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Fernando F, Veenboer GJ, Oudijk MA, Kampman MA, Heida KY, Lagendijk LJ, van der Post JA, Jongejan A, Afink GB, Ris-Stalpers C. TBX2, a Novel Regulator of Labour. ACTA ACUST UNITED AC 2021; 57:medicina57060515. [PMID: 34064060 PMCID: PMC8224059 DOI: 10.3390/medicina57060515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/11/2021] [Accepted: 05/17/2021] [Indexed: 11/16/2022]
Abstract
Background and Objectives: Therapeutic interventions targeting molecular factors involved in the transition from uterine quiescence to overt labour are not substantially reducing the rate of spontaneous preterm labour. The identification of novel rational therapeutic targets are essential to prevent the most common cause of neonatal mortality. Based on our previous work showing that Tbx2 (T-Box transcription factor 2) is a putative upstream regulator preceding progesterone withdrawal in mouse myometrium, we now investigate the role of TBX2 in human myometrium. Materials and Methods: RNA microarray analysis of (A) preterm human myometrium samples and (B) myometrial cells overexpressing TBX2 in vitro, combined with subsequent analysis of the two publicly available datasets of (C) Chan et al. and (D) Sharp et al. The effect of TBX2 overexpression on cytokines/chemokines secreted to the myometrium cell culture medium were determined by Luminex assay. Results: Analysis shows that overexpression of TBX2 in myometrial cells results in downregulation of TNFα- and interferon signalling. This downregulation is consistent with the decreased expression of cytokines and chemokines of which a subset has been previously associated with the inflammatory pathways relevant for human labour. In contrast, CXCL5 (C-X-C motif chemokine ligand 5), CCL21 and IL-6 (Interleukin 6), previously reported in relation to parturition, do not seem to be under TBX2 control. The combined bioinformatical analysis of the four mRNA datasets identifies a subset of upstream regulators common to both preterm and term labour under control of TBX2. Surprisingly, TBX2 mRNA levels are increased in preterm contractile myometrium. Conclusions: We identified a subset of upstream regulators common to both preterm and term labour that are activated in labour and repressed by TBX2. The increased TBX2 mRNA expression in myometrium collected during a preterm caesarean section while in spontaneous preterm labour compared to tissue harvested during iatrogenic preterm delivery does not fit the bioinformatical model. We can only explain this by speculating that the in vivo activity of TBX2 in human myometrium depends not only on the TBX2 expression levels but also on levels of the accessory proteins necessary for TBX2 activity.
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Affiliation(s)
- Febilla Fernando
- Reproductive Biology Laboratory, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (F.F.); (G.J.M.V.); (L.J.M.L.); (G.B.A.)
| | - Geertruda J.M. Veenboer
- Reproductive Biology Laboratory, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (F.F.); (G.J.M.V.); (L.J.M.L.); (G.B.A.)
| | - Martijn A. Oudijk
- Department of Obstetrics and Gynaecology, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (M.A.O.); (J.A.M.v.d.P.)
| | - Marlies A.M. Kampman
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ Groningen, The Netherlands;
| | - Karst Y. Heida
- Department of Obstetrics, Division of Woman and Baby, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands;
| | - Louise J.M. Lagendijk
- Reproductive Biology Laboratory, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (F.F.); (G.J.M.V.); (L.J.M.L.); (G.B.A.)
| | - Joris A.M. van der Post
- Department of Obstetrics and Gynaecology, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (M.A.O.); (J.A.M.v.d.P.)
| | - Aldo Jongejan
- Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands;
| | - Gijs B. Afink
- Reproductive Biology Laboratory, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (F.F.); (G.J.M.V.); (L.J.M.L.); (G.B.A.)
| | - Carrie Ris-Stalpers
- Reproductive Biology Laboratory, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (F.F.); (G.J.M.V.); (L.J.M.L.); (G.B.A.)
- Department of Obstetrics and Gynaecology, Amsterdam Reproduction and Development, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (M.A.O.); (J.A.M.v.d.P.)
- Correspondence: ; Tel.: +312-0566-5625
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Green ES, Arck PC. Pathogenesis of preterm birth: bidirectional inflammation in mother and fetus. Semin Immunopathol 2020; 42:413-429. [PMID: 32894326 PMCID: PMC7508962 DOI: 10.1007/s00281-020-00807-y] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 07/14/2020] [Indexed: 12/18/2022]
Abstract
Preterm birth (PTB) complicates 5–18% of pregnancies globally and is a leading cause of maternal and fetal morbidity and mortality. Most PTB is spontaneous and idiopathic, with largely undefined causes. To increase understanding of PTB, much research in recent years has focused on using animal models to recapitulate the pathophysiology of PTB. Dysfunctions of maternal immune adaptations have been implicated in a range of pregnancy pathologies, including PTB. A wealth of evidence arising from mouse models as well as human studies is now available to support that PTB results from a breakdown in fetal-maternal tolerance, along with excessive, premature inflammation. In this review, we examine the current knowledge of the bidirectional communication between fetal and maternal systems and its role in the immunopathogenesis of PTB. These recent insights significantly advance our understanding of the pathogenesis of PTB, which is essential to ultimately designing more effective strategies for early prediction and subsequent prevention of PTB.
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Affiliation(s)
- Ella Shana Green
- Department of Obstetrics and Fetal Medicine, Laboratory for Experimental Feto-Maternal Medicine, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20251, Hamburg, Germany
| | - Petra Clara Arck
- Department of Obstetrics and Fetal Medicine, Laboratory for Experimental Feto-Maternal Medicine, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20251, Hamburg, Germany.
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Wahid HH, Chin PY, Sharkey DJ, Diener KR, Hutchinson MR, Rice KC, Moldenhauer LM, Robertson SA. Toll-Like Receptor-4 Antagonist (+)-Naltrexone Protects Against Carbamyl-Platelet Activating Factor (cPAF)-Induced Preterm Labor in Mice. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1030-1045. [PMID: 32084361 DOI: 10.1016/j.ajpath.2020.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 12/24/2019] [Accepted: 01/17/2020] [Indexed: 02/06/2023]
Abstract
Spontaneous preterm labor is frequently caused by an inflammatory response in the gestational tissues elicited by either infectious or sterile agents. In sterile preterm labor, the key regulators of inflammation are not identified, but platelet-activating factor (PAF) is implicated as a potential rate-limiting effector agent. Since Toll-like receptor (TLR)-4 can amplify PAF signaling, we evaluated whether TLR4 contributes to inflammation and fetal loss in a mouse model of PAF-induced sterile preterm labor, and whether a small-molecule TLR4 inhibitor, (+)-naltrexone, can mitigate adverse PAF-induced effects. The administration of carbamyl (c)-PAF caused preterm labor and fetal loss in wild-type mice but not in TLR4-deficient mice. Treatment with (+)-naltrexone prevented preterm delivery and alleviated fetal demise in utero elicited after cPAF administered by i.p. or intrauterine routes. Pups born after cPAF and (+)-naltrexone treatment exhibited comparable rates of postnatal survival and growth to carrier-treated controls. (+)-Naltrexone suppressed the cPAF-induced expression of inflammatory cytokine genes Il1b, Il6, and Il10 in the decidua; Il6, Il12b, and Il10 in the myometrium; and Il1b and Il6 in the placenta. These data demonstrate that the TLR4 antagonist (+)-naltrexone inhibits the inflammatory cascade induced by cPAF, preventing preterm birth and perinatal death. The inhibition of TLR4 signaling warrants further investigation as a candidate strategy for fetal protection and delay of preterm birth elicited by sterile stimuli.
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Affiliation(s)
- Hanan H Wahid
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Peck Yin Chin
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - David J Sharkey
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Kerrilyn R Diener
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia; School of Pharmacy and Medical Science, University of South Australia, Adelaide, South Australia, Australia
| | - Mark R Hutchinson
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia; Australian Research Council Centre of Excellence for Nanoscale BioPhotonics, Adelaide, South Australia, Australia
| | - Kenner C Rice
- Drug Design and Synthesis Section, National Institute on Drug Abuse and National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, Maryland
| | - Lachlan M Moldenhauer
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
| | - Sarah A Robertson
- Robinson Research Institute and Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia.
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Mendelson CR, Gao L, Montalbano AP. Multifactorial Regulation of Myometrial Contractility During Pregnancy and Parturition. Front Endocrinol (Lausanne) 2019; 10:714. [PMID: 31708868 PMCID: PMC6823183 DOI: 10.3389/fendo.2019.00714] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Accepted: 10/03/2019] [Indexed: 12/30/2022] Open
Abstract
The steroid hormones progesterone (P4) and estradiol-17β (E2), produced by the placenta in humans and the ovaries in rodents, serve crucial roles in the maintenance of pregnancy, and the initiation of parturition. Because of their critical importance for species survival, the mechanisms whereby P4 and its nuclear receptor (PR) maintain myometrial quiescence during pregnancy, and for the decline in P4/PR and increase in E2/estrogen receptor (ER) function leading to parturition, are multifaceted, cooperative, and redundant. These actions of P4/PR include: (1) PR interaction with proinflammatory transcription factors, nuclear factor κB (NF-κB), and activating protein 1 (AP-1) bound to promoters of proinflammatory and contractile/contraction-associated protein (CAP) genes and recruitment of corepressors to inhibit NF-κB and AP-1 activation of gene expression; (2) upregulation of inhibitors of proinflammatory transcription factor activation (IκBα, MKP-1); (3) induction of transcriptional repressors of CAP genes (e.g., ZEB1). In rodents and most other mammals, circulating maternal P4 levels remain elevated throughout most of pregnancy and decline precipitously near term. By contrast, in humans, circulating P4 levels and myometrial PR levels remain elevated throughout pregnancy and into labor. However, even in rodents, wherein P4 levels decline near term, P4 levels remain higher than the Kd for PR binding. Thus, parturition is initiated in all species by a series of molecular events that antagonize the P4/PR maintenance of uterine quiescence. These events include: direct interaction of inflammatory transcription factors (e.g., NF-κB, AP-1) with PR; increased expression of P4 metabolizing enzymes; increased expression of truncated/inhibitory PR isoforms; altered expression of PR coactivators and corepressors. This article will review various mechanisms whereby P4 acting through PR isoforms maintains myometrial quiescence during pregnancy as well as those that underlie the decline in PR function leading to labor. The roles of P4- and E2-regulated miRNAs in the regulation and integration of these mechanisms will also be considered.
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Mendelson CR, Montalbano AP, Gao L. Fetal-to-maternal signaling in the timing of birth. J Steroid Biochem Mol Biol 2017; 170:19-27. [PMID: 27629593 PMCID: PMC5346347 DOI: 10.1016/j.jsbmb.2016.09.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/05/2016] [Accepted: 09/10/2016] [Indexed: 12/13/2022]
Abstract
Preterm birth remains the major cause of neonatal morbidity and mortality throughout the world. This is due, in part, to our incomplete understanding of the mechanisms that underlie the maintenance of pregnancy and the initiation of parturition at term. In this article, we review our current knowledge of the complex, interrelated and concerted mechanisms whereby progesterone maintains myometrial quiescence throughout most of pregnancy, as well as those that mediate the upregulation of the inflammatory response and decline in progesterone receptor function leading to parturition. Herein, we review findings that demonstrate a role of the fetus in the timing of birth. Specifically, we focus on our own studies indicating that maturation of the fetal lung and enhanced secretion of the surfactant components, surfactant protein A (SP-A) and the potent inflammatory glycerophospholipid, platelet-activating factor (PAF), initiate a signaling cascade culminating in parturition. Our studies suggest an essential role of steroid receptor coactivators, SRC-1 and SRC-2, which activate expression of genes encoding SP-A and LPCAT1. LPCAT1 is a key enzyme in the synthesis of PAF, as well as DPPC, a highly surface-active glycerophospholipid component of surfactant. Thus, we describe a novel pathway through which the fetus contributes to the initiation of labor by signaling the mother when its lungs have achieved sufficient maturity for survival in an aerobic environment.
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Affiliation(s)
- Carole R Mendelson
- Departments of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA; Obstetrics & Gynecology, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA.
| | - Alina P Montalbano
- Departments of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
| | - Lu Gao
- Departments of Biochemistry, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX, USA
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Gao L, Rabbitt EH, Condon JC, Renthal NE, Johnston JM, Mitsche MA, Chambon P, Xu J, O'Malley BW, Mendelson CR. Steroid receptor coactivators 1 and 2 mediate fetal-to-maternal signaling that initiates parturition. J Clin Invest 2015; 125:2808-24. [PMID: 26098214 DOI: 10.1172/jci78544] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 05/06/2015] [Indexed: 12/22/2022] Open
Abstract
The precise mechanisms that lead to parturition are incompletely defined. Surfactant protein-A (SP-A), which is secreted by fetal lungs into amniotic fluid (AF) near term, likely provides a signal for parturition; however, SP-A-deficient mice have only a relatively modest delay (~12 hours) in parturition, suggesting additional factors. Here, we evaluated the contribution of steroid receptor coactivators 1 and 2 (SRC-1 and SRC-2), which upregulate SP-A transcription, to the parturition process. As mice lacking both SRC-1 and SRC-2 die at birth due to respiratory distress, we crossed double-heterozygous males and females. Parturition was severely delayed (~38 hours) in heterozygous dams harboring SRC-1/-2-deficient embryos. These mothers exhibited decreased myometrial NF-κB activation, PGF2α, and expression of contraction-associated genes; impaired luteolysis; and elevated circulating progesterone. These manifestations also occurred in WT females bearing SRC-1/-2 double-deficient embryos, indicating that a fetal-specific defect delayed labor. SP-A, as well as the enzyme lysophosphatidylcholine acyltransferase-1 (LPCAT1), required for synthesis of surfactant dipalmitoylphosphatidylcholine, and the proinflammatory glycerophospholipid platelet-activating factor (PAF) were markedly reduced in SRC-1/-2-deficient fetal lungs near term. Injection of PAF or SP-A into AF at 17.5 days post coitum enhanced uterine NF-κB activation and contractile gene expression, promoted luteolysis, and rescued delayed parturition in SRC-1/-2-deficient embryo-bearing dams. These findings reveal that fetal lungs produce signals to initiate labor when mature and that SRC-1/-2-dependent production of SP-A and PAF is crucial for this process.
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Abstract
Multiple processes are capable of activating the onset of parturition; however, the specific contributions of the mother and the fetus to this process are not fully understood. In this issue of the JCI, Gao and colleagues present evidence that steroid receptor coactivators 1 and 2 (SRC-1 and SRC-2) regulate surfactant protein-A (SP-A) and platelet-activating factor (PAF) expression, which increases in the developing fetal lung. WT dams crossed with males deficient for both SRC-1 and SRC-2 had suppressed myometrial inflammation, increased serum progesterone, and delayed parturition, which could be reconciled by injection of either SP-A or PAF into the amnion. Together, the results of this study demonstrate that the fetal lungs produce signals to initiate labor in the mouse. This work underscores the importance of the fetus as a contributor to the onset of murine, and potentially human, parturition.
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Sahlin L, Stjernholm-Vladic Y, Roos N, Masironi B, Ekman-Ordeberg G. Impaired leukocyte influx in cervix of postterm women not responding to prostaglandin priming. Reprod Biol Endocrinol 2008; 6:36. [PMID: 18764934 PMCID: PMC2551600 DOI: 10.1186/1477-7827-6-36] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Accepted: 09/02/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Prolonged pregnancies are associated with increased rate of maternal and fetal complications. Post term women could be divided into at least two subgroups, one where parturition is possible to induce by prostaglandins and one where it is not. Our aim was to study parameters in cervical biopsies in women with spontaneous delivery at term (controls) and compare to those that are successfully induced post term (responders), and those that are not induced (non-responders), by local prostaglandin treatment. METHODS Stromal parameters examined in this study were the accumulation of leukocytes (CD45, CD68), mRNAs and/or proteins for the extracellular matrix degrading enzymes (matrix metalloproteinase (MMP)-2, MMP-8 and MMP-9), their inhibitors (tissue inhibitor of MMP (TIMP)-1 and TIMP-2), interleukin-8 (IL-8), the platelet activating factor-receptor (PAF-R), syndecan-1 and estrogen binding receptors (estrogen receptor (ER)alpha, ERbeta and G-coupled protein receptor (GPR) 30) as well as the proliferation marker Ki-67. RESULTS The influx of leukocytes as assessed by CD45 was strongest in the responders, thereafter in the controls and significantly lower in the non-responders. IL-8, PAF-R and MMP-9, all predominantly expressed in leukocytes, showed significantly reduced immunostaining in the group of non-responders, while ERalpha and GPR30 were more abundant in the non-responders, as compared to the controls. CONCLUSION The impaired leukocyte influx, as reflected by the reduced number of CD45 positive cells as well as decreased immunostaining of IL-8, PAF-R and MMP-9 in the non-responders, could be one explanation of the failed ripening of the cervix in post term women. If the decreased leukocyte influx is a primary explanation to absent ripening or secondary, as a result of other factors, is yet to be established.
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Affiliation(s)
- Lena Sahlin
- Division for Reproductive Endocrinology, Q2:08, Karolinska University Hospital – Solna, Karolinska Institutet, Stockholm, Sweden
| | - Ylva Stjernholm-Vladic
- Division of Obstetrics and Gynecology, H2:01, Department of Woman and Child Health, Karolinska University Hospital – Solna, Karolinska Institutet, Stockholm, Sweden
| | - Nathalie Roos
- Division of Obstetrics and Gynecology, H2:01, Department of Woman and Child Health, Karolinska University Hospital – Solna, Karolinska Institutet, Stockholm, Sweden
| | - Britt Masironi
- Division for Reproductive Endocrinology, Q2:08, Karolinska University Hospital – Solna, Karolinska Institutet, Stockholm, Sweden
| | - Gunvor Ekman-Ordeberg
- Division of Obstetrics and Gynecology, H2:01, Department of Woman and Child Health, Karolinska University Hospital – Solna, Karolinska Institutet, Stockholm, Sweden
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Tiemann U. The role of platelet-activating factor in the mammalian female reproductive tract. Reprod Domest Anim 2008; 43:647-55. [PMID: 18363604 DOI: 10.1111/j.1439-0531.2007.00959.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Platelet-activating factor (PAF) is a potent lipid mediator produced by various cell types of mammals and is involved in an inflammatory-like process with increased vascular permeability. Platelet-activating factor exerts its actions through the activation of specific PAF receptors (PAF-R) found in cells and tissues of the female reproductive tract. The aim of this article was summarized briefly in the current research on the role of PAF in female reproductive functions. Platelet-activating factor has been implicated in processes of ovulation, implantation and parturition because of its angiogenic and growth factor properties. This factor is influenced by ovarian steroid hormones in bringing about changes in the uterus and is a candidate molecule for initial embryo-maternal dialogue. Tissue concentrations of PAF are regulated by the equilibrium between biosynthesis and degradation by PAF-acetylhydrolase (PAF-AH). Antagonists of PAF interfere with ovulation and implantation. Platelet-activating factor, its receptor, and PAF-AH activity play an important role in the maintenance of pregnancy.
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Affiliation(s)
- U Tiemann
- Department of Reproductive Biology, Research Institute for the Biology of Farm Animals, Dummerstorf, Germany.
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Harayama T, Shindou H, Ogasawara R, Suwabe A, Shimizu T. Identification of a novel noninflammatory biosynthetic pathway of platelet-activating factor. J Biol Chem 2008; 283:11097-106. [PMID: 18285344 DOI: 10.1074/jbc.m708909200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Platelet-activating factor (PAF) is a potent lipid mediator playing various inflammatory and physiological roles. PAF is biosynthesized through two independent pathways called the de novo and remodeling pathways. Lyso-PAF acetyltransferase (lyso-PAF AT) was believed to biosynthesize PAF under inflammatory conditions, through the remodeling pathway. The first isolated lyso-PAF AT (LysoPAFAT/LPCAT2) had consistent properties. However, we show in this study the finding of a second lyso-PAF AT working under noninflammatory conditions. We partially purified a Ca(2+)-independent lyso-PAF AT from mouse lung. Immunoreactivity for lysophosphatidylcholine acyltransferase 1 (LPCAT1) was detected in the active fraction. Lpcat1-transfected Chinese hamster ovary cells exhibited both LPCAT and lyso-PAF AT activities. We confirmed that LPCAT1 transfers acetate from acetyl-CoA to lyso-PAF by the identification of an acetyl-CoA (and other acyl-CoAs) interacting site in LPCAT1. We further showed that LPCAT1 activity and expression are independent of inflammatory signals. Therefore, these results suggest the molecular diversity of lyso-PAF ATs is as follows: one (LysoPAFAT/LPCAT2) is inducible and activated by inflammatory stimulation, and the other (LPCAT1) is constitutively expressed. Each lyso-PAF AT biosynthesizes inflammatory and physiological amounts of PAF, depending on the cell type. These findings provide important knowledge for the understanding of the diverse pathological and physiological roles of PAF.
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Affiliation(s)
- Takeshi Harayama
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033
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Maul H, Mackay L, Garfield RE. Cervical ripening: biochemical, molecular, and clinical considerations. Clin Obstet Gynecol 2006; 49:551-63. [PMID: 16885662 DOI: 10.1097/00003081-200609000-00015] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The physiologic and pathologic changes of the uterine cervix during pregnancy leading to cervical ripening are not well understood though are related to the chief pathology and a commonly performed intervention in obstetrics: Preterm birth and labor induction. Normal cervical ripening is thought to be controlled by a variety of hormonal changes occurring during pregnancy leading to softening and dilation. Abnormal premature ripening, usually resulting in preterm labor, is thought to be associated with infection and inflammatory events. Despite many studies of the cervix, we still rely upon relatively crude methods for clinical evaluation of the cervix. In the past several years, we have developed and evaluated a method to measure cervical collagen noninvasively using an instrument called Collascope. Studies in animals and humans conducted in a variety of settings indicate that cervical function can be successfully monitored using the Collascope during pregnancy. We suggest that this technique might be useful to better define management in cases of spontaneous preterm and induced term cervical ripening.
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Affiliation(s)
- Holger Maul
- Department of Obstetrics and Gynecology, University of Heidelberg, Heidelberg, Germany
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Factors involved in the inflammatory events of cervical ripening in humans. Reprod Biol Endocrinol 2004; 2:74. [PMID: 15500686 PMCID: PMC534613 DOI: 10.1186/1477-7827-2-74] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2004] [Accepted: 10/22/2004] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Cervical ripening is an inflammatory reaction. The glucocorticoid receptor (GR) mediates glucocorticoid anti-inflammatory reactions, whereas nuclear factor (NF)kappaB is a key pro-inflammatory transcription factor. Prostaglandins as well as platelet activating factor (PAF) are inflammatory mediators. Inducible nitric oxide synthase (iNOS) regulates the level of nitric oxide (NO) in response to various inflammatory stimuli. We hypothesize that a changed biological response to glucocorticoids could be a mechanism regulating the inflammatory events resulting in cervical ripening. METHODS We monitored GR and NFkappaB, prostaglandin synthases cyclooxygenase (COX)-1 and -2, iNOS, as well as the PAF-receptor (PAF-R) in the uterine cervix from term pregnant women (with unripe cervices) before the onset of labor (TP), immediately after parturition (PP), as compared to non-pregnant (NP), using immunohistochemistry and RT-PCR. RESULTS The GR protein was detected by immunohistochemistry in the nuclei of stroma and squamous epithelium (SQ). Stromal GR staining was increased in TP as compared to the NP group and decreased again after parturition. GR staining in SQ was decreased after parturition as compared to term. NFkappaB was present in SQ and glandular epithelium (GE), stroma and vascular endothelium. Increased nuclear NFkappaB staining was observed postpartum as compared to term pregnancy in stroma and GE. Stromal immunostaining for COX-1 as well as COX-2 was increased in the TP and PP groups as compared to the NP, and GE displayed an intensely increased COX-2 immunostaining at term and postpartum. Stromal PAF-R immunostaining was highest at term, while it was greatly increased in GE postpartum. No difference in the immunostaining for iNOS was found between the groups. RT-PCR showed a predominance of GRalpha to GRbeta mRNA in cervical tissue. The COX-2 mRNA level was increased in the PP group as compared to the TP group. CONCLUSIONS There is a decrease in GR levels in human cervix at parturition. Concomitantly there is an increase of factors such as NFkappaB, PAF-R, COX-1 and COX-2, suggesting that they may participate in the sequence of events leading to the final cervical ripening.
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Maul H, Shi L, Marx SG, Garfield RE, Saade GR. Platelet-activating factor antagonist WEB-2170 inhibits lipopolysaccharide-induced, but not antiprogestin-induced, preterm cervical ripening in timed-pregnant rats. Am J Obstet Gynecol 2003; 189:963-7. [PMID: 14586335 DOI: 10.1067/s0002-9378(03)00722-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this study was to determine whether the platelet-activating factor antagonist WEB-2170 inhibits preterm cervical ripening induced by lipopolysaccharide or by antiprogestin RU 486. STUDY DESIGN Timed-pregnant rats were killed on day 16 after treatment with (1) WEB-2170, lipopolysaccharide, lipopolysaccharide plus WEB-2170, or vehicle control and (2) with WEB-2170, RU 486, RU 486 plus WEB-2170, or vehicle control. Cervical ripening was assessed by light-induced fluorescence and resistance to stretch. Statistics were assessed by 1-way analysis of variance followed by Tukey-test (P <.05). RESULTS Light-induced fluorescence and resistance to stretch were significantly lower in the lipopolysaccharide-treated and in the RU486-treated animals compared with vehicle control (lipopolysaccharide:light-induced fluorescence, 7.0+/-0.6 vs 12.8+/-0.8 [P=.001]; resistance to stretch, 0.41+/-0.03 N/mm vs 0.54+/-0.04 N/mm [P <.05]; RU486:light-induced fluorescence, 9.6+/-0.6 vs 11.7+/-0.6 [P <.05]; resistance to stretch, 0.28+/-0.06 N/mm vs 0.61+/-0.02 N/mm [P <.001]). Compared with vehicle control, WEB-2170 alone did not alter cervical light-induced fluorescence or resistance to stretch. Although WEB-2170 significantly blocked cervical ripening after lipopolysaccharide administration (light-induced fluorescence, 11.3+/-1.3 [P <.05]; resistance to stretch, 0.61+/-0.04 [P <.01]), WEB-2170 did not inhibit the RU 486-induced cervical ripening. CONCLUSION Although infection-related cervical ripening is inhibited by platelet-activating factor antagonists, the physiologic process of cervical ripening appears to be unaffected. Platelet-activating factor inhibition may be of clinical value in the infection-related pathologic processes that are responsible for premature cervical ripening.
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Affiliation(s)
- Holger Maul
- Department of Obstetrics and Gynecology, Division of Reproductive Sciences, University of Texas Medical Branch, Galveston 77550-1062, USA
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Maul H, Shi L, Marx SG, Garfield RE, Saade GR. Local application of platelet-activating factor induces cervical ripening accompanied by infiltration of polymorphonuclear leukocytes in rats. Am J Obstet Gynecol 2002; 187:829-33. [PMID: 12388958 DOI: 10.1067/mob.2002.126983] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE The purpose of this study was to determine the effect of locally applied platelet-activating factor on cervical ripening and leukocyte infiltration. STUDY DESIGN Timed-pregnant rats were treated vaginally twice each day on days 14 and 15 of gestation with platelet-activating factor 5 x 10(-8) mol/L (low-dose), 5 x 10(-7) mol/L (high-dose), or solvent and were killed on day 16. Cervical ripening was assessed by cervical resistance-to-stretch and light-induced autofluorescence of cross-linked collagen. Longitudinal sections of the cervix were hematoxylin and eosin stained, and the number of polymorphonuclear leukocytes in eight high-power fields was determined. RESULTS Cervical resistance-to-stretch and light-induced autofluorescence were decreased in rats that were treated with high-dose platelet-activating factor compared with controls (0.4375 +/- 0.0126 N/mm vs 0.5528 +/- 0.0294 N/mm, and 2.739 +/- 0.150 N/mm vs 3.475 +/- 0.236 N/mm; P <.05). High-dose platelet-activating factor led to infiltration with polymorphonuclear leukocytes compared with control (22.1 +/- 5.2 vs 2.1 +/- 1.3 cells/8 high-power fields, P <.05). CONCLUSION Local platelet-activating factor application induces cervical ripening accompanied by stromal polymorphonuclear leukocyte infiltration. Platelet-activating factor may play a major role in parturition under physiologic and pathologic conditions.
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Affiliation(s)
- Holger Maul
- Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77550-1062, USA
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15
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Aravindakshan TV, Sharma A. Effect of platelet activating factor on the motility and acrosome reaction of buffalo () spermatozoa. Theriogenology 1996; 45:991-9. [PMID: 16727858 DOI: 10.1016/0093-691x(96)00027-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/1994] [Accepted: 08/14/1995] [Indexed: 10/16/2022]
Abstract
Platelet activating factor (PAF; 1-0-alkyl-2 acetyl-sn-glycerol-3 phosphocholine) has been shown to have a wide range of biological activities. In this study, PAF was used to induce acrosome reactions in fresh as well as frozen-thawed buffalo spermatozoa at different incubation periods and PAF levels. As the period of incubation increased, there was a gradual decrease in motility and increase in acrosome reaction in both fresh and frozen-thawed spermatozoa. With increasing PAF levels, the motility of fresh spermatozoa decreased and acrosome reaction increased whereas in frozen-thawed semen, motility remained almost constant, and the increase in acrosome reaction was not pronounced. Differences in motility and acrosome reaction among different bulls, types of semen, periods of incubation and PAF levels were significant (P < 0.01). A PAF level of 100 microM and an incubation period of 15 min were found to be optimum for inducing acrosome reaction in buffalo spermatozoa, since at this combination acrosome reaction increased significantly (P < 0.01) over that of the control without much loss of motility.
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Affiliation(s)
- T V Aravindakshan
- Biotechnology Laboratory, National Dairy Research Institute, Karnal-132 001, India
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16
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The role of PAF in reproductive biology. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1874-5245(96)80011-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Kim BK, Ozaki H, Lee SM, Karaki H. Increased sensitivity of rat myometrium to the contractile effect of platelet activating factor before delivery. Br J Pharmacol 1995; 115:1211-4. [PMID: 7582547 PMCID: PMC1908802 DOI: 10.1111/j.1476-5381.1995.tb15027.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
1. The contractile effects of platelet activating factor (PAF) were compared in the myometrium isolated from non-pregnant and pregnant rats. 2. In the non-pregnant myometrium, PAF, at a concentration of 0.1 microM, did not change muscle tension and induced only a small transient contraction at 10 microM. 3. The contractile responses to PAF increased with the progress of gestation. In the late pregnant myometrium (21 day after gestation), PAF (0.1 nM-10 microM) induced large and relatively sustained contractions. The threshold concentration of PAF was decreased by approximately 10,000 times and the maximum contraction was increased 5 times by day 21 of gestation. 4. PAF (10 microM) increased the cytosolic Ca2+ concentration ([Ca2+]i) and muscle contraction to levels higher than those induced by high K+ in the pregnant rat myometrium (day 21). Verapamil (10 microM), a voltage-dependent Ca2+ channel blocker, decreased the stimulated [Ca2+]i and muscle tension to 49.6% and 22.7%, respectively, while the same concentration of verapamil completely inhibited the high K(+)-induced responses. 5. PAF (10 microM) induced a transient increase in [Ca2+]i with no contraction in the absence of external Ca2+ in the pregnant myometrium (day 21). 6. These results suggest that PAF induces contraction in rat myometrium by increasing Ca2+ influx. Although PAF released Ca2+ from stored sites, this Ca2+ does not seem to contribute to the PAF-induced contraction. Our major finding is that the sensitivity of the myometrium to PAF increased after gestation and that this may play a role in delivery.
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Affiliation(s)
- B K Kim
- Department of Veterinary Pharmacology, Faculty of Agriculture, University of Tokyo, Japan
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18
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Bieńkiewicz A, Pajszczyk-Kieszkiewicz T, Kuś E, Dabrowski R. The effect of platelet activating factor antagonist (BN 52021) on pregnancy duration and collagen content in the pregnant rat uterus and cervix. Endocr Res 1994; 20:387-93. [PMID: 7882900 DOI: 10.3109/07435809409030414] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In order to study the role of Platelet Activating Factor (PAF) in the mechanism of parturition and connective tissue metabolism in the pregnant rat uterus, we investigated the influence of the Platelet Activating Factor Receptor Antagonist (BN 52021) on gestation duration and collagen concentration in pregnant rat uterus and cervix at term. Total and soluble collagen as well as dry tissue/wet tissue ratio were measured in the BN 52021 treated group (n = 9) and in the control group (n = 13). Gestation duration was evaluated in a group receiving BN 52021 (n = 10) and in a control group (n = 19) receiving pure solvent. There were no significant differences in water content. The total and soluble collagen concentration was also similar to the control in both the uterus and the cervix. The only significant difference was observed in the soluble collagen/total collagen ratio in the uterus. BN 52021 administration did not alter the gestational period. Basing on this experiment we suggest that not all the phospholipid metabolites activated by phospholipase A2 significantly influence the duration of pregnancy and connective tissue metabolism in the pregnant rat uterus.
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Affiliation(s)
- A Bieńkiewicz
- Institute of Obstetrics and Gynecology, University of Lódź, Poland
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19
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Baldi E, Bonaccorsi L, Finetti G, Luconi M, Muratori M, Susini T, Forti G, Serio M, Maggi M. Platelet-activating factor in human endometrium. J Steroid Biochem Mol Biol 1994; 49:359-63. [PMID: 8043501 DOI: 10.1016/0960-0760(94)90280-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Platelet-activating factor (PAF) is a phospholipid actively produced by human endometrium and deeply involved in the processes of ovoimplantation and labor. We recently found that PAF represents a new autocrine growth factor for a human adenocarcinoma cell line, HEC-1A. Indeed, biologically active PAF is synthesized by HEC-1A cells, under progesterone control. In HEC-1A cells, PAF regulates intracellular calcium concentration ([Ca2+]), DNA synthesis and expression of early oncogenes. All these effects are blocked by the receptor antagonist L659,989. However, while nanomolar concentrations of PAF mobilize [Ca2+], only micromolar concentrations affect cell growth, suggesting heterogeneity of PAF receptors or signaling. Two distinct populations of PAF receptors are present in HEC-1A cells, which bind PAF in nanomolar and micromolar concentrations, respectively. Since HEC-1A cells are producing elevated concentrations of PAF and micromolar concentrations of the PAF antagonist L659,989 inhibit cell proliferation, an autocrine role for PAF is suggested in HEC-1A cells.
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Affiliation(s)
- E Baldi
- Dipartimento di Fisiopatologia Clinica, Università di Firenze, Italy
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20
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Platelet-Activating Factor Antagonists: Scientific Background and Possible Clinical Applications. ADVANCES IN PHARMACOLOGY 1994. [DOI: 10.1016/s1054-3589(08)60494-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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21
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Rice GE, Aitken M, Scott KF, Brennecke SP. The role of gestational tissue type II phospholipase A2 in human labor and delivery. Placenta 1994. [DOI: 10.1016/s0143-4004(05)80370-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Ripps BA, Zhu YP, Burwinkel TH, Kim HN, Buster JE, Minhas BS. Platelet-activating factor production from in vitro and in vivo fertilized murine embryos is similar. Am J Reprod Immunol 1993; 30:101-4. [PMID: 8311917 DOI: 10.1111/j.1600-0897.1993.tb00609.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
PROBLEM This study measured platelet-activating factor (PAF) production of in vitro and in vivo fertilized murine embryos to ascertain whether site of fertilization impacted subsequent embryonic PAF production. METHOD Oocytes and embryo were collected from stimulated B6D2F1 mice. PAF production throughout the preimplantation phase from the two-celled stage through expanded blastocysts was measured and compared among normally developing embryos with the only difference being site of fertilization. RESULTS A striking increase in PAF production was noted for both in vivo and in vitro fertilized embryos over the four days of culture. Significantly higher (P < .001) levels of PAF production were noted with development from the two-celled stage (47.22 +/- 4.13; 44.30 +/- 2.43) to expanded blastocysts (254.31 +/- 24.01; 255.11 +/- 5.35 ng/embryo/24 h) for both in vitro and in vivo fertilized embryos, respectively. There was no significant difference (P > .05) in PAF production between the two groups of embryos. CONCLUSIONS Embryonic PAF production in the mouse increases in a stage-specific manner, and specifically the site of fertilization in vitro versus in vivo does not affect PAF production in normally developing embryos.
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Affiliation(s)
- B A Ripps
- Department of Obstetrics and Gynecology, University of Tennessee, Memphis 38163
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23
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López Bernal A, Newman GE, Phizackerley PJ, Laird E, Ross C, Barlow DH. Platelet-activating factor levels in human follicular and amniotic fluids. Eur J Obstet Gynecol Reprod Biol 1992; 46:39-44. [PMID: 1426500 DOI: 10.1016/0028-2243(92)90277-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Platelet-activating factor (PAF) was estimated in extracts of human follicular and amniotic fluids using a commercially available 125I-radioimmunoassay. Levels obtained before and after purification of the extracts by thin-layer chromatography were similar and PAF could be estimated with high accuracy and reproducibility over a wide dilution range. PAF levels in fluid aspirated from mature (17 mm average diameter) follicles from in vitro fertilization patients were 1005 +/- 129 fmol/ml in successful (clinical pregnancy) cycles and 949 +/- 75 fmol/ml in unsuccessful (failure of implantation) cycles. PAF levels were also similar in follicles containing eggs and those where no egg was found, and in fluid from follicular cysts characterised by low oestradiol and progesterone levels. PAF was detected in midtrimester amniotic fluid (60 +/- 20 fmol/ml). At term, PAF was low or undetectable in amniotic fluid obtained at elective caesarean section before the onset of labour, but increased to 102 +/- 28 fmol/ml in samples obtained following spontaneous labour and vaginal delivery. The data suggest that PAF may be involved in ovulation and parturition but further studies into the mechanism of action of PAF are necessary. The good performance of the radioimmunoassay and the convenience of gamma-counting are strong advantages of this method over the available bioassays, but its expense remains a drawback.
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Affiliation(s)
- A López Bernal
- Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Headington, Oxford, UK
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Zhu YP, Word RA, Johnston JM. The presence of platelet-activating factor binding sites in human myometrium and their role in uterine contraction. Am J Obstet Gynecol 1992; 166:1222-7. [PMID: 1314480 DOI: 10.1016/s0002-9378(11)90610-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
It has recently been suggested that platelet-activating factor is involved in a number of processes associated with reproductive biology. We have demonstrated a critical role for this autacoid in the initiation and maintenance of parturition both in animals and man. In the present investigation, it has been demonstrated that platelet-activating factor affects contraction in strips of human myometrium at concentrations as low as 10(-10) mol/L. A platelet-activating factor receptor has been identified and characterized in human myometrium. Platelet-activating factor acts to cause an increase in intracellular Ca2+ concentration of isolated myometrial smooth muscle cells in culture and an increase in the phosphorylation of the 20 kd light chain of myosin in a concentration-dependent fashion. The presence of platelet-activating factor receptors in human myometrium, the observed increase in Ca2+ concentration and phosphorylation of myosin light chain in the presence of platelet-activating factor provide further support for the importance of this autacoid in the initiation of parturition.
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Affiliation(s)
- Y P Zhu
- Department of Biochemistry, Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas 75235-9051
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25
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Miyaura S, Maki N, Byrd W, Johnston JM. The hormonal regulation of platelet-activating factor acetylhydrolase activity in plasma. Lipids 1991; 26:1015-20. [PMID: 1819685 DOI: 10.1007/bf02536494] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have previously reported that certain fetal tissues including the lung and kidney have an increased platelet-activating factor (PAF) content and enzymatic mechanism for its elevated biosynthesis during the latter stages of pregnancy. In contrast, in the maternal plasma compartment of both the rabbit and human, a decreased capacity to inactivate PAF has been demonstrated. The PAF acetylhydrolase in the fetal plasma is also suppressed. The present study was undertaken to determine the mechanism(s) involved in the regulation of PAF acetylhydrolase. The 17 alpha-ethynylestradiol was administered (intraperitoneal [i.p.] 2.5 mg/kg body wt 5 days) to female and male rats. The plasma PAF acetylhydrolase activity decreased 5-fold. A decrease was observed when a concentration of the estrogen as low as 50 micrograms/kg was employed. The injection of dexamethasone (i.p., 1.3 mg/kg body wt, 5 days) to male and female rats resulted in a 3-fold increase in the plasma PAF acetylhydrolase activity. The activity returned to the values prior to hormone treatment 4 days after cessation of treatment. Testosterone and progesterone were without effect on plasma acetylhydrolase activity. The change in PAF acetylhydrolase activity caused by estrogen and the glucocorticoid was reflected by a change in the activity in the HDL fraction and not due to the presence of an inhibitor or activator in the plasma of the hormone-treated animals. Human serum obtained from a group of women, in which the 17 beta-estradiol concentration was elevated in preparation for an in vitro fertilization procedure, showed an inverse relationship between the plasma estrogen concentration and the PAF acetylhydrolase activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Miyaura
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas 75235-9038
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