1
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White A, Stremming J, Brown LD, Rozance PJ. Attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep does not persist in isolated islets. J Dev Orig Health Dis 2023; 14:353-361. [PMID: 37114757 PMCID: PMC10205682 DOI: 10.1017/s2040174423000090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Insulin-like growth factor-1 (IGF-1) is a critical fetal growth hormone that has been proposed as a therapy for intrauterine growth restriction. We previously demonstrated that a 1-week IGF-1 LR3 infusion into fetal sheep reduces in vivo and in vitro insulin secretion suggesting an intrinsic islet defect. Our objective herein was to determine whether this intrinsic islet defect was related to chronicity of exposure. We therefore tested the effects of a 90-min IGF-1 LR3 infusion on fetal glucose-stimulated insulin secretion (GSIS) and insulin secretion from isolated fetal islets. We first infused late gestation fetal sheep (n = 10) with either IGF-1 LR3 (IGF-1) or vehicle control (CON) and measured basal insulin secretion and in vivo GSIS utilizing a hyperglycemic clamp. We then isolated fetal islets immediately following a 90-min IGF-1 or CON in vivo infusion and exposed them to glucose or potassium chloride to measure in vitro insulin secretion (IGF-1, n = 6; CON, n = 6). Fetal plasma insulin concentrations decreased with IGF-1 LR3 infusion (P < 0.05), and insulin concentrations during the hyperglycemic clamp were 66% lower with IGF-1 LR3 infusion compared to CON (P < 0.0001). Insulin secretion in isolated fetal islets was not different based on infusion at the time of islet collection. Therefore, we speculate that while acute IGF-1 LR3 infusion may directly suppress insulin secretion, the fetal β-cell in vitro retains the ability to recover GSIS. This may have important implications when considering the long-term effects of treatment modalities for fetal growth restriction.
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Affiliation(s)
- Alicia White
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jane Stremming
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Laura D Brown
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Paul J Rozance
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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2
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Camacho LE, Davis MA, Kelly AC, Steffens NR, Anderson MJ, Limesand SW. Prenatal Oxygen and Glucose Therapy Normalizes Insulin Secretion and Action in Growth Restricted Fetal Sheep. Endocrinology 2022; 163:6585511. [PMID: 35560217 PMCID: PMC9113332 DOI: 10.1210/endocr/bqac053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Indexed: 11/19/2022]
Abstract
Placental insufficiency (PI) lowers fetal oxygen and glucose concentrations, which disrupts glucose-insulin homeostasis and promotes fetal growth restriction (FGR). To date, prenatal treatments for FGR have not attempted to correct the oxygen and glucose supply simultaneously. Therefore, we investigated whether a five-day correction of oxygen and glucose concentrations in PI-FGR fetuses would normalize insulin secretion and glucose metabolism. Experiments were performed in near-term FGR fetal sheep with maternal hyperthermia-induced PI. Fetal arterial oxygen tension was increased to normal levels by increasing the maternal inspired oxygen fraction and glucose was infused into FGR fetuses (FGR-OG). FGR-OG fetuses were compared to maternal air insufflated, saline-infused fetuses (FGR-AS) and control fetuses. Prior to treatment, FGR fetuses were hypoxemic and hypoglycemic and had reduced glucose-stimulated insulin secretion (GSIS). During treatment, oxygen, glucose, and insulin concentrations increased, and norepinephrine concentrations decreased in FGR-OG fetuses, whereas FGR-AS fetuses were unaffected. On treatment day 4, glucose fluxes were measured with euglycemic and hyperinsulinemic-euglycemic clamps. During both clamps, rates of glucose utilization and production were greater in FGR-AS than FGR-OG fetuses, while glucose fluxes in FGR-OG fetuses were not different than control rates. After five-days of treatment, GSIS increased in FGR-OG fetuses to control levels and their ex vivo islet GSIS was greater than FGR-AS islets. Despite normalization in fetal characteristics, GSIS, and glucose fluxes, FGR-OG and FGR-AS fetuses weighed less than controls. These findings show that sustained, simultaneous correction of oxygen and glucose normalized GSIS and whole-body glucose fluxes in PI-FGR fetuses after the onset of FGR.
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Affiliation(s)
- Leticia E Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
| | - Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
| | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
| | - Nathan R Steffens
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
| | - Miranda J Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719, USA
- Correspondence: Sean W. Limesand, PhD, Animal and Comparative Biomedical Sciences, The University of Arizona, 1650 E Limberlost Dr, Tucson AZ 85719, USA.
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3
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White A, Stremming J, Boehmer BH, Chang EI, Jonker SS, Wesolowski SR, Brown LD, Rozance PJ. Reduced glucose-stimulated insulin secretion following a 1-wk IGF-1 infusion in late gestation fetal sheep is due to an intrinsic islet defect. Am J Physiol Endocrinol Metab 2021; 320:E1138-E1147. [PMID: 33938236 PMCID: PMC8285601 DOI: 10.1152/ajpendo.00623.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Insulin and insulin-like growth factor-1 (IGF-1) are fetal hormones critical to establishing normal fetal growth. Experimentally elevated IGF-1 concentrations during late gestation increase fetal weight but lower fetal plasma insulin concentrations. We therefore hypothesized that infusion of an IGF-1 analog for 1 wk into late gestation fetal sheep would attenuate fetal glucose-stimulated insulin secretion (GSIS) and insulin secretion in islets isolated from these fetuses. Late gestation fetal sheep received infusions with IGF-1 LR3 (IGF-1, n = 8), an analog of IGF-1 with low affinity for the IGF binding proteins and high affinity for the IGF-1 receptor, or vehicle control (CON, n = 9). Fetal GSIS was measured with a hyperglycemic clamp (IGF-1, n = 8; CON, n = 7). Fetal islets were isolated, and insulin secretion was assayed in static incubations (IGF-1, n = 8; CON, n = 7). Plasma insulin and glucose concentrations in IGF-1 fetuses were lower compared with CON (P = 0.0135 and P = 0.0012, respectively). During the GSIS study, IGF-1 fetuses had lower insulin secretion compared with CON (P = 0.0453). In vitro, glucose-stimulated insulin secretion remained lower in islets isolated from IGF-1 fetuses (P = 0.0447). In summary, IGF-1 LR3 infusion for 1 wk into fetal sheep lowers insulin concentrations and reduces fetal GSIS. Impaired insulin secretion persists in isolated fetal islets indicating an intrinsic islet defect in insulin release when exposed to IGF-1 LR3 infusion for 1 wk. We speculate this alteration in the insulin/IGF-1 axis contributes to the long-term reduction in β-cell function in neonates born with elevated IGF-1 concentrations following pregnancies complicated by diabetes or other conditions associated with fetal overgrowth.NEW & NOTEWORTHY After a 1-wk infusion of IGF-1 LR3, late gestation fetal sheep had lower plasma insulin and glucose concentrations, reduced fetal glucose-stimulated insulin secretion, and decreased fractional insulin secretion from isolated fetal islets without differences in pancreatic insulin content.
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Affiliation(s)
- Alicia White
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jane Stremming
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Brit H Boehmer
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Eileen I Chang
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Sonnet S Jonker
- Knight Cardiovascular Institute, Center for Developmental Health, Oregon Health & Science University, Portland, Oregon
| | - Stephanie R Wesolowski
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Laura D Brown
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Paul J Rozance
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
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Davis MA, Camacho LE, Pendleton AL, Antolic AT, Luna-Ramirez RI, Kelly AC, Steffens NR, Anderson MJ, Limesand SW. Augmented glucose production is not contingent on high catecholamines in fetal sheep with IUGR. J Endocrinol 2021; 249:195-207. [PMID: 33994373 PMCID: PMC8175032 DOI: 10.1530/joe-21-0071] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 04/22/2021] [Indexed: 01/04/2023]
Abstract
Fetuses with intrauterine growth restriction (IUGR) have high concentrations of catecholamines, which lowers the insulin secretion and glucose uptake. Here, we studied the effect of hypercatecholaminemia on glucose metabolism in sheep fetuses with placental insufficiency-induced IUGR. Norepinephrine concentrations are elevated throughout late gestation in IUGR fetuses but not in IUGR fetuses with a bilateral adrenal demedullation (IAD) at 0.65 of gestation. Euglycemic (EC) and hyperinsulinemic-euglycemic (HEC) clamps were performed in control, intact-IUGR, and IAD fetuses at 0.87 of gestation. Compared to controls, basal oxygen, glucose, and insulin concentrations were lower in IUGR groups. Norepinephrine concentrations were five-fold higher in IUGR fetuses than in IAD fetuses. During the EC, rates of glucose entry (GER, umbilical + exogenous), glucose utilization (GUR), and glucose oxidation (GOR) were greater in IUGR groups than in controls. In IUGR and IAD fetuses with euglycemia and euinsulinemia, glucose production rates (GPR) remained elevated. During the HEC, GER and GOR were not different among groups. In IUGR and IAD fetuses, GURs were 40% greater than in controls, which paralleled the sustained GPR despite hyperinsulinemia. Glucose-stimulated insulin concentrations were augmented in IAD fetuses compared to IUGR fetuses. Fetal weights were not different between IUGR groups but were less than controls. Regardless of norepinephrine concentrations, IUGR fetuses not only develop greater peripheral insulin sensitivity for glucose utilization but also develop hepatic insulin resistance because GPR was maintained and unaffected by euglycemia or hyperinsulinemia. These findings show that adaptation in glucose metabolism of IUGR fetuses are independent of catecholamines, which implicate that hypoxemia and hypoglycemia cause the metabolic responses.
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Affiliation(s)
- Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Leticia E Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Alexander L Pendleton
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Andrew T Antolic
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Rosa I Luna-Ramirez
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Nathan R Steffens
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Miranda J Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona, USA
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5
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Boehmer BH, Brown LD, Wesolowski SR, Hay WW, Rozance PJ. A Chronic Fetal Leucine Infusion Potentiates Fetal Insulin Secretion and Increases Pancreatic Islet Size, Vascularity, and β Cells in Late-Gestation Sheep. J Nutr 2020; 150:2061-2069. [PMID: 32470982 PMCID: PMC7398779 DOI: 10.1093/jn/nxaa138] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 02/27/2020] [Accepted: 04/22/2020] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Infusion of a complete amino acid mixture into normal late-gestation fetal sheep potentiates glucose-stimulated insulin secretion (GSIS). Leucine acutely stimulates insulin secretion in late-gestation fetal sheep and isolated fetal sheep islets in vitro. OBJECTIVES We hypothesized that a 9-d leucine infusion would potentiate GSIS in fetal sheep. METHODS Columbia-Rambouillet fetal sheep at 126 days of gestation received a 9-d leucine infusion to achieve a 50%-100% increase in leucine concentrations or a control infusion. At the end of the infusion we measured GSIS, pancreatic morphology, and expression of pancreatic mRNAs. Pancreatic islet endothelial cells (ECs) were isolated from fetal sheep and incubated with supplemental leucine or vascular endothelial growth factor A (VEGFA) followed by collection of mRNA. Data measured at multiple time points were compared with a repeated-measures 2-factor ANOVA. Data measured at 1 time point were compared using Student's t test or the Mann-Whitney test. RESULTS Glucose-stimulated insulin concentrations were 80% higher in leucine-infused (LEU) fetuses than in controls (P < 0.05). In the pancreas, LEU fetuses had a higher proportion of islets >5000 μm2 than controls (75% more islets >5000 μm2; P < 0.05) and a larger proportion of the pancreas that stained for β cells (12% greater; P < 0.05). Pancreatic and pancreatic islet vascularity were both 25% greater in LEU fetuses (P < 0.05). Pancreatic VEGFA and hepatocyte growth factor (HGF) mRNA expressions were 38% and 200% greater in LEU fetuses than in controls (P < 0.05), respectively. In isolated islet ECs, HGF mRNA was 20% and 50% higher after incubation in supplemental leucine (P < 0.05) or VEGFA (P < 0.01), respectively. CONCLUSIONS A 9-d leucine infusion potentiates fetal GSIS, demonstrating that glucose and leucine act synergistically to stimulate insulin secretion in fetal sheep. A greater proportion of the pancreas being comprised of β cells and higher pancreatic vascularity contributed to the higher GSIS.
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Affiliation(s)
- Brit H Boehmer
- Perinatal Research Center, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Laura D Brown
- Perinatal Research Center, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Stephanie R Wesolowski
- Perinatal Research Center, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - William W Hay
- Perinatal Research Center, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA
| | - Paul J Rozance
- Perinatal Research Center, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA,Address correspondence to PJR (e-mail: )
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6
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Spiroski AM, Oliver MH, Jaquiery AL, Prickett TCR, Espiner EA, Harding JE, Bloomfield FH. Postnatal effects of intrauterine treatment of the growth-restricted ovine fetus with intra-amniotic insulin-like growth factor-1. J Physiol 2018; 596:5925-5945. [PMID: 29235113 PMCID: PMC6265545 DOI: 10.1113/jp274999] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 11/22/2017] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Fetal growth restriction increases the risk of fetal and neonatal mortality and morbidity, and contributes to increased risk of chronic disease later in life. Intra-amniotic insulin-like growth factor-1 (IGF1) treatment of the growth-restricted ovine fetus improves fetal growth, but postnatal effects are unknown. Here we report that intra-amniotic IGF1 treatment of the growth-restricted ovine fetus alters size at birth and mechanisms of early postnatal growth in a sex-specific manner. We also show that maternal plasma C-type natriuretic peptide (CNP) products are related to fetal oxygenation and size at birth, and hence may be useful for non-invasive monitoring of fetal growth restriction. Intrauterine IGF1 treatment in late gestation is a potentially clinically relevant intervention that may ameliorate the postnatal complications of fetal growth restriction. ABSTRACT Placental insufficiency-mediated fetal growth restriction (FGR) is associated with altered postnatal growth and metabolism, which are, in turn, associated with increased risk of adult disease. Intra-amniotic insulin-like growth factor-1 (IGF1) treatment of ovine FGR increases growth rate in late gestation, but the effects on postnatal growth and metabolism are unknown. We investigated the effects of intra-amniotic IGF1 administration to ovine fetuses with uteroplacental embolisation-induced FGR on phenotypical and physiological characteristics in the 2 weeks after birth. We measured early postnatal growth velocity, amino-terminal propeptide of C-type natriuretic peptide (NTproCNP), body composition, tissue-specific mRNA expression, and milk intake in singleton lambs treated weekly with 360 μg intra-amniotic IGF1 (FGRI; n = 13 females, 19 males) or saline (FGRS; n = 18 females, 12 males) during gestation, and in controls (CON; n = 15 females, 22 males). There was a strong positive correlation between maternal NTproCNP and fetal oxygenation, and size at birth in FGR lambs. FGR lambs were ∼20% lighter at birth and demonstrated accelerated postnatal growth velocity. IGF1 treatment did not alter perinatal mortality, partially abrogated the reduction in newborn size in females, but not males, and reduced accelerated growth in both sexes. IGF1-mediated upregulation of somatotrophic genes in males during the early postnatal period could suggest that treatment effects are associated with delayed axis maturation, whilst treatment outcomes in females may rely on the reprogramming of nutrient-dependent mechanisms of growth. These data suggest that the growth-restricted fetus is responsive to intra-amniotic intervention with IGF1, and that sex-specific somatotrophic effects persist in the early postnatal period.
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Affiliation(s)
- A. M. Spiroski
- The Liggins InstituteUniversity of AucklandAucklandNew Zealand
| | - M. H. Oliver
- The Liggins InstituteUniversity of AucklandAucklandNew Zealand
| | - A. L. Jaquiery
- The Liggins InstituteUniversity of AucklandAucklandNew Zealand
| | | | - E. A. Espiner
- Department of MedicineUniversity of OtagoChristchurchNew Zealand
| | - J. E. Harding
- The Liggins InstituteUniversity of AucklandAucklandNew Zealand
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7
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Kelly AC, Bidwell CA, Chen X, Macko AR, Anderson MJ, Limesand SW. Chronic Adrenergic Signaling Causes Abnormal RNA Expression of Proliferative Genes in Fetal Sheep Islets. Endocrinology 2018; 159:3565-3578. [PMID: 30124804 PMCID: PMC6150948 DOI: 10.1210/en.2018-00540] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 08/10/2018] [Indexed: 12/22/2022]
Abstract
Intrauterine growth restriction (IUGR) increases the risk of developing diabetes in later life, which indicates developmental programming of islets. IUGR fetuses with placental insufficiency develop hypoxemia, elevating epinephrine and norepinephrine (NE) concentrations throughout late gestation. To isolate the programming effects of chronically elevated catecholamines, NE was continuously infused into normally grown sheep fetuses for 7 days. High plasma NE concentrations suppress insulin, but after the NE infusion was terminated, persistent hypersecretion of insulin occurred. Our objective was to identify differential gene expression with RNA sequencing (RNAseq) in fetal islets after chronic adrenergic stimulation. After determining the NE-regulated genes, we identified the subset of differentially expressed genes that were common to both islets from NE fetuses and fetuses with IUGR to delineate the adrenergic-induced transcriptional responses. A portion of these genes were investigated in mouse insulinoma (Min6) cells chronically treated with epinephrine to better approximate the β-cell response. In islets from NE fetuses, RNAseq identified 321 differentially expressed genes that were overenriched for metabolic and hormone processes, and the subset of 96 differentially expressed genes common to IUGR islets were overenriched for protein digestion, vitamin metabolism, and cell replication pathways. Thirty-eight of the 96 NE-regulated IUGR genes changed similarly between models with functional enrichment for proliferation. In Min6 cells, chronic epinephrine stimulation slowed proliferation and augmented insulin secretion after treatment. These data establish molecular mechanisms underlying persistent adrenergic stimulation in hyperfunctional fetal islets and identify a subset of genes dysregulated by catecholamines in IUGR islets that may represent programming of β-cell proliferation capacity.
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Affiliation(s)
- Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | | | - Xiaochuan Chen
- Chongqing Key Laboratory of Forage & Herbivore, College of Animal Science and Technology, Southwest University, Chongqing, China
| | - Antoni R Macko
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Miranda J Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
- Correspondence: Sean W. Limesand, PhD, School of Animal and Comparative Biomedical Sciences, University of Arizona, 1650 East Limberlost Drive, Tucson, Arizona 85719. E-mail:
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8
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Boehmer BH, Brown LD, Wesolowski SR, Hay WW, Rozance PJ. Pulsatile hyperglycemia increases insulin secretion but not pancreatic β-cell mass in intrauterine growth-restricted fetal sheep. J Dev Orig Health Dis 2018; 9:492-499. [PMID: 29973299 PMCID: PMC6293458 DOI: 10.1017/s2040174418000417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Impaired β-cell development and insulin secretion are characteristic of intrauterine growth-restricted (IUGR) fetuses. In normally grown late gestation fetal sheep pancreatic β-cell numbers and insulin secretion are increased by 7-10 days of pulsatile hyperglycemia (PHG). Our objective was to determine if IUGR fetal sheep β-cell numbers and insulin secretion could also be increased by PHG or if IUGR fetal β-cells do not have the capacity to respond to PHG. Following chronic placental insufficiency producing IUGR in twin gestation pregnancies (n=7), fetuses were administered a PHG infusion, consisting of 60 min, high rate, pulsed infusions of dextrose three times a day with an additional continuous, low-rate infusion of dextrose to prevent a decrease in glucose concentrations between the pulses or a control saline infusion. PHG fetuses were compared with their twin IUGR fetus, which received a saline infusion for 7 days. The pulsed glucose infusion increased fetal arterial glucose concentrations an average of 83% during the infusion. Following the 7-day infusion, a square-wave fetal hyperglycemic clamp was performed in both groups to measure insulin secretion. The rate of increase in fetal insulin concentrations during the first 20 min of a square-wave hyperglycemic clamp was 44% faster in the PHG fetuses compared with saline fetuses (P0.23). Chronic PHG increases early phase insulin secretion in response to acute hyperglycemia, indicating that IUGR fetal β-cells are functionally responsive to chronic PHG.
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Affiliation(s)
- B H Boehmer
- Department of Pediatrics,Perinatal Research Center,University of Colorado School of Medicine,Aurora,CO,USA
| | - L D Brown
- Department of Pediatrics,Perinatal Research Center,University of Colorado School of Medicine,Aurora,CO,USA
| | - S R Wesolowski
- Department of Pediatrics,Perinatal Research Center,University of Colorado School of Medicine,Aurora,CO,USA
| | - W W Hay
- Department of Pediatrics,Perinatal Research Center,University of Colorado School of Medicine,Aurora,CO,USA
| | - P J Rozance
- Department of Pediatrics,Perinatal Research Center,University of Colorado School of Medicine,Aurora,CO,USA
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9
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Bloomfield FH. Impact of prematurity for pancreatic islet and beta-cell development. J Endocrinol 2018; 238:R161-R171. [PMID: 29895718 DOI: 10.1530/joe-18-0021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 06/12/2018] [Indexed: 12/22/2022]
Abstract
As increasing numbers of babies born preterm survive into adulthood, it is becoming clear that, in addition to the well-described risks of neurodevelopmental sequelae, there also are increased risks for non-communicable diseases, including diabetes. Epidemiological studies indicate that risks are increased even for birth at late preterm and early term gestations and for both type 1 and type 2 diabetes. Thus, factors related to preterm birth likely affect development of the fetal and neonatal beta-cell in addition to effects on peripheral insulin sensitivity. These factors could operate prior to preterm birth and be related to the underlying cause of preterm birth, to the event of being born preterm itself, to the postnatal care of the preterm neonate or to a combination of these exposures. Experimental evidence indicates that factors may be operating during all these critical periods to contribute to altered development of beta-cell mass in those born preterm. Greater understanding of how these factors impact upon development of the pancreas may lead to interventions or management approaches that mitigate the increased risk of later diabetes.
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10
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Ito S, Yokoyama U, Saito J, Sato S, Usuda H, Watanabe S, Kitanishi R, Miura Y, Saito M, Hanita T, Matsuda T, Ishikawa Y. Attenuation of ductus arteriosus intimal thickening in preterm sheep twins compared with singletons. J Physiol Sci 2017; 67:723-729. [PMID: 28836167 PMCID: PMC10717531 DOI: 10.1007/s12576-017-0565-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Accepted: 08/14/2017] [Indexed: 10/19/2022]
Abstract
Preterm twins have a higher morbidity rate of patent ductus arteriosus (PDA) than do singletons. However, the effect of multiple births on maturation of the ductus arteriosus (DA) has not been reported. Because intimal thickening (IT) is required for DA anatomical closure, we examined IT development in the DA of preterm twins and singletons. Sheep DA tissues obtained from preterm fetuses were subjected to elastica van Gieson staining to evaluate IT. The total IT score in each DA was the sum of the IT scores obtained from six evenly divided parts of the DA, which was positively correlated with gestational ages in singletons. Total IT scores were smaller in preterm twins than in singletons, although no difference in gestational age, birth weight, or gender ratio was observed. These data suggest that IT development of the DA is attenuated in sheep preterm twins, which may affect the higher morbidity of PDA.
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Affiliation(s)
- Satoko Ito
- Cardiovascular Research Institute, Yokohama City University, 3-9, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Utako Yokoyama
- Cardiovascular Research Institute, Yokohama City University, 3-9, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan.
| | - Junichi Saito
- Cardiovascular Research Institute, Yokohama City University, 3-9, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan
| | - Shinichi Sato
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Haruo Usuda
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Shimpei Watanabe
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Ryuta Kitanishi
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Yuichiro Miura
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Masatoshi Saito
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Takushi Hanita
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Tadashi Matsuda
- Center for Perinatal-Neonatal Medicine, Tohoku University Hospital, Sendai, Japan
| | - Yoshihiro Ishikawa
- Cardiovascular Research Institute, Yokohama City University, 3-9, Fukuura, Kanazawa-ku, Yokohama, Kanagawa, 236-0004, Japan.
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11
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Kelly AC, Bidwell CA, McCarthy FM, Taska DJ, Anderson MJ, Camacho LE, Limesand SW. RNA Sequencing Exposes Adaptive and Immune Responses to Intrauterine Growth Restriction in Fetal Sheep Islets. Endocrinology 2017; 158:743-755. [PMID: 28200173 PMCID: PMC5460795 DOI: 10.1210/en.2016-1901] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 02/03/2017] [Indexed: 11/19/2022]
Abstract
The risk of type 2 diabetes is increased in children and adults who exhibited fetal growth restriction. Placental insufficiency and intrauterine growth restriction (IUGR) are common obstetrical complications associated with fetal hypoglycemia and hypoxia that reduce the β-cell mass and insulin secretion. In the present study, we have defined the underlying mechanisms of reduced growth and proliferation, impaired metabolism, and defective insulin secretion previously established as complications in islets from IUGR fetuses. In an IUGR sheep model that recapitulates human IUGR, high-throughput RNA sequencing showed the transcriptome of islets isolated from IUGR and control sheep fetuses and identified the transcripts that underlie β-cell dysfunction. Functional analysis expanded mechanisms involved in reduced proliferation and dysregulated metabolism that include specific cell cycle regulators and growth factors and mitochondrial, antioxidant, and exocytotic genes. These data also identified immune responses, wnt signaling, adaptive stress responses, and the proteasome as mechanisms of β-cell dysfunction. The reduction of immune-related gene expression did not reflect a change in macrophage density within IUGR islets. The present study reports the islet transcriptome in fetal sheep and established processes that limit insulin secretion and β-cell growth in fetuses with IUGR, which could explain the susceptibility to premature islet failure in adulthood. Islet dysfunction formed by intrauterine growth restriction increases the risk for diabetes.
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Affiliation(s)
- Amy C. Kelly
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
| | | | - Fiona M. McCarthy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
| | - David J. Taska
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
| | - Miranda J. Anderson
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
| | - Leticia E. Camacho
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
| | - Sean W. Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona 85719
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Chen X, Kelly AC, Yates DT, Macko AR, Lynch RM, Limesand SW. Islet adaptations in fetal sheep persist following chronic exposure to high norepinephrine. J Endocrinol 2017; 232:285-295. [PMID: 27888197 PMCID: PMC5173394 DOI: 10.1530/joe-16-0445] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 11/08/2022]
Abstract
Complications in pregnancy elevate fetal norepinephrine (NE) concentrations. Previous studies in NE-infused sheep fetuses revealed that sustained exposure to high NE resulted in lower expression of α2-adrenergic receptors in islets and increased insulin secretion responsiveness after acutely terminating the NE infusion. In this study, we determined if the compensatory increase in insulin secretion after chronic elevation of NE is independent of hyperglycemia in sheep fetuses and whether it is persistent in conjunction with islet desensitization to NE. After an initial assessment of glucose-stimulated insulin secretion (GSIS) at 129 ± 1 days of gestation, fetuses were continuously infused for seven days with NE and maintained at euglycemia with a maternal insulin infusion. Fetal GSIS studies were performed again on days 8 and 12. Adrenergic sensitivity was determined in pancreatic islets collected at day 12. NE infusion increased (P < 0.01) fetal plasma NE concentrations and lowered (P < 0.01) basal insulin concentrations compared to vehicle-infused controls. GSIS was 1.8-fold greater (P < 0.05) in NE-infused fetuses compared to controls at both one and five days after discontinuing the infusion. Glucose-potentiated arginine-induced insulin secretion was also enhanced (P < 0.01) in NE-infused fetuses. Maximum GSIS in islets isolated from NE-infused fetuses was 1.6-fold greater (P < 0.05) than controls, but islet insulin content and intracellular calcium signaling were not different between treatments. The half-maximal inhibitory concentration for NE was 2.6-fold greater (P < 0.05) in NE-infused islets compared to controls. These findings show that chronic NE exposure and not hyperglycemia produce persistent adaptations in pancreatic islets that augment β-cell responsiveness in part through decreased adrenergic sensitivity.
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Affiliation(s)
- Xiaochuan Chen
- Chongqing Key Laboratory of Forage & HerbivoreCollege of Animal Science and Technology, Southwest University, Chongqing, China
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
| | - Amy C Kelly
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
| | - Dustin T Yates
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
| | - Antoni R Macko
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
| | - Ronald M Lynch
- Department of PhysiologyUniversity of Arizona, Tucson, Arizona, USA
| | - Sean W Limesand
- School of Animal and Comparative Biomedical SciencesUniversity of Arizona, Tucson, Arizona, USA
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Benjamin JS, Culpepper CB, Brown LD, Wesolowski SR, Jonker SS, Davis MA, Limesand SW, Wilkening RB, Hay WW, Rozance PJ. Chronic anemic hypoxemia attenuates glucose-stimulated insulin secretion in fetal sheep. Am J Physiol Regul Integr Comp Physiol 2017; 312:R492-R500. [PMID: 28100476 PMCID: PMC5407078 DOI: 10.1152/ajpregu.00484.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 01/04/2017] [Accepted: 01/11/2017] [Indexed: 01/15/2023]
Abstract
Fetal insulin secretion is inhibited by acute hypoxemia. The relationship between prolonged hypoxemia and insulin secretion, however, is less well defined. To test the hypothesis that prolonged fetal hypoxemia impairs insulin secretion, studies were performed in sheep fetuses that were bled to anemic conditions for 9 ± 0 days (anemic, n = 19) and compared with control fetuses (n = 15). Arterial hematocrit and oxygen content were 34% and 52% lower, respectively, in anemic vs. control fetuses (P < 0.0001). Plasma glucose concentrations were 21% higher in the anemic group (P < 0.05). Plasma norepinephrine and cortisol concentrations increased 70% in the anemic group (P < 0.05). Glucose-, arginine-, and leucine-stimulated insulin secretion all were lower (P < 0.05) in anemic fetuses. No differences in pancreatic islet size or β-cell mass were found. In vitro, isolated islets from anemic fetuses secreted insulin in response to glucose and leucine as well as control fetal islets. These findings indicate a functional islet defect in anemic fetuses, which likely involves direct effects of low oxygen and/or increased norepinephrine on insulin release. In pregnancies complicated by chronic fetal hypoxemia, increasing fetal oxygen concentrations may improve insulin secretion.
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Affiliation(s)
- Joshua S Benjamin
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - Christine B Culpepper
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - Laura D Brown
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.,Center for Women's Health Research, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - Stephanie R Wesolowski
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado.,Center for Women's Health Research, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - Sonnet S Jonker
- Knight Cardiovascular Institute Center for Developmental Health, Oregon Health & Science University, Portland, Oregon; and
| | - Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Randall B Wilkening
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - William W Hay
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado
| | - Paul J Rozance
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, Colorado; .,Center for Women's Health Research, University of Colorado Denver School of Medicine, Aurora, Colorado
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14
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Brown LD, Davis M, Wai S, Wesolowski SR, Hay WW, Limesand SW, Rozance PJ. Chronically Increased Amino Acids Improve Insulin Secretion, Pancreatic Vascularity, and Islet Size in Growth-Restricted Fetal Sheep. Endocrinology 2016; 157:3788-3799. [PMID: 27501184 PMCID: PMC5045508 DOI: 10.1210/en.2016-1328] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Placental insufficiency is associated with reduced supply of amino acids to the fetus and leads to intrauterine growth restriction (IUGR). IUGR fetuses are characterized by lower glucose-stimulated insulin secretion, smaller pancreatic islets with less β-cells, and impaired pancreatic vascularity. To test whether supplemental amino acids infused into the IUGR fetus could improve these complications of IUGR we used acute (hours) and chronic (11 d) direct fetal amino acid infusions into a sheep model of placental insufficiency and IUGR near the end of gestation. IUGR fetuses had attenuated acute amino acid-stimulated insulin secretion compared with control fetuses. These results were confirmed in isolated IUGR pancreatic islets. After the chronic fetal amino acid infusion, fetal glucose-stimulated insulin secretion and islet size were restored to control values. These changes were associated with normalization of fetal pancreatic vascularity and higher fetal pancreatic vascular endothelial growth factor A protein concentrations. These results demonstrate that decreased fetal amino acid supply contributes to the pathogenesis of pancreatic islet defects in IUGR. Moreover, the results show that pancreatic islets in IUGR fetuses retain their ability to respond to increased amino acids near the end of gestation after chronic fetal growth restriction.
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Affiliation(s)
- Laura D Brown
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Melissa Davis
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Sandra Wai
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Stephanie R Wesolowski
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - William W Hay
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Sean W Limesand
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
| | - Paul J Rozance
- Perinatal Research Center (L.D.B., S.W., W.W.H., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; School of Animal and Comparative Biomedical Sciences (M.D., S.W.L.), University of Arizona, Tucson, Arizona 85719; and Center for Women's Health Research (L.D.B., S.R.W., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045
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15
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Macko AR, Yates DT, Chen X, Shelton LA, Kelly AC, Davis MA, Camacho LE, Anderson MJ, Limesand SW. Adrenal Demedullation and Oxygen Supplementation Independently Increase Glucose-Stimulated Insulin Concentrations in Fetal Sheep With Intrauterine Growth Restriction. Endocrinology 2016; 157:2104-15. [PMID: 26937714 PMCID: PMC4870878 DOI: 10.1210/en.2015-1850] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In pregnancies complicated by placental insufficiency and intrauterine growth restriction (IUGR), fetal glucose and oxygen concentrations are reduced, whereas plasma norepinephrine and epinephrine concentrations are elevated throughout the final third of gestation. Here we study the effects of chronic hypoxemia and hypercatecholaminemia on β-cell function in fetal sheep with placental insufficiency-induced IUGR that is produced by maternal hyperthermia. IUGR and control fetuses underwent a sham (intact) or bilateral adrenal demedullation (AD) surgical procedure at 0.65 gestation. As expected, AD-IUGR fetuses had lower norepinephrine concentrations than intact-IUGR fetuses despite being hypoxemic and hypoglycemic. Placental insufficiency reduced fetal weights, but the severity of IUGR was less with AD. Although basal plasma insulin concentrations were lower in intact-IUGR and AD-IUGR fetuses compared with intact-controls, glucose-stimulated insulin concentrations were greater in AD-IUGR fetuses compared with intact-IUGR fetuses. Interestingly, AD-controls had lower glucose- and arginine-stimulated insulin concentrations than intact-controls, but AD-IUGR and AD-control insulin responses were not different. To investigate chronic hypoxemia in the IUGR fetus, arterial oxygen tension was increased to normal levels by increasing the maternal inspired oxygen fraction. Oxygenation of IUGR fetuses enhanced glucose-stimulated insulin concentrations 3.3-fold in intact-IUGR and 1.7-fold in AD-IUGR fetuses but did not lower norepinephrine and epinephrine concentrations. Together these findings show that chronic hypoxemia and hypercatecholaminemia have distinct but complementary roles in the suppression of β-cell responsiveness in IUGR fetuses.
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Affiliation(s)
- Antoni R Macko
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Dustin T Yates
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Xiaochuan Chen
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Leslie A Shelton
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Amy C Kelly
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Melissa A Davis
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Leticia E Camacho
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Miranda J Anderson
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
| | - Sean W Limesand
- School of Animal and Comparative Biomedical Sciences, The University of Arizona, Tucson, Arizona 85719
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16
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Field ME, Anthony RV, Engle TE, Archibeque SL, Keisler DH, Han H. Duration of maternal undernutrition differentially alters fetal growth and hormone concentrations. Domest Anim Endocrinol 2015; 51:1-7. [PMID: 25460066 DOI: 10.1016/j.domaniend.2014.09.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 09/12/2014] [Accepted: 09/12/2014] [Indexed: 01/12/2023]
Abstract
To investigate the impact of duration of maternal undernutrition in twin sheep pregnancies, ewes were either fed 100% (C) or 50% of their nutrient requirements from 28 to 78 d gestational age (dGA) and readjusted to 100% beginning at 79 dGA (LC) or continuously restricted from 28 to 135 dGA (LL). Weights of the fetus, empty carcass, brain, and liver were greater in the LC than LL fetuses at 135 dGA (P ≤ 0.05). Although umbilical vein (UmV) glucose concentrations did not differ, the UmV:umbilical artery (UmA) glucose gradient was smaller (0.26 ± 0.03 vs 0.38 ± 0.03 and 0.39 ± 0.04 mmol L(-1); P ≤ 0.05) in LL than C and LC fetuses, respectively. Umbilical vein concentrations of IGF-1 were less (46.7 ± 5.62 vs 74.3 ± 6.71 ng/mL; P ≤ 0.05) in LL than LC fetuses. Additionally, LL fetuses tended (P ≤ 0.10) to have lower UmA concentrations of insulin (0.24 ± 0.13 vs 0.70 ± 0.15 ng/mL) and IGF-1 (66.6 ± 7.51 vs 91.4 ± 8.97 ng/mL) than LC fetuses. Although most of the observed differences occurred between LC and LL pregnancies, LC fetuses tended (P ≤ 0.10) to have greater UmV and UmA pCO2 than C fetuses. Furthermore, the UmV:UmA O2 content gradient tended to be greater (5.02 ± 0.43 vs 3.41 ± 0.47; P ≤ 0.10) in C than LL fetuses. UmA placental lactogen also tended to be greater (46.6 ± 4.40 vs 31.1 ± 4.69 ng/mL; P ≤ 0.10) in LL than C fetuses. These data suggest that in twin pregnancies, maternal undernutrition followed by realimentation induces a different fetal outcome compared with continuous nutrient restriction, and both may differ physiologically from control fed pregnancies.
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Affiliation(s)
- M E Field
- Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - R V Anthony
- Animal Reproduction and Biotechnology Laboratory, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - T E Engle
- Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - S L Archibeque
- Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - D H Keisler
- Division of Animal Sciences, University of Missouri, Columbia, MO 65211, USA
| | - H Han
- Department of Animal Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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17
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Andrews SE, Brown LD, Thorn SR, Limesand SW, Davis M, Hay WW, Rozance PJ. Increased adrenergic signaling is responsible for decreased glucose-stimulated insulin secretion in the chronically hyperinsulinemic ovine fetus. Endocrinology 2015; 156:367-76. [PMID: 25343274 PMCID: PMC4272391 DOI: 10.1210/en.2014-1393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Insulin may stimulate its own insulin secretion and is a potent growth factor for the pancreatic β-cell. Complications of pregnancy, such as diabetes and intrauterine growth restriction, are associated with changes in fetal insulin concentrations, secretion, and β-cell mass. However, glucose concentrations are also abnormal in these conditions. The direct effect of chronic fetal hyperinsulinemia with euglycemia on fetal insulin secretion and β-cell mass has not been tested. We hypothesized that chronic fetal hyperinsulinemia with euglycemia would increase glucose-stimulated insulin secretion (GSIS) and β-cell mass in the ovine fetus. Singleton ovine fetuses were infused with iv insulin to produce high physiological insulin concentrations, or saline for 7-10 days. The hyperinsulinemic animals also received a direct glucose infusion to maintain euglycemia. GSIS, measured at 133 ± 1 days of gestation, was significantly attenuated in the hyperinsulinemic fetuses (P < .05). There was no change in β-cell mass. The hyperinsulinemic fetuses also had decreased oxygen (P < .05) and higher norepinephrine (1160 ± 438 vs 522 ± 106 pg/mL; P < .005). Acute pharmacologic adrenergic blockade restored GSIS in the hyperinsulinemic-euglycemic fetuses, demonstrating that increased adrenergic signaling mediates decreased GSIS in these fetuses.
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Affiliation(s)
- Sasha E Andrews
- Department of Obstetrics and Gynecology (S.E.A.), University of Colorado School of Medicine, Aurora, Colorado 80045; Perinatal Research Center (L.D.B., S.R.T., W.W.H., P.J.R.), Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045; Center for Women's Health Research (L.D.B., P.J.R.), University of Colorado School of Medicine, Aurora, Colorado 80045; and School of Animal and Comparative Biomedical Sciences (S.W.L., M.D.), University of Arizona, Tucson, Arizona 85719
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18
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Elevated plasma norepinephrine inhibits insulin secretion, but adrenergic blockade reveals enhanced β-cell responsiveness in an ovine model of placental insufficiency at 0.7 of gestation. J Dev Orig Health Dis 2014; 4:402-10. [PMID: 24358443 DOI: 10.1017/s2040174413000093] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In pregnancies complicated by placental insufficiency (PI), fetal hypoglycemia and hypoxemia progressively worsen during the third trimester, which increases circulating norepinephrine (NE). Pharmacological adrenergic blockade (ADR-block) at 0.9 gestation revealed that NE inhibits insulin secretion and enhanced β-cell responsiveness in fetuses with PI-induced intrauterine growth restriction (IUGR). NE concentrations in PI fetuses at 0.7 gestation were threefold greater compared with age-matched controls, but the levels were similar to near-term controls. Therefore, our objective was to determine whether elevations in plasma NE concentrations inhibit insulin secretion and produce compensatory β-cell responsiveness in PI fetuses at 0.7 gestation. Fetal insulin was measured under basal, glucose-stimulated insulin secretion (GSIS) and glucose-potentiated arginine-stimulated insulin secretion (GPAIS) conditions in the absence and presence of an ADR-block. Placental weights were 38% lower (P < 0.05) in PI fetus than in controls, but fetal weights were not different. PI fetuses had lower (P < 0.05) basal blood oxygen content, plasma glucose, insulin-like growth factor-1 and insulin concentrations and greater plasma NE concentrations (891 ± 211 v. 292 ± 65 pg/ml; P < 0.05) than controls. GSIS was lower in PI fetuses than in controls (0.34 ± 0.03 v. 1.08 ± 0.06 ng/ml; P < 0.05). ADR-block increased GSIS in PI fetuses (1.19 ± 0.11 ng/ml; P < 0.05) but decreased GSIS in controls (0.86 ± 0.02 ng/ml; P < 0.05). Similarly, GPAIS was 44% lower (P < 0.05) in PI fetuses than in controls, and ADR-block increased (P < 0.05) GPAIS in PI fetuses but not in controls. Insulin content per islet was not different between treatments. We conclude that elevations in fetal plasma NE suppress insulin concentrations, and that compensatory β-cell stimulus-secretion responsiveness is present before IUGR.
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Brown LD, Thorn SR, O'Meara MC, Lavezzi JR, Rozance PJ. A physiological increase in insulin suppresses muscle-specific ubiquitin ligase gene activation in fetal sheep with sustained hypoglycemia. Physiol Rep 2014; 2:2/6/e12045. [PMID: 24944291 PMCID: PMC4208658 DOI: 10.14814/phy2.12045] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Decreased glucose transfer to the fetus is characteristic of pregnancies complicated by maternal under nutrition and placental insufficiency. Chronic experimental restriction of glucose transfer to the sheep fetus for the final 40% of gestation with a maternal insulin infusion (HG fetuses) results in fetal hypoglycemia, hypoinsulinemia, and decreased rates of fetal growth and protein accretion compared to controls (CON). Lower rates of fetal protein accretion are due to increased fetal protein breakdown and not decreased protein synthesis. However, the specific skeletal muscle pathways responsible for increased protein breakdown have not been determined. Nor has it been determined if low fetal glucose or insulin concentrations are more important for regulating these skeletal muscle protein breakdown pathways. We tested whether chronic restriction of glucose transfer to the fetus increased the ubiquitin-proteosome pathway or autophagy-lysosome pathway in fetal sheep skeletal muscle and found no evidence for an increase in the autophagy-lysosome pathway. However, HG fetuses had increase mRNA expression of MaFBx1 (twofold, P < 0.01) and a trend for increased mRNA expression of MuRF1 (P = 0.08) compared to CON. A subset of chronically hypoglycemic fetuses received an isoglycemic insulin infusion for the final 7 days of the maternal insulin infusion (HG + INS fetuses) and had MaFBx1 and MuRF1 mRNA concentrations similar to CON fetuses. These results demonstrate that fetuses exposed to sustained hypoglycemia have decreased protein accretion due to activation of the skeletal muscle ubiquitin-proteosome pathway and that a fetal hyperinsulinemic clamp can suppress this pathway even in the context of continued hypoglycemia.
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Affiliation(s)
- Laura D Brown
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA Center for Women's Health Research, University of Colorado Denver, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Stephanie R Thorn
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA Center for Women's Health Research, University of Colorado Denver, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Meghan C O'Meara
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA
| | - Jinny R Lavezzi
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA
| | - Paul J Rozance
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver, Aurora, Colorado, USA Center for Women's Health Research, University of Colorado Denver, University of Colorado School of Medicine, Aurora, Colorado, USA
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Chen X, Green AS, Macko AR, Yates DT, Kelly AC, Limesand SW. Enhanced insulin secretion responsiveness and islet adrenergic desensitization after chronic norepinephrine suppression is discontinued in fetal sheep. Am J Physiol Endocrinol Metab 2014; 306:E58-64. [PMID: 24253046 PMCID: PMC3920003 DOI: 10.1152/ajpendo.00517.2013] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intrauterine growth-restricted (IUGR) fetuses experience prolonged hypoxemia, hypoglycemia, and elevated norepinephrine (NE) concentrations, resulting in hypoinsulinemia and β-cell dysfunction. Previously, we showed that acute adrenergic blockade revealed enhanced insulin secretion responsiveness in the IUGR fetus. To determine whether chronic exposure to NE alone enhances β-cell responsiveness afterward, we continuously infused NE into fetal sheep for 7 days and, after terminating the infusion, evaluated glucose-stimulated insulin secretion (GSIS) and glucose-potentiated arginine-induced insulin secretion (GPAIS). During treatment, NE-infused fetuses had greater (P < 0.05) plasma NE concentrations and exhibited hyperglycemia (P < 0.01) and hypoinsulinemia (P < 0.01) compared with controls. GSIS during the NE infusion was also reduced (P < 0.05) compared with pretreatment values. GSIS and GPAIS were approximately fourfold greater (P < 0.01) in NE fetuses 3 h after the 7 days that NE infusion was discontinued compared with age-matched controls or pretreatment GSIS and GPAIS values of NE fetuses. In isolated pancreatic islets from NE fetuses, mRNA concentrations of adrenergic receptor isoforms (α1D, α2A, α2C, and β1), G protein subunit-αi-2, and uncoupling protein 2 were lower (P < 0.05) compared with controls, but β-cell regulatory genes were not different. Our findings indicate that chronic exposure to elevated NE persistently suppresses insulin secretion. After removal, NE fetuses demonstrated a compensatory enhancement in insulin secretion that was associated with adrenergic desensitization and greater stimulus-secretion coupling in pancreatic islets.
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Affiliation(s)
- Xiaochuan Chen
- College of Animal Science and Technology, Southwest University, Chongqing, China; and
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Bloomfield FH, Spiroski AM, Harding JE. Fetal growth factors and fetal nutrition. Semin Fetal Neonatal Med 2013; 18:118-123. [PMID: 23639574 DOI: 10.1016/j.siny.2013.03.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Optimal fetal growth is important for a healthy pregnancy outcome and also for lifelong health. Fetal growth is largely regulated by fetal nutrition, and mediated via the maternal and fetal glucose/insulin/insulin-like growth factor axes. Fetal nutrition may reflect maternal nutrition, but abnormalities of placental function can also affect fetal growth, as the placenta plays a key intermediary role in nutritional signalling between mother and fetus. Fetal nutrition also impacts on the development of key fetal endocrine systems such as the glucose-insulin and insulin-like growth factor axes. This is likely to contribute to the link between both fetal growth restriction and fetal overgrowth, and increased risks of obesity and impaired glucose tolerance in later life. This review focuses on the associations between maternal and fetal nutrition, fetal growth and later disease risk, with particular emphasis on the role of insulin-like growth factors and the importance of the periconceptional period.
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Affiliation(s)
- F H Bloomfield
- Liggins Institute, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Gravida: National Centre for Growth and Development, University of Auckland, Auckland, New Zealand; Department of Paediatrics: Child and Youth Health, University of Auckland, Auckland, New Zealand
| | - Ana-Mishel Spiroski
- Liggins Institute, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand; Gravida: National Centre for Growth and Development, University of Auckland, Auckland, New Zealand
| | - J E Harding
- Liggins Institute, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand.
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22
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Limesand SW, Rozance PJ, Macko AR, Anderson MJ, Kelly AC, Hay WW. Reductions in insulin concentrations and β-cell mass precede growth restriction in sheep fetuses with placental insufficiency. Am J Physiol Endocrinol Metab 2013; 304:E516-23. [PMID: 23277186 PMCID: PMC3602661 DOI: 10.1152/ajpendo.00435.2012] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In pregnancy complicated by placental insufficiency (PI) and intrauterine growth restriction (IUGR), the fetus near term has reduced basal and glucose-stimulated insulin concentrations and reduced β-cell mass. To determine whether suppression of insulin concentrations and β-cell mass precedes reductions in fetal weight, which would implicate insulin deficiency as a cause of subsequent IUGR, we measured basal and glucose-stimulated insulin concentrations and pancreatic histology at 0.7 gestation in PI fetuses. Placental weights in the PI pregnancies were 40% lower than controls (265 ± 26 vs. 442 ± 41 g, P < 0.05), but fetal weights were not different. At basal conditions blood oxygen content, plasma glucose concentrations, and plasma insulin concentrations were lower in PI fetuses compared with controls (2.5 ± 0.3 vs. 3.5 ± 0.3 mmol/l oxygen, P < 0.05; 1.11 ± 0.09 vs. 1.44 ± 0.12 mmol/l glucose; 0.12 ± 0.01 vs. 0.27 ± 0.02 ng/ml insulin; P < 0.05). During a steady-state hyperglycemic clamp (~2.5 ± 0.1 mmol/l), glucose-stimulated insulin concentrations were lower in PI fetuses than controls (0.28 ± 0.02 vs. 0.55 ± 0.04 ng/ml; P < 0.01). Plasma norepinephrine concentrations were 3.3-fold higher (P < 0.05) in PI fetuses (635 ± 104 vs. 191 ± 91 pg/ml). Histological examination revealed less insulin area and lower β-cell mass and rates of mitosis. The pancreatic parenchyma was also less dense (P < 0.01) in PI fetuses, but no differences were found for pancreatic progenitor cells or other endocrine cell types. These findings show that hypoglycemia, hypoxemia, and hypercatecholaminemia are present and potentially contribute to lower insulin concentrations and β-cell mass due to slower proliferation rates in early third-trimester PI fetuses before discernible reductions in fetal weight.
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Affiliation(s)
- Sean W Limesand
- Dept. of Animal Sciences, Univ. of Arizona, 1650 E. Limberlost Dr., Tucson, AZ 85719, USA.
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23
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Rae M, Grace C, Hogg K, Wilson LM, McHaffie SL, Ramaswamy S, MacCallum J, Connolly F, McNeilly AS, Duncan C. The pancreas is altered by in utero androgen exposure: implications for clinical conditions such as polycystic ovary syndrome (PCOS). PLoS One 2013; 8:e56263. [PMID: 23457541 PMCID: PMC3574134 DOI: 10.1371/journal.pone.0056263] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/07/2013] [Indexed: 11/18/2022] Open
Abstract
Using an ovine model of polycystic ovary syndrome (PCOS), (pregnant ewes injected with testosterone propionate (TP) (100 mg twice weekly) from day (d)62 to d102 of d147 gestation (maternal injection - MI-TP)), we previously reported female offspring with normal glucose tolerance but hyperinsulinemia. We therefore examined insulin signalling and pancreatic morphology in these offspring using quantitative (Q) RT-PCR and western blotting. In addition the fetal pancreatic responses to MI-TP, and androgenic and estrogenic contributions to such responses (direct fetal injection (FI) of TP (20 mg) or diethylstilbestrol (DES) (20 mg) at d62 and d82 gestation) were assessed at d90 gestation. Fetal plasma was assayed for insulin, testosterone and estradiol, pancreatic tissue was cultured, and expression of key β-cell developmental genes was assessed by QRT-PCR. In female d62MI-TP offspring insulin signalling was unaltered but there was a pancreatic phenotype with increased numbers of β-cells (P<0.05). The fetal pancreas expressed androgen receptors in islets and genes involved in β-cell development and function (PDX1, IGF1R, INSR and INS) were up-regulated in female fetuses after d62MI-TP treatment (P<0.05-0.01). In addition the d62MI-TP pancreas showed increased insulin secretion under euglycaemic conditions (P<0.05) in vitro. The same effects were not seen in the male fetal pancreas or when MI-TP was started at d30, before the male programming window. As d62MI-TP increased both fetal plasma testosterone (P<0.05) and estradiol concentrations (P<0.05) we assessed the relative contribution of androgens and estrogens. FI-TP (commencing d62) (not FI-DES treatment) caused elevated basal insulin secretion in vitro and the genes altered by d62MI-TP treatment were similarly altered by FI-TP but not FI-DES. In conclusion, androgen over-exposure alters fetal pancreatic development and β-cell numbers in offspring. These data suggest that that there may be a primary pancreatic phenotype in models of PCOS, and that there may be a distinct male and female pancreas.
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Affiliation(s)
- Mick Rae
- School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh, United Kingdom.
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24
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Gadhia MM, Maliszewski AM, O'Meara MC, Thorn SR, Lavezzi JR, Limesand SW, Hay WW, Brown LD, Rozance PJ. Increased amino acid supply potentiates glucose-stimulated insulin secretion but does not increase β-cell mass in fetal sheep. Am J Physiol Endocrinol Metab 2013; 304:E352-62. [PMID: 23211516 PMCID: PMC3566506 DOI: 10.1152/ajpendo.00377.2012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amino acids and glucose acutely stimulate fetal insulin secretion. In isolated adult pancreatic islets, amino acids potentiate glucose-stimulated insulin secretion (GSIS), but whether amino acids have this same effect in the fetus is unknown. Therefore, we tested the effects of increased fetal amino acid supply on GSIS and morphology of the pancreas. We hypothesized that increasing fetal amino acid supply would potentiate GSIS. Singleton fetal sheep received a direct intravenous infusion of an amino acid mixture (AA) or saline (CON) for 10-14 days during late gestation to target a 25-50% increase in fetal branched-chain amino acids (BCAA). Early-phase GSIS increased 150% in the AA group (P < 0.01), and this difference was sustained for the duration of the hyperglycemic clamp (105 min) (P < 0.05). Glucose-potentiated arginine-stimulated insulin secretion (ASIS), pancreatic insulin content, and pancreatic glucagon content were similar between groups. β-Cell mass and area were unchanged between groups. Baseline and arginine-stimulated glucagon concentrations were increased in the AA group (P < 0.05). Pancreatic α-cell mass and area were unchanged. Fetal and pancreatic weights were similar. We conclude that a sustained increase of amino acid supply to the normally growing late-gestation fetus potentiated fetal GSIS but did not affect the morphology or insulin content of the pancreas. We speculate that increased β-cell responsiveness (insulin secretion) following increased amino acid supply may be due to increased generation of secondary messengers in the β-cell. This may be enhanced by the paracrine action of glucagon on the β-cell.
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Affiliation(s)
- Monika M Gadhia
- Perinatal Research Center, Department of Pediatrics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA
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25
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van der Linden DS, Sciascia Q, Sales F, McCoard SA. Placental nutrient transport is affected by pregnancy rank in sheep. J Anim Sci 2012; 91:644-53. [PMID: 23097400 DOI: 10.2527/jas.2012-5629] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Understanding the link between placental function and fetal growth is critical to comprehend the mechanisms underlying altered fetal growth. This study investigated the relationship between fetal weight and placentome type and size in placentae of singleton and twin fetuses and fetuses within a twin pair from ad libitum-fed ewes at d 140 of pregnancy. In addition, insulin, IGF-I, metabolites, and free AA profiles in fetal, umbilical artery, and vein plasma of singleton and twin fetuses were investigated and used as an indicator of placental nutrient transport. Individual placentae per fetus were dissected, placentomes were classed per type (A to D) and size (light to heavy), and placentome number and individual weight were recorded. Twin fetuses were 16% lighter (P = 0.01) than singletons and had a smaller placenta, with 28% decreased placentome weight (P = 0.03) and 35% fewer placentomes (P = 0.001). Twins also had a different distribution of placentome type and size compared with placentae of singletons, such that twins showed a greater proportion of type B and light placentomes compared with singletons. In twins, umbilical artery plasma had less Glu (P < 0.05) and greater Gln (P < 0.05) concentrations than fetal plasma or umbilical vein plasma, but no differences in AA concentrations were observed between these pools in singletons. Glutamate is a major oxidation energy source for the placenta, and the fetal liver is the net producer of Glu using Gln as its main precursor, indicating that the functionality of the fetoplacental unit may be different between singletons and twins. Twin fetuses had 13% less insulin (P = 0.04) concentrations in umbilical artery plasma than singletons. plasma of twin fetuses had 39% less IGF-I (P = 0.003), 33% less His (P = 0.03), and 22% less Gln (P = 0.02) concentrations and tended to have 44% less Arg (P = 0.07) and 20% less Leu (P = 0.06) concentrations than singletons. Arginine, His, and Leu are examples of AA that can promote insulin secretion, and in turn, insulin can increase fetal IGF-I concentrations. In addition, insulin and IGF-I are important fetal growth factors by stimulating and regulating AA transport across the placenta. Collectively, these results indicate that the functionality of the fetoplacental unit may be different between singletons and twins and that AA transport may be reduced in twin placentae.
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Affiliation(s)
- D S van der Linden
- Animal Nutrition and Health, AgResearch, Grasslands Research Centre, Palmerston North, New Zealand.
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26
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Differential effects of chronic pulsatile versus chronic constant maternal hyperglycemia on fetal pancreatic β-cells. J Pregnancy 2012; 2012:812094. [PMID: 23133755 PMCID: PMC3486011 DOI: 10.1155/2012/812094] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/02/2012] [Indexed: 11/17/2022] Open
Abstract
Constant maternal hyperglycemia limits, while pulsatile maternal hyperglycemia may enhance, fetal glucose-stimulated insulin secretion (GSIS) in sheep. However, the impact of such different patterns of hyperglycemia on the development of the fetal β-cell is unknown. We measured the impact of one week of chronic constant hyperglycemia (CHG, n = 6) versus pulsatile hyperglycemia (PHG, n = 5) versus controls (n = 7) on the percentage of the fetal pancreas staining for insulin (β-cell area), mitotic and apoptotic indices and size of fetal β-cells, and fetal insulin secretion in sheep. Baseline insulin concentrations were higher in CHG fetuses (P < 0.05) compared to controls and PHG. GSIS was lower in the CHG group (P < 0.005) compared to controls and PHG. PHG β-cell area was increased 50% (P < 0.05) compared to controls and CHG. CHG β-cell apoptosis was increased over 400% (P < 0.05) compared to controls and PHG. These results indicate that late gestation constant maternal hyperglycemia leads to significant β-cell toxicity (increased apoptosis and decreased GSIS). Furthermore, pulsatile maternal hyperglycemia increases pancreatic β-cell area but did not increase GSIS, indicating decreased β-cell responsiveness. These findings demonstrate differential effects that the pattern of maternal hyperglycemia has on fetal pancreatic β-cell development, which might contribute to later life limitation in insulin secretion.
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27
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Morel O, Laporte-Broux B, Tarrade A, Chavatte-Palmer P. The use of ruminant models in biomedical perinatal research. Theriogenology 2012; 78:1763-73. [PMID: 22925634 DOI: 10.1016/j.theriogenology.2012.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Revised: 06/05/2012] [Accepted: 06/10/2012] [Indexed: 01/21/2023]
Abstract
Animal models are of critical importance in biomedical research. Although rodents and lagomorphs are the most commonly used species, larger species are required, especially when surgical approaches or new medical devices have to be evaluated. In particular, in the field of perinatal medicine, they are critical for the evaluation of new pharmacologic treatments and the development of new invasive procedures in fetuses. In some areas, such as developmental genetics, reproductive biotechnologies and metabolic programming, the contribution of ruminants is essential. The current report focuses on some of the most outstanding examples of great biomedical advances carried out with ruminant models in the field of perinatal research. Experiments recently carried in our research unit using ruminants are also briefly described.
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Affiliation(s)
- O Morel
- INRA, UMR1198 Biologie du Développement et Reproduction, Jouy-en-Josas, France
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28
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Yates DT, Macko AR, Chen X, Green AS, Kelly AC, Anderson MJ, Fowden AL, Limesand SW. Hypoxaemia-induced catecholamine secretion from adrenal chromaffin cells inhibits glucose-stimulated hyperinsulinaemia in fetal sheep. J Physiol 2012; 590:5439-47. [PMID: 22907052 DOI: 10.1113/jphysiol.2012.237347] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Abstract Hypoxaemia elicits adrenergic suppression of fetal glucose-stimulated hyperinsulinaemia. We postulate that this effect is mediated by catecholamines, exclusively, from fetal adrenal chromaffin cells. To investigate this hypothesis, square-wave hyperglycaemic clamp studies were performed under normoxaemic (26 ± 0.9 mmHg) and hypoxaemic (14 ± 0.3 mmHg) steady-state conditions in near-term fetal sheep that had undergone either surgical sham or bilateral adrenal demedullation (AD), values mentioned are ± SEM. Under normoxaemic conditions plasma noradrenaline concentrations were lower in AD fetuses than in sham-operated fetuses (457 ± 122 versus 1073 ± 103 pg ml(-1), P < 0.05). Plasma insulin concentrations were not different at euglycaemia between shams (0.46 ± 0.07 ng ml(-1)) and AD fetuses (0.44 ± 0.04 ng ml(-1)) and increased (P < 0.05) with hyperglycaemia in both groups although to a lesser extent in AD fetuses (0.94 ± 0.19 ng ml(-1)) compared to shams (1.31 ± 0.15 ng ml(-1); P < 0.05). Hypoxaemia increased plasma adrenaline (26-fold) and noradrenaline (5-fold) in shams but elicited no change in AD fetuses. Under hypoxaemic conditions, euglycaemic plasma insulin concentrations were reduced (P < 0.05) in both sham and AD fetuses to 0.30 ± 0.05 ng ml(-1) and 0.27 ± 0.01 ng ml(-1) respectively, and the insulin response to hyperglycaemia was abolished in shams but not affected in AD fetuses (0.33 ± 0.06 versus 0.73 ± 0.02 ng ml(-1), P < 0.05). Hypoxaemia also induced hyperlactacaemia and hypocarbia to a greater extent in shams than in AD fetuses, indicating that catecholamines potentiate reductions in oxidative metabolism independently of insulin. These findings demonstrate that the fetal adrenal chromaffin cells are the source for acute hypoxaemia-induced elevations in fetal plasma catecholamines and suppression of glucose-stimulated hyperinsulinaemia, but other factors reduce plasma insulin at euglycaemia.
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Affiliation(s)
- Dustin T Yates
- Department of Animal Sciences, University of Arizona, Tucson, AZ 85719, USA
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29
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Green AS, Chen X, Macko AR, Anderson MJ, Kelly AC, Hart NJ, Lynch RM, Limesand SW. Chronic pulsatile hyperglycemia reduces insulin secretion and increases accumulation of reactive oxygen species in fetal sheep islets. J Endocrinol 2012; 212:327-42. [PMID: 22182602 PMCID: PMC3516619 DOI: 10.1530/joe-11-0300] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Children from diabetic pregnancies have a greater incidence of type 2 diabetes. Our objective was to determine if exposure to mild-moderate hyperglycemia, by modeling managed diabetic pregnancies, affects fetal β-cell function. In sheep fetuses, β-cell responsiveness was examined after 2 weeks of sustained hyperglycemia with 3 pulses/day, mimicking postprandial excursions, and compared to saline-infused controls (n = 10). Two pulsatile hyperglycemia (PHG) treatments were studied: mild (mPHG, n = 5) with +15% sustained and +55% pulse; and moderate (PHG, n = 10) with +20% sustained and +100% pulse. Fetal glucose-stimulated insulin secretion and glucose-potentiated arginine insulin secretion were lower (P < 0.05) in PHG (0.86 ± 0.13 and 2.91 ± 0.39 ng/ml plasma insulin) but not in mPHG fetuses (1.21 ± 0.08 and 4.25 ± 0.56 ng/ml) compared to controls (1.58 ± 0.25 and 4.51 ± 0.56 ng/ml). Islet insulin content was 35% lower in PHG and 35% higher in mPHG vs controls (P < 0.01). Insulin secretion and maximally stimulated insulin release were also reduced (P < 0.05) in PHG islets due to lower islet insulin content. Isolated PHG islets also had 63% greater (P < 0.01) reactive oxygen species (ROS) accumulation at 11.1 mmol/l glucose than controls (P < 0.01), but oxidative damage was not detected in islet proteins. PHG fetuses showed evidence of oxidative damage to skeletal muscle proteins (P < 0.05) but not insulin resistance. Our findings show that PHG induced dysregulation of islet ROS handling and decreased islet insulin content, but these outcomes are independent. The β-cell outcomes were dependent on the severity of hyperglycemia because mPHG fetuses had no distinguishable impairments in ROS handling or insulin secretion but greater insulin content.
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Affiliation(s)
- Alice S. Green
- Department of Animal Sciences, University of Arizona, Tucson AZ
| | - Xiaochuan Chen
- Department of Animal Sciences, University of Arizona, Tucson AZ
| | - Antoni R. Macko
- Department of Animal Sciences, University of Arizona, Tucson AZ
| | | | - Amy C. Kelly
- Department of Animal Sciences, University of Arizona, Tucson AZ
| | - Nathaniel J. Hart
- Departments of Pharmacology and Physiology, University of Arizona, Tucson AZ
| | - Ronald M. Lynch
- Departments of Pharmacology and Physiology, University of Arizona, Tucson AZ
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Hancock SN, Oliver MH, McLean C, Jaquiery AL, Bloomfield FH. Size at birth and adult fat mass in twin sheep are determined in early gestation. J Physiol 2011; 590:1273-85. [PMID: 22183720 DOI: 10.1113/jphysiol.2011.220699] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Size at birth is related to adult health outcomes. Twins are born smaller than singletons; this has been assumed to be secondary to limited nutrient supply in late gestation.We hypothesised that growth trajectory in twins, and the adult consequences of being conceived a twin, are determined in early gestation. Twin pregnancies in sheep were randomised to reduction of one twin on day 42 of a 148 day pregnancy by intra-thoracic KCl (Reductions, n =46) or a sham procedure (Twins, n =22). Singleton-bearing ewes also underwent a sham procedure (n =27). Ewes lambed spontaneously. Linear measures of size at birth were similar in Twins and Reductions, and significantly less than in Singletons. Birthweight was lower in Twins and Reductions than in Singletons, and less in Twins than in Reductions (means (SEM): Singletons, liveborn n =23: 6.59 (0.17) kg; Twins, liveborn n =36: 5.23 (0.16) kg; Reductions, liveborn n =27: 5.76 (0.15) kg; all comparisons P <0.05). Reductions grew most rapidly between birth and weaning (Singletons, 20.0 (0.4) g kg⁻¹ day⁻¹; Twins, 20.0 (0.3) g kg⁻¹ day⁻¹; Reductions, 21.0 (0.3) g kg⁻¹ day⁻¹, P <0.05) and were of similar weight as Singletons by weaning; Twins remained smaller by weaning but grew most rapidly thereafter (Singletons, 1.6 (0.1) g kg⁻¹ day⁻¹; Twins, 2.1 (0.1) g kg⁻¹ day⁻¹; Reductions, 1.6 (0.1) g kg⁻¹ day⁻¹, P <0.01), so that all groups had similar weight at 2 years. However, Twins and Reductions had greater percentage fat mass than Singletons at 2 years (Singletons, 11.1 (1.1)%; Twins, 14.8 (1.2)%; Reductions, 15.5 (1.1)%, P <0.05). Thus, in twins, fetal growth trajectory, linear size at birth and adult fat mass are largely determined in early gestation. If this is also true in humans, there are important implications for interventions aimed at optimising fetal growth and pregnancy outcome.
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Affiliation(s)
- S N Hancock
- Liggins Institute, University of Auckland and National Research Centre for Growth and Development, Auckland, New Zealand
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