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Jellyman JK, Fletcher AJW, Fowden AL, Giussani DA. Glucocorticoid Maturation of Fetal Cardiovascular Function. Trends Mol Med 2020; 26:170-184. [PMID: 31718939 DOI: 10.1016/j.molmed.2019.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 09/17/2019] [Accepted: 09/30/2019] [Indexed: 12/27/2022]
Abstract
The last decade has seen rapid advances in the understanding of the central role of glucocorticoids in preparing the fetus for life after birth. However, relative to other organ systems, maturation by glucocorticoids of the fetal cardiovascular system has been ignored. Here, we review the effects of glucocorticoids on fetal basal cardiovascular function and on the fetal cardiovascular defense responses to acute stress. This is important because glucocorticoid-driven maturational changes in fetal cardiovascular function under basal and stressful conditions are central to the successful transition from intra- to extrauterine life. The cost-benefit balance for the cardiovascular health of the preterm baby of antenatal glucocorticoid therapy administered to pregnant women threatened with preterm birth is also discussed.
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Affiliation(s)
- Juanita K Jellyman
- Department of Biological Sciences, California State Polytechnic University, Pomona, CA, USA.
| | | | - Abigail L Fowden
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, UK; Cambridge Cardiovascular Strategic Research Initiative, Cambridge, UK; Cambridge Strategic Research Initiative in Reproduction, Cambridge, UK
| | - Dino A Giussani
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, UK; Cambridge Cardiovascular Strategic Research Initiative, Cambridge, UK; Cambridge Strategic Research Initiative in Reproduction, Cambridge, UK.
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Morgado J, Sanches B, Anjos R, Coelho C. Programming of Essential Hypertension: What Pediatric Cardiologists Need to Know. Pediatr Cardiol 2015; 36:1327-37. [PMID: 26015087 DOI: 10.1007/s00246-015-1204-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 05/14/2015] [Indexed: 01/11/2023]
Abstract
Hypertension is recognized as one of the major contributing factors to cardiovascular disease, but its etiology remains incompletely understood. Known genetic and environmental influences can only explain a small part of the variability in cardiovascular disease risk. The missing heritability is currently one of the most important challenges in blood pressure and hypertension genetics. Recently, some promising approaches have emerged that move beyond the DNA sequence and focus on identification of blood pressure genes regulated by epigenetic mechanisms such as DNA methylation, histone modification and microRNAs. This review summarizes information on gene-environmental interactions that lead toward the developmental programming of hypertension with specific reference to epigenetics and provides pediatricians and pediatric cardiologists with a more complete understanding of its pathogenesis.
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Affiliation(s)
- Joana Morgado
- Pediatrics Department, Hospital do Espírito Santo de Évora, Largo Senhor da Pobreza, 7000-811, Évora, Portugal.
| | - Bruno Sanches
- Pediatrics Department, Hospital Garcia de Orta, Almada, Portugal
| | - Rui Anjos
- Pediatric Cardiology Department, Hospital Santa Cruz, Lisbon, Portugal
| | - Constança Coelho
- Genetics Laboratory, Environmental Health Institute, Lisbon Medical School, Lisbon, Portugal
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Forhead AJ, Jellyman JK, De Blasio MJ, Johnson E, Giussani DA, Broughton Pipkin F, Fowden AL. Maternal Dexamethasone Treatment Alters Tissue and Circulating Components of the Renin-Angiotensin System in the Pregnant Ewe and Fetus. Endocrinology 2015; 156:3038-46. [PMID: 26039155 PMCID: PMC4511127 DOI: 10.1210/en.2015-1197] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Antenatal synthetic glucocorticoids promote fetal maturation in pregnant women at risk of preterm delivery and their mechanism of action may involve other endocrine systems. This study investigated the effect of maternal dexamethasone treatment, at clinically relevant doses, on components of the renin-angiotensin system (RAS) in the pregnant ewe and fetus. From 125 days of gestation (term, 145 ± 2 d), 10 ewes carrying single fetuses of mixed sex (3 female, 7 male) were injected twice im, at 10-11 pm, with dexamethasone (2 × 12 mg, n = 5) or saline (n = 5) at 24-hour intervals. At 10 hours after the second injection, maternal dexamethasone treatment increased angiotensin-converting enzyme (ACE) mRNA levels in the fetal lungs, kidneys, and heart and ACE concentration in the circulation and lungs, but not kidneys, of the fetuses. Fetal cardiac mRNA abundance of angiotensin II (AII) type 2 receptor decreased after maternal dexamethasone treatment. Between the two groups of fetuses, there were no significant differences in plasma angiotensinogen or renin concentrations; in transcript levels of renal renin, or AII type 1 or 2 receptors in the lungs and kidneys; or in pulmonary, renal or cardiac protein content of the AII receptors. In the pregnant ewes, dexamethasone administration increased pulmonary ACE and plasma angiotensinogen, and decreased plasma renin, concentrations. Some of the effects of dexamethasone treatment on the maternal and fetal RAS were associated with altered insulin and thyroid hormone activity. Changes in the local and circulating RAS induced by dexamethasone exposure in utero may contribute to the maturational and tissue-specific actions of antenatal glucocorticoid treatment.
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Affiliation(s)
- Alison J Forhead
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Juanita K Jellyman
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Miles J De Blasio
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Emma Johnson
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Dino A Giussani
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Fiona Broughton Pipkin
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
| | - Abigail L Fowden
- Department of Physiology, Development and Neuroscience (A.J.F., J.K.J., M.J.D.B., E.J., D.A.G., A.L.F.), University of Cambridge, Cambridge CB2 3EG, United Kingdom; Department of Biological and Medical Sciences (A.J.F.), Oxford Brookes University, Oxford OX3 0BP, United Kingdom; and Department of Obstetrics and Gynaecology (F.B.P.), University of Nottingham, Nottingham NG5 1PB, United Kingdom
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Guberman C, Jellyman JK, Han G, Ross MG, Desai M. Maternal high-fat diet programs rat offspring hypertension and activates the adipose renin-angiotensin system. Am J Obstet Gynecol 2013; 209:262.e1-8. [PMID: 23743273 PMCID: PMC4010310 DOI: 10.1016/j.ajog.2013.05.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 04/30/2013] [Accepted: 05/10/2013] [Indexed: 12/24/2022]
Abstract
OBJECTIVE A maternal high-fat diet creates an increased risk of offspring obesity and systemic hypertension. Although the renal renin-angiotensin system (RAS) is known to regulate blood pressure, it is now recognized that the RAS is also activated in adipose tissue during obesity. We hypothesized that programmed offspring hypertension is associated with the activation of the adipose tissue RAS in the offspring of obese rat dams. STUDY DESIGN At 3 weeks of age, female rats were weaned to a high-fat diet (60% k/cal; n = 6) or control diet (10% k/cal; n = 6). At 11 weeks of age, these rats were mated and continued on their respective diets during pregnancy. After birth, at 1 day of age, subcutaneous adipose tissue was collected; litter size was standardized, and pups were cross-fostered to either control or high-fat diet dams, which created 4 study groups. At 21 days of age, offspring were weaned to control or high-fat diet. At 6 months of age, body fat and blood pressure were measured. Thereafter, subcutaneous and retroperitoneal adipose tissue was harvested from male offspring. Protein expression of adipose tissue RAS components were determined by Western blotting. RESULTS The maternal high-fat diet induced early and persistent alterations in offspring adipose RAS components. These changes were dependent on the period of exposure to the maternal high-fat diet, were adipose tissue specific (subcutaneous and retroperitoneal), and were exacerbated by a postnatal high-fat diet. Maternal high-fat diet increased adiposity and blood pressure in offspring, regardless of the period of exposure. CONCLUSION These findings suggest that programmed adiposity and the activation of the adipose tissue RAS are associated with hypertension in offspring of obese dams.
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Affiliation(s)
- Cristiane Guberman
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90502, USA
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Mathai S, Booth LC, Davidson JO, Drury PP, Fraser M, Jensen EC, George S, Naylor A, Gunn AJ, Bennet L. Acute on chronic exposure to endotoxin in preterm fetal sheep. Am J Physiol Regul Integr Comp Physiol 2012; 304:R189-97. [PMID: 23235324 DOI: 10.1152/ajpregu.00388.2012] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Acute, high-dose exposure to endotoxin lipopolysaccharide (LPS) in preterm fetal sheep can trigger periventricular white matter lesions (PVL), in association with severe hypotension/hypoxemia and significant mortality. Intriguingly, however, chronic or repeated exposure to LPS can induce tachyphylaxis. We therefore tested the hypothesis that progressive, acute on chronic fetal infection would be associated with white matter injury with little fetal mortality. Chronically instrumented preterm (0.7 gestational age) fetal sheep were exposed to a continuous low-dose LPS infusion (100 ng over 24 h, followed by 250 ng/24 h for 96 h) or saline. Boluses of 1 μg LPS or saline were given at 48, 72, and 96 h; sheep were killed at day 10. Six of 11 fetal sheep exposed to saline infusion + LPS boluses died 4-7 h after the first bolus. In contrast, there was no fetal mortality after saline infusions alone (n = 9), low-dose LPS infusion + saline boluses (n = 5), or low-dose LPS + LPS boluses (n = 9). Low-dose LPS infusion + LPS boluses was associated with greater microglial induction than low-dose LPS + saline boluses but a similar area of periventricular white matter inflammation. One fetus developed severe focal white matter necrosis after LPS infusion + boluses. The acute cardiovascular compromise associated with high-dose, acute exposure to LPS is markedly attenuated by previous low-dose infusions, with limited apparent exacerbation of periventricular white matter injury compared with low-dose infusion alone.
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Affiliation(s)
- Sam Mathai
- Department of Physiology, the University of Auckland, New Zealand
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Abstract
Epidemiological evidence suggests that exposure to an adverse environment in early life is associated with an increased risk of cardio-metabolic and behavioral disorders in adulthood, a phenomenon termed 'early life programming'. One major hypothesis for early life programming is fetal glucocorticoid overexposure. In animal studies, prenatal glucocorticoid excess as a consequence of maternal stress or through exogenous administration to the mother or fetus is associated with programming effects on cardiovascular and metabolic systems and on the brain. These effects can be transmitted to subsequent generations. Studies in humans provide some evidence that prenatal glucocorticoid exposure may exert similar programming effects on glucose/insulin homeostasis, blood pressure and neurodevelopment. The mechanisms by which glucocorticoids mediate these effects are unclear but may include a role for epigenetic modifications. This review discusses the evidence for glucocorticoid programming in animal models and in humans.
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Affiliation(s)
- Batbayar Khulan
- Endocrinology Unit, Centre for Cardiovascular Science, University of Edinburgh, Queen's Medical Research Institute, Edinburgh, UK.
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Ojeda NB, Grigore D, Alexander BT. Role of fetal programming in the development of hypertension. Future Cardiol 2009; 4:163-74. [PMID: 19672482 DOI: 10.2217/14796678.4.2.163] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Epidemiological studies have suggested that size at birth contributes to increased cardiovascular disease (CVD) risk in later life. Findings from experimental studies are providing insight into the mechanisms linking impaired fetal growth and the increased risk of CVD and hypertension in adulthood. This article summarizes potential mechanisms involved in the fetal programming of hypertension and CVD, including alterations in the organs and regulatory systems critical to long-term control of sodium and volume homeostasis.
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Affiliation(s)
- Norma B Ojeda
- University of Mississippi Medical Center, Department of Physiology & Biophysics, The Center for Excellence in Cardiovascular-Renal Research, 2500 North State Street, Jackson, MS 39216-4505, USA.
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Drake AJ, Tang JI, Nyirenda MJ. Mechanisms underlying the role of glucocorticoids in the early life programming of adult disease. Clin Sci (Lond) 2007; 113:219-32. [PMID: 17663659 DOI: 10.1042/cs20070107] [Citation(s) in RCA: 147] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Compelling epidemiological evidence suggests that exposure to an adverse intrauterine environment, manifested by low-birth weight, is associated with cardiometabolic and behavioural disorders in adulthood. These observations have led to the concept of ‘fetal programming’. The molecular mechanisms that underlie this relationship remain unclear, but are being extensively investigated using a number of experimental models. One major hypothesis for early life physiological programming implicates fetal overexposure to stress (glucocorticoid) hormones. Several animal studies have shown that prenatal glucocorticoid excess, either from endogenous overproduction with maternal stress or through exogenous administration to the mother or fetus, reduces birth weight and causes lifelong hypertension, hyperglycaemia and behavioural abnormality in the offspring. Intriguingly, these effects are transmitted across generations without further exposure to glucocorticoids, which suggests an epigenetic mechanism. These animal observations could have huge implications if extrapolated to humans, where glucocorticoids have extensive therapeutic use in obstetric and neonatal practice.
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Affiliation(s)
- Amanda J Drake
- Endocrinology Unit, Centre for Cardiovascular Science, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, Scotland, UK
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King AJ, Olivier NB, Mohankumar PS, Lee JS, Padmanabhan V, Fink GD. Hypertension caused by prenatal testosterone excess in female sheep. Am J Physiol Endocrinol Metab 2007; 292:E1837-41. [PMID: 17327368 DOI: 10.1152/ajpendo.00668.2006] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Polycystic ovary syndrome (PCOS), a leading cause of infertility, affects approximately 10% of women of reproductive age. The etiology and pathophysiology of PCOS are poorly understood. PCOS is multifaceted and includes reproductive abnormalities and components of the metabolic syndrome such as insulin resistance, obesity, dyslipidemia, and hypertension. Exposure to excess testosterone (T) during the prenatal period may predispose individuals to PCOS phenotype. The goal of this study was to determine whether hypertension and dyslipidemia occur in a well-characterized model of PCOS produced by prenatal treatment of sheep with T. Radiotelemetry was used to measure blood pressure over a 24-h period in conscious, undisturbed animals. To normalize circulating estradiol levels across treatment, control (n = 4) and prenatal T-treated (100 mg T propionate im twice weekly from days 30 to 90 of fetal life, n = 4) 2-yr-old females were ovariectomized, instrumented with a radiotelemetry transmitter, and clamped with early follicular phase levels of estrogen using an implant. Six days later, a 24-h recording period commenced. Prenatal T-treated sheep were hypertensive compared with control sheep, and heart rate tended to be higher. T-treated sheep had hyperglycemia, insulin resistance, hypernatremia, and hyperchloremia, and both total and LDL cholesterol tended to be higher. Plasma aldosterone and epinephrine were significantly lower in T-treated sheep, whereas norepinephrine was unchanged. This first-ever use of radiotelemetric blood pressure recordings in sheep demonstrates that mild hypertension, a risk factor reported in some women with PCOS, is also a feature of the sheep model of PCOS produced by prenatal T treatment.
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Affiliation(s)
- Andrew J King
- Deparetment of Pharmacology and Toxicology, B440 Life Sciences, Michigan State University, East Lansing, MI 48824, USA.
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Schreuder M, Delemarre-van de Waal H, van Wijk A. Consequences of Intrauterine Growth Restriction for the Kidney. Kidney Blood Press Res 2006; 29:108-25. [PMID: 16837795 DOI: 10.1159/000094538] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Low birth weight due to intrauterine growth restriction is associated with various diseases in adulthood, such as hypertension, cardiovascular disease, insulin resistance and end-stage renal disease. The purpose of this review is to describe the effects of intrauterine growth restriction on the kidney. Nephrogenesis requires a fine balance of many factors that can be disturbed by intrauterine growth restriction, leading to a low nephron endowment. The compensatory hyperfiltration in the remaining nephrons results in glomerular and systemic hypertension. Hyperfiltration is attributed to several factors, including the renin-angiotensin system (RAS), insulin-like growth factor (IGF-I) and nitric oxide. Data from human and animal studies are presented, and suggest a faltering IGF-I and an inhibited RAS in intrauterine growth restriction. Hyperfiltration makes the kidney more vulnerable during additional kidney disease, and is associated with glomerular damage and kidney failure in the long run. Animal studies have provided a possible therapy with blockage of the RAS at an early stage in order to prevent the compensatory glomerular hyperfiltration, but this is far from being applicable to humans. Research is needed to further unravel the effect of intrauterine growth restriction on the kidney.
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Affiliation(s)
- Michiel Schreuder
- Department of Pediatric Nephrology, VU University Medical Center, Amsterdam, The Netherlands.
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Abstract
Compelling epidemiological evidence suggests that the early environment is an important determinant of later risk of disease. In particular, low birth weight has been associated with an increased risk of cardiovascular and metabolic disorders, including hypertension, Type 2 diabetes mellitus and ischemic heart disease, independent of classical adult lifestyle risk factors such as smoking, adult weight, social class, excess alcohol intake and sedentary lifestyle. These observations have led to a revolutionary concept of early life physiological programming. The molecular mechanisms that underlie this relationship remain unclear, but one major hypothesis implicates fetal overexposure to glucocorticoid stress hormones. This article will review evidence for this hypothesis.
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Affiliation(s)
- Moffat J Nyirenda
- a University of Edinburgh, Centre for Cardiovascular Science, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ Scotland, UK.
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Roelfsema V, Gunn AJ, Fraser M, Quaedackers JS, Bennet L. Cortisol and ACTH responses to severe asphyxia in preterm fetal sheep. Exp Physiol 2005; 90:545-55. [PMID: 15755816 DOI: 10.1113/expphysiol.2005.030320] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It has been hypothesized that the hypothalamic-pituitary-adrenal (HPA) axis is immature in the preterm fetus and that this compromises their ability to adapt to hypoxic stress; however, there are few direct data. We therefore examined the effects of asphyxia on HPA responses in chronically instrumented preterm fetal sheep (104 days of gestation; term is 147 days), allocated to a sham control group (n = 7) or 25 min of complete umbilical cord occlusion (n = 8), followed by recovery for 72 h. During umbilical cord occlusion there was a rapid rise in ACTH levels (230.4 +/- 63.5 versus 14.1 +/- 1.8 ng ml(-1) in sham controls, 16-fold) and cortisol levels (7.4 +/- 4.9 versus 0.2 +/- 0.1 ng ml(-1), 31-fold), with further increases after release of cord occlusion. ACTH levels were normalized by 24 h, while plasma cortisol levels returned to sham control values 72 h after asphyxia. Fetal arterial blood pressure was elevated in the first 36 h, with a marked increase in femoral vascular resistance, and correlated positively with cortisol levels after asphyxia (P = 0.05). In conclusion, the preterm fetus shows a brisk, substantial HPA response to severe hypoxia.
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Affiliation(s)
- Vincent Roelfsema
- Department of Physiology, Faculty of Medicine and Health Science, The University of Auckland, Private Bag 92019, Auckland, New Zealand
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Quaedackers JS, Roelfsema V, Fraser M, Gunn AJ, Bennet L. Cardiovascular and endocrine effects of a single course of maternal dexamethasone treatment in preterm fetal sheep. BJOG 2005; 112:182-91. [PMID: 15663582 DOI: 10.1111/j.1471-0528.2004.00344.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine the effects of a single course of maternally administered dexamethasone on preterm fetal sheep in utero. DESIGN Prospective randomised controlled trial. SETTING University laboratory. SAMPLE Pregnant sheep at 0.7 of gestation. METHODS Pregnant ewes at 103 days of pregnancy (term = 147 days) were given two intramuscular injections of vehicle (n= 7) or 12 mg of dexamethasone (DEX; n= 8) 24 hours apart. Fetuses were continuously monitored for five days. MAIN OUTCOME MEASURES Fetal mean arterial blood pressure, carotid and femoral arterial blood flow and vascular resistance, heart rate, heart rate variability, fetal plasma cortisol and ACTH and fetal body movements. RESULTS DEX injections led to an acute increase in mean arterial blood pressure with a rise in carotid and femoral vascular resistance, a fall in femoral arterial blood flow, and a brief fall in fetal heart rate followed by significant tachycardia. From 24 hours after the injections, mean arterial blood pressure and vascular resistance returned to control values, however, a mild tachycardia [200 (3) vs 184 (4) bpm, P < 0.05] and loss of the circadian pattern of fetal heart rate variability persisted until the end of recording. Plasma ACTH and cortisol were markedly suppressed by DEX (P < 0.05), with values returning to control levels 32 and 72 hours after the first injection, respectively. There was no effect on basal fetal heart rate variability, body movements, carotid arterial blood flow, or the circadian pattern of fetal heart rate. CONCLUSION In contrast to previous experiments utilising direct fetal infusion of steroids, maternal administration of DEX was associated with only transient hypertension.
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