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Gemperli K, Folorunso F, Norin B, Joshua R, Hill C, Rykowski R, Galindo R, Aravamuthan BR. Mice born preterm develop gait dystonia and reduced cortical parvalbumin immunoreactivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.01.578353. [PMID: 38352408 PMCID: PMC10862908 DOI: 10.1101/2024.02.01.578353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/25/2024]
Abstract
Preterm birth leading to cerebral palsy (CP) is the most common cause of childhood dystonia, a movement disorder that is debilitating and often treatment refractory. Dystonia has been typically associated with dysfunction of striatal cholinergic interneurons, but clinical imaging data suggests that cortical injury may best predict dystonia following preterm birth. Furthermore, abnormal sensorimotor cortex inhibition has been found in many studies of non-CP dystonias. To assess the potential for a cortical etiology of dystonia following preterm birth, we developed a new model of preterm birth in mice. Noting that term delivery in mice on a C57BL/6J background is embryonic day 19.1 (E19.1), we induced preterm birth at the limits of pup viability at embryonic day (E) 18.3, equivalent to human 22 weeks gestation. Mice born preterm demonstrate display clinically validated metrics of dystonia during gait (leg adduction amplitude and variability) and also demonstrate reduced parvalbumin immunoreactivity in the sensorimotor cortex, suggesting dysfunction of cortical parvalbumin-positive inhibitory interneurons. Notably, reduced parvalbumin immunoreactivity or changes in parvalbumin-positive neuronal number were not observed in the striatum. These data support the association between cortical dysfunction and dystonia following preterm birth. We propose that our mouse model of preterm birth can be used to study this association and potentially also study other sequelae of extreme prematurity.
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Affiliation(s)
- Kat Gemperli
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
| | - Femi Folorunso
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
| | - Benjamin Norin
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
| | - Rebecca Joshua
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
| | - Clayton Hill
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
| | - Rachel Rykowski
- Department of Neurology, Washington University School of Medicine, St. Louis, MO
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The Impact of Mouse Preterm Birth Induction by RU-486 on Microglial Activation and Subsequent Hypomyelination. Int J Mol Sci 2022; 23:ijms23094867. [PMID: 35563258 PMCID: PMC9105222 DOI: 10.3390/ijms23094867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 04/21/2022] [Accepted: 04/21/2022] [Indexed: 02/04/2023] Open
Abstract
Preterm birth (PTB) represents 15 million births every year worldwide and is frequently associated with maternal/fetal infections and inflammation, inducing neuroinflammation. This neuroinflammation is mediated by microglial cells, which are brain-resident macrophages that release cytotoxic molecules that block oligodendrocyte differentiation, leading to hypomyelination. Some preterm survivors can face lifetime motor and/or cognitive disabilities linked to periventricular white matter injuries (PWMIs). There is currently no recommendation concerning the mode of delivery in the case of PTB and its impact on brain development. Many animal models of induced-PTB based on LPS injections exist, but with a low survival rate. There is a lack of information regarding clinically used pharmacological substances to induce PTB and their consequences on brain development. Mifepristone (RU-486) is a drug used clinically to induce preterm labor. This study aims to elaborate and characterize a new model of induced-PTB and PWMIs by the gestational injection of RU-486 and the perinatal injection of pups with IL-1beta. A RU-486 single subcutaneous (s.c.) injection at embryonic day (E)18.5 induced PTB at E19.5 in pregnant OF1 mice. All pups were born alive and were adopted directly after birth. IL-1beta was injected intraperitoneally from postnatal day (P)1 to P5. Animals exposed to both RU-486 and IL-1beta demonstrated microglial reactivity and subsequent PWMIs. In conclusion, the s.c. administration of RU-486 induced labor within 24 h with a high survival rate for pups. In the context of perinatal inflammation, RU-486 labor induction significantly decreases microglial reactivity in vivo but did not prevent subsequent PWMIs.
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Does Birth Trigger Cell Death in the Developing Brain? eNeuro 2020; 7:ENEURO.0517-19.2020. [PMID: 32015098 PMCID: PMC7031855 DOI: 10.1523/eneuro.0517-19.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 12/27/2022] Open
Abstract
Developmental cell death eliminates half of the neurons initially generated in the mammalian brain, and occurs perinatally in many species. It is possible that the timing of neuronal cell death is developmentally programmed, and only coincidentally associated with birth. Alternatively, birth may play a role in shaping cell death. To test these competing hypotheses, we experimentally advanced or delayed birth by 1 d in mice (within the normal range of gestation for the species) and examined effects on the temporal pattern and magnitude (amount) of neuronal cell death, using immunohistochemical detection of activated caspase-3 as a cell death marker. In order to detect effects of subtle changes in birth timing, we focused on brain areas that exhibit sharp postnatal peaks in cell death. We find that advancing birth advances peak cell death, supporting the hypothesis that birth triggers cell death. However, a delay of birth does not delay cell death. Thus, birth can advance cell death, but if postponed, a developmental program governs. Advancing or delaying birth also caused region-specific changes in the overall magnitude of cell death. Our findings shed light on the long-standing question of what controls the timing and magnitude of developmental neuronal cell death, and position birth as an orchestrator of brain development. Because humans across the world now routinely alter birth timing, these findings may have implications for current obstetric practices.
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Johnston ZC, Bellingham M, Filis P, Soffientini U, Hough D, Bhattacharya S, Simard M, Hammond GL, King P, O'Shaughnessy PJ, Fowler PA. The human fetal adrenal produces cortisol but no detectable aldosterone throughout the second trimester. BMC Med 2018; 16:23. [PMID: 29429410 PMCID: PMC5808459 DOI: 10.1186/s12916-018-1009-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 01/18/2018] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Human fetal adrenal glands are highly active and, with the placenta, regulate circulating progesterone, estrogen and corticosteroids in the fetus. At birth the adrenals are essential for neonate salt retention through secretion of aldosterone, while adequate glucocorticoids are required to prevent adrenal insufficiency. The objective of this study was to carry out the first comprehensive analysis of adrenal steroid levels and steroidogenic enzyme expression in normal second trimester human fetuses. METHODS This was an observational study of steroids, messenger RNA transcripts and proteins in adrenals from up to 109 second trimester fetuses (11 weeks to 21 weeks) at the Universities of Aberdeen and Glasgow. The study design was balanced to show effects of maternal smoking. RESULTS Concentrations of 19 intra-adrenal steroids were quantified using liquid chromatography and mass spectrometry. Pregnenolone was the most abundant steroid while levels of 17α-hydroxyprogesterone, dehydroepiandrosterone sulphate (DHEAS) and progesterone were also high. Cortisol was present in all adrenals, but aldosterone was undetected and Δ4 androgens were low/undetected. CYP17A1, CYP21A2 and CYP11A1 were all highly expressed and the proteins localized to the adrenal fetal zone. There was low-level expression of HSD3B and CYP11B2, with HSD3B located mainly in the definitive zone. Maternal smoking altered fetal plasma adrenocorticotropic hormone (ACTH) (P = 0.052) and intra-adrenal progesterone, 17α-hydroxyprogesterone and 16α-hydroxyprogesterone, but not plasma or intra-adrenal cortisol, or intra-adrenal DHEAS. Fetal adrenal GATA6 and NR5A1 were increased by maternal smoking. CONCLUSIONS The human fetal adrenal gland produces cortisol but very low levels of Δ4 androgens and no detectable aldosterone throughout the second trimester. The presence of cortisol in fetal adrenals suggests that adrenal regulation of circulating fetal ACTH remains a factor in development of congenital adrenal hyperplasia during the second trimester, while a relative lack of aldosterone explains the salt-wasting disorders frequently seen in extreme pre-term neonates. Finally, maternal smoking may alter fetal adrenal sensitivity to ACTH, which could have knock-on effects on post-natal health.
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Affiliation(s)
- Zoe C Johnston
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Michelle Bellingham
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Panagiotis Filis
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Ugo Soffientini
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Denise Hough
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Siladitya Bhattacharya
- Institute of Applied Health Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK
| | - Marc Simard
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, British Columbia, V6T 1Z3, Canada
| | - Geoffrey L Hammond
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, British Columbia, V6T 1Z3, Canada
| | - Peter King
- Centre for Endocrinology, William Harvey Research Institute, Barts and the London, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Peter J O'Shaughnessy
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical, Veterinary & Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Paul A Fowler
- Institute of Medical Sciences, School of Medicine, Medical Sciences & Nutrition, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
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Spitz IM. Progesterone receptor antagonists and selective progesterone receptor modulators: proven and potential clinical applications. ACTA ACUST UNITED AC 2014. [DOI: 10.1586/17474108.2.2.227] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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Ceccaldi PF, Saada J, Nicolas M, Ducarme G, Blot P, Guibourdenche J, Luton D. Modulation of Free Corticotrophin-Releasing Hormone, Adrenal and Placental Steroid Hormone Levels Induced by Mifepristone during Pregnancy. Fetal Diagn Ther 2012; 32:267-70. [DOI: 10.1159/000338927] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/18/2012] [Indexed: 11/19/2022]
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Benagiano G, Bastianelli C, Farris M. Selective progesterone receptor modulators 1: use during pregnancy. Expert Opin Pharmacother 2008; 9:2459-72. [DOI: 10.1517/14656566.9.14.2459] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Fassett MJ, Lachelin GCL, McGarrigle HHG, Wing DA. Alterations in Saliva Steroid Hormone Levels After Oral Mifepristone Administration in Women With Pregnancies of Greater Than 41 Weeks' Gestation. Reprod Sci 2008; 15:394-9. [DOI: 10.1177/1933719107310305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Michael J. Fassett
- Maternal-Fetal Medicine, Kaiser Permanente Medical Center, Los Angeles, California,
| | - Gillian C. L. Lachelin
- Department of Obstetrics and Gynaecology, University College London, London, United Kingdom
| | - Hugh H. G. McGarrigle
- Department of Obstetrics and Gynaecology, University College London, London, United Kingdom
| | - Deborah A. Wing
- Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of California, Irvine, Orange, California
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von Hertzen H, Baird D. Frequently asked questions about medical abortion. Contraception 2006; 74:3-10. [PMID: 16781252 DOI: 10.1016/j.contraception.2006.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
The development of methods of inducing abortion medically (nonsurgically) has created alternative options to make abortion available to women in a variety of health-care settings. Medical abortion is induced with a regimen of mifepristone followed by a prostaglandin analogue. Since its first introduction in the late 1980s, the regimen has undergone some modifications based on research evidence, and, in many countries, clinicians are using regimens that may differ from the one that has been licensed. This causes confusion among providers, also because only a few countries have developed national guidelines for the provision of medical abortion. We approached health care personnel providing abortion services in various countries and asked them to send us questions that they, or their colleagues, might have concerning the clinical practice of medical abortion in the early first trimester (up to 63 days since the first day of the last menstrual period). These questions were sent to experts representing the fields of biomedical and clinical research, clinical practice and family planning, who conducted literature reviews so that, whenever possible, the answers could be based on existing evidence. A consensus meeting was held in Bellagio, Italy, between November 1 and 5, 2004, to review the questions and to discuss the answers. The aim of this article is to provide a brief overview of some of the questions asked and the answers discussed.
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Affiliation(s)
- Helena von Hertzen
- Department of Reproductive Health and Research, World Health Organization, CH-1211 Geneva 27, Switzerland.
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Berkane N, Verstraete L, Uzan S, Boog G, Maria B. Use of mifepristone to ripen the cervix and induce labor in term pregnancies. Am J Obstet Gynecol 2005; 192:114-20. [PMID: 15672012 DOI: 10.1016/j.ajog.2004.05.084] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE This study was undertaken to determine the efficacy of mifepristone for ripening the cervix and inducing labor in term pregnancies. STUDY DESIGN In a double-blind placebo-controlled dose-finding study, 346 women received 50, 100, 200, 400, or 600 mg of mifepristone or placebo. The main endpoint for efficacy was the number of patients in whom labor occurred between 12 and 45 and 54 hours after treatment or who had a Bishop score 6 or greater. Maternal and fetal tolerability was also studied. RESULTS No significant efficacy was observed whatever the dose of mifepristone. Mifepristone was well tolerated by the mother and fetus. CONCLUSION Mifepristone, at doses up to 600 mg, does not induce labor within 54 hours in patients with unfavourable cervical status.
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Affiliation(s)
- Nadia Berkane
- Department of Gynecology-Obstetrics and Reproductive Medicine, Hôpital Tenon, Paris, France.
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12
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Abstract
Since the original description of the structure of the antiprogestin, mifepristone, was published, numerous related compounds have been synthesized which may function as progesterone antagonists (PAs) or progesterone receptor modulators (PRMs). The latter are mixed agonists-antagonists. Both PAs and PRMs have therapeutic applications in female health care. Mifepristone is predominantly a PA and displays only minimum agonist activity in certain systems. Together with a prostaglandin, mifepristone can terminate pregnancies of less than 9 weeks duration, and it may also be used at later gestational ages. Mifepristone causes expulsion of the uterine contents following intrauterine fetal death. A mifepristone-prostaglandin combination has been shown to be very effective treatment in women with menses delay of 11 days or less. Many PAs and PRMs display antiproliferative effects in the endometrium. Serum estradiol levels however remain in the early to mid-follicular phase range. For this reason, they have application in the treatment of endometriosis and myoma without being associated with bone loss and hypoestrogenism. PRMs may also find application in the treatment of dysfunctional bleeding as well as an adjunct to estrogens in hormone replacement therapy in postmenopausal women. Many PAs have contraceptive potential by suppressing follicular development and blocking the LH surge. Low doses may also be potential contraceptives by retarding endometrial maturation without affecting ovulation or inducing bleeding. Mifepristone is an excellent agent for use as an emergency "postcoital" contraceptive. PAs may also be useful in IVF programs to prevent a premature LH surge and to delay the emergence of the implantation window. In addition to their use in women's health care, mifepristone and several other PAs are potent antiglucocorticoid agents and may be used to treat ACTH-independent Cushing's syndrome. They may also be used in the treatment of tumors containing steroid receptors and in other situations which require suppression of the ACTH-cortisol axis.
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Affiliation(s)
- Irving M Spitz
- Institute of Hormone Research, Shaare Zedek Medical Center, P.O. Box 3235, Jerusalem 91031, Israel.
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Affiliation(s)
- Irving M Spitz
- Institute of Hormone Research, Shaare Zedek Medical Center, PO Box 3235, Jerusalem 91031, Israel.
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Giacalone PL, Daurés JP, Faure JM, Boulot P, Hedon B, Laffargue F. The effects of mifepristone on uterine sensitivity to oxytocin and on fetal heart rate patterns. Eur J Obstet Gynecol Reprod Biol 2001; 97:30-4. [PMID: 11435005 DOI: 10.1016/s0301-2115(00)00506-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To compare the incidences of tachysystole, hypertonia and fetal heart rate (FHR) abnormalities in women treated by mifepristone plus prostaglandins (PGs), mifepristone alone or PGs alone for an unfavourable cervix. STUDY DESIGN In this retrospective study, all women between 37 and 42 weeks were eligible for the study if they had undergone cervical ripening prior to labour induction. In group 1, the women were treated with mifepristone plus PGs (n=103). Group 2 women were treated with mifepristone alone (n=96) and group 3 women with PGs alone (n=100). Incidences of tachysystole, hypertonia and FHR abnormalities were compared. RESULTS During induction of labour, tachysystole and hypertonia occurred more frequently in women treated with mifepristone. Severe bradycardia and recurrent late decelerations were more frequent after the initiation of oxytocin in groups 1 and 2 than in group 3. CONCLUSIONS In this study, mifepristone increased the incidences of tachysystole, hypertonia and FHR abnormality.
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Affiliation(s)
- P L Giacalone
- Department of Obstetrics and Gynecology, Hôpital Arnaud de Villeneuve, University of Montpellier, 371 rue du Doyen Gaston Giraud, 34295 Montpellier Cedex 5, France.
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Abstract
OBJECTIVE To review the literature concerning the mechanism of action and pharmacodynamics of mifepristone (RU486), potential new uses of RU486, and its current use not only as an abortifacient but also as therapy for endometriosis, leiomyoma, breast cancer, and meningioma. DATA IDENTIFICATION AND SELECTION Studies that relate to RU486 were identified through a MEDLINE search. CONCLUSION(S) RU486 is an 11 beta-dimethyl-amino-phenyl derivative of norethindrone with a high affinity for P and glucocorticoid receptors. The receptor binding is not followed by transcription of P-dependent genes. Mifepristone effectively blocks P receptors in the placenta, resulting in the termination of pregnancy. In addition, it has been used in the treatment of leiomyomata, endometriosis, advanced breast cancer, and meningioma. It is a powerful tool to study the molecular action of P and in the future may be used as an estrogen-free contraceptive.
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MESH Headings
- Abortifacient Agents, Steroidal/pharmacokinetics
- Abortifacient Agents, Steroidal/pharmacology
- Abortifacient Agents, Steroidal/therapeutic use
- Abortion, Induced/methods
- Animals
- Breast Neoplasms/drug therapy
- Contraceptives, Oral, Synthetic/pharmacokinetics
- Contraceptives, Oral, Synthetic/pharmacology
- Contraceptives, Oral, Synthetic/therapeutic use
- Contraceptives, Postcoital, Synthetic/pharmacokinetics
- Contraceptives, Postcoital, Synthetic/pharmacology
- Endometriosis/drug therapy
- Female
- Humans
- Leiomyoma/drug therapy
- Mifepristone/pharmacokinetics
- Mifepristone/pharmacology
- Mifepristone/therapeutic use
- Pregnancy
- Uterine Neoplasms/drug therapy
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Affiliation(s)
- D K Mahajan
- Department of Obstetrics and Gynecology, Louisiana State University School of Medicine, Shreveport 71130, USA.
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Abstract
Bartter syndrome, an autosomal recessive disorder of hyperaldosteronism and increased plasma renin, was suspected in an at-risk pregnancy due to the early occurrence of polyhydramnios. Further establishment of the diagnosis was accomplished by demonstrating increased levels of aldosterone in amniotic fluid and fetal cord blood. Electrolyte levels did not differ significantly from reported controls. It is thus suggested that polyhydramnios is the result of increased fetal urine output in Bartter syndrome and that amniotic fluid aldosterone is a reliable marker for the prenatal diagnosis of this condition.
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Affiliation(s)
- H Shalev
- Pediatric Division, Soroka Medical Center, Beer-Sheva, Israel
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Spitz IM, Bardin CW. Clinical pharmacology of RU 486--an antiprogestin and antiglucocorticoid. Contraception 1993; 48:403-44. [PMID: 8275693 DOI: 10.1016/0010-7824(93)90133-r] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- I M Spitz
- Center for Biomedical Research, Population Council, New York, NY 10021
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Affiliation(s)
- I M Spitz
- Center for Biomedical Research, Population Council, New York, NY 10021
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Weinstein MA, Pleim ET, Barfield RJ. Effects of neonatal exposure to the antiprogestin mifepristone, RU 486, on the sexual development of the rat. Pharmacol Biochem Behav 1992; 41:69-74. [PMID: 1539081 DOI: 10.1016/0091-3057(92)90061-j] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
RU 38486 (RU 486, mifepristone) is a potent progesterone receptor antagonist that has been used in humans in the pharmacologic induction of abortion. The effects of exposure to RU 486 during the neonatal period of the rat has not been previously reported. We examined the consequences of such exposure in the context of sexual development. Long-Evans rat pups were subcutaneously injected with either 100 micrograms RU 486, 300 micrograms RU 486, 500 micrograms progesterone (P), or 50 micrograms testosterone propionate (TP) in 0.05 ml sesame oil, or oil vehicle alone within 8 hours of birth, and 24 and 48 hours later. Treatment with either dose of RU 486 significantly advanced the onset of vaginal opening in females and attenuated defeminization of the lordosis response measured in males castrated as adults. As expected, TP-treated subjects were masculinized and defeminized, with females displaying fused vaginas and neither males nor females demonstrating lordosis behavior. Treatment with P caused no significant alterations in either the timing of vaginal opening or sexual behavior. These results indicate that RU 486 has clear developmental effects in the rat. Since this may well be a result of progesterone receptor blockade, further research is needed to clarify the processes involved.
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Affiliation(s)
- M A Weinstein
- Department of Biological Sciences, Rutgers University, Piscataway, NJ 08855
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