role of prostaglandins in pregnancy
Leukotriene D4: A potent vasoconstrictor of the pulmonary and systemic circulations in the newborn lamb. In: Cohen MM (ed), Biological Protection with Prostaglandins, vol 1, p 27. FASEB J 1987;1:186, Letts LG, Cirino M. Vascular actions of leukotrienes. Arachidonic acid first is converted to the HPETEs and then to the HETEs, lipoxins, or leukotrienes.1, 2 The 5-lipoxygenase is the primary pathway to the leukotrienes. Placenta 1985;6:435, Maigaard S, Forman A, Andersson K-E. Relaxant and contractile effects of some amines and prostanoids in myometrial and vascular smooth muscle within the human uteroplacental unit. Am J Obstet Gynecol 1985;152:335.). The ratio of thromboxane to prostacyclin is altered by low-dose aspirin in favor of restoring a balance between thromboxane and prostacyclin. Am J Obstet Gynecol 1975;123:364, Schwartz A, Brook I, Insler V et al. The importance of lipoxins in normal and abnormal pregnancy is not known, but the fact that lipoxin A dilates arterioles implies that they may serve to augment vasodilatation during normal pregnancy. Clinical trial to assess the effect of physical exercise on endothelial function and insulin resistance in pregnant women. Prostaglandins and the regulation of myometrial activity: A working model. Bethesda, MD 20894, Copyright The role of arachidonic acid metabolites in preeclampsia. Prostaglandins Leukotrienes Med 1986;21:323, Mak KKW, Gude NM, Walters WAW et al. N Engl J Med 1979;300:1142, Moncada S, Vane JR. Pharmacology and endogenous roles of prostaglandin endoperoxides, thromboxane A2, and prostacyclin. Several in vivo studies have been reported concerning the vasoactive effects of prostaglandins in the placenta. Prostaglandins 1978;15:1035, Tuvemo T. Action of prostaglandins and blockers of prostaglandin synthesis on the isolated human umbilical artery. J Clin Invest 1985;75:1381, Billah MM, Johnston JM. Inhibition of prostaglandin synthesis by human amniotic fluid: Acute reduction in inhibitory activity of amniotic fluid obtained during labor. Case Rep Obstet Gynecol. In: Creasy RK, Resnik R (eds), Maternal–Fetal Medicine: Principles and Practice, p 679. A summary diagram is presented in Fig. This idea is supported by the facts that blood pressure typically decreases during pregnancy and that simply turning a pregnant patient from the lateral to the supine position causes an increase in blood pressure despite a decrease in cardiac output.21, 22 Women in their third trimester (28–32 weeks' gestation) in whom preeclampsia is destined to develop have a greater increase in blood pressure than do healthy pregnant women when turned from the lateral to the supine position.28 One explanation for the increase in blood pressure in the supine position is that the gravid uterus compresses the vena cava and thereby reduces venous return to the heart, leading to decreased cardiac output. In: Scarpelli EM, Cosmi EV (eds), Reviews in Perinatal Medicine, vol 5, p 151. Plasma levels of prostacyclin's stable metabolite 6-keto-PGF1α in preeclampsia have been reported to be decreased, unchanged, or increased compared with normal pregnancy. New York: Alan R. Liss, Clark MA, Littlejohn D, Mong S et al. Indirect evidence suggests that prostacyclin is important for in vivo vasodilation in the human placenta. There are so few data available for the lipoxygenase compounds in association with pregnancy and labor that one can only speculate as to their physiologic functions. Cervical ripening as an inflammatory reaction. The fetal membranes as a possible source of amniotic fluid prostaglandins. In: Lewis PJ, Moncada S, O'Grady J (eds), Prostacyclin in Pregnancy, p 15. New York: Appleton-Century-Crofts; 1978, Dennis EJ III, McFarland KF, Hester LL Jr. 9. Prostacyclin and the kidney. This results in “progesterone withdrawal,” allowing the uterus to contract, and simultaneously results in estrogen stimulation of prostaglandin production, causing the uterus to contract. Pill compliance was significantly associated with a beneficial effect of aspirin for prevention of preeclampsia. Williams Obstetrics, 17th ed. Would you like email updates of new search results? J Clin Endocrinol Metab 1978;46:947, Green K, Bygdeman M, Toppozada M et al. Data represent mean ± SE (n = 10 vs. 11). Estrogens also are formed in these tissues, and they inhibit this enzyme system. Prostaglandins 1985;30:13, Wilson T, Liggins GC, Aimer GP et al. Under normal conditions, prostacyclin released by the vascular endothelial cells acts to stimulate an increase in adenosine 3',5'-cyclic phosphate (cAMP) levels within the platelets, thus inhibiting aggregation.30 Within the platelets, thromboxane can prevent prostacyclin-induced increases in cAMP, so under typical circumstances, thromboxane and prostacyclin counteract each other's actions to maintain homeostasis with respect to platelet function. Arachidonic acid is metabolized by lipoxygenase enzymes in several tissues, organs, and cells of the body, most notably the lungs and leukocytes (in which they were first discovered and from which the leukotrienes derive their name). The concentrations of LTC4 in amniotic fluid of monkeys also increase significantly with the onset of labor (Fig. The effects of prostacyclin and thromboxane analogue (U46619) on the fetal circulation and umbilical flow velocity waveforms. In utero evidence for a functional fetoplacental unit in rhesus monkeys. There is agreement among investigators that fetal administration of PGE2 or PGF2α causes umbilical–placental vasoconstriction in the sheep.72, 73, 74, 75, 76 The thromboxane mimic U46619 is a potent vasoconstrictor in the ovine fetal systemic circulation and in the umbilical–placental circulation.77, 78 Furthermore, fetal infusion of thromboxane can result in respiratory acidosis in the fetus, a further indication of its detrimental vasoconstrictive effects on the fetoplacental vasculature. Gynecol Obstet Invest 1986;22:1, Glance DG, Elder MG, Myatt L. The actions of prostaglandins and their interactions with angiotensin II in the isolated perfused human placental cotyledon. eCollection 2013. Blood pressure changes are small in normotensive women, but generally there is a slight decrease of 2–3 mmHg in systolic pressure and 5–10 mmHg in diastolic pressure. Clin Exp Hypertens [B] 1988;B7:171, Wallenburg HCS, Dekker GA, Makovitz JW et al. A role of prostaglandins in the regulation of the placental blood flow. New York: Raven Press; 1982, Samuelsson B. In vitro studies show that placental arterial production of thromboxane is decreased 84% by low-dose aspirin, but production of prostacyclin is not inhibited significantly.137 Similarly, incubation of whole placental tissue with aspirin can result in significant inhibition of thromboxane but not prostacyclin production.138 Clinical studies with low-dose aspirin suggest that placental thromboxane production is preferentially inhibited in vivo, as indicated by increased umbilical–placental blood flow and perfusion, increased fetal growth, increased neonatal weight, and increased placental weight.123, 124, 139, 140, 141, 142, 143, 144, 145, 146, Analysis of maternal urinary metabolites of thromboxane and prostacyclin gives an indication of renal production (TXB2 and 6-keto-PGF1α) or overall production (2,3-dinor-TXB2 and 2,3-dinor-6-keto-PGF1α). Am J Obstet Gynecol 1989;161:1593, Gastaldi A, Frusca T, Gregorini G: Prevention of preeclampsia and possible correlation with physiopathology. The mechanisms through which the primate fetus influences the timing of birth are not known, but they may involve nocturnal activity of the fetal adrenal glands. J Soc Gynecol Investig 2003;9:125, Mesiano S. Myometrial progesterone responsiveness and the control of human parturition.