin
authors.initials: K
authors.lastname: Zámbó
authors.affiliation: Department of Obstetrics and Gynecology, University of Pécs, 7624 Pécs Édesanyák útja 17, Hungary.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Hatzipetros
authors.affiliation: Department of Laboratory Medicine, University of Pécs, 7624 Pécs Ifjúság u. 13, Hungary ; Szentagothai Research Centre, University of Pécs, 7624 Pécs, Ifjúsag u. 20., Hungary.
authors.forename: Gábor L
authors.initials: GL
authors.lastname: Kovács
mesh_terms: D000818:Animals; D001777:Blood Coagulation; D001792:Blood Platelets / Q000502:physiology*; D005260:Female; D006487:Hemostasis; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism / Q000503:physiopathology; D010974:Platelet Aggregation; D011247:Pregnancy
keywords: Cardiovascular system; Endocrine organs; Hypothalamo-pituitary-ovarian system; Platelets; Tumorgenesis