Endocrine regulation of fetal growth

1995 ◽  
Vol 7 (3) ◽  
pp. 351 ◽  
Author(s):  
AL Fowden
Keyword(s):  
Gene Expression ◽  
Growth Factors ◽  
Fetal Growth ◽  
Growth Regulation ◽  
Fetal Liver ◽  
In Utero ◽  
Tissue Differentiation ◽  
Late Gestation ◽  
Endocrine Regulation ◽  
Tissue Accretion

Hormones have an important role in the control of fetal growth. They act on both tissue accretion and differentiation and enable a precise and orderly pattern of growth to occur during late gestation. In part, their actions on growth may be mediated by other growth factors such as the insulin-like growth factors (IGFs). Insulin stimulates fetal growth by increasing the mitotic drive and nutrient availability for tissue accretion. It has little effect on tissue differentiation. In contrast, the main effects of cortisol in utero are on tissue differentiation and maturation. Cortisol appears to act directly on the cells to alter gene transcription or post-translational processing of the gene products. Cortisol may also initiate the transition from the fetal to the adult modes of growth regulation by inducing the switch from IGF-II to IGF-I gene expression in the fetal liver. Thyroxine affects both tissue accretion and differentiation in the fetus by a combination of metabolic and non-metabolic mechanisms. Pituitary growth hormone, on the other hand, appears to have little part in the control of fetal growth, unlike its role postnatally. Fetal hormones, therefore, promote growth and development in utero by altering both the metabolism and gene expression of the fetal tissues. These hormonal actions ensure that fetal growth rate is commensurate with the nutrient supply and that prepartum maturation occurs in preparation for extrauterine life.

Circulating insulin-like growth factors-I and -II and substrates in fetal sheep following restriction of placental growth

1994 ◽  
Vol 140 (1) ◽  
pp. 5-13 ◽  
Author(s):  
J A Owens ◽  
K L Kind ◽  
F Carbone ◽  
J S Robinson ◽  
P C Owens
Keyword(s):  
Growth Factors ◽  
Blood Glucose ◽  
Fetal Growth ◽  
Fetal Liver ◽  
Liver Weight ◽  
Fetal Weight ◽  
Fetal Sheep ◽  
Arterial Blood ◽  
Igf I ◽  
Insulin Like Growth Factors

Abstract To determine the relationship between placental delivery of oxygen and glucose, circulating insulin-like growth factors (IGFs) and fetal growth, the effect of variable restriction of placental growth was determined in sheep in late gestation. Arterial blood was obtained via indwelling catheters at 120 and 127 days of gestation, prior to necropsy at 130 days to measure fetal and placental weights. Plasma was acidified and subjected to size-exclusion high-performance liquid chromatography at pH 2·8 to dissociate and separate IGFs from their binding proteins. The acid-dissociated IGF fraction was analysed by sensitive and highly specific radioligand assays for IGF-I and IGF-II, previously defined using ovine IGFs. Fetal weight and blood pO2 and glucose at 120 and 127 days of gestation correlated positively with placental weight. Plasma IGF-I was positively associated with fetal weight and fetal liver weight, and with blood pO2 and glucose at both ages. Plasma IGF-II levels also correlated positively with fetal weight, fetal liver weight and with blood glucose and pO2, but only at 127 days of gestation. In the most severely growth-retarded fetal sheep, blood glucose and pO2 and plasma IGF-I were significantly reduced when compared with normal fetuses at 120 days. All decreased further by 127 days of gestation as did plasma IGF-II in severely growth-retarded fetal sheep compared with normal fetuses. These observations are consistent with the hypothesis that both IGF-I and IGF-II are chronically regulated by oxygen and nutrition in utero and mediate part of the influence of placental supply of substrate over fetal growth. Journal of Endocrinology (1994) 140, 5–13

A-To-I RNA Editing By ADAR1 Is Essential For Hematopoiesis

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1199-1199 ◽  
Author(s):  
Brian Liddicoat ◽  
Robert Piskol ◽  
Alistair Chalk ◽  
Miyoko Higuchi ◽  
Peter Seeburg ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Editing ◽  
Fetal Liver ◽  
Expression Profiles ◽  
In Utero ◽  
Tamoxifen Treatment ◽  
Rna Seq ◽  
Data Set ◽  
Hematopoietic Stem

Abstract The role of RNA and its regulation is becoming increasingly appreciated as a vital component of hematopoietic development. RNA editing by members of the Adenosine Deaminase Acting on RNA (ADAR) gene family is a form of post-transcriptional modification which converts genomically encoded adenosine to inosine (A-to-I) in double-stranded RNA. A-to-I editing by ADAR directly converts the sequence of the RNA substrate and can alter the structure, function, processing, and localization of the targeted RNA. ADAR1 is ubiquitously expressed and we have previously described essential roles in the development of hematopoietic and hepatic organs. Germline ablation of murine ADAR1 results in a significant upregulation of interferon (IFN) stimulated genes and embryonic death between E11.5 and E12.5 associated with fetal liver disintegration and failed hemopoiesis. To determine the biological importance of A-to-I editing by ADAR1, we generated an editing dead knock-in allele of ADAR1 (ADAR1E861A). Mice homozygous for the ADAR1E861A allele died in utero at ∼E13.5. The fetal liver (FL) was small and had significantly lower cellularity than in controls. Analysis of hemopoiesis demonstrated increased apoptosis and a loss of hematopoietic stem cells (HSC) and all mature lineages. Most notably erythropoiesis was severely impaired with ∼7-fold reduction across all erythrocyte progenitor populations compared to controls. These data are consistent with our previous findings that ADAR1 is essential for erythropoiesis (unpublished data) and suggest that the ADAR1E861A allele phenocopies the null allele in utero. To assess the requirement of A-to-I editing in adult hematopoiesis, we generated mice where we could somatically delete the wild-type ADAR1 allele and leave only ADAR1E861A expressed in HSCs (hScl-CreERAdar1fl/E861A). In comparison to hScl-CreERAdar1fl/+ controls, hScl-CreERAdar1fl/E861A mice were anemic and had severe leukopenia 20 days post tamoxifen treatment. Investigation of marrow hemopoiesis revealed a significant loss of all cells committed to the erythroid lineage in hScl-CreERAdar1fl/E861A mice, despite having elevated phenotypic HSCs. Upon withdrawal of tamoxifen diet, all blood parameters were restored to control levels within 12 weeks owing to strong selection against cells expressing only the ADAR1E861A allele. To understand the mechanism through which ADAR1 mediated A-to-I editing regulates hematopoiesis, RNA-seq was performed. Gene expression profiles showed that a loss of ADAR1 mediated A-to-I editing resulted in a significant upregulation of IFN signatures, consistent with the gene expression changes in ADAR1 null mice. To define substrates of ADAR1 we assessed A-to-I mismatches in the RNA-seq data sets. 3,560 previously known and 353 novel A-to-I editing sites were identified in our data set. However, no single editing substrate discovered could account for the IFN signature observed or the lethality of ADAR1E861A/E861A mice. These results demonstrate that ADAR1 mediated A-to-I editing is essential for the maintenance of both fetal and adult hemopoiesis in a cell-autonomous manner and a key suppressor of the IFN response in hematopoiesis. Furthermore the ADAR1E861A allele demonstrates the essential role of ADAR1 in vivo is A-to-I editing. Disclosures: Hartner: TaconicArtemis: Employment.

scholarly journals Loss of the pregnancy-induced rise in cortisol concentrations in the ewe impairs the fetal insulin-like growth factor axis

2011 ◽  
Vol 23 (5) ◽  
pp. 665 ◽  
Author(s):  
Ellen C. Jensen ◽  
Laura Bennet ◽  
Charles Wood ◽  
Mark Vickers ◽  
Bernhard Breier ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fetal Growth ◽  
Fetal Liver ◽  
Plasma Concentrations ◽  
Late Gestation ◽  
Control Group ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Igf I ◽  
Low Cortisol

Maternal cortisol levels increase during pregnancy. Although this change is important for optimal fetal growth, the mechanisms of the changes in growth remain unclear. The hypothesis examined was that alterations in maternal plasma cortisol concentrations are associated with changes in the fetal insulin-like growth factor (IGF) axis. Pregnant ewes in late gestation (115 ± 0.4 days) were studied: six control animals, five ewes given 1 mg kg–1 day–1 cortisol (high cortisol) and five adrenalectomised ewes given 0.5–0.6 mg kg–1 day–1 cortisol (low cortisol). Blood samples were taken throughout the experiment and at necropsy (130 ± 0.2 days) and fetal liver was frozen for mRNA analysis. Fetal IGF-I and insulin plasma concentrations were lower and insulin-like growth factor-binding protein-1 (IGFBP-1) concentrations were higher in the low cortisol group compared with those in the control group (P < 0.05). Fetal liver IGF-II and IGFBP-3 mRNA were decreased in low cortisol animals compared with controls (P < 0.05). There were no significant changes in these parameters in the high cortisol group, and there were no changes in fetal liver IGF-I, growth hormone receptor, IGF-I receptor, IGF-II receptor, IGFBP-1 or IGFBP-2 mRNA levels between the groups. These data suggest that reduced fetal IGF availability contributes to reduced fetal growth when maternal cortisol secretion is impaired, but not during exposure to moderate increases in cortisol.

Prenatal glucocorticoid exposure in the sheep alters renal development in utero: implications for adult renal function and blood pressure control

2011 ◽  
Vol 301 (2) ◽  
pp. R500-R509 ◽  
Author(s):  
Karen M. Moritz ◽  
Robert De Matteo ◽  
Miodrag Dodic ◽  
Andrew J. Jefferies ◽  
Debbie Arena ◽  
...  
Keyword(s):  
Gene Expression ◽  
Renal Function ◽  
Arterial Pressure ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Salt Intake ◽  
Female Offspring ◽  
In Utero ◽  
Late Gestation ◽  
Elevated Arterial Pressure

Treatment of the pregnant ewe with glucocorticoids early in pregnancy results in offspring with hypertension. This study examined whether glucocorticoids can reduce nephron formation or alter gene expression for sodium channels in the late gestation fetus. Sodium channel expression was also examined in 2-mo-old lambs, while arterial pressure and renal function was examined in adult female offspring before and during 6 wk of increased dietary salt intake. Pregnant ewes were treated with saline (SAL), dexamethasone (DEX; 0.48 mg/h) or cortisol (CORT; 5 mg/h) over days 26–28 of gestation (term = 150 days). At 140 days of gestation, glomerular number in CORT and DEX animals was 40 and 25% less, respectively, compared with SAL controls. Real-time PCR showed greater gene expression for the epithelial sodium channel (α-, β-, γ-subunits) and Na+-K+-ATPase (α-, β-, γ-subunits) in both the DEX and CORT group fetal kidneys compared with the SAL group with some of these changes persisting in 2-mo-old female offspring. In adulthood, sheep treated with dexamethasone or cortisol in utero had elevated arterial pressure and an apparent increase in single nephron glomerular filtration rate, but global renal hemodynamics and excretory function were normal and arterial pressure was not salt sensitive. Our findings show that the nephron-deficit in sheep exposed to glucocorticoids in utero is acquired before birth, so it is a potential cause, rather than a consequence, of their elevated arterial pressure in adulthood. Upregulation of sodium channels in these animals could provide a mechanistic link to sustained increases in arterial pressure in cortisol- and dexamethasone-exposed sheep, since it would be expected to promote salt and water retention during the postnatal period.

Differential regulation of suppressor of cytokine signaling-3 in the liver and adipose tissue of the sheep fetus in late gestation

2006 ◽  
Vol 290 (4) ◽  
pp. R1044-R1051 ◽  
Author(s):  
Sheridan Gentili ◽  
Michael J. Waters ◽  
I. Caroline McMillen
Keyword(s):  
Adipose Tissue ◽  
Mrna Expression ◽  
Fetal Growth ◽  
Fetal Liver ◽  
Late Gestation ◽  
Cytokine Signaling ◽  
Suppressor Of Cytokine Signaling ◽  
Perirenal Adipose Tissue ◽  
Plasma Prl ◽  
Sheep Fetus

It is unknown whether the JAK/STAT/suppressor of cytokine signaling-3 (SOCS-3) intracellular signaling pathway plays a role in tissue growth and metabolism during fetal life. We investigated whether there is a differential profile of SOCS-3 expression in the liver and perirenal adipose tissue during the period of increased fetal growth in late gestation and the impact of fetal growth restriction on SOCS-3 expression in the fetal liver. We also determined whether basal SOCS-3 expression in the fetal liver and perirenal adipose tissue is regulated by endogenous fetal prolactin (PRL). SOCS-3 mRNA abundance was higher in the liver than in the pancreas, spleen, and kidney of the sheep fetus during late gestation. In the liver, SOCS-3 mRNA expression was increased ( P < 0.05) between 125 ( n = 4) and 145 days ( n = 7) gestation and lower ( P < 0.05) in growth-restricted compared with normally grown fetal sheep in late gestation. The relative expression of SOCS-3 mRNA in the fetal liver was directly related to the mean plasma PRL concentrations during a 48-h infusion of either a dopaminergic agonist, bromocriptine ( n = 7), or saline ( n = 5), such that SOCS-3 mRNA expression was lower when plasma PRL concentrations decreased below ∼20 ng/ml [ y = 0.99 − (2.47/ x) + (4.96/ x2); r2 = 0.91, P < 0.0001, n = 12]. No relationship was shown between the abundance of phospho-STAT5 in the fetal liver and circulating PRL. SOCS-3 expression in perirenal adipose tissue decreased ( P < 0001) between 90–91 ( n = 6) and 140–145 days ( n = 9) gestation and was not related to endogenous PRL concentrations. Thus SOCS-3 is differentially expressed and regulated in key fetal tissues and may play an important and tissue-specific role in the regulation of cellular proliferation and differentiation before birth.

scholarly journals Glucocorticoid exposure and tissue gene expression of 11β HSD-1, 11β HSD-2, and glucocorticoid receptor in a porcine model of differential fetal growth

Reproduction ◽  
2007 ◽  
Vol 133 (3) ◽  
pp. 653-661 ◽  
Author(s):  
Christopher J McNeil ◽  
Margaret O Nwagwu ◽  
Angela M Finch ◽  
Kenneth R Page ◽  
Alan Thain ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fetal Growth ◽  
Plasma Cortisol ◽  
Porcine Model ◽  
Critical Role ◽  
Hydroxysteroid Dehydrogenase ◽  
Maternal Plasma ◽  
Late Gestation ◽  
Differential Growth ◽  
Fetal Organs

Glucocorticoids play a critical role in fetal development, but inappropriate exposure is associated with reduced fetal growth. We investigated cortisol exposure and supply in a porcine model of differential fetal growth. This model compares the smallest fetus of a litter with an average-sized sibling at three stages of gestation. At day 45, small fetuses had reduced plasma cortisol (16.8 ± 3.4 ng/ml) relative to average fetuses (34.4 ± 3.4 ng/ml, P < 0.001). At day 65 levels had reduced in small and average fetuses to similar concentrations (5.7 ± 1.0 vs 4.8 ± 0.5 ng/ml, P = 0.128). By day 100, elevated levels were found in small fetuses (10.7 ± 1.5 vs 7.6 ± 0.7 ng/ml, P < 0.001). Maternal plasma cortisol was unchanged over gestation (day 45, 56.7 ± 21.6 ng/ml; day 65, 57.8 ± 14.4 ng/ml; day 100, 55.7 ± 6.5 ng/ml). We examined the cause of altered cortisol by investigating the fetal hypothalamic–pituitary–adrenal axis through the measurement of adrenocorticotropic hormone and assessing exposure to maternal cortisol by quantifying placental 11β-hydroxysteroid dehydrogenase-isoform 2 (11β HSD-2) gene expression. These data suggest that altered cortisol supply was of fetal origin. We examined organ glucocorticoid (GC) metabolism by the measurement of GC receptor (GR) and 11β-hydroxysteroid dehydrogenase-isoform 1 (11β HSD-1) gene expression. We found that fetal organs have different temporal patterns of 11β HSD-1 and GR expression, with the liver particularly sensitive to cortisol in late gestation. This study examines GC exposure in naturally occurring differential growth and simultaneously explores tissue GC sensitivity and handling, at three key stages of gestation.

scholarly journals Regulation of fetal liver growth in a model of diet restriction in the pregnant rat

2016 ◽  
Vol 311 (3) ◽  
pp. R478-R488 ◽  
Author(s):  
Joan M. Boylan ◽  
Jennifer A. Sanders ◽  
Philip A. Gruppuso
Keyword(s):  
Gene Expression ◽  
Fetal Liver ◽  
Mrna Translation ◽  
Well Being ◽  
Late Gestation ◽  
Initiation Factor ◽  
Liver Protein ◽  
Translation Control ◽  
Liver Growth ◽  
Pregnant Rat

Limited nutrient availability is a cause of intrauterine growth restriction (IUGR), a condition that has important implications for the well being of the offspring. Using the established IUGR model of maternal fasting in the rat, we investigated mechanisms that control gene expression and mRNA translation in late-gestation fetal liver. Maternal fasting for 48 h during the last one-third of gestation was associated with a 10–15% reduction in fetal body weight and a disproportionate one-third reduction in total fetal liver protein. The fetal liver transcriptome showed only subtle changes consistent with reduced cell proliferation and enhanced differentiation in IUGR. Effects on the transcriptome could not be attributed to specific transcription factors. We purified translating polysomes to profile the population of mRNAs undergoing active translation. Microarray analysis of the fetal liver translatome indicated a global reduction of translation. The only targeted effect was enhanced translation of mitochondrial ribosomal proteins in IUGR, consistent with enhanced mitochondrial biogenesis. There was no evidence for attenuated signaling through the mammalian target of rapamycin (mTOR). Western blot analysis showed no changes in fetal liver mTOR signaling. However, eukaryotic initiation factor 2α (eIF2α) phosphorylation was increased in livers from IUGR fetuses, consistent with a role in global translation control. Our data indicate that IUGR-associated changes in hepatic gene expression and mRNA translation likely involve a network of complex regulatory mechanisms, some of which are novel and distinct from those that mediate the response of the liver to nutrient restriction in the adult rat.

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