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Briffa JF, Bevens W, Gravina S, Said JM, Wlodek ME. Pregnant biglycan knockout mice have altered cardiorenal adaptations and a shorter gestational length, but do not develop a pre-eclamptic phenotype. Placenta 2022; 119:52-62. [PMID: 35150975 DOI: 10.1016/j.placenta.2022.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 01/23/2022] [Accepted: 02/03/2022] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Pre-eclampsia complicates 4.6% of pregnancies and is linked to impaired placentation; likely due to dysregulated vasculogenesis/angiogenesis. Proteoglycans, such as biglycan, are located on the endothelial surface of fetal capillaries. Biglycan is reduced in the placenta of pregnancies complicated by fetal growth restriction and pre-eclampsia. Importantly, biglycan stimulates angiogenesis in numerous tissues. Therefore, this study investigated whether biglycan knockdown in mice results in a pre-eclamptic phenotype. METHODS Wild-type (WT) and Bgn-/- mice underwent cardiorenal measurements prior to and during pregnancy. One cohort of mice underwent post-mortem on gestational day 18 (E18) and another cohort underwent post-mortem on postnatal day 1 (PN1), with maternal and offspring tissues of relevance collected. RESULTS Bgn-/- dams had increased heart rate (+9%, p < 0.037) and reduced systolic (-11%, p < 0.001), diastolic (-15%, p < 0.001), and mean arterial (-12%, p < 0.001) pressures at all ages investigated compared to WT. Additionally, Bgn-/- dams had reduced urine flow rate (-64%, p < 0.001) as well as reduced urinary excretions (-49%, p < 0.004) during late gestation compared to WT. Bgn-/- pups had higher body weight (+8%, p = 0.004; E18 only) and a higher liver-to-brain weight ratio (+43%, p < 0.001). Placental weight was unaltered with only minor changes in vasculogenic and angiogenic gene abundances detected, which did not correlate to changes in protein expression. DISCUSSION This study demonstrated that total knockdown of biglycan is not associated with features of pre-eclampsia.
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Affiliation(s)
- J F Briffa
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - W Bevens
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - S Gravina
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - J M Said
- Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, 3010, Australia; Maternal Fetal Medicine, Sunshine Hospital, Western Health, St Albans, VIC, 3021, Australia
| | - M E Wlodek
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, 3010, Australia; Department of Obstetrics and Gynaecology, The University of Melbourne, Parkville, VIC, 3010, Australia.
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Booth SA, Wadley GD, Marques FZ, Wlodek ME, Charchar FJ. Fetal growth restriction shortens cardiac telomere length, but this is attenuated by exercise in early life. Physiol Genomics 2018; 50:956-963. [PMID: 30192712 DOI: 10.1152/physiolgenomics.00042.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND AIMS Fetal and postnatal growth restriction cause a predisposition to cardiovascular disease (CVD) in adulthood. Telomeres are repetitive DNA-protein structures that protect chromosome ends, and the loss of these repeats (a reduction in telomere length) is associated with CVD. As exercise preserves telomere length and cardiovascular health, the aim of this study was to determine the effects of growth restriction and exercise training on cardiac telomere length and telomeric genes. METHODS AND RESULTS Pregnant Wistar Kyoto rats underwent bilateral uterine vessel ligation to induce uteroplacental insufficiency and fetal growth restriction ("Restricted"). Sham-operated rats had either intact litters ("Control") or their litters reduced to five pups with slowed postnatal growth ("Reduced"). Control, Restricted, and Reduced male rats were assigned to Sedentary, Early exercise (5-9 wk of age), or Late exercise (20-24 wk of age) groups. Hearts were excised at 24 wk of age for telomere length and gene expression measurements by quantitative PCR. Growth restriction shortened cardiac telomere length ( P < 0.001), but this was rescued by early exercise ( P < 0.001). Early and Late exercise increased cardiac weight index ( P < 0.001), but neither this nor telomere length was associated with expression of the telomeric genes Tert, Terc, Trf2, Pnuts, or Sirt1. DISCUSSION AND CONCLUSIONS Growth restriction shortens cardiac telomere length, reflecting the cardiac pathologies associated with low birth weight. Exercise in early life may offer long-term protective effects on cardiac telomere length, which could help prevent CVD in later life.
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Affiliation(s)
- S A Booth
- School of Health and Life Sciences, Federation University Australia , Victoria , Australia
| | - G D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University , Geelong, Victoria , Australia
| | - F Z Marques
- School of Health and Life Sciences, Federation University Australia , Victoria , Australia.,Heart Failure Research Group, Baker Heart and Diabetes Institute , Melbourne , Australia.,Central Clinical School, Faculty of Medicine Nursing and Health Sciences, Monash University , Melbourne , Australia
| | - M E Wlodek
- Department of Physiology, The University of Melbourne , Parkville, Victoria , Australia
| | - F J Charchar
- School of Health and Life Sciences, Federation University Australia , Victoria , Australia.,Department of Physiology, The University of Melbourne , Parkville, Victoria , Australia.,Department of Cardiovascular Sciences, University of Leicester , Leicester , United Kingdom
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Cuffe JSM, Briffa JF, Rosser S, Siebel AL, Romano T, Hryciw DH, Wlodek ME, Moritz KM. Uteroplacental insufficiency in rats induces renal apoptosis and delays nephrogenesis completion. Acta Physiol (Oxf) 2018; 222. [PMID: 29047216 DOI: 10.1111/apha.12982] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 10/08/2017] [Accepted: 10/10/2017] [Indexed: 12/28/2022]
Abstract
AIM Uteroplacental insufficiency in rats reduces nephron endowment, leptin concentrations and programmes cardiorenal disease in offspring. Cross-fostering growth-restricted (Restricted) offspring onto a mother with normal lactation restores leptin concentrations and nephron endowment. This study aimed to determine whether the reduced nephron endowment in Restricted offspring is due to delayed glomerular formation and dysregulation of renal genes regulating branching morphogenesis, apoptosis or leptin signalling. Furthermore, we aimed to investigate whether cross-fostering Restricted offspring onto Control mothers could improve glomerular maturation and restore renal gene abundance. METHODS Uteroplacental insufficiency was induced by bilateral uterine vessel ligation (Restricted) or sham (Control) surgery on gestation day 18 (E18). Kidneys were collected at E20, postnatal day 1 (PN1) and PN7. An additional cohort was cross-fostered onto separate mothers at birth and kidneys collected at PN7. RESULTS Kidneys were lighter in the Restricted group, but weight was restored with cross-fostering. At E20, abundance of Bax, Flt1 and Vegfa was increased in Restricted offspring, while Ret and Bcl2 transcripts were increased only in Restricted females. At PN7, abundance of Gdnf and Ret was higher in Restricted offspring, as was Casp3. Restricted offspring had a wider nephrogenic zone with more immature glomeruli suggesting a delayed or extended nephrogenic period. Cross-fostering had subtle effects on gene abundance and glomerular maturity. CONCLUSION Uteroplacental insufficiency induced apoptosis in the developing kidney and delayed and extended nephrogenesis. Cross-fostering Restricted offspring onto Control mothers had beneficial effects on kidney growth and renal maturity, which may contribute to the restoration of nephron endowment.
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Affiliation(s)
- J. S. M. Cuffe
- School of Biomedical Sciences; The University of Queensland; St. Lucia Qld Australia
- School of Medical Science; Menzies Health Institute Queensland; Griffith University; Southport Qld Australia
| | - J. F. Briffa
- Department of Physiology; The University of Melbourne; Parkville Vic. Australia
| | - S. Rosser
- School of Biomedical Sciences; The University of Queensland; St. Lucia Qld Australia
| | - A. L. Siebel
- Department of Physiology; The University of Melbourne; Parkville Vic. Australia
| | - T. Romano
- Department of Physiology, Anatomy and Microbiology; La Trobe University; Bundoora Vic. Australia
| | - D. H. Hryciw
- Department of Physiology; The University of Melbourne; Parkville Vic. Australia
| | - M. E. Wlodek
- Department of Physiology; The University of Melbourne; Parkville Vic. Australia
| | - K. M. Moritz
- School of Biomedical Sciences; The University of Queensland; St. Lucia Qld Australia
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Asif Y, Wlodek ME, Black MJ, Russell AP, Soeding PF, Wadley GD. Sustained cardiac programming by short-term juvenile exercise training in male rats. J Physiol 2017; 596:163-180. [PMID: 29143975 DOI: 10.1113/jp275339] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 11/14/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cardiac hypertrophy following endurance-training is thought to be due to hypertrophy of existing cardiomyocytes. The benefits of endurance exercise on cardiac hypertrophy are generally thought to be short-lived and regress to sedentary levels within a few weeks of stopping endurance training. We have now established that cardiomyocyte hyperplasia also plays a considerable role in cardiac growth in response to just 4 weeks of endurance exercise in juvenile (5-9 weeks of age) rats. The effect of endurance exercise on cardiomyocyte hyperplasia diminishes with age and is lost by adulthood. We have also established that the effect of juvenile exercise on heart mass is sustained into adulthood. ABSTRACT The aim of this study was to investigate if endurance training during juvenile life 'reprogrammes' the heart and leads to sustained improvements in the structure, function, and morphology of the adult heart. Male Wistar Kyoto rats were exercise trained 5 days week-1 for 4 weeks in either juvenile (5-9 weeks of age), adolescent (11-15 weeks of age) or adult life (20-24 weeks of age). Juvenile exercise training, when compared to 24-week-old sedentary rats, led to sustained increases in left ventricle (LV) mass (+18%; P < 0.05), wall thickness (+11%; P < 0.05), the longitudinal area of binucleated cardiomyocytes (P < 0.05), cardiomyocyte number (+36%; P < 0.05), and doubled the proportion of mononucleated cardiomyocytes (P < 0.05), with a less pronounced effect of exercise during adolescent life. Adult exercise training also increased LV mass (+11%; P < 0.05), wall thickness (+6%; P < 0.05) and the longitudinal area of binucleated cardiomyocytes (P < 0.05), despite no change in cardiomyocyte number or the proportion of mono- and binucleated cardiomyocytes. Resting cardiac function, LV chamber dimensions and fibrosis levels were not altered by juvenile or adult exercise training. At 9 weeks of age, juvenile exercise significantly reduced the expression of microRNA-208b, which is a known regulator of cardiac growth, but this was not sustained to 24 weeks of age. In conclusion, juvenile exercise leads to physiological cardiac hypertrophy that is sustained into adulthood long after exercise training has ceased. Furthermore, this cardiac reprogramming is largely due to a 36% increase in cardiomyocyte number, which results in an additional 20 million cardiomyocytes in adulthood.
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Affiliation(s)
- Y Asif
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, 3125, Australia
| | - M E Wlodek
- Department of Physiology, The University of Melbourne, VIC, 3010, Australia
| | - M J Black
- Department of Anatomy & Developmental Biology, Monash University, Clayton, Melbourne, VIC, 3800, Australia
| | - A P Russell
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, 3125, Australia
| | - P F Soeding
- Department of Pharmacology, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - G D Wadley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, VIC, 3125, Australia.,Department of Physiology, The University of Melbourne, VIC, 3010, Australia
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Richter VFI, Briffa JF, Moritz KM, Wlodek ME, Hryciw DH. The role of maternal nutrition, metabolic function and the placenta in developmental programming of renal dysfunction. Clin Exp Pharmacol Physiol 2016; 43:135-41. [PMID: 26475203 DOI: 10.1111/1440-1681.12505] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 09/21/2015] [Accepted: 10/12/2015] [Indexed: 11/27/2022]
Abstract
The intrauterine environment is critical for the development of the foetus. Barker and colleagues were the first to identify that adverse perturbations during foetal development are associated with an increased risk of developing diseases in adulthood, including cardiorenal disease. Specifically for the kidney, perturbations in utero can lead to nephron deficits and renal dysfunction by a number of mechanisms. Altered programming of nephron number is associated with an increased risk of developing kidney disease via glomerular hypertrophy and reduced vasodilative capacity of the renal blood vessels; both of which would contribute to hypertension in adulthood, with males being more susceptible to disease outcomes. Additionally, alterations in the renin-angiotensin system (RAS) such as an upregulation or downregulation of specific receptors, depending on the nature of the insult, have also been implicated in the development of renal dysfunction. Sex-specific differences in the expression of the RAS during late gestation and in the early postnatal environment have also been identified. Extensive research has demonstrated that both uteroplacental insufficiency and maternal malnutrition alter renal development in utero. Equally, exposure to maternal diabetes and maternal obesity during development are also associated with an increased risk of developing renal disease, however, the mechanism behind this association is poorly understood. Therefore, identifying the link between an adverse intrauterine environment and the programmed kidney disease risk in adulthood may facilitate the development of strategies to alleviate the epidemics of cardiorenal disease worldwide, in addition to understanding why males are more susceptible to adult-onset cardiovascular diseases.
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Affiliation(s)
- V F I Richter
- Department of Physiology, The University of Melbourne, Parkville, Vic., Australia
| | - J F Briffa
- Department of Physiology, The University of Melbourne, Parkville, Vic., Australia
| | - K M Moritz
- School of Biomedical Sciences, University of Queensland, St. Lucia, Qld, Australia
| | - M E Wlodek
- Department of Physiology, The University of Melbourne, Parkville, Vic., Australia
| | - D H Hryciw
- Department of Physiology, The University of Melbourne, Parkville, Vic., Australia
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Menuet C, Wlodek ME, Fong AY, Allen AM. Respiratory modulation of sympathetic nerve activity is enhanced in male rat offspring following uteroplacental insufficiency. Respir Physiol Neurobiol 2015; 226:147-51. [PMID: 26593642 DOI: 10.1016/j.resp.2015.11.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 10/22/2015] [Accepted: 11/12/2015] [Indexed: 11/25/2022]
Abstract
Sympathetic nerve activity to the cardiovascular system displays prominent respiratory-related modulation which leads to the generation of rhythmic oscillations in blood pressure called Traube-Hering waves. An amplification of this respiratory modulation of sympathetic activity is observed in hypertension of both genetic, the spontaneously hypertensive rat, and induced, chronic intermittent hypoxia or maternal protein restriction during gestation, origin. Male offspring of mothers with uteroplacental insufficiency, induced by bilateral uterine vessel ligation at 18 days of gestation, are also hypertensive in adulthood. In this study we examined whether these male offspring display altered respiratory modulation of sympathetic activity at pre-hypertensive ages compared to controls. Respiratory, cardiovascular and sympathetic parameters were examined using the working heart-brainstem preparation in 35 day old male rats that had reduced birth weight due to uteroplacental insufficiency. Whilst all respiratory parameters were not different between groups, we observed an enhanced respiratory-related burst of thoracic sympathetic nerve activity and amplified Traube-Hering waves in the growth-restricted group. This group also showed an increased sympathetic and bradycardic response to activation of peripheral chemoreceptors. The observations add support to the view that altered respiratory modulation of sympathetic activity represents a common mechanism involved in the development of several forms of hypertension.
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Affiliation(s)
- C Menuet
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia.
| | - M E Wlodek
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
| | - A Y Fong
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
| | - A M Allen
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
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7
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Gårdebjer EM, Cuffe JSM, Pantaleon M, Wlodek ME, Moritz KM. Periconceptional alcohol consumption causes fetal growth restriction and increases glycogen accumulation in the late gestation rat placenta. Placenta 2013; 35:50-7. [PMID: 24239160 DOI: 10.1016/j.placenta.2013.10.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 10/18/2013] [Accepted: 10/18/2013] [Indexed: 12/14/2022]
Abstract
INTRODUCTION Alcohol consumption is a common social practice among women of childbearing age. With 50% of pregnancies being unplanned, many embryos are exposed to alcohol prior to pregnancy recognition and formation of the placenta. The effects of periconceptional (PC) alcohol exposure on the placenta are unknown. METHODS Sprague-Dawley rats were exposed to alcohol (12.5% v/v ad libitum) from 4 days prior to 4 days after conception and effects on placental growth, morphology and gene/protein expression examined at embryonic day (E) 20. RESULTS PC ethanol (EtOH)-exposed fetuses were growth restricted and their placental/body weight ratio and placental cross-sectional area were increased. This was associated with an increase in cross-sectional area of the junctional zone and glycogen cells, especially in PC EtOH-exposed placentas from female fetuses. Junctional Glut1 and Igf2 mRNA levels were increased. Labyrinth Igf1 mRNA levels were decreased in placentas from both sexes, but protein IGF1R levels were decreased in placentas from male fetuses only. Labyrinth mRNA levels of Slc38a2 were decreased and Vegfa were increased in placentas following PC EtOH-exposure but only placentas from female fetuses exhibited increased Kdr expression. Augmented expression of the protective enzyme 11βHsd2 was found in PC EtOH-exposed labyrinth. DISCUSSION These observations are consistent with a stress response, apparent well beyond the period of EtOH-exposure and demonstrate that PC EtOH alters placental development in a sex specific manner. CONCLUSION Public awareness should be increased to educate women about how excessive drinking even before falling pregnant may impact on placental development and fetal health.
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Affiliation(s)
- E M Gårdebjer
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - J S M Cuffe
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - M Pantaleon
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - M E Wlodek
- The Department of Physiology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - K M Moritz
- School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia.
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Crawford KE, Stevenson JL, Wlodek ME, Gude NM. No change in calreticulin with fetal growth restriction in human and rat pregnancies. Placenta 2013; 34:1066-71. [PMID: 23972286 DOI: 10.1016/j.placenta.2013.07.068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 07/24/2013] [Accepted: 07/29/2013] [Indexed: 01/25/2023]
Abstract
INTRODUCTION Calreticulin is a ubiquitously expressed protein that was detected in the circulation and is significantly increased in maternal blood during human pregnancy compared to the non-pregnant state. Calreticulin is further increased in the plasma of women with the pregnancy-related disorder pre-eclampsia compared to normotensive pregnancy. The aims of this study were to compare calreticulin in human pregnancy with calreticulin in rat pregnancy, and to compare calreticulin during fetal growth restriction with normal control pregnancies. METHODS Women were recruited who either had normal pregnancies or had pregnancies complicated with fetal growth restriction; maternal blood samples and placentas were collected. Blood was also taken from women who were not-pregnant. Growth restriction was induced in pregnant rats by uterine vessel ligation; blood and placental samples were collected. Blood was also taken from non-pregnant rats. Western blot was used to quantify the placental expression of calreticulin and the concentrations of calreticulin in plasma. RESULTS Although calreticulin was significantly increased in maternal plasma during human pregnancy compared to the non-pregnant state; it did not increase in plasma during rat pregnancy. These results suggest that there may be differences in the role of extracellular calreticulin in human compared to rat pregnancy. Calreticulin was not significantly altered in either placental extracts or maternal plasma in both the human and rat pregnancies complicated by fetal growth restriction compared to gestational matched control pregnancies. CONCLUSION This study found that there was no change in calreticulin during human pregnancy complicated with fetal growth restriction or when growth restriction is induced in rats.
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Affiliation(s)
- K E Crawford
- Department of Perinatal Medicine, Royal Women's Hospital, Parkville 3052, Victoria, Australia; Department of Obstetrics and Gynaecology, University of Melbourne, Parkville 3052, Victoria, Australia.
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Moritz KM, Cuffe JSM, Wilson LB, Dickinson H, Wlodek ME, Simmons DG, Denton KM. Review: Sex specific programming: a critical role for the renal renin-angiotensin system. Placenta 2010; 31 Suppl:S40-6. [PMID: 20116093 DOI: 10.1016/j.placenta.2010.01.006] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 01/06/2010] [Accepted: 01/06/2010] [Indexed: 12/21/2022]
Abstract
The "Developmental Origins of Health and Disease" hypothesis has caused resurgence of interest in understanding the factors regulating fetal development. A multitude of prenatal perturbations may contribute to the onset of diseases in adulthood including cardiovascular and renal diseases. Using animal models such as maternal glucocorticoid exposure, maternal calorie or protein restriction and uteroplacental insufficiency, studies have identified alterations in kidney development as being a common feature. The formation of a low nephron endowment may result in impaired renal function and in turn may contribute to disease. An interesting feature in many animal models of developmental programming is the disparity between males and females in the timing of onset and severity of disease outcomes. The same prenatal insult does not always affect males and females in the same way or to the same degree. Recently, our studies have focused on changes induced in the kidney of both the fetus and the offspring, following a perturbation during pregnancy. We have shown that changes in the renin-angiotensin system (RAS) occur in the kidney. The changes are often sex specific which may in part explain the observed sex differences in disease outcomes and severity. This review explores the evidence suggesting a critical role for the RAS in sex specific developmental programming of disease with particular reference to the immediate and long term changes in the local RAS within the kidney.
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Affiliation(s)
- K M Moritz
- School of Biomedical Sciences, The University of Queensland, St Lucia 4072, Australia.
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10
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Needham BE, Wlodek ME, Ciccotosto GD, Fam BC, Masters CL, Proietto J, Andrikopoulos S, Cappai R. Identification of the Alzheimer's disease amyloid precursor protein (APP) and its homologue APLP2 as essential modulators of glucose and insulin homeostasis and growth. J Pathol 2008; 215:155-63. [PMID: 18393365 DOI: 10.1002/path.2343] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The amyloid precursor protein (APP), the source of the neurotoxic amyloid beta (A beta) peptide involved in Alzheimer's disease (AD), belongs to a conserved family of related proteins. In mammals, the APP family contains amyloid precursor-like protein 1 (APLP1) and amyloid precursor-like protein 2 (APLP2). Whilst a number of activities have been attributed to the APP family, an overall function has not been definitively established. While ablating either the APP or APLP2 gene in mice produces minimal phenotypic change, the combined knockout of these genes in mice causes postnatal mortality. Postnatal survival therefore requires a shared but unknown function of APP and APLP2. To investigate the biochemical basis for the postnatal lethality, plasma was analysed from double knockout mice (APP-/- APLP2-/-) 2 days before birth, at gestational day E17, and from mice at 12-16 h after birth. The postnatal double knockouts had 66% lower plasma glucose levels than their wild-type controls and 50% lower than their single knockout counterparts. Interestingly, the postnatal double knockouts displayed hyperinsulinaemia, as shown by inappropriate plasma insulin levels, given their degree of hypoglycaemia. The single knockout mice also showed hyperinsulinaemia and had 31% lower plasma glucose than the wild-types. While the double knockouts did not survive more than 24 h after birth, the single knockouts reached adulthood and their hypoglycaemia continued. Therefore, APP and APLP2 expression modulates plasma insulin and glucose concentrations. Plasma calcium, magnesium and phosphate were also significantly reduced in the double knockouts compared to the wild-types, and they showed distinctive growth restriction, suggesting the involvement of a metabolic impairment. These results link the expression of the APP and APLP2 genes with glucose homeostasis and growth and therefore identify a novel function for the APP family.
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Affiliation(s)
- B E Needham
- Department of Pathology, The University of Melbourne, Victoria 3010, Australia
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11
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Vodstrcil LA, Novak J, Tare M, Wlodek ME, Parry LJ. 221. Localisation of relaxin receptors (Rxfp1) in the uterine artery and the effects of blocking circulating relaxin on passive mechanical wall properties in the uterine artery of late pregnant rats. Reprod Fertil Dev 2008. [DOI: 10.1071/srb08abs221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
During pregnancy, the uteroplacental circulation undergoes dramatic alterations to allow for the large increase in blood flow to the feto-placental unit. These alterations are achieved through several mechanisms including structural changes in the uterine artery wall and endothelium-dependent vasodilation. Small renal arteries of relaxin-deficient mice and rats have enhanced myogenic reactivity and decreased passive compliance, and are relatively vasoconstricted (Novak et al. 2001, 2006). To date, no study has identified relaxin receptors (Rxfp1) in arteries or investigated the effects of relaxin deficiency in pregnancy on uterine artery function. The aims of this current study were to: 1) localise Rxfp1 in the uterine arteries, 2) measure myogenic reactivity in small uterine arteries after relaxin treatment, and 3) test the hypothesis that blocking circulating relaxin in late pregnancy will increase uterine artery wall stiffness. We demonstrated that Rxfp1 is expressed in the uterine arteries of pregnant mice and rats. Brightfield immunohistochemistry and immunofluorescence using antibodies specific for rat Rxfp1, α-smooth muscle actin and CD31 localised Rxfp1 protein predominantly to the vascular smooth muscle in the uterine artery of pregnant rats. Administration of recombinant human H2 relaxin (4 ug/h) for 6 h or 5 days in intact and ovariectomised rats reduced myogenic reactivity of small uterine arteries in vitro. Pregnant rats were treated with a monoclonal antibody against circulating relaxin (MCA1) or control (MCAF) for 3 days (Days 17–19) and uterine arteries were mounted on a pressure myograph to assess passive mechanical wall properties. Neutralising circulating relaxin in late pregnancy resulted in a significant increase in uterine artery wall stiffness. These data demonstrate that relaxin acts on the vascular smooth muscle cells in the uterine artery and may be involved in the pregnancy-specific vascular remodelling of uterine arteries to increase vasodilation and blood flow to the uterus and placenta.
(1) Novak J et al. (2001). J Clin Invest 107: 1469–75
(2) Novak J et al. (2006). FASEB J 20: 2352–62
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Lappas M, Permezel M, Ho PW, Moseley JM, Wlodek ME, Rice GE. Effect of nuclear factor-kappa B inhibitors and peroxisome proliferator-activated receptor-gamma ligands on PTHrP release from human fetal membranes. Placenta 2004; 25:699-704. [PMID: 15450387 DOI: 10.1016/j.placenta.2004.02.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 02/06/2004] [Indexed: 11/16/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) has been implicated in many processes during normal and pathological pregnancies. In the human fetal membranes, PTHrP exhibits cytokine-like actions. We have recently shown that inhibitors of the nuclear factor-kappa B (NF-kappaB) and activators of the peroxisome proliferator-activated receptor (PPAR)-gamma signalling pathways down-regulate cytokine release from human gestational tissues. Therefore, the aim of this study was to determine whether NF-kappaB and PPAR-gamma also regulate PTHrP release from human fetal membranes. Human amnion and choriodecidua explants were incubated in the absence (control) or presence of two known NF-kappaB inhibitors (1, 5 and 10 mM sulphasalazine (SASP) or 5, 10 and 15 mM N-acetyl-cysteine (NAC)), and two PPAR-gamma ligands (15 and 30 microM 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) or 15 and 30 microM troglitazone), under basal conditions. After 18 h incubation, the tissues were collected and NF-kappaB p65 DNA binding activity in nuclear extracts was assessed by ELISA, and the incubation medium was collected and the release of PTHrP was quantified by RIA. Treatment of amnion and choriodecidual tissues with SASP concentrations greater than 5 mM, 15 mM NAC, 30 microM 15d-PGJ(2) and 30 microM troglitazone significantly reduced the release of PTHrP (p < 0.05). This study demonstrates that PTHrP release from human fetal membranes is regulated by inhibitors of NF-kappaB, and ligands of PPAR-gamma.
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Affiliation(s)
- M Lappas
- Department of Obstetrics and Gynaecology, The University of Melbourne and Mercy Perinatal Research Center, Mercy Hospital for Women, 126 Clarendon Street, East Melbourne, Victoria, Australia 3002.
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13
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de Gooyer TE, Skinner SL, Wlodek ME, Kelly DJ, Wilkinson-Berka JL. Angiotensin II influences ovarian follicle development in the transgenic (mRen-2)27 and Sprague-Dawley rat. J Endocrinol 2004; 180:311-24. [PMID: 14765984 DOI: 10.1677/joe.0.1800311] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
There is accumulating evidence that local renin-angiotensin systems (RASs) influence cell growth and organ function in a variety of tissues including the ovary. The first aim of this study was to characterise the cellular location of RAS components in the rat ovary. This was facilitated by the use of the hypertensive transgenic (mRen-2)27 rat which overexpresses renin and angiotensin in extra-renal tissues. Comparisons were made with normal Sprague-Dawley (SD) rats. The second aim was to determine if the upregulated RAS of the transgenic (mRen-2)27 rat and infusion of angiotensin II (ANG II) in SD rats influences follicle number and litter size. Gene expression, immunohistochemical and autoradiographic techniques were used to identify a discrete RAS including ANG II receptors in the ovarian stroma, follicles (particularly atretic) and to a lesser extent corpora lutea. The RAS at these sites was most abundant in homozygous (HMZ) followed by heterozygous (HTZ) (mRen-2)27 rats and then SD rats. Large antral and preovulatory follicles and litter size were reduced in (mRen-2)27 rats. In HMZ (mRen-2)27 rats and SD rats infused with ANG II, angiotensin 1a (AT(1a)) receptor mRNA in the ovarian stroma was lower than control SD rats and was associated with a reduction in large antral and preovulatory follicles. These findings indicate that upregulation of the ovarian RAS in the rat influences follicular development and, potentially, reproductive capacity.
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Affiliation(s)
- T E de Gooyer
- Department of Physiology, The University of Melbourne, Grattan Street, Parkville, Victoria 3010, Australia.
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14
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Wlodek ME, Di Nicolantonio R, Westcott KT, Farrugia W, Ho PWM, Moseley JM. PTH/PTHrP Receptor and Mid-molecule PTHrP Regulation of Intrauterine PTHrP: PTH/PTHrP Receptor Antagonism Increases SHR Fetal Weight. Placenta 2004; 25:53-61. [PMID: 15013639 DOI: 10.1016/j.placenta.2003.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Revised: 08/05/2003] [Accepted: 08/05/2003] [Indexed: 11/23/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) has important roles in fetal growth and development through stimulation of placental calcium transport, vasodilatation of the uteroplacental vasculature and regulation of cellular growth and differentiation. The growth restricted spontaneously hypertensive rat (SHR) has reduced fetal plasma, placental and amniotic fluid PTHrP concentrations compared to its progenitor, the Wistar Kyoto (WKY) rat. The aim of this study was to determine whether intrauterine PTHrP infusions can restore PTHrP levels and promote SHR fetal growth. PTHrP(1-34), midmolecule PTHrP(67-94), the PTH/PTHrP receptor antagonist [Asn(10), Leu(11)]-PTHrP(7-34) or vehicle were infused via a mini-osmotic pump between 10 and 20 days of gestation into the uterine lumen of SHR and WKY rats. Uterine, placental, amniotic fluid and plasma (fetal and maternal) PTHrP were measured via N-terminal radioimmunoassay. PTH/PTHrP receptor antagonism and mid-molecule PTHrP(67-94) induced endogenous intrauterine PTHrP production with receptor antagonism eliciting a greater and more wide spread effect. The PTH/PTHrP receptor antagonist [Asn(10), Leu(11)]-PTHrP(7-34) acting through a receptor other than the PTH/PTHrP receptor increased SHR fetal and placental weights above vehicle (P<0.05) to that of the WKY and restored SHR amniotic fluid volume (P<0.05). This was associated with a highly significant up regulation of placental, uterine and plasma (fetal and maternal) PTHrP (P<0.05). Modest increases in placental and uterine PTHrP (P<0.05) following intrauterine infusions of PTHrP(1-34) and PTHrP(67-94) had no effect on WKY and SHR fetal weight. Effective growth promoting actions of increased endogenous PTHrP were observed following PTH/PTHrP receptor antagonism rather than exogenous PTHrP administration. A novel finding was that mid-molecule PTHrP also up regulates endogenous intrauterine N-terminal PTHrP production supporting the existence of a mid-molecule receptor. This study highlights that an increase in endogenous uterine, placental and fetal plasma PTHrP following PTH/PTHrP receptor antagonism was associated with increased SHR fetal growth presumably by improving placental growth and function.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, The University of Melbourne, Grattan Street, Carlton,Victoria, Australia 3010.
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15
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Wlodek ME, Westcott KT, Serruto A, O'Dowd R, Wassef L, Ho PWM, Moseley JM. Impaired mammary function and parathyroid hormone-related protein during lactation in growth-restricted spontaneously hypertensive rats. J Endocrinol 2003; 178:233-45. [PMID: 12904171 DOI: 10.1677/joe.0.1780233] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Evidence implicates pivotal roles for parathyroid hormone-related protein (PTHrP) during lactation, including stimulation of mammary and pup growth. As spontaneously hypertensive rat (SHR) pups are growth restricted compared with the control Wistar Kyoto (WKY), we examined the relative roles of pup suckling and maternal lactational environment on pup growth, mammary PTHrP, and milk PTHrP and calcium concentrations. SHR pups were lighter compared with the control from 6 days. SHR mammary PTHrP content and milk PTHrP were lower but maternal plasma PTHrP was raised compared with WKY. SHR mammary morphological development was also impaired compared with control. Cross fostering growth-restricted pups onto WKY mothers increased pup weight in association with normal mammary function and higher milk PTHrP and calcium. Control pups suckling on an SHR mother had reduced body weight. Both cross fostering groups were associated with increased maternal and milk PTHrP concentrations, indicating the importance of suckling, together with a functional mammary gland. The results suggested that impaired SHR mammary function and milk PTHrP are associated with a reduced SHR postnatal growth. Our data also indicated that milk and mammary PTHrP are regulated by different mechanisms but that they are influenced by the maternal lactational environment and the suckling pup.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, University of Melbourne, Victoria 3010, Australia.
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16
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Wlodek ME, Koutsis K, Westcott KT, Ho PW, Di Nicolantonio R, Moseley JM. The spontaneously hypertensive rat fetus, not the mother, is responsible for the reduced amniotic fluid PTHrP concentrations and growth restriction. Placenta 2001; 22:646-51. [PMID: 11504533 DOI: 10.1053/plac.2001.0699] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Intrauterine parathyroid hormone-related protein (PTHrP) concentrations are reduced in association with growth restriction in the spontaneously hypertensive rat (SHR) compared to those of its normotensive control, the Wistar Kyoto (WKY) rat, implicating PTHrP as a pivotal fetal growth factor. The aim of this study was to examine, by embryo cross-transplanation between SHR and WKY, whether the mother, fetus, or both, are responsible for the suppressed SHR amniotic fluid PTHrP. One-day-old SHR embryos were gestated in either an SHR (SHR-in-SHR) or WKY (SHR-in-WKY) surrogate, similarly one-day-old WKY embryos were gestated in either an SHR (WKY-in-SHR) or WKY (WKY-in-WKY) mother. At 20 days gestation, maternal plasma and amniotic fluid samples were collected and assayed for PTHrP concentrations. Data were analysed by two-way ANOVA (mean+/-sem, n=5-9 mothers/group). There were no differences in litter number or maternal plasma PTHrP concentrations. Fetal weight (P< 0.009), fetal/placental weight ratio (P< 0.004) and amniotic fluid PTHrP concentrations (P< 0.001) were lower and amniotic fluid volume (P< 0.0001) was higher with an SHR fetus compared to the WKY fetus irrespective of maternal strain. Thus, the SHR fetus is growth restricted and has suppressed amniotic fluid PTHrP, which are largely determined by the fetus or gestational tissues and are independent of maternal hypertension or maternal PTHrP. We suggest that the low SHR amniotic fluid PTHrP may play a role in the development of SHR growth restriction.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, The University of Melbourne, Victoria, 3010, Australia.
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Curtis NE, King RG, Moseley JM, Ho PW, Rice GE, Wlodek ME. Preterm fetal growth restriction is associated with increased parathyroid hormone-related protein expression in the fetal membranes. Am J Obstet Gynecol 2000; 183:700-5. [PMID: 10992196 DOI: 10.1067/mob.2000.106593] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE Parathyroid hormone-related protein has roles in normal fetal growth, placental calcium transport, and vascular tone regulation; these factors are compromised in growth-restricted fetuses. Our objective was to determine whether intrauterine parathyroid hormone-related protein expression was increased in association with fetal growth restriction. STUDY DESIGN The expression of parathyroid hormone-related protein was examined in intrauterine tissues from women with idiopathic fetal growth restriction with preterm (n = 8-10) and term (n = 8-10) gestations and from gestation-matched control subjects. The abundance and immunoreactive content of parathyroid hormone-related protein messenger ribonucleic acid were determined by Northern blot and radioimmunoassay, respectively, in the placenta, amnion, and chorion-decidua. RESULTS The expression of parathyroid hormone-related protein messenger ribonucleic acid was increased in the amnion (placental and reflected) in association with preterm fetal growth restriction (P <.05). Both parathyroid hormone-related protein messenger ribonucleic acid and protein expression were increased in chorion-decidua in association with preterm fetal growth restriction (P <.05). In term gestations both parathyroid hormone-related protein messenger ribonucleic acid and protein expression were greater in amnion over placenta than in reflected amnion (P <.05); these in turn were greater than those in chorion-decidua (P <.05). No significant changes were detected in parathyroid hormone-related protein messenger ribonucleic acid or in protein expression in association with term fetal growth restriction. CONCLUSION Either parathyroid hormone-related protein messenger ribonucleic acid or protein expression, or both, was increased in the fetal membranes in association with fetal growth restriction in preterm but not term gestations, suggesting that parathyroid hormone-related protein may be involved in the pathogenesis of preterm fetal growth restriction.
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Affiliation(s)
- N E Curtis
- Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Australia
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Farrugia W, de Gooyer T, Rice GE, Moseley JM, Wlodek ME. Parathyroid hormone(1-34) and parathyroid hormone-related protein(1-34) stimulate calcium release from human syncytiotrophoblast basal membranes via a common receptor. J Endocrinol 2000; 166:689-95. [PMID: 10974662 DOI: 10.1677/joe.0.1660689] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The placental syncytiotrophoblast is the site for mineral and nutrient exchange across the maternal-fetal interface. It has been proposed that parathyroid hormone-related protein (PTHrP) is a key factor in the maintenance of a maternal-fetal calcium gradient. Using simultaneously prepared microvillous (maternal facing) and basal (fetal facing) syncytiotrophoblast membranes from term human placentae (n=8), we determined the relative contribution of PTH(1-34), PTHrP(1-34) and PTHrP(67-94) to the regulation of syncytiotrophoblast calcium efflux. The vesicles had correct right-side-out membrane orientation and specific markers validated the fractionation of microvillous and basal membrane vesicles. Calcium efflux was studied by preloading vesicles with calcium-45 in the presence of calcium and magnesium and then incubating the vesicles at 37 degrees C for 15 min with the peptides. In basal membranes, PTHrP(1-! 34) significantly stimulated calcium efflux at a dose of 12.5 nmol/l, whereas PTH(1-34)-stimulated efflux was significant at 50 nmol/l (P<0.05, ANOVA). This efflux was significantly reduced in the presence of the PTH/PTHrP receptor antagonist (PTHrP(7-34)). Midmolecule PTHrP(67-94) had no significant effect on basal membrane calcium efflux. PTH(1-34), PTHrP(1-34) or PTHrP(67-94) had no significant effects on MVM calcium efflux. This study, using the human syncytiotrophoblast in vitro membrane system, demonstrated that PTHrP(1-34) and PTH(1-34) stimulate calcium transport across the basal, but not microvillous, syncytiotrophoblast membrane vesicles, mediated via the PTH/PTHrP receptor.
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Affiliation(s)
- W Farrugia
- Department of Physiology, University of Melbourne, Victoria 3010, Australia
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19
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Abstract
1. Epidemiological studies indicate that a reduced birthweight increases the likelihood of human cardiovascular disease later in life. The role of hormonal factors in this finding is not known. Given that angiotensin II is believed to be a fetal regulator of growth, we have examined in the hypertensive Ren-2 transgenic rat whether it has active renin in its amniotic fluid and whether this is associated with fetal underdevelopment. 2. We found that while the Sprague-Dawley rat contained no active renin in its amniotic fluid near term (20 days), Ren-2 amniotic fluid contains high levels of active renin and is associated with a reduced fetal weight. 3. This is the first report of active renin in the rat and allows the possibility that renin overproduction plays a role in reduced fetal growth and the prenatal 'programming' of essential hypertension that has been proposed to occur in humans.
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Affiliation(s)
- A Caragounis
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia
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20
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Wlodek ME, Westcott KT, Ho PW, Serruto A, Di Nicolantonio R, Farrugia W, Moseley JM. Reduced fetal, placental, and amniotic fluid PTHrP in the growth-restricted spontaneously hypertensive rat. Am J Physiol Regul Integr Comp Physiol 2000; 279:R31-8. [PMID: 10896861 DOI: 10.1152/ajpregu.2000.279.1.r31] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Evidence implicates pivotal roles for parathyroid hormone-related protein (PTHrP) in stimulating cell growth and differentiation, placental calcium transport, and placental vasodilatation. As spontaneously hypertensive rat (SHR) fetuses are growth restricted compared with those of its normotensive control, the Wistar Kyoto (WKY) rat, we examined intrauterine PTHrP and total and ionic calcium concentrations in these rats. Fetal plasma PTHrP concentrations, but not total calcium concentrations, were lower in the SHR compared with WKY (P < 0.05). SHR placental concentrations of PTHrP were lower than in WKY (P < 0.03) and failed to show the increase observed in WKY near term (P < 0.05). PTHrP concentrations in amniotic fluid from SHR were not raised near term and were lower compared with WKY (P < 0.0005). The increased ionic calcium concentrations in amniotic fluid in the WKY near term (P < 0.05) were not detected in the SHR. Thus SHR fetal plasma, placental, and amniotic fluid PTHrP concentrations were reduced and associated with fetal growth restriction. We suggest that PTHrP may play a role in the etiology of both growth restriction during pregnancy and hypertension later in life.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia 3065.
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21
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Farrugia W, Ho PW, Rice GE, Moseley JM, Permezel M, Wlodek ME. Parathyroid hormone-related protein(1-34) in gestational fluids and release from human gestational tissues. J Endocrinol 2000; 165:657-62. [PMID: 10828849 DOI: 10.1677/joe.0.1650657] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) is present in fetal and gestational tissues, in which its proposed roles include stimulation of epithelial growth and differentiation, vasodilatation of the uteroplacental vasculature, relaxation of uterine muscle and stimulation of placental calcium transport. The aim of this study was to determine whether the release of PTHrP from gestational tissue explants was tissue specific. In addition, PTHrP concentrations were measured in maternal plasma, umbilical artery and vein plasma, and amniotic fluid from term, uncomplicated pregnancies before the onset of labour. PTHrP was detected in low concentrations in the mother, fetus and placental tissue. Amniotic fluid had ten times the PTHrP concentration compared with that in the maternal or fetal circulations. Using late pregnant human gestational tissues in an in vitro explant system, we found that amnion over placenta, choriodecidua, reflected amnion, and placenta released PTHrP into culture medium in progressively greater amounts over 24 h (P<0.05). This release was not associated with a loss of cell membrane integrity, as indicated by measurement of the intracellular enzyme, lactate dehydrogenase, in the incubation media. After 24 h incubation, the fetal membranes released significantly (P<0.05) greater amounts of PTHrP than did the placenta (placenta 3. 7+/-0.5 pmol PTHrP/g protein). Amnion over placenta released significantly more PTHrP (139.3+/- 43.1 pmol PTHrP/g protein) than did reflected amnion (29.0+/-8.3 pmol PTHrP/g protein) (P<0.05). This study unequivocally demonstrated that human gestational tissues release PTHrP and it was concluded that the main contributors to PTHrP in amniotic fluid were the human fetal membranes, particularly amnion over placenta. Fetal membrane-derived and amniotic fluid PTHrP are proposed to have stimulatory effects on epithelial growth and differentiation in fetal lung, gut, skin and hair follicles and paracrine effects on placental vascular tone and calcium transport.
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Affiliation(s)
- W Farrugia
- Department of Physiology, The University of Melbourne, Victoria 3010, Australia
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22
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Abstract
OBJECTIVE Epidemiological studies indicate that a reduced birth weight and enlarged placenta increase the likelihood of human cardiovascular disease later in life. The relative importance of fetal versus maternal factors in these phenomena is not known. To assess the relative role of genotypic versus environmental factors in this effect, we examined whether the altered fetal and placental growth rates and amniotic fluid volume of spontaneously hypertensive rat (SHR) fetuses of the Okamoto strain, are modified by gestation in normotensive Wistar- Kyoto (WKY) rat mothers and vice versa. DESIGN One-day-old SHR embryos were gestated for 16 days in either SHR or WKY recipients. Similarly, 1-day-old WKY rat embryos were gestated for 16 days in either SHR or WKY surrogates. At 16 days, fetal and placental weights were recorded. Paternal and maternal donor and recipient blood pressures, maternal body weight and average litter size within the four groups were also studied. METHODS One cell SHR and WKY embryos were harvested from timed matings and transferred to psuedopregnant mothers of the same or opposite strain. Timed matings required routine vaginal smears for the detection of proestrus and the presence of sperm following overnight matings. Harvested embryos were temporarily maintained in culture medium in a 37 degrees C incubator until injection into the oviduct of recipients. Blood pressures were meaured using indirect tail-cuff plethysmography and a computerized data acquisition system. RESULTS SHR fetal and placental weights at 16 days gestation were significantly lower than WKY fetal and placental weights, irrespective of maternal strain. At 16 days of gestation, the fetal and placental weights of SHR fetuses gestated in WKY rat surrogate mothers (0.21 +/- 0.01 g and 0.19 +/- 0.01 g, respectively) were not significantly different from those of SHR gestated in a surrogate SHR mother (0.21 +/- 0.01 g and 0.18 +/- 0.01 g, respectively). Similarly, the fetal and placental weights of WKY fetuses gestated in a WKY rat (0.27 +/- 0.01 g and 0.25 +/- 0.01 g, respectively) were unaltered by gestation in a SHR recipient (0.25 +/- 0.01 g and 0.23 +/- 0.01 g, respectively). The amniotic fluid volumes of SHR gestated in WKY rats and those of WKY fetuses gestated in SHR were not significantly different to each other (0.37 +/- 0.01 ml versus 0.38 +/- 0.01 ml, respectively) and were intermediate between the values for SHR and WKY fetuses gestated in a mother of the same strain (0.34 +/- 0.01 ml versus 0.44 +/- 0.02 ml, respectively). CONCLUSION The SHR fetus exhibited reduced growth rate and placental size irrespective of maternal surrogate strain, suggesting that these measures are likely to be determined by the fetus or the placenta and, presumably, are independent of maternal blood pressure or altered electrolyte and hormonal milieu.
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Affiliation(s)
- R Di Nicolantonio
- Department of Physiology, University of Melbourne, Parkville, Victoria, Australia.
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Abstract
OBJECTIVE The present study aimed to determine whether there were alterations in intestinal calcium homeostasis in the spontaneously hypertensive rats (SHR) and to identify at which interface of the intestinal epithelial cell (brush border or basolateral) this occurs. DESIGN Controversy exists as to whether intestinal calcium transport is altered in association with hypertension. Studies using perfused duodenal segments of the SHR have shed little light on the problem; other studies have only measured calcium transport in brush border membrane vesicles. This study allows specific focus on calcium transport mechanisms at both the brush border and basolateral membrane using simultaneously prepared membrane vesicles. METHODS Calcium transport was studied by measuring radiolabelled calcium (45Ca) uptake in isolated brush border and basolateral membrane vesicles, prepared from the small intestines of SHR and Wistar-Kyoto (WKY) rats. Calcium uptake was measured when vesicles were incubated in solutions containing different concentrations of ATP and calcium. Orientation and membrane marker assays were used to confirm the phenotypes of the two membrane vesicle preparations. RESULTS ATP-dependent calcium efflux was only observed in the basolateral membrane, which contains the Ca2+ -ATPase pump. SHR brush border membrane vesicles displayed no significant increase in calcium incorporation, whereas WKY brush border vesicles showed a 500% increase in uptake (ANOVA, P<0.05, n = 7). CONCLUSIONS This study indicates that deficiencies exist in SHR intestinal calcium transport at the brush border membrane of intestinal epithelial cells. While further studies are required to ascertain the exact mechanisms involved, postulated deficiencies in the actions of calcium regulating hormones at this membrane suggest the need for concurrent intake of a calcitrophic agent to assist calcium uptake at the brush border membrane.
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Affiliation(s)
- T E de Gooyer
- Department of Physiology, The University of Melbourne, Parkville, Australia
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Abstract
Maternal hypertension, vasoconstriction and placental insufficiency are features of pre-eclampsia. Alterations in calcium homeostasis and in the production of calciotropic hormones and vasoactive agents have also been described in association with pre-eclampsia. Parathyroid hormone-related protein (PTHrP) is abundantly expressed in intrauterine tissues during normal pregnancy and has roles in fetal growth and calcium homeostasis, placental calcium transport and vascular tone regulation. Intrauterine PTHrP mRNA expression and tissue PTHrP content were determined by Northern blot analysis and radio-immunoassay, respectively, in preterm and term pre-eclamptic women. PTHrP mRNA expression and PTHrP content in placenta, amnion over placenta, reflected amnion and choriodecidua from preterm pre-eclamptic women (n=8-10) were not different from preterm controls (n= 10-12). PTHrP mRNA expression and content in amnion over placenta and reflected amnion were significantly greater in term compared to preterm pre-eclamptics (P<0.05). PTHrP mRNA expression was significantly lower in choriodecidua from term pre-eclamptic women (n=8) compared to term controls (n=28, P<0.05), but was not different in placenta or amnion. PTHrP content was not altered in term pre-eclamptic women (n=8) compared to controls (n=25) for any tissue. In summary, PTHrP expression in placenta and amnion was not increased in pre-eclamptic women in association with maternal hypertension, placental insufficiency and vasoconstriction. PTHrP mRNA expression was decreased in choriodecidua in association with term but not preterm pre-eclampsia, however, levels of the protein were not decreased. The data suggest that PTHrP is not involved in the placental pathophysiology of pre-eclampsia in late gestation.
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Affiliation(s)
- N E Curtis
- Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Victoria, Australia
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Wlodek ME, Hooper SB, Thorburn GD, Tester ML, Harding R. Effects of prostaglandin E2 on renal function and lung liquid dynamics in foetal sheep. Clin Exp Pharmacol Physiol 1998; 25:805-12. [PMID: 9784920 DOI: 10.1111/j.1440-1681.1998.tb02157.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. The aim of the present study was to determine the effects of prolonged prostaglandin E2 (PGE2) administration on the function of the foetal kidneys and lungs in order to gain a greater understanding of the role played by PGE2 in the control of foetal fluid balance. By studying the effects of PGE2 at two gestational ages, we have also been able to examine the influence of age. 2. We studied the effects of 26 h PGE2 infusion on foetal sheep at a mean (+/- SEM) of 120.0 +/- 0.6 (n = 6) and 139.0 +/- 0.8 (n = 4) days of gestation. In both groups, foetal urine production was significantly inhibited throughout the infusion period (P < 0.05). In younger, but not older foetuses, urine production returned to control values within 24 h of ending the infusion (P < 0.05). This PGE2-induced anti-diuresis was associated with foetal hypoxaemia and acidaemia, a reduction in free water clearance and an increase in foetal plasma arginine vasopressin concentrations (P < 0.05). 3. During PGE2 infusions, foetal breathing movements were inhibited, the effect being greater and more sustained in older foetuses (P < 0.05). 4. Infusions of PGE2 led to increased lung liquid production at both ages (P < 0.05); lung liquid volumes were reduced in older foetuses (P < 0.05), but were unchanged in younger foetuses. The reduction in lung liquid volume in older foetuses may have been due to inhibition of foetal breathing. 5. We conclude that increased circulating levels of PGE2 have profound effects on foetal renal and lung function which, if sustained, could compromise foetal lung development and perinatal well-being.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Clayton, Victoria, Australia.
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Curtis NE, Thomas RJ, Gillespie MT, King RG, Rice GE, Wlodek ME. Parathyroid hormone-related protein (PTHrP) mRNA splicing and parathyroid hormone/PTHrP receptor mRNA expression in human placenta and fetal membranes. J Mol Endocrinol 1998; 21:225-34. [PMID: 9801466 DOI: 10.1677/jme.0.0210225] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
During human pregnancy, parathyroid hormone-related protein (PTHrP) and parathyroid hormone (PTH)/PTHrP receptor are produced by the uterus, placenta, fetal membranes (amnion and chorion) and developing fetus. PTHrP alternative 3' mRNA splicing results in transcripts which encode three PTHrP isoforms and have been identified in amnion. Uteroplacental PTHrP expression is greatest in amnion and increases dramatically during late pregnancy. The aims of this study were to determine PTH/PTHrP receptor mRNA expression at preterm and term gestations and to determine 3' alternative splicing patterns in placenta, amnion and choriodecidua at preterm and term gestations. Using semiquantitative reverse transcription-polymerase chain reaction, PTHrP and PTH/PTHrP receptor transcripts were identified in preterm (n=5) and term (n=7) gestational tissues. PTH/PTHrP receptor mRNA expression did not differ between tissue types or change with advancing gestation. In contrast, PTHrP expression in the same tissues increased with advancing gestation and was significantly greater in amnion than in placenta and choriodecidua. Thus PTHrP, although produced predominantly in amnion, may act in amnion and other tissues including placenta, choriodecidua and myometrium. In amnion over placenta, transcripts encoding PTHrP 1-139 and 1-173 were detected in some preterm and all term samples and those encoding PTHrP 1-141 were detected in all samples. Similar results were obtained for reflected amnion. In placenta and choriodecidua, PTHrP 1-139 and 1-173 transcripts were undetectable or of low abundance. PTHrP 1-141 transcripts were detected in some placenta and choriodecidua samples. In summary, transcripts encoding PTHrP 1-141 appeared to be more abundantly expressed than those encoding PTHrP 1-139 or 1-173. However, the up-regulation of PTHrP expression in amnion at term may involve each of the alternative 3' mRNA splicing pathways since transcripts for each isoform appeared to be more consistently expressed at term.
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Affiliation(s)
- N E Curtis
- Perinatal Research Centre, Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Victoria, Australia
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Abstract
The aim of this study was to examine the vasodilatory effects of parathyroid hormone-related protein (PTHrP) (1-34) and parathyroid hormone (PTH) (1-34) on the human fetal-placental circulation utilising an in vitro placental perfusion model. In all experiments, the vasculature of an isolated human placental cotyledon was pre-constricted with the thromboxane A2 mimetic U46619. A simple dose of PTHrP (1-34) or PTH (1-34) (1.7-300 nM) was then infused into the fetal-placental circulation of the cotyledon. In other experiments, cotyledons were repeatedly infused with PTHrP (1-34) or PTH (1-34) (51.3 nM). Vasodilatory responses were significantly reduced in response to repeated exposure to PTHrP (1-34) (P < 0.001), indicating that this peptide desensitizes the fetal-placental vasculature. PTHrP (1-34) and PTH (1-34) equipotently stimulated a significant vasodilation of the fetal-placental circulation (P < 0.0001). The PTHrP receptor antagonist [Asn10, Leu 11]PTHrP (7-34) (102 nM) was infused in U46619-constricted placentae in the presence and absence of PTHrP (1-34) (10.2 nM). The PTHrP antagonist alone had no significant effect in the fetal-placental circulation. The antagonist significantly attenuated the response to PTHrP (1-34) (P < 0.015). Based on the data obtained in this study it is suggested that locally produced PTHrP (1-34) may be involved in the regulation of normal human fetal-placental vascular tone in autocrine and/or paracrine fashion.
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Affiliation(s)
- K Macgill
- Department of Perinatal Medicine, Royal Women's Institute of Medical Research, Fitzroy, Victoria, Australia
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28
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Miller S, Wongprasartsuk S, Young IR, Wlodek ME, McFarlane JR, de Kretser DM, Jenkin G. Source of inhibin in ovine fetal plasma and amniotic fluid during late gestation: half-life of fetal inhibin. Biol Reprod 1997; 57:347-53. [PMID: 9241049 DOI: 10.1095/biolreprod57.2.347] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Immunoactive inhibin (ir-inhibin) concentrations were determined in chronically catheterized sheep between 120 and 145 days gestation. Maternal plasma ir-inhibin concentrations remained basal (0.19 +/- 0.05 ng/ml) throughout the period of study. Immunoactive inhibin concentrations in male and female fetal plasma were elevated above those observed in maternal plasma, with the concentrations in plasma of male fetuses (7.38 +/- 0.04 ng/ml) being significantly greater (p < 0.001) than those in female fetuses (1.07 +/- 0.14 ng/ml). The concentrations of ir-inhibin in amniotic fluid of ewes bearing male fetuses (10.93 +/- 1.55 ng/ml) were significantly greater than in ewes bearing female fetuses (2.81 +/- 0.32 ng/ml; p < 0.05) but not significantly different from the concentrations in male fetal plasma. Immunoactive inhibin concentrations decreased following surgery in gonadectomized fetuses, to 3.25 +/- 0.99 ng/ml within 6 h, and remained at a mean value of 0.75 +/- 0.38 ng/ml from 24 h after gonadectomy. The half-life of circulating inhibin in fetal plasma, estimated from the decay curve during the first 6 h after surgery, was 3.94 +/- 0.88 h. There was a significant (p < 0.05) decrease in the concentration of ir-inhibin in amniotic fluid after gonadectomy; however, this decrease occurred gradually over 7 days, and ir-inhibin concentrations did not fall to those concentrations observed in fetal circulation at any time after gonadectomy. It is concluded that the major source of circulating ir-inhibin in male fetal plasma, but not in amniotic fluid, is the gonads.
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Affiliation(s)
- S Miller
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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29
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Curtis NE, Ho PW, King RG, Farrugia W, Moses EK, Gillespie MT, Moseley JM, Rice GE, Wlodek ME. The expression of parathyroid hormone-related protein mRNA and immunoreactive protein in human amnion and choriodecidua is increased at term compared with preterm gestation. J Endocrinol 1997; 154:103-12. [PMID: 9246943 DOI: 10.1677/joe.0.1540103] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Parathyroid hormone-related protein (PTHrP) gene expression and/or immunoreactive protein have previously been identified in the uterus and intrauterine gestational tissues. The putative roles of PTHrP during pregnancy include vasodilatation, regulation of placental calcium transfer, uterine smooth muscle relaxation and normal fetal development. The aims of this study were 1) to determine the tissue-specific and temporal expression of PTHrP mRNA and immunoreactive protein in human gestational tissues collected at preterm and term; and 2) to determine the effect of labour on PTHrP expression by collecting these tissues from women undergoing elective caesarean section (before labour), intra-partum caesarean section during spontaneous-onset labour (during labour), and women with spontaneous labour and normal vaginal delivery (after labour). Total RNA and protein were extracted from placenta, amnion (over placenta and reflected) and choriodecidua for analysis by Northern blot (using a specific human PTHrP cDNA probe), and by N-terminal PTHrP RIA respectively. In amnion over placenta, reflected amnion and choriodecidua both PTHrP mRNA relative abundance and immunoreactive protein were significantly elevated at term compared with preterm (P < 0.01). At term, both PTHrP and its mRNA were significantly greater in amnion than in placenta and choriodecidua (P < 0.05). Also, both PTHrP and its mRNA were significantly elevated in amnion over placenta compared with reflected amnion (P < 0.05). The expression of PTHrP and its mRNA did not change in association with term labour or rupture of the fetal membranes, therefore this study provides no evidence for a specific PTHrP role in the onset and/or maintenance of term labour. However, the significant up-regulation of PTHrP mRNA and protein in the fetal membranes at term compared with preterm suggests an important role in late human pregnancy.
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Affiliation(s)
- N E Curtis
- Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Victoria, Australia
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Abstract
OBJECTIVE Our purpose was to determine the effects of prolonged hypoxemia on fetal renal function and amniotic fluid volume and composition. STUDY DESIGN Twelve pregnant ewes underwent surgery at 115 +/- 2 days after mating (term approximately 147 days) for the implantation of fetal vascular, bladder, and amniotic sac catheters. At 125 +/- 1 days seven fetuses were studied during 6 days of hypoxemia and five control fetuses were studied over six days of normoxemia. Index values of fetal renal function and amniotic fluid volume were measured. RESULTS During hypoxemia fetal SaO2 and PaO2 were reduced from 60.9% +/- 1.6% and 21.9 +/- 0.6 mm Hg to 29.6% +/- 3.8% and 14.9 +/- 0.8 mm Hg, respectively. Fetal hypoxemia was associated with a transient acidemia (arterial pH 7.29 +/- 0.02) at 4 hours. There were no sustained alterations in fetal urine production (9.5 +/- 0.8 ml/hr/kg) or glomerular filtration rate (1.3 +/- 0.1 ml/min/kg) during hypoxemia. In control fetuses the amniotic fluid volume increased over 7 days, from 717 +/- 169 ml to 1031 +/- 147 ml, whereas in the hypoxemic fetuses it did not change (741 +/- 68 ml) over the same period. CONCLUSION During prolonged fetal hypoxemia in the absence of acidemia, fetal urine production is maintained, whereas the normal gestational increase in amniotic fluid volume is prevented, raising the possibility that intramembranous reabsorption of amniotic fluid is increased by hypoxemia.
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Affiliation(s)
- M L Cock
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
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Cock ML, Wlodek ME, McCrabb GJ, Harding R. Alterations in fetal urine production during prolonged hypoxaemia induced by reduced uterine blood flow in sheep: mechanisms. Clin Exp Pharmacol Physiol 1996; 23:57-63. [PMID: 8713497 DOI: 10.1111/j.1440-1681.1996.tb03062.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
1. Our aim was to identify mechanisms whereby prolonged fetal hypoxaemia alters renal function and urine production in fetal sheep. 2. Fetal hypoxaemia was induced for 24 h by reducing uterine blood flow at 129.0 +/- 2.1 days of gestation (term 145-147 days), causing a reduction in fetal arterial O2 saturation (SaO2) from 52.5 +/- 2.3 to 22.0 +/- 1.3% (P < 0.05). This hypoxaemia was initially associated with a mild acidaemia (pH 7.23 +/- 0.03). 3. The glomerular filtration rate (GFR) increased from a control value of 1.8 +/- 0.3 mL/min per kg to a maximal value of 2.8 +/- 0.6 mL/min per kg (P < 0.05) at 4-5 h of hypoxaemia, returning to control levels by 6-9 h of hypoxaemia. After 4 h of hypoxaemia renal blood flow was no different to control values (144 +/- 8 mL/min per 100 g kidney weight) but after 24 h of hypoxaemia it had increased to 190 +/- 8 mL/min per 100 g kidney weight (P < 0.05). Fractional reabsorption of Na+ in the proximal tubules decreased from a control value of 81.5 +/- 2.2 to 65.2 +/- 3.9% at 2-3 h of hypoxaemia (P < 0.05) and remained reduced (68.5 +/- 3.1%) at the end of hypoxaemia (P < 0.05). Fetal mean arterial pressure transiently increased (P < 0.05) but returned to control values by 4-5 h of hypoxaemia. Fetal renal vascular resistance was not significantly altered during hypoxaemia. Fetal urine production increased from a control value of 12.3 +/- 2.1 mL/h per kg to a maximal value of 19.1 +/- 4.2 mL/h per kg at 4-5 h of hypoxaemia (P < 0.05) and returned to control by 24 h of hypoxaemia. 4. Our results indicated that prolonged fetal hypoxaemia leads to the inhibition of Na+ reabsorption in the proximal portion of the renal tubules. Changes in GFR induced by hypoxaemia were similar to those in fetal urine production and were not associated with changes in renal blood flow. We conclude that prolonged fetal hypoxaemia affects renal haemodynamics and the reabsorptive capacity of the renal tubules, resulting in a diuresis.
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Affiliation(s)
- M L Cock
- Fetal and Neonatal Research Unit, Department of Physiology, Monash University, Victoria, Australia
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Xiao Q, Challis JR, Fraser M, Wlodek ME, Thorburn GD, Cuttita F, Hill DJ, St-Pierre S, Spindel ER, McDonald TJ. Locations and molecular forms of gastrin-releasing peptide-like immunoreactive entities in ovine pregnancy. Peptides 1996; 17:489-95. [PMID: 8735977 DOI: 10.1016/0196-9781(96)00003-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Large quantities of gastrin-releasing peptide-like immunoreactivity (GRP-LI) are present in ovine pregnancy fluids (allantoic fluid > fetal plasma > esophageal fluid = amniotic fluid = urine > maternal plasma) and in term endometrium (60 +/- 29 pmol.g-1) and myometrium (4.5 +/- 1.2 pmol.g-1). The larger molecular size [greater than GRP (1-27)] of this GRP-LI entity is not due to a GRP binding protein nor to a C-terminal extension of GRP. In contrast, ovine fetal colon extracts appear to contain the usual GRP (1-27) and GRP (18-27) forms. Hence, the uterus, not the fetus, is the probable source of this novel GRP-like peptide. It apparently acts as a hormone in ovine pregnancy and may play an important role in fetal-placental development.
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Affiliation(s)
- Q Xiao
- Department of Medicine, University of Western Ontario, London, Canada
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33
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Wlodek ME, Brace RA, Cock ML, Hooper SB, Harding R. Endocrine responses of fetal sheep to prolonged hypoxemia with and without acidemia: relation to urine production. Am J Physiol 1995; 268:F868-75. [PMID: 7771516 DOI: 10.1152/ajprenal.1995.268.5.f868] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Our aim was to examine the endocrine changes associated with alterations in fetal urine production during 24 h of hypoxemia induced by either reduced uterine blood flow (RUBF) or maternal N2 inhalation (N2). In contrast to RUBF, which caused a diuresis, N2 caused a transient antidiuresis; during both posthypoxemia periods (RUBF and N2), fetal urine production was increased. RUBF, but not N2, was associated with a transient acidemia. Fetal plasma arginine vasopressin (AVP) and atrial natriuretic factor (ANF) concentrations increased during RUBF and were inversely correlated to pH; there were no detectable AVP or ANF responses to N2. Fetal prostaglandin E2 (PGE2) increased during the hypoxemia and posthypoxemia periods induced by both methods, but RUBF caused the greater increase. AVP and PGE2 concentrations were positively correlated with urine production. Fetal arterial blood pressure increased during RUBF but not N2. During RUBF, the increases in AVP and PGE2 concentrations and/or fetal arterial blood pressure may have contributed to the diuresis. During N2, we suggest that low, but increased, levels of AVP may have caused the transient antidiuresis, whereas the diuresis observed during both posthypoxemia periods may have been mediated by elevated PGE2 concentrations and/or increased fetal arterial blood pressure.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Wlodek ME, Ho PW, Rice GE, Moseley JM, Martin TJ, Brennecke SP. Parathyroid hormone-related protein (PTHrP) concentrations in human amniotic fluid during gestation and at the time of labour. Reprod Fertil Dev 1995; 7:1509-13. [PMID: 8743156 DOI: 10.1071/rd9951509] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
To establish the changes associated with gestational age and labour status in parathyroid hormone-related protein (PTHrP) concentrations in the amniotic fluid, human amniotic fluid was collected from non-labouring and labouring women at < 37 weeks of gestation (preterm) and at term (> or = 37 weeks). PTHrP was assayed by a specific N-terminal radioimmunoassay. PTHrP concentrations in amniotic fluid obtained from non-labouring women were significantly lower at preterm (15-36 weeks; 14.1 +/- 2.5 pmol L(-1); n = 11) than at term (37-42 weeks; 39.3 +/- 7.6 pmol L(-1); n = 16; P < 0.0009). Concentrations of PTHrP in amniotic fluid obtained from labouring women were also significantly lower at preterm (27-36 week; 12.2 +/- 4.7 pmol L(-1); n = 4; P < 0.01) than at term (37-42 weeks; 63. 8 +/- 19.6 pmol L(-1); n = 9). There were no significant changes in concentration associated with labour status, either at preterm or at term. The physiological significance of elevated amniotic fluid concentrations of PTHrP has yet to be established, but the data are consistent with the suggestion that PTHrP plays a role in fetal membrane function during late gestation.
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Affiliation(s)
- M E Wlodek
- Department of Perinatal Medicine, Royal Women's Hospital, Carlton, Vic., Australia
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Abstract
OBJECTIVE The lungs of the mammalian fetus secrete large volumes of fluid daily. The purpose of this study was to estimate the fraction of the lung liquid that is swallowed as it exits the fetal trachea versus that which enters the amniotic fluid under normoxic and hypoxic conditions. STUDY DESIGN In chronically catheterized fetal sheep at 119 to 133 days' gestation the volume of fluid swallowed by the fetus was monitored five times per day for three consecutive 24-hour periods: control, hypoxia, and recovery. The Na+, K+, and Cl- concentrations of the swallowed fluid, lung liquid, and amniotic fluid were measured simultaneously. The fraction of the swallowed fluid that originated from the lungs or amniotic fluid was calculated from 24-hour average compositions and the assumption that the fetus swallowed only amniotic fluid and lung liquid. RESULTS During the control, hypoxia, and recovery periods the fetuses swallowed 264 +/- 43 (SE), 92 +/- 23, and 271 +/- 24 ml/kg of fetal weight per day, respectively. As determined from Cl- concentrations, this swallowed fluid was composed of 17.7% +/- 2.7%, 24.8% +/- 5.8%, and 11.9% +/- 3.4% lung liquid, respectively, with the remainder being amniotic fluid. Throughout the three 24-hour observation periods there was an inverse relationship between the net 24-hour swallowed volume and the fraction of the swallowed fluid that originated from the lungs. Calculations based on Na+ concentrations yielded essentially the same results with slightly more scatter, whereas calculations based on K+ concentrations were unreliable. CONCLUSIONS (1) Chloride concentrations provide the best of the three index values for a compositional analysis of fluids swallowed by the fetus. (2) Under normoxic conditions around 18% of swallowed fluid is derived from the fetal lungs. (3) On the basis of published fluid secretion rates for the fetal lung, an average of 50% of the liquid that exits the fetal trachea is swallowed and the rest mixes with the amniotic fluid.
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Affiliation(s)
- R A Brace
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Cock ML, Wlodek ME, Hooper SB, McCrabb GJ, Harding R. The effects of twenty-four hours of reduced uterine blood flow on fetal fluid balance in sheep. Am J Obstet Gynecol 1994; 170:1442-51. [PMID: 8178887 DOI: 10.1016/s0002-9378(94)70177-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Our aim was to determine the effects of a sustained reduction in uteroplacental perfusion, leading to fetal hypoxia, on determinants of amniotic fluid volume in sheep. STUDY DESIGN Surgery was performed on five pregnant ewes 110 to 116 days after mating. At 127.3 +/- 2.2 days uterine blood flow was reduced for 24 hours, which reduced fetal SaO2 from 61.9% +/- 1.2% to 24.9% +/- 0.8%. RESULTS Fetal urine production was increased from a control value of 193.0 +/- 24.0 ml/kg per 24 hours to 279.3 +/- 30.0 ml/kg per 24 hours during periods of reduced uterine blood flow and remained above control values for up to 48 hours after the reduced uterine blood flow period. A substantial loss of fetal water and electrolytes occurred through urine, which was associated with changes in the composition of fetal plasma and fetal tracheal, fetal swallowed, and amniotic fluids. Fetal swallowing was reduced throughout the reduced uterine blood flow period from a control value of 200.8 +/- 56.0 ml/kg per 24 hours to 32.7 +/- 8.4 ml/kg per 24 hours and returned to control levels after the cessation of the reduced uterine blood flow. CONCLUSION We conclude that 24 hours of reduced uterine blood flow causes major changes in fetal renal function and fetal swallowing that, in spite of an expected reduction in lung liquid production, would increase the flow of fluid and electrolytes from the fetus into the amniotic sac.
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Affiliation(s)
- M L Cock
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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Abstract
The aim of this study was to determine the effects of 24 h of hypoxia on fetal swallowing and urine flow rates. The study design included successive 24-h control, hypoxia, and recovery periods. To induce hypoxia, we infused nitrogen into the trachea of late-gestation pregnant sheep. During hypoxia, there were decreases in fetal arterial oxygen saturation [from 62.7 +/- 2.2 to 30.9 +/- 2.9% (SE)] and PO2 (from 21.1 +/- 1.0 to 14.1 +/- 0.9 mmHg) (n = 7). Fetal arterial pH decreased maximally by 0.04 +/- 0.01 at 6 h and returned to control thereafter. Fetal swallowing decreased from 13.4 +/- 2.1 to 0.6 +/- 0.2 ml.h-1.kg fetal wt-1 with the onset of hypoxia and gradually increased, but only to one-half control levels, during the last 12 h of hypoxia. Fetal urine flow gradually decreased from 9.6 +/- 1.6 ml.h-1.kg-1 to a minimum of 5.3 +/- 0.5 ml.h-1.kg-1 at 2-3 h of hypoxia and returned to control thereafter. During the first hour of the recovery period, fetal swallowing transiently increased to twice control levels before returning to control. This was followed by a delayed, transient increase in urine flow to 63% above control levels at 2-6 h after hypoxia. We conclude that the fetal swallowing and urine flow responses to prolonged hypoxia in the absence of acidemia are distinctly different from the initial inhibitory responses, in that swallowing partially and urine flow fully recovers from the initial suppression.
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Affiliation(s)
- R A Brace
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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38
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Wlodek ME, Harding R, Thorburn GD. Effects of inhibition of prostaglandin synthesis on flow and composition of fetal urine, lung liquid, and swallowed fluid in sheep. Am J Obstet Gynecol 1994; 170:186-95. [PMID: 8296820 DOI: 10.1016/s0002-9378(94)70406-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVE Our aim was to determine the effects of blocking prostaglandin synthesis, by infusion of indomethacin into the fetal circulation, on factors regulating amniotic fluid volume and on plasma composition in the mother and fetus. STUDY DESIGN Indomethacin was administered to fetal sheep during 8 hours at 124.0 +/- 1.2 days of gestation (n = 7) and at 134.7 +/- 0.8 days of gestation (n = 7) (term approximately 147 days). Vehicle infusions were performed at 128.8 +/- 1.4 days of gestation (n = 5). RESULTS Fetal urine production was significantly reduced and both fetal urine osmolality and plasma arginine vasopressin concentrations were significantly elevated in response to indomethacin infusions at both gestational ages. Fetal blood and urine lactate concentrations were elevated in response to indomethacin. Later in gestation, fetal lung liquid flow was significantly changed from a net efflux to a net influx. There was no significant effect of indomethacin on the volume of fluid swallowed by the fetus. CONCLUSION Inhibition of fetal prostaglandin synthesis profoundly reduces the production of the two major fetal fluids contributing to amniotic fluid, namely, urine and lung liquid. These findings may explain why indomethacin reduces amniotic fluid volume.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Clayton, Victoria, Australia
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39
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Abstract
Our aim was to determine the effects of prolonged removal of fetal urine during late gestation on fetal-maternal fluid and electrolyte relationships. We measured the volume and composition of fetal urine and amniotic and allantoic fluids and the composition of fetal and maternal plasma in sheep before and during continuous urine drainage, which began at 130 days of gestation and continued until the onset of labor; a control group was also studied. The response to fetal urine drainage occurred in two phases. In the "acute" phase (1-3 days), amniotic and allantoic fluid volumes decreased significantly, presumably due to their reabsorption into the fetal chorionic circulation or swallowing of amniotic fluid by the fetus. During the "chronic" phase, starting 3-5 days after urine drainage, a significant reversal in the transplacental osmotic gradient occurred due to a decrease in maternal plasma osmolality. During the entire drainage period (14.1 +/- 1.1 days, mean +/- SE, n = 5) at least 542 ml/day of water and 24 mmol/day of electrolytes passed from the mother into the fetal circulation and fetal plasma osmolality was unchanged. We conclude that, despite the loss of substantial water and electrolytes, the fetus is able to maintain its growth and fluid and electrolyte homeostasis by obtaining water and electrolytes initially from the amniotic and allantoic fluids and subsequently from its mother. The movement of water and electrolytes to the fetus would have been facilitated by the reversed transplacental osmotic gradient.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
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Wlodek ME, Harding R, Thorburn GD. The influence of gestational age and onset of labour on determinants of fetal-maternal fluid and electrolyte balance in sheep. J Dev Physiol 1992; 18:111-9. [PMID: 1301415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Our aim was to compare the effects of gestational age and the timing of the onset of labour on factors influencing fetal fluid and electrolyte balance and urine production in fetal sheep. We measured the volume and composition of fetal urine and amniotic and allantoic fluids, as well as fetal and maternal plasma composition and micturition episodes in sheep during late gestation until the onset of labour. We found that daily fetal urine production and urethral urine flow per micturition episode increased significantly in relation to the onset of labour but not to gestational age (P < 0.05). In the 2 days preceding the onset of labour fetal urine and amniotic fluid K+ concentrations and urine osmolality increased significantly and the Na+/K+ ratio in allantoic fluid decreased significantly (P < 0.05). There was also a significant fall in fetal arterial SaO2 (P < 0.05) but no significant changes occurred in fetal plasma electrolyte composition, osmolality or AVP concentrations. Fetal plasma cortisol and prolactin concentrations and amniotic and allantoic fluid prolactin concentrations increased significantly and progressively in association with both advancing gestation and the onset of labour whereas maternal plasma prolactin concentrations increased significantly only in the 2 days before the onset of labour (P < 0.05). We conclude that some developmental aspects of fetal fluid and electrolyte balance, including renal function, are more closely related to the timing of parturition than to gestational age per se.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Melbourne, Australia
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Wlodek ME, Challis JR, Richardson B, Patrick J. The effects of hypoxemia with progressive acidemia on fetal renal function in sheep. J Dev Physiol 1989; 12:323-8. [PMID: 2640226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In order to determine the effects of fetal hypoxemia on renal blood flow, glomerular filtration rate (GFR) and urethral and urachal urine output, we examined the effects of 3 h maternally-induced (9% O2, 3% CO2, 88% N2) fetal hypoxaemia on 10 chronically-instrumented fetal sheep between 127-135 days of gestation. Fetal arterial pH fell significantly during the second and third hours of hypoxia and this coincided with a significant increase in fetal arterial blood pressure (P less than 0.05). During the second hour of hypoxia, with mild acidaemia, fetal GFR decreased significantly and then, during the third hour, fetal GFR, urethral and total urine output were significantly elevated. During the 2-h recovery period urachal and total, but not urethral urine output, were significantly elevated (P less than 0.05). The data suggested that the increase in GFR and urine output measured during the third hour of hypoxia and the recovery period may reflect a pressure diuresis.
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Affiliation(s)
- M E Wlodek
- Department of Obstetrics and Gynaecology, University of Western Ontario, Canada
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Abstract
Fetal bladder contractions, indicative of micturition (voiding), and behavioral states were monitored in unanesthetized fetal sheep in utero during the last third of gestation. Fetal voids began during low-voltage electrocortical activity (LV ECoG) at a greater frequency (91.4 +/- 1.0%) than expected (57.2%) and began during high-voltage electrocortical activity (HV ECoG) with a lower frequency (8.7 +/- 1.0%) than expected (42.8%). Fetal voids began significantly sooner after the onset of LV ECoG (5.84 +/- 0.13 min) than after the onset of HV ECoG (10.88 +/- 0.04 min). Electroocular and nuchal muscle activities were associated with 96.2 and 66.0% of the voids, respectively, but there was no significant association between fetal voiding and swallowing episodes. Abolition of spontaneous voiding, by urine drainage (24 h), caused no significant differences, relative to a 24-h control period, in the duration or number of episodes of LV or HV ECoG or percentage of time spent in these states. Also, induction of voiding by infusing saline into the bladder did not significantly alter the time to the next change of ECoG state. However, the mean time to the next void and the mean volume of saline infused into the bladder to induce voiding tended to be less during LV ECoG than HV ECoG, although not significantly less. Our data show that most spontaneous voids in the fetus begin during LV ECoG, suggesting that voiding is regulated by descending information from the brain. Furthermore, these experiments demonstrate that fetal bladder contractions and voiding, either spontaneous or induced, do not influence the normal cycling of fetal ECoG states.
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Affiliation(s)
- M E Wlodek
- Department of Physiology, Monash University, Melbourne, Australia
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Wlodek ME, Challis JR, Patrick J. Urethral and urachal urine output to the amniotic and allantoic sacs in fetal sheep. J Dev Physiol 1988; 10:309-19. [PMID: 2849619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A chronic fetal sheep preparation was developed to measure, without interruption in utero, urethral and urachal urine output to the amniotic and allantoic sacs, respectively. Fetal urethral, urachal and total urine output was measured during a 5 day post-operative period, in late gestation. Total fetal urine output increased from day 1 to a volume of 1216 +/- 115 ml/day (SEM) on day 5 post-operative. Urachal urine output increased significantly from 12 ml/day on day 1 to 467 ml/day on day 5 (P less than 0.05). Fetal arterial blood gases, pH and immunoreactive ACTH, cortisol and immunoreactive arginine vasopressin concentrations were stable throughout the 5-day recovery period. Fetal urachal urine output to the allantoic cavity and total fetal urine output appears to require 4-5 days to stabilize post-operatively. Fetal urine is a major source of amniotic and allantoic fluid in late gestation and the volume of these sacs may be influenced, in part, by the distribution of urethral and urachal urine output.
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Affiliation(s)
- M E Wlodek
- Department of Obstetrics & Gynecology, University of Western Ontario, London, Canada
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Clarke DW, Patrick J, Wlodek ME, Smith GN, Richardson B, Brien JF. The role of fetal urinary excretion in the transfer of ethanol into amniotic fluid after maternal administration of ethanol to the near-term pregnant ewe. Can J Physiol Pharmacol 1987; 65:1120-4. [PMID: 3621059 DOI: 10.1139/y87-176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The objective of this study was to determine whether fetal urinary excretion is a major route of ethanol transfer into the amniotic fluid surrounding the fetus following maternal administration of ethanol. Conscious instrumented pregnant ewes between 130 and 137 days' gestation (term, 147 days) with (n = 3) or without (n = 3) a catheter in the fetal bladder were administered 1 g ethanol/kg maternal body weight as a 1-h maternal intravenous infusion. Maternal blood, fetal blood, and amniotic fluid samples were collected at selected times, and fetal urine was collected continuously from the bladder-cannulated fetus during the 14-h study for the determination of ethanol concentrations. Fetal urinary excretion of ethanol occurred, and the total amount of ethanol excreted represented 0.30 +/- 0.07 (SD)% of the maternal ethanol dose. The renal clearance of ethanol by the fetus was 0.43 +/- 0.06 mL/min. The pharmacokinetics of ethanol in the maternal-fetal unit and the amniotic fluid for the bladder-cannulated fetal preparation were similar to the data for the nonbladder-cannulated preparation. The data indicate that fetal urinary excretion of ethanol is a secondary route of ethanol transfer into the amniotic fluid. It would appear that diffusion of ethanol across membranes from the maternal and fetal circulations is a major route of ethanol transfer into this intrauterine compartment.
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Clarke DW, Wlodek ME, Patrick J, Richardson B, Brien JF. Decreased urine production in the near-term fetal lamb after maternal ethanol infusion. Am J Obstet Gynecol 1987; 156:1273-4. [PMID: 3578446 DOI: 10.1016/0002-9378(87)90161-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Intravenous infusion of 1 gm ethanol/kg maternal body weight over 1 hour to three conscious catheterized near-term pregnant ewes decreased fetal urine production for 3 hours (overall decrease of 54% from control). This effect in the near-term fetus is opposite to the ethanol-induced diuresis that occurs in adults.
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Challis JR, Richardson BS, Rurak D, Wlodek ME, Patrick JE. Plasma adrenocorticotropic hormone and cortisol and adrenal blood flow during sustained hypoxemia in fetal sheep. Am J Obstet Gynecol 1986; 155:1332-6. [PMID: 3024490 DOI: 10.1016/0002-9378(86)90169-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
We examined the effect of sustained hypoxemia with progressive acidemia on pituitary-adrenal endocrine function (adrenocorticotropic hormone, cortisol) and on adrenal blood flow in fetal sheep. Hypoxemia was induced by the maternal sheep breathing a gas mixture containing 9% oxygen, with 3% carbon dioxide added. Induced hypoxemia resulted in a progressive fetal metabolic acidosis but with little change in maternal pH. During induced hypoxemia there was little change in maternal plasma adrenocorticotropic hormone or cortisol level. Fetal adrenocorticotropic hormone and cortisol increased to peak values within 2.8 hours of induced hypoxia but by 7.2 hours had begun to fall to values that were not significantly different from those at 1.4 hours. Fetal adrenal blood flow (microsphere technique) also increased significantly and remained elevated throughout the duration (7.2 hours) of hypoxemia. The maximum fetal adrenal blood flow achieved during hypoxemia was significantly correlated with the basal (prehypoxemia) flow to the adrenals. We conclude that the changes in fetal adrenocorticotropic hormone, cortisol, and adrenal blood flow seen in short-term hypoxemia are reproduced during sustained hypoxemia with acidemia. Furthermore, the noted rise in the fetal adrenocorticotropic hormone level may be an important factor contributing to the increase in adrenal blood flow during hypoxemia.
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Norman LJ, Lye SJ, Wlodek ME, Challis JR. Changes in pituitary responses to synthetic ovine corticotrophin releasing factor in fetal sheep. Can J Physiol Pharmacol 1985; 63:1398-403. [PMID: 3000558 DOI: 10.1139/y85-230] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The rise in cortisol in fetal sheep during late pregnancy has been related to increased responsiveness of the adrenal to ACTH. Most reports have suggested that plasma ACTH concentrations rise coincident with or after the prepartum increase in cortisol. To reexamine the relationship of cortisol with basal immunoreactive ACTH (IR-ACTH) throughout the last 40 days of pregnancy and to determine changes in fetal pituitary responsiveness during this time, we measured basal and synthetic ovine corticotrophin-releasing factor (oCRF) (10 ng-10 micrograms) induced rises in ACTH and cortisol in fetal sheep at days 110-115, 125-130, and 135-140 of pregnancy. The fetuses were catheterized on day 105-120 and entered spontaneous labour at greater than 140 days. Basal IR-ACTH (picograms per millilitre +/- SEM) rose from 16.7 +/- 2.9 pg/mL at day 110-115 to 34.8 +/- 8.7 pg/mL at day 141-145. There was a significant effect of time on basal ACTH concentrations with a mean increase of approximately 5 pg ACTH per millilitre of plasma per 5-day sampling interval. Plasma cortisol changed gradually between day 110 and 125 of gestation and then more rapidly to term. At day 110-115 of gestation there was no significant change in plasma ACTH after 10 or 100 ng oCRF, but there was a significant increase in ACTH after 1 microgram of oCRF. Plasma cortisol did not change after any CRF injection. The change in IR-ACTH after oCRF at day 125-130 of gestation was significantly greater than that at day 110-115. Plasma cortisol concentrations were elevated following 1- and 10-micrograms injections of oCRF.(ABSTRACT TRUNCATED AT 250 WORDS)
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Abstract
Uterine contractions, induced by the administration of oxytocin to sheep between d 123-144 of pregnancy, were associated with a mean transient decrease in fetal PaO2 of 2.8 mm Hg within 5 min. These changes were associated with a rapid increase in the concentration of ACTH in fetal plasma. There was a significant (P less than 0.05) increase in the percentage change (+40 to +47%) over basal ACTH levels in fetal plasma at +5, +15 and +20 min after oxytocin. Administration of saline had no significant effect on intrauterine pressure, fetal PaO2 or fetal plasma ACTH levels. We speculate that increases in uterine activity and/or transient decreases in fetal PaO2 may contribute to short-term fluctuations in plasma ACTH in fetal sheep.
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Lye SJ, Wlodek ME, Challis JR. Relation between fetal arterial PO2 and oxytocin-induced uterine contractions in pregnant sheep. Can J Physiol Pharmacol 1984; 62:1337-40. [PMID: 6509382 DOI: 10.1139/y84-224] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The relation between oxytocin-induced type A uterine contractions and fetal arterial PO2, measured continuously with an intravascular oxygen electrode, was studied in nine chronically catheterized sheep during late pregnancy. Oxytocin provoked dose-related increases in intrauterine pressure (IUP) and decreases in fetal PaO2. There was a significant positive relationship between changes in IUP and the maximum decrease in fetal PaO2 (average r = 0.696, df = 92; P less than 0.001). We conclude that changes in uterine activity contribute to transient fetal hypoxemia, and that administration of exogenous oxytocin provides an experimental paradigm to examine the consequences of this relationship.
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