Consequences of a compromised intrauterine environment on islet function

Can sonographic imaging of the fetal pancreas predict perinatal outcomes in gestational diabetes mellitus?

OBJECTIVES

To evaluate whether fetal pancreatic echogenicity and its measurements are associated with gestational diabetes mellitus (GDM) and perinatal outcomes.

METHODS

A prospective cohort study was conducted with 150 pregnant women with a singleton pregnancy. The study included pregnant women between 30 and 41 weeks with or without GDM. Fetal pancreatic circumference was measured using the free-hand tracking function. The echogenicity of the fetal pancreas was compared with the echogenicity of the liver and bone (ribs, spine) and classified as Grades 1, 2 and 3. The relationship between maternal characteristics and perinatal outcomes with fetal pancreas measurements and echogenicity was evaluated.

RESULTS

Pregnant women with 75 GDM and 75 without GDM were included in the study. Mean fetal pancreas circumference measurements were significantly higher in pregnant women with GDM than in those without GDM (p=0.001). Hyperechogenic (Grade 3) fetal pancreas was significantly higher in pregnant women with GDM than in pregnant women without GDM, and there was a positive correlation between pancreatic echogenicity and HbA_1c levels in pregnant women with GDM (r=0.631, p<0.01). There was a significant relationship between pancreatic echogenicity, measurements and adverse neonatal outcomes in pregnant women with GDM, and pancreas measurements were significantly higher in pregnant women with cesarean delivery.

CONCLUSIONS

Fetal pancreatic echogenicity and measurements in pregnant women with GDM can give an idea about glucose regulation and adverse perinatal outcomes.

Prenatal dexamethasone exposure induced pancreatic β-cell dysfunction and glucose intolerance of male offspring rats: Role of the epigenetic repression of ACE2

The prevalence of diabetes in children and adolescents has been rising gradually, which is relevant to adverse environment during development, especially prepartum. We aimed to explore the effects of prenatal dexamethasone exposure (PDE) on β-cell function and glucose homeostasis in juvenile offspring rats. Pregnant Wistar rats were subcutaneously administered with dexamethasone [0.1, 0.2, 0.4mg/(kg.d)] from gestational day 9 to 20. PDE impaired glucose tolerance in the male offspring rather than the females. In male offspring, PDE impaired the development and function of β-cells, accompanied with lower H3K9ac, H3K14ac and H3K27ac levels in the promoter region of angiotensin-converting enzyme 2 (ACE2) as well as suppressed ACE2 expression. Meanwhile, PDE increased expression of glucocorticoid receptor (GR) and histone deacetylase 3 (HDAC3) in fetal pancreas. Dexamethasone also inhibited ACE2 expression and insulin production in vitro. Recombinant expression of ACE2 restored insulin production inhibited by dexamethasone. In addition, dexamethasone activated GR and HDAC3, increased protein interaction of GR with HDAC3, and promoted the binding of GR-HDAC3 complex to ACE2 promoter region. Both RU486 and TSA abolished dexamethasone-induced decline of histone acetylation and ACE2 expression. In summary, suppression of ACE2 is involved in PDE induced β-cell dysfunction and glucose intolerance in juvenile male offspring rats.

Association between fetal famine exposure and risk of type 2 diabetes: a prospective cohort study

The objective of this study was to explore the effects of fetal experience of famine on the onset of type 2 diabetes mellitus (T2DM) in adults. The analysis included 16 594 participants from the Kailuan Study who were free of diabetes at baseline (2006). According to the date of birth, the individuals born on October 1, 1962 - September 30, 1964, were divided into the non-exposed group (used as the reference group), individuals born on October 1, 1959 - September 30, 1961, were divided into the fetal exposure group, and the early childhood exposure group included those born on October 1, 1956 - September 30, 1958. The cumulative incidence of T2DM for each group was calculated and compared among the 3 groups, and the Cox regression model was used to analyze the effects of fetal famine experience on the risk of diabetes. During a median 10.27 years (170 358 person-years) (2006-2017), 3509 incident T2DM cases were identified, with a cumulative incidence rate of 19.46%. The cumulative incidences of T2DM in the non-exposed, fetal exposure, and early childhood exposure groups were 17.38%, 20.85%, and 20.65%, respectively (P < 0.01). After adjusting for confounding factors, the hazard ratio (HR) of T2DM in the fetal exposure group was 1.222 (95% confidence interval: 1.087-1.374, P < 0.01), compared with the reference group. The association was modified by sex and hypertension (both P interaction less than 0.05). Fetal famine exposure may increase the risk of developing T2DM in adults. This association was more pronounced among women and those with hypertension. Novelty: The association was modified by sex and hypertension. Long follow-up time.

Placenta-specific Slc38a2/SNAT2 knockdown causes fetal growth restriction in mice

Fetal growth restriction (FGR) is a complication of pregnancy that reduces birth weight, markedly increases infant mortality and morbidity and is associated with later-life cardiometabolic disease. No specific treatment is available for FGR. Placentas of human FGR infants have low abundance of sodium-coupled neutral amino acid transporter 2 (Slc38a2/SNAT2), which supplies the fetus with amino acids required for growth. We determined the mechanistic role of placental Slc38a2/SNAT2 deficiency in the development of restricted fetal growth, hypothesizing that placenta-specific Slc38a2 knockdown causes FGR in mice. Using lentiviral transduction of blastocysts with a small hairpin RNA (shRNA), we achieved 59% knockdown of placental Slc38a2, without altering fetal Slc38a2 expression. Placenta-specific Slc38a2 knockdown reduced near-term fetal and placental weight, fetal viability, trophoblast plasma membrane (TPM) SNAT2 protein abundance, and both absolute and weight-specific placental uptake of the amino acid transport System A tracer, 14C-methylaminoisobutyric acid (MeAIB). We also measured human placental SLC38A2 gene expression in a well-defined term clinical cohort and found that SLC38A2 expression was decreased in late-onset, but not early-onset FGR, compared with appropriate for gestational age (AGA) control placentas. The results demonstrate that low placental Slc38a2/SNAT2 causes FGR and could be a target for clinical therapies for late-onset FGR.

Western-style diet consumption impairs maternal insulin sensitivity and glucose metabolism during pregnancy in a Japanese macaque model

The prevalence of maternal obesity is increasing in the United States. Offspring born to women with obesity or poor glycemic control have greater odds of becoming obese and developing metabolic disease later in life. Our group has utilized a macaque model to study the metabolic effects of consumption of a calorically-dense, Western-style diet (WSD; 36.3% fat) during pregnancy. Here, our objective was to characterize the effects of WSD and obesity, alone and together, on maternal glucose tolerance and insulin levels in dams during each pregnancy. Recognizing the collinearity of maternal measures, we adjusted for confounding factors including maternal age and parity. Based on intravenous glucose tolerance tests, dams consuming a WSD showed lower glucose area under the curve during first study pregnancies despite increased body fat percentage and increased insulin area under the curve. However, with (1) prolonged WSD feeding, (2) multiple diet switches, and/or (3) increasing age and parity, WSD was associated with increasingly higher insulin levels during glucose tolerance testing, indicative of insulin resistance. Our results suggest that prolonged or recurrent calorically-dense WSD and/or increased parity, rather than obesity per se, drive excess insulin resistance and metabolic dysfunction. These observations in a highly relevant species are likely of clinical and public health importance given the comparative ease of maternal dietary modifications relative to the low likelihood of successfully reversing obesity in the course of any given pregnancy.

Reduced glucose-stimulated insulin secretion following a 1-wk IGF-1 infusion in late gestation fetal sheep is due to an intrinsic islet defect

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.

Obesity and Metabolic Care of Children of South Asian Ethnicity in Western Society

South Asians constitute one-fourth of the world’s population and are distributed significantly in western countries. With exponentially growing numbers, childhood obesity is of global concern. Children of South Asian ancestry have a higher likelihood of developing obesity and associated metabolic risks. The validity of commonly used measures for quantifying adiposity and its impact on metabolic outcomes differ by race and ethnicity. In this review we aim to discuss the validity of body mass index (BMI) and other tools in screening for adiposity in South Asian children. We also discuss the prevalence of overweight and obesity amongst South Asian children in western countries and the differences in body fat percentage, adiposity distribution, and metabolic risks specific to these children compared to Caucasian children. South Asian children have a characteristic phenotype: lower lean mass and higher body fat percentage favoring central fat accumulation. Hence, BMI is a less reliable predictor of metabolic status in these children than it is for Caucasian children. Furthermore, the relatively lower birth weight and rapid growth acceleration in early childhood of South Asian children increase the risk of their developing cardiometabolic disorders at a younger age than that of Caucasians. We emphasize the need to use modified tools for assessment of adiposity, which take into consideration the ethnic differences and provide early and appropriate intervention to prevent obesity and its complications.

Chronically elevated norepinephrine concentrations lower glucose uptake in fetal sheep

Fetal conditions associated with placental insufficiency and intrauterine growth restriction (IUGR) chronically elevate plasma norepinephrine (NE) concentrations. Our objective was to evaluate the effects of chronically elevated NE on insulin-stimulated glucose metabolism in normally grown, non-IUGR fetal sheep, which are independent of other IUGR-related reductions in nutrients and oxygen availability. After surgical placement of catheters, near-term fetuses received either a saline (control) or NE intravenous infusion with controlled euglycemia. In NE fetuses, plasma NE concentrations were 5.5-fold greater than controls, and fetal euglycemia was maintained with a maternal insulin infusion. Insulin secretion was blunted in NE fetuses during an intravenous glucose tolerance test. Weight-specific fluxes for glucose were measured during a euinsulinemic-euglycemic clamp (EEC) and a hyperinsulinemic-euglycemic clamp (HEC). Plasma glucose and insulin concentrations were not different between groups within each clamp, but insulin concentrations increased 10-fold between the EEC and the HEC. During the EEC, rates of glucose uptake (umbilical uptake + exogenous infusion) and glucose utilization were 47% and 35% lower (P < 0.05) in NE fetuses compared with controls. During the HEC, rates of glucose uptake were 28% lower (P < 0.05) in NE fetuses than controls. Glucose production was undetectable in either group, and glucose oxidation was unaffected by the NE infusion. These findings indicate that chronic exposure to high plasma NE concentrations lowers rates of net glucose uptake in the fetus without affecting glucose oxidation rates or initiating endogenous glucose production. Lower fetal glucose uptake was independent of insulin, which indicates insulin resistance as a consequence of chronically elevated NE.

Epigenetic repression of AT2 receptor is involved in β cell dysfunction and glucose intolerance of adult female offspring rats exposed to dexamethasone prenatally

Prenatal exposure to dexamethasone (PDE) impairs pancreatic β cell development and glucose homeostasis in offspring especially females. To explore the underlying intrauterine programming mechanism, pregnant Wistar rats were subcutaneously administered with dexamethasone (0, 0.2 and 0.8 mg/kg·d) from gestational days (GD) 9 to 20. Female offspring were collected on GD20 (fetus) and in postnatal week 28 (adult), respectively. PDE reduced the serum insulin levels, β cell mass, and pancreatic insulin expressions in fetuses and adults, causing glucose intolerance after maturity. The persistent suppression of pancreatic angiotensin II receptor type 2 (AT2R) expression before and after birth could be observed in the PDE females, which is accompanied with decreased histone 3 lysine 14 acetylation (H3K14ac) and H3K27ac levels in AT2R promoter. PDE increased the gene expressions of glucocorticoid receptor (GR) and histone deacetylase 2 (HDAC2) in fetal pancreas. Furthermore, dexamethasone inhibited insulin biosynthesis while activated GR and HDAC2 expression in the rat INS-1 cells. The AT2R expression was repressed by dexamethasone in vitro but only H3K27ac levels in AT2R promoter were lowered. Dexamethasone enhanced the interaction between GR and HDAC2 proteins as well as the binding of GR/HDAC2 complex to AT2R promoter. Moreover, overexpression of AT2R could restore the suppressed insulin biosynthesis induced by dexamethasone in vitro, and both GR antagonist and histone deacetylase abolished the decreased H3K27ac level and gene expression of AT2R. In conclusion, continuous epigenetic repression of AT2R before and after birth may be involved in β cell dysfunction and glucose intolerance of the PDE adult female offspring.

Early-life Programming of Type 2 Diabetes Mellitus: Understanding the Association between Epigenetics/Genetics and Environmental Factors

Type 2 Diabetes Mellitus is an increasing public health problem that poses a severe social and economic burden affecting both developed and developing countries. Defects in insulin signaling itself are among the earliest indications that an individual is predisposed to the development of insulin resistance and subsequently Type 2 Diabetes Mellitus. To date, however, the underlying molecular mechanisms which result in resistance to the actions of insulin are poorly understood. Furthermore, it has been shown that maternal obesity is associated with an increased risk of obesity and insulin resistance in the offspring. However, the genetic and/or epigenetic modifications within insulin-sensitive tissues such as the liver and skeletal muscle, which contribute to the insulin-resistant phenotype, still remain unknown. More importantly, a lack of in-depth understanding of how the early life environment can have long-lasting effects on health and increased risk of Type 2 Diabetes Mellitus in adulthood poses a major limitation to such efforts. The focus of the current review is thus to discuss recent experimental and human evidence of an epigenetic component associated with components of nutritional programming of Type 2 Diabetes Mellitus, including altered feeding behavior, adipose tissue, and pancreatic beta-cell dysfunction, and transgenerational risk transmission.

Sex Differences Across the Lifespan: A Focus on Cardiometabolism

Women's health and sex differences research remain understudied. In 2016, to address the topic of sex differences, the Center for Women' s Health Research (CWHR) at the University of Colorado (cwhr@ucdenver.edu) held its inaugural National Conference, "Sex Differences Across the Lifespan: A Focus on Metabolism" and published a report summarizing the presentations. Two years later, in 2018, CWHR organized the 2nd National Conference. The research presentations and discussions from the 2018 conference also addressed sex differences across the lifespan with a focus on cardiometabolism and expanded the focus by including circadian physiology and effects of sleep on cardiometabolic health. Over 100 participants, including basic scientists, clinicians, policymakers, advocacy group leaders, and federal agency leadership participated. The meeting proceedings reveal that although exciting advances in the area of sex differences have taken place, significant questions and gaps remain about women's health and sex differences in critical areas of health. Identifying these gaps and the subsequent research that will result may lead to important breakthroughs.

Dietary Supplementation of L-Arginine and N-Carbamylglutamate Attenuated the Hepatic Inflammatory Response and Apoptosis in Suckling Lambs with Intrauterine Growth Retardation

L-arginine (Arg) is a semiessential amino acid with several physiological functions. N-Carbamylglutamate (NCG) can promote the synthesis of endogenous Arg in mammals. However, the roles of Arg or NCG on hepatic inflammation and apoptosis in suckling lambs suffering from intrauterine growth restriction (IUGR) are still unclear. The current work is aimed at examining the effects of dietary Arg and NCG on inflammatory and hepatocyte apoptosis in IUGR suckling lambs. On day 7 after birth, 48 newborn Hu lambs were selected from a cohort of 432 twin lambs. Normal-birthweight and IUGR Hu lambs were allocated randomly (n = 12/group) to control (CON), IUGR, IUGR+1% Arg, or IUGR+0.1% NCG groups. Lambs were fed for 21 days from 7 to 28 days old. Compared with CON lambs, relative protein 53 (P53), apoptosis antigen 1 (Fas), Bcl-2-associated X protein (Bax), caspase-3, cytochrome C, tumor necrosis factor alpha (TNF-α), nuclear factor kappa-B (NF-κB) p65, and NF-κB pp65 protein levels were higher (P < 0.05) in liver from IUGR lambs, whereas those in liver from IUGR lambs under Arg or NCG treatment were lower than those in IUGR lambs. These findings indicated that supplementing Arg or NCG reduced the contents of proinflammatory cytokines at the same time when the apoptosis-related pathway was being suppressed, thus suppressing the IUGR-induced apoptosis of hepatic cells.

Effects of intrauterine insulin-like growth factor-1 therapy for fetal growth restriction on adult metabolism and body composition are sex specific

Fetal growth restriction (FGR) is associated with compromised growth and metabolic function throughout life. Intrauterine therapy of FGR with intra-amniotic insulin-like growth factor-1 (IGF1) enhances fetal growth and alters perinatal metabolism and growth in a sex-specific manner, but the adult effects are unknown. We investigated the effects of intra-amniotic IGF1 treatment of FGR on adult growth and body composition, adrenergic sensitivity, and glucose-insulin axis regulation. Placental embolization-induced FGR was treated with four weekly doses of 360 µg intra-amniotic IGF1 (FGRI) or saline (FGRS). Offspring were raised to adulthood (18 mo: FGRI, n = 12 females, 12 males; FGRS, n = 13 females, 10 males) alongside offspring from unembolized and untreated sheep (CON; n = 12 females, 21 males). FGRI females had increased relative lean mass compared with CON but not FGRS (P < 0.05; 70.6 ± 8.2% vs. 61.4 ± 8.2% vs. 67.6 ± 8.2%), decreased abdominal adipose compared with CON and FGRS (P < 0.05; 43.7 ± 1.2% vs. 49.3 ± 0.9% vs. 48.5 ± 1.0%), increased glucose utilization compared with FGRS but not CON (P < 0.05; 9.6 ± 1.0 vs. 6.0 ± 0.9 vs. 7.6 ± 0.9 mg·kg^-1·min^-1), and increased β-hydroxybutyric acid:nonesterified fatty acid ratio in response to adrenaline compared with CON and FGRS (P < 0.05; 3.9 ± 1.4 vs. 1.1 ± 1.4 vs. 1.8 ± 1.4). FGRS males were smaller and lighter compared with CON but not FGRI (P < 0.05; 86.8 ± 6.3 vs. 93.5 ± 6.1 vs. 90.7 ± 6.3 kg), with increased peak glucose concentration (10%) in response to a glucose load but few other differences. These effects of intra-amniotic IGF1 therapy on adult body composition, glucose-insulin axis function, and adrenergic sensitivity could indicate improved metabolic regulation during young adulthood in female FGR sheep.

Exposure to Chinese Famine in Fetal Life and the Risk of Dysglycemiain Adulthood

Undernutrition in early life may have a long consequence of type 2 diabetes in adulthood. The current study was aimed to explore the association between famine exposure in fetal life during China's Great Famine (1959-1961) and dysglycemia in adulthood. The cross-sectional data from 7830 adults from the 2010-2012 China National Nutrition and Health Surveillance was utilized. Participants who were born between 1960 and 1961 were selected as the exposed group, while the participants who were born in 1963 were selected as the unexposed group. Logistic regression was utilized to examine the relationship between fetal famine exposure and dysglycemia in adulthood. The prevalence of type 2 diabetes in the exposed and control group was 6.4% and 5.1%, respectively, and the risk of type 2 diabetes in the exposed group was 1.23 times higher than that of the control group (95%CI, 1.01-1.50; P = 0.042) in adulthood, and 1.40 times in the severely affected area (95%CI, 1.11-1.76; P = 0.004). The fasting plasma glucose of the exposed group was higher than that of the control group, which was only found in the severely affected area (P = 0.014) and females (P = 0.037). The association between famine and impaired fasting glucose was observed only in females (OR 1.31, 95%CI, 1.01-1.70; P = 0.040). Our results suggested that fetal exposure to Chinese famine increased the risk of dysglycemia in adulthood. This association was stronger in the severely affected area and females.

Oxidative Stress, Intrauterine Growth Restriction, and Developmental Programming of Type 2 Diabetes

Intrauterine growth restriction (IUGR) leads to reduced birth weight and the development of metabolic diseases such as Type 2 diabetes in adulthood. Mitochondria dysfunction and oxidative stress are commonly found in key tissues (pancreatic islets, liver, and skeletal muscle) of IUGR individuals. In this review, we explore the role of oxidative stress in IUGR-associated diabetes etiology.

Nutrient sensor signaling pathways and cellular stress in fetal growth restriction

Fetal growth restriction is one of the most common obstetrical complications resulting in significant perinatal morbidity and mortality. The most frequent etiology of human singleton fetal growth restriction is placental insufficiency, which occurs secondary to reduced utero-placental perfusion, abnormal placentation, impaired trophoblast invasion and spiral artery remodeling, resulting in altered nutrient and oxygen transport. Two nutrient-sensing proteins involved in placental development and glucose and amino acid transport are mechanistic target of rapamycin (mTOR) and O-linked N-acetylglucosamine transferase (OGT), which are both regulated by availability of oxygen. Impairment in either of these pathways is associated with fetal growth restriction and accompanied by cellular stress in the forms of hypoxia, oxidative and endoplasmic reticulum (ER) stress, metabolic dysfunction and nutrient starvation in the placenta. Recent evidence has emerged regarding the potential impact of nutrient sensors on fetal stress response, which occurs in a sexual dysmorphic manner, indicating a potential element of genetic gender susceptibility to fetal growth restriction. In this mini review, we focus on the known role of mTOR and OGT in placental development, nutrient regulation and response to cellular stress in human fetal growth restriction with supporting evidence from rodent models.

Age-Characteristic Changes of Glucose Metabolism, Pancreatic Morphology and Function in Male Offspring Rats Induced by Prenatal Ethanol Exposure

Intrauterine growth restricted offspring suffer from abnormal glucose homeostasis and β cell dysfunction. In this study, we observed the dynamic changes of glucose metabolic phenotype, pancreatic morphology, and insulin synthesis in prenatal ethanol exposure (PEE) male offspring rats, and to explore the potential intrauterine programming mechanism of the glucocorticoid-insulin-like growth factor 1 (GC-IGF1) axis. Ethanol (4 g/kg·d) was administered through oral gavage during gestational day (GD) 9-20. Serum glucose and insulin levels, pancreatic β cell mass, and expression of glucocorticoid receptor (GR), IGF1 and insulin were determined on GD20, postnatal week (PW) 6, PW12 with/without chronic stress (CS), and PW24, respectively. Both intraperitoneal glucose and insulin tolerance tests were conducted at PW12 and PW24. Results showed that the serum glucose and insulin levels as well as pancreatic β cell mass were reduced on GD20 in PEE males compared with the controls, while pancreatic GR expression was enhanced but IGF1 and INS1/2 expression were suppressed. After birth, compared with the controls, β cell mass in the PEE males was initially decreased at PW6 and gradually recovered from PW12 to PW24, which was accompanied by increased serum glucose/insulin levels and insulin resistance index (IRI) at PW6 and decreased serum glucose contents at PW12, as well as unchanged serum glucose/insulin concentrations at PW24. In addition, both improved glucose tolerance and impaired insulin sensitivity of the PEE males at PW12 were inversed at PW24. Moreover, at PW6 and PW12, pancreatic GR expression in the PEE group was decreased, while IGF1 expression was reversely increased, resulting in a compensatory increase of insulin expression. Moreover, CS induced pancreatic GR activation and inhibited IGF1 expression, resulting in impaired insulin biosynthesis. Conclusively, the above changes were associated with age and the intrauterine programming alteration of GC-IGF1 axis may be involved in prenatal and postnatal pancreatic dysplasia and impaired insulin biosynthesis in PEE male offspring.

Chronic Adrenergic Signaling Causes Abnormal RNA Expression of Proliferative Genes in Fetal Sheep Islets

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.

Body composition analysis and references in children: clinical usefulness and limitations

The prevalence of obesity is increasing over the world. Especially in Asians compared to Caucasians, there has been a significant increase in the population with major chronic diseases. This has developed over a shorter time period which is associated with socioeconomic changes in recent decades and a greater predisposition to cardiometabolic disorders. Many Asians could be classified has having normal weight but with obesity as evidenced by body composition (BC) and fat distribution. Overweight in Asian adults is classified as a BMI > 23 kg/m² and obesity as a BMI > 25 kg/m². An effective strategy to manage the obesity epidemic by focusing on childhood obesity is needed because of the huge impact that obesity exerts on population health. However, monitoring tools are limited to anthropometry such as BMI and BMI z-scores which define overweight and obese as a BMI exceeding the 85th and 95th percentiles, respectively, on reference growth charts. To overcome the limitations of BMI, reference values for BC components have been produced using various techniques. The use of BC charts for children in personalized therapeutic approach has increased, although there is a lack of a consensus on a single reference technique. Zones on BC charts and the personalized values of BC components could be practical, especially for the detection of metabolically unhealthy normal weight (MUN) children. BC charts should be included in the growth chart package and BC monitoring through the entire life course will help us understand the association between growth, aging, health and disease.

Impact of prematurity for pancreatic islet and beta-cell development

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.

A 1 week IGF-1 infusion decreases arterial insulin concentrations but increases pancreatic insulin content and islet vascularity in fetal sheep

Fetal insulin is critical for regulation of growth. Insulin concentrations are partly determined by the amount of β-cells present and their insulin content. Insulin-like growth factor-1 (IGF-1) is a fetal anabolic growth factor which also impacts β-cell mass in models of β-cell injury and diabetes. The extent to which circulating concentrations of IGF-1 impact fetal β-cell mass and pancreatic insulin content is unknown. We hypothesized that an infusion of an IGF-1 analog for 1 week into the late gestation fetal sheep circulation would increase β-cell mass, pancreatic islet size, and pancreatic insulin content. After the 1-week infusion, pancreatic insulin concentrations were 80% higher than control fetuses (P < 0.05), but there were no differences in β-cell area, β-cell mass, or pancreatic vascularity. However, pancreatic islet vascularity was 15% higher in IGF-1 fetuses and pancreatic VEGFA, HGF, IGF1, and IGF2 mRNA expressions were 70-90% higher in IGF-1 fetuses compared to control fetuses (P < 0.05). Plasma oxygen, glucose, and insulin concentrations were 25%, 22%, and 84% lower in IGF-1 fetuses, respectively (P < 0.05). The previously described role for IGF-1 as a β-cell growth factor may be more relevant for local paracrine signaling in the pancreas compared to circulating endocrine signaling.

ASAS-SSR Triennnial Reproduction Symposium: Looking Back and Moving Forward-How Reproductive Physiology has Evolved: Fetal origins of impaired muscle growth and metabolic dysfunction: Lessons from the heat-stressed pregnant ewe

Intrauterine growth restriction (IUGR) is the second leading cause of perinatal mortality and predisposes offspring to metabolic disorders at all stages of life. Muscle-centric fetal adaptations reduce growth and yield metabolic parsimony, beneficial for IUGR fetal survival but detrimental to metabolic health after birth. Epidemiological studies have reported that IUGR-born children experience greater prevalence of insulin resistance and obesity, which progresses to diabetes, hypertension, and other metabolic disorders in adulthood that reduce quality of life. Similar adaptive programming in livestock results in decreased birth weights, reduced and inefficient growth, decreased carcass merit, and substantially greater mortality rates prior to maturation. High rates of glucose consumption and metabolic plasticity make skeletal muscle a primary target for nutrient-sparing adaptations in the IUGR fetus, but at the cost of its contribution to proper glucose homeostasis after birth. Identifying the mechanisms underlying IUGR pathophysiology is a fundamental step in developing treatments and interventions to improve outcomes in IUGR-born humans and livestock. In this review, we outline the current knowledge regarding the adaptive restriction of muscle growth and alteration of glucose metabolism that develops in response to progressively exacerbating intrauterine conditions. In addition, we discuss the evidence implicating developmental changes in β adrenergic and inflammatory systems as key mechanisms for dysregulation of these processes. Lastly, we highlight the utility and importance of sheep models in developing this knowledge.

Ovine prenatal growth restriction impacts glucose metabolism and body composition throughout life in both sexes

Low birthweight is a risk factor for later adverse health. Here the impact of placentally mediated prenatal growth restriction followed by postnatal nutrient abundance on growth, glucose metabolism and body composition was assessed in both sexes at key stages from birth to mid-adult life. Singleton-bearing adolescent dams were fed control or high nutrient intakes to induce normal or growth-restricted pregnancies respectively. Restricted lambs had ~40% reduced birthweight. Fractional growth rates were higher in restricted lambs of both sexes predominantly during suckling/juvenile phases. Thereafter, rates and patterns of growth differed by sex. Absolute catch-up was not achieved and restricted offspring had modestly reduced weight and stature at mid-adulthood necropsy (~109 weeks). Dual-energy X-ray absorptiometry revealed lower bone mineral density in restricted vs normal lambs at 11, 41, 64 and 107 weeks, with males > females from 41 weeks onwards. Body fat percentage was higher in females vs males throughout, in restricted vs normal lambs at weaning (both sexes) and in restricted vs normal females at mid-adulthood. Insulin secretion after glucose challenge was greater in restricted vs normal of both sexes at 7 weeks and in restricted males at 32 weeks. In both sexes, fasting glucose concentrations were greater in restricted offspring across the life course, while glucose area under the curve after challenge was higher in restricted offspring at 32, 60, 85 and 106 weeks, indicative of persistent glucose intolerance. Therefore, prenatal growth restriction has negative consequences for body composition and metabolism throughout the life course with the effects modulated by sex differences in postnatal growth rates, fat deposition and bone mass accrual.

Perfluoroalkyl acid levels in first-time mothers in relation to offspring weight gain and growth

We investigated if maternal body burdens of perfluoroalkyl acids (PFAAs) at the time of delivery are associated with birth outcome and if early life exposure (in utero/nursing) is associated with early childhood growth and weight gain. Maternal PFAA body burdens were estimated by analysis of serum samples from mothers living in Uppsala County, Sweden (POPUP), sampled three weeks after delivery between 1996 and 2011. Data on child length and weight were collected from medical records and converted into standard deviation scores (SDS). Multiple linear regression models with appropriate covariates were used to analyze associations between maternal PFAA levels and birth outcomes (n=381). After birth Generalized Least Squares models were used to analyze associations between maternal PFAA and child growth (n=200). Inverse associations were found between maternal levels of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), and birth weight SDS with a change of -0.10 to -0.18 weight SDS for an inter-quartile range (IQR) increase in ng/g PFAA. After birth, weight and length SDS were not significantly associated with maternal PFAA. However, BMI SDS was significantly associated with PFOA, PFNA, and PFHxS at 3 and 4years of age, and with PFOS at 4 and 5years of age. If causal, these associations suggest that PFAA affects fetal and childhood body development in different directions.

The impact of IUGR on pancreatic islet development and β-cell function

Placental insufficiency is a primary cause of intrauterine growth restriction (IUGR). IUGR increases the risk of developing type 2 diabetes mellitus (T2DM) throughout life, which indicates that insults from placental insufficiency impair β-cell development during the perinatal period because β-cells have a central role in the regulation of glucose tolerance. The severely IUGR fetal pancreas is characterized by smaller islets, less β-cells, and lower insulin secretion. Because of the important associations among impaired islet growth, β-cell dysfunction, impaired fetal growth, and the propensity for T2DM, significant progress has been made in understanding the pathophysiology of IUGR and programing events in the fetal endocrine pancreas. Animal models of IUGR replicate many of the observations in severe cases of human IUGR and allow us to refine our understanding of the pathophysiology of developmental and functional defects in islet from IUGR fetuses. Almost all models demonstrate a phenotype of progressive loss of β-cell mass and impaired β-cell function. This review will first provide evidence of impaired human islet development and β-cell function associated with IUGR and the impact on glucose homeostasis including the development of glucose intolerance and diabetes in adulthood. We then discuss evidence for the mechanisms regulating β-cell mass and insulin secretion in the IUGR fetus, including the role of hypoxia, catecholamines, nutrients, growth factors, and pancreatic vascularity. We focus on recent evidence from experimental interventions in established models of IUGR to understand better the pathophysiological mechanisms linking placental insufficiency with impaired islet development and β-cell function.

Ponderal index at birth associates with later risk of gestational diabetes mellitus

PURPOSE

Low birth weight (BW) and low ponderal index (PI) are associated with increased risk of type 2 diabetes mellitus. This study has two purposes: first to investigate the influence of PI on the risk of gestational diabetes mellitus (GDM); second, to study the association between glucose metabolism and BW in women with previous GDM.

METHODS

GDM cohort: 185 women with GDM in 1978-1996, attending a follow-up study in 2000-2002. Control cohort: 1137 women from a population-based diabetes screening study (Inter99) in a neighbouring county in 1999-2001. BW and birth length were collected from the original midwifery records. BW and PI were stratified into tertiles for analysis.

RESULTS

PI in the lower tertiles was associated with an increased risk of GDM [odds ratio 1.59 (95% confidence interval 1.07-2.36, p = 0.021)]. Among women with previous GDM, the area under the curve (AUC) for plasma levels of glucose and insulin during an OGTT was highest for the lower tertiles of BW (for AUCglucose p = 0.048, for AUCinsulin p = 0.047 adjusted for age and BMI).

CONCLUSIONS

Lower PI is associated with increased risk of GDM. In women with previous GDM, lower BW is associated with a more severe impairment of glucose metabolism one to two decades after the pregnancy complicated by GDM.

Fetal adaptations in insulin secretion result from high catecholamines during placental insufficiency

Placental insufficiency and intrauterine growth restriction (IUGR) of the fetus affects approximately 8% of all pregnancies and is associated with short- and long-term disturbances in metabolism. In pregnant sheep, experimental models with a small, defective placenta that restricts delivery of nutrients and oxygen to the fetus result in IUGR. Low blood oxygen concentrations increase fetal plasma catecholamine concentrations, which lower fetal insulin concentrations. All of these observations in sheep models with placental insufficiency are consistent with cases of human IUGR. We propose that sustained high catecholamine concentrations observed in the IUGR fetus produce developmental adaptations in pancreatic β-cells that impair fetal insulin secretion. Experimental evidence supporting this hypothesis shows that chronic elevation in circulating catecholamines in IUGR fetuses persistently inhibits insulin concentrations and secretion. Elevated catecholamines also allow for maintenance of a normal fetal basal metabolic rate despite low fetal insulin and glucose concentrations while suppressing fetal growth. Importantly, a compensatory augmentation in insulin secretion occurs following inhibition or cessation of catecholamine signalling in IUGR fetuses. This finding has been replicated in normally grown sheep fetuses following a 7-day noradrenaline (norepinephrine) infusion. Together, these programmed effects will potentially create an imbalance between insulin secretion and insulin-stimulated glucose utilization in the neonate which probably explains the transient hyperinsulinism and hypoglycaemia in some IUGR infants.

Enhanced insulin secretion and insulin sensitivity in young lambs with placental insufficiency-induced intrauterine growth restriction

Intrauterine growth restriction (IUGR) is associated with persistent metabolic complications, but information is limited for IUGR infants. We determined glucose-stimulated insulin secretion (GSIS) and insulin sensitivity in young lambs with placental insufficiency-induced IUGR. Lambs with hyperthermia-induced IUGR (n = 7) were compared with control lambs (n = 8). GSIS was measured at 8 ± 1 days of age, and at 15 ± 1 days, body weight-specific glucose utilization rates were measured with radiolabeled d-glucose during a hyperinsulinemic-euglycemic clamp (HEC). IUGR lambs weighed 23% less (P < 0.05) than controls at birth. Fasting plasma glucose and insulin concentrations were not different between IUGR and controls for either study. First-phase insulin secretion was enhanced 2.3-fold in IUGR lambs compared with controls. However, second-phase insulin concentrations, glucose-potentiated arginine-stimulated insulin secretion, and β-cell mass were not different, indicating that IUGR β-cells have an intrinsic enhancement in acute GSIS. Compared with controls, IUGR lambs had higher body weight-specific glucose utilization rates and greater insulin sensitivity at fasting (1.6-fold) and hyperinsulinemic periods (2.4-fold). Improved insulin sensitivity for glucose utilization was not due to differences in skeletal muscle insulin receptor and glucose transporters 1 and 4 concentrations. Plasma lactate concentrations during HEC were elevated in IUGR lambs compared with controls, but no differences were found for glycogen content or citrate synthase activity in liver and muscle. Greater insulin sensitivity for glucose utilization and enhanced acute GSIS in young lambs are predicted from fetal studies but may promote conditions that exaggerate glucose disposal and lead to episodes of hypoglycemia in IUGR infants.

RNA Sequencing Exposes Adaptive and Immune Responses to Intrauterine Growth Restriction in Fetal Sheep Islets

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.

Early-Life Nutritional Programming of Type 2 Diabetes: Experimental and Quasi-Experimental Evidence

Consistent evidence from both experimental and human studies suggest that inadequate nutrition in early life can contribute to risk of developing metabolic disorders including type 2 diabetes (T2D) in adult life. In human populations, most findings supporting a causative relationship between early-life malnutrition and subsequent risk of T2D were obtained from quasi-experimental studies (‘natural experiments’). Prenatal and/or early postnatal exposures to famine were demonstrated to be associated with higher risk of T2D in many cohorts around the world. Recent studies have highlighted the importance of epigenetic regulation of gene expression as a possible major contributor to the link between the early-life famine exposure and T2D in adulthood. Findings from these studies suggest that prenatal exposure to the famine may result in induction of persistent epigenetic changes that have adaptive significance in postnatal development but can predispose to metabolic disorders including T2D at the late stages of life. In this review, quasi-experimental data on the developmental programming of T2D are summarized and recent research findings on changes in DNA methylation that mediate these effects are discussed.

Complications during pregnancy and fetal development: implications for the occurrence of chronic kidney disease

INTRODUCTION

Numerous epidemiological studies indicate an inverse association between birth weight and the risk for chronic kidney disease. Areas covered: Historically, the first studies to address the developmental origins of chronic disease focused on the inverse relationship between birth weight and blood pressure. A reduction in nephron number was a consistent finding in low birth weight individuals and experimental models of developmental insult. Recent studies indicate that a congenital reduction in renal reserve in conjunction with an increase in blood pressure that has its origins in fetal life increases vulnerability to renal injury and disease. Expert commentary: Limited experimental studies have investigated the mechanisms that contribute to the developmental origins of kidney disease. Several studies suggest that enhanced susceptibility to renal injury following a developmental insult is altered by sex and age. More in-depth studies are needed to clarify how low birth weight contributes to enhanced renal risk, and how sex and age influence this adverse relationship.

Developmental programming: Interaction between prenatal BPA and postnatal overfeeding on cardiac tissue gene expression in female sheep

Epidemiologic studies and studies in rodents point to potential risks from developmental exposure to BPA on cardiometabolic diseases. Furthermore, it is becoming increasingly evident that the manifestation and severity of adverse outcomes is the result of interaction between developmental insults and the prevailing environment. Consistent with this premise, recent studies in sheep found prenatal BPA treatment prevented the adverse effects of postnatal obesity in inducing hypertension. The gene networks underlying these complex interactions are not known. mRNA-seq of myocardium was performed on four groups of four female sheep to assess the effects of prenatal BPA exposure, postnatal overfeeding and their interaction on gene transcription, pathway perturbations and functional effects. The effects of prenatal exposure to BPA, postnatal overfeeding, and prenatal BPA with postnatal overfeeding all resulted in transcriptional changes (85-141 significant differentially expressed genes). Although the effects of prenatal BPA and postnatal overfeeding did not involve dysregulation of many of the same genes, they affected a remarkably similar set of biological pathways. Furthermore, an additive or synergistic effect was not found in the combined treatment group, but rather prenatal BPA treatment led to a partial reversal of the effects of overfeeding alone. Many genes previously known to be affected by BPA and involved in obesity, hypertension, or heart disease were altered following these treatments, and AP-1, EGR1, and EGFR were key hubs affected by BPA and/or overfeeding. Environ. Mol. Mutagen. 58:4-18, 2017. © 2016 Wiley Periodicals, Inc.

Developmental programming: Interaction between prenatal BPA and postnatal overfeeding on cardiac tissue gene expression in female sheep

Epidemiologic studies and studies in rodents point to potential risks from developmental exposure to BPA on cardiometabolic diseases. Furthermore, it is becoming increasingly evident that the manifestation and severity of adverse outcomes is the result of interaction between developmental insults and the prevailing environment. Consistent with this premise, recent studies in sheep found prenatal BPA treatment prevented the adverse effects of postnatal obesity in inducing hypertension. The gene networks underlying these complex interactions are not known. mRNA-seq of myocardium was performed on four groups of four female sheep to assess the effects of prenatal BPA exposure, postnatal overfeeding and their interaction on gene transcription, pathway perturbations and functional effects. The effects of prenatal exposure to BPA, postnatal overfeeding, and prenatal BPA with postnatal overfeeding all resulted in transcriptional changes (85-141 significant differentially expressed genes). Although the effects of prenatal BPA and postnatal overfeeding did not involve dysregulation of many of the same genes, they affected a remarkably similar set of biological pathways. Furthermore, an additive or synergistic effect was not found in the combined treatment group, but rather prenatal BPA treatment led to a partial reversal of the effects of overfeeding alone. Many genes previously known to be affected by BPA and involved in obesity, hypertension, or heart disease were altered following these treatments, and AP-1, EGR1, and EGFR were key hubs affected by BPA and/or overfeeding. Environ. Mol. Mutagen. 58:4-18, 2017. © 2016 Wiley Periodicals, Inc.

Neonatal milk supplementation in lambs has persistent effects on growth and metabolic function that differ by sex and gestational age

The perinatal environment has a major influence on long-term health and disease risk. Preterm birth alters early-life environment and is associated with altered metabolic function in adulthood. Whether preterm birthper seor the early nutritional interventions used to support growth in preterm infants underpins this association is unknown. Lambs born preterm, following dexamethasone induction of labour, or spontaneously at term were randomised to receive nutrient supplementation, analogous to the milk fortifier used clinically or water as a control for the first 2 weeks after birth. Thereafter, nutrition was not different between groups. Growth was monitored, and the glucose–insulin axis function was assessed in juvenile (4 months) and adult life (14 months). Early nutrition influenced adult metabolic function and body composition to a greater extent than preterm birth. In supplemented females, arginine-stimulated insulin secretion was increased in preterm but reduced in term-born juveniles compared with controls (repeated-measures ANOVAP<0·01). In supplemented preterm males, adult weight, ponderal index (PI) and fasting insulin concentrations were elevated compared with preterm controls (weight, 75 (sem3)v. 69 (sem2) kg; PI, 48·0 (sem2·1)v. 43·7 (sem1·7) kg/m3; fasting insulin, 0·19 (sem0·02)v. 0·10 (sem0·02) ng/ml). Conversely, supplemented term-born males had reduced adult weight, PI and fasting insulin concentrations compared with term-born controls (weight, 64 (sem2)v. 70 (sem2) kg; PI, 44·4 (sem1·8)v. 48·2 (sem1·7) kg/m3; fasting insulin, 0·09 (sem0·02)v. 0·14 (sem0·02) ng/ml; all group×supplement interactionsP<0·05). Adult metabolic health may reflect both gestational age at birth and early nutrition. Human studies are urgently needed to investigate the adult sex-specific health implications of neonatal nutritional strategies.

Effects of intrauterine growth restriction during late pregnancy on the cell apoptosis and related gene expression in ovine fetal liver

This study investigated the effect of intrauterine growth restriction (IUGR) during late pregnancy on the cell apoptosis and related gene expression in ovine fetal liver. Eighteen time-mated Mongolian ewes with singleton fetuses were allocated to three groups at d 90 of pregnancy: Restricted Group 1 (RG1, 0.18 MJ ME kg BW^-0.75 d^-1, n = 6), Restricted Group 2 (RG2, 0.33 MJ ME kg BW^-0.75 d^-1, n = 6) and a Control Group (CG, ad libitum, 0.67 MJ ME kg BW ^-0.75 d ^-1, n = 6). Fetuses were recovered at slaughter on d 140. Fetal liver weight, DNA content and protein/DNA ratio, proliferation index, cytochrome c, activities of Caspase-3, 8, and 9 were examined, along with relative expression of genes related to apoptosis. Fetuses in both restricted groups exhibited decreased BW, hepatic weight, DNA content, and protein/DNA ratio when compared to CG (P < 0.05), as well as reduced proliferation index (P < 0.05). However, the increased numbers of apoptotic cells in fetal liver were observed in both restricted groups (P < 0.05). Fetuses with severe IUGR (RG1) exhibited increased (P < 0.05) activities of Caspase-3, 8, 9, as higher levels of mitochondrial cytochrome c in fetal liver; intermediate changes were found in RG2 fetuses, but the difference were not significant (P > 0.05). Hepatic expression of gene related to apoptosis showed reduced protein 21 (P21), B-cell lymphoma 2 (Bcl-2) and apoptosis antigen 1 ligand (FasL) expression in RG1 and RG2 (P < 0.05). In contrast, the increased hepatic expression of protein 53 (P53), Bcl-2 associated X protein (Bax) and apoptosis antigen 1 (Fas) in both IUGR fetuses were found (P < 0.05). These results indicate that the fetal hepatocyte proliferation were arrested in G1 cell cycle, and the fetal hepatocyte apoptosis was sensitive to the IUGR resulted from maternal undernutrition. The cell apoptosis in IUGR fetal liver were the potential mechanisms for its retarded proliferation and impaired development.

Dysregulation of calcium channels decreases parasecretion in pancreatic β-cells in rats born small for gestational age

OBJECTIVE

To investigate the role of intrauterine malnourishment in the development and function of pancreatic islet β-cells.

METHODS

Whole-cell patch clamping was used to record voltage-gated calcium channel (VGCC)-mediated currents. Insulin secretion was detected by measuring capacitance using a sequence of sine wave stimuli. VGCC currents and insulin secretion were measured in the small for gestational age (SGA) group treated with human recombinant growth hormone (hGH).

RESULTS

The membrane capacitance in the SGA group (6.4 ± 0.9 fF/Pf) was significantly reduced. Calcium current density and peak current density in the SGA group were also markedly decreased, whereas other measurements of calcium channels were unaltered. Treatment with hGH significantly rescued the membrane capacitance, whereas calcium channels were not affected.

CONCLUSION

Our data suggest that decreased β-cell secretion is caused by a decreased expression of calcium channels and reduced calcium currents. hGH restores β-cell secretion in SGA animals, possibly independently of VGCC.

Brief neonatal nutritional supplementation has sex-specific effects on glucose tolerance and insulin regulating genes in juvenile lambs

BACKGROUND

The nutritional plane and composition during fetal life can impact upon growth and epigenetic regulation of genes affecting pancreatic β-cell development and function. However, it is not clear whether β-cell development can be altered by nutritional factors or growth rate after birth. We therefore investigated the effect of neonatal nutritional supplements on growth, glucose tolerance, and pancreatic development in lambs.

METHODS

Newborn lambs were randomized to daily nutritional supplements, calculated to increase macronutrient intake to a similar degree as human breast milk fortifier, or an equivalent volume of water, for 2 wk while continuing to suckle ewe milk. Intravenous glucose tolerance test (IVGTT) was performed at 4 mo of age, and pancreata collected for molecular analysis.

RESULTS

Supplemented lambs had slower weight gain than controls. In supplemented lambs, insulin response to IVGTT was increased in males but decreased in females, compared to same sex controls, and was unrelated to growth rate. mRNA expression of key genes in β-cell development showed sexually dimorphic effects. Epigenetic change occurred in the promotor region of PDX1 gene with decreased suppression and increased activation marks in supplemented lambs of both sexes.

CONCLUSION

Nutritional interventions in early life have long-term, sex-specific effects on pancreatic function.

Pancreatic islet hepatocyte growth factor and vascular endothelial growth factor A signaling in growth restricted fetuses

Placental insufficiency leads to intrauterine growth restriction (IUGR) and a lifelong risk of developing type 2 diabetes. Impaired islet development in the growth restricted fetus, including decreased β-cell replication, mass, and insulin secretion, is strongly implicated in the pathogenesis of later life type 2 diabetes. Currently, standard medical management of a woman with a pregnancy complicated by placental insufficiency and fetal IUGR is increased fetal surveillance and indicated preterm delivery. This leads to the dual complications of IUGR and preterm birth - both of which may increase the lifelong risk for type 2 diabetes. In order to develop therapeutic interventions in IUGR pregnancies complicated by placental insufficiency and decrease the risk of later development of type 2 diabetes in the offspring, the mechanisms responsible for impaired islet development in these cases must be determined. This review focuses on current investigations testing the hypothesis that decreased nutrient supply to the IUGR fetus inhibits an intra-islet hepatocyte growth factor - vascular endothelial growth factor A (HGF - VEGFA) feed forward signaling pathway and that this is responsible for developmental islet defects.

Chronically Increased Amino Acids Improve Insulin Secretion, Pancreatic Vascularity, and Islet Size in Growth-Restricted Fetal Sheep

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.

Environmental Contaminants and Pancreatic Beta-Cells

Despite health policies as well as clinical and research efforts, diabetes prevalence is still rising around the world. A multitude of causes have been suggested for this increase, mostly related to familial background, the occidental diet which is rich in fat/carbohydrates, and sedentary life style. Type 2 diabetes involves malfunctions of the primary pancreatic beta-cells, usually attributed to local damage; however, it can be associated with other stressful environmental agents, such as chemical contaminants from food, plastic and air, among others. Indeed, exposure to these chemical agents during perinatal and adolescent life can increase the risk of developing cardiometabolic diseases later in life. This review explores data showing which environmental chemical agents may produce injury in beta-cells and further impair the insulinotropic process of type 2 diabetes. Additionally, it points the need to also consider unusual causes of metabolic diseases, such as environmental contaminants.

Challenges in nourishing the intrauterine growth-restricted foetus - Lessons learned from studies in the intrauterine growth-restricted foetal sheep

Previous attempts to improve growth and development of the intrauterine growth-restricted (IUGR) foetus during pregnancy have not worked or caused harm. Our research identifies tissue-specific mechanisms underlying foetal growth restriction and then tests strategies to improve growth and ameliorate many of the metabolic problems before the infant is born. The goal of our studies is to reduce the impact of foetal growth restriction at critical stages of development on the lifelong complications of IUGR offspring.

CONCLUSION

Defining specific mechanisms that cause growth restriction in the foetus might identify specific nutrients and hormones that could be given to the mother to improve foetal growth and reduce metabolic complications, using strategies first tested in our IUGR animal model.

The Elevated Susceptibility to Diabetes in India: An Evolutionary Perspective

India has rapidly become a "diabetes capital" of the world, despite maintaining high rates of under-nutrition. Indians develop diabetes at younger age and at lower body weights than other populations. Here, we interpret these characteristics in terms of a "capacity-load" model of glucose homeostasis. Specifically, we assume that glycemic control depends on whether the body's "metabolic capacity," referring to traits, such as pancreatic insulin production and muscle glucose clearance, is able to resolve the "metabolic load" generated by high levels of body fat, high dietary glycemic load, and sedentary behavior. We employ data from modern cohorts to support the model and the interpretation that elevated diabetic risk among Indian populations results from the high metabolic load imposed by westernized lifestyles acting on a baseline of low metabolic capacity. We attribute this low metabolic capacity to the low birth weight characteristic of Indian populations, which is associated with short stature and low lean mass in adult life. Using stature as a marker of metabolic capacity, we review archeological and historical evidence to highlight long-term declines in Indian stature associated with adaptation to several ecological stresses. Underlying causes may include increasing population density following the emergence of agriculture, the spread of vegetarian diets, regular famines induced by monsoon failure, and the undermining of agricultural security during the colonial period. The reduced growth and thin physique that characterize Indian populations elevate susceptibility to truncal obesity, and increase the metabolic penalties arising from sedentary behavior and high glycemic diets. Improving metabolic capacity may require multiple generations; in the meantime, efforts to reduce the metabolic load will help ameliorate the situation.

Maternal protein restriction during gestation impairs female offspring pancreas development in the rat

A maternal low-protein (LP) diet programs fetal pancreatic islet β-cell development and function and predisposes offspring to metabolic dysfunction later in life. We hypothesized that maternal protein restriction during pregnancy differentially alters β- and α-cell populations in offspring by modifying islet ontogeny and function throughout life. We aimed to investigate the effect of an LP maternal diet on pancreatic islet morphology and cellular composition in female offspring on postnatal days (PNDs) 7, 14, 21, 36, and 110. Mothers were divided into 2 groups: during pregnancy, the control group (C) was fed a diet containing 20% casein, and the LP group was fed an isocaloric diet with 10% casein. Offspring pancreases were obtained at each PND and then processed. β and α cells were detected by immunohistochemistry, and cellular area and islet size were quantified. Islet cytoarchitecture and total area were similar in C and LP offspring at all ages studied. At the early ages (PNDs 7-21), the proportion of β cells was lower in LP than C offspring. The proportion of α cells was lower in LP than C offspring on PND 14 and higher on PND 21. The β/α-cell ratio was lower in LP compared with C offspring on PNDs 7 and 21 and higher on PND 36 (being similar on PNDs 14 and 110). We concluded that maternal protein restriction during pregnancy modifies offspring islet cell ontogeny by altering the proportions of islet sizes and by reducing the number of β cells postnatally, which may impact pancreatic function in adult life.

Maternal fat mass at mid-pregnancy and birth weight in Brazilian women

BACKGROUND

The relationship between maternal body composition and foetal development is unclear.

AIM

To determine the relationship between maternal body composition [fat mass (FM) and fat-free mass (FFM)] and foetal growth and birth weight, independent of potential confounding factors.

SUBJECTS AND METHODS

This study consisted of 92 women, normal and overweight/obese, recruited from the Instituto Fernandes Figueira in Rio de Janeiro, Brazil. Body composition (FM and FFM) was estimated using bioelectrical impedance. Foetal growth was assessed using serial ultrasound measurements at the second and third trimester and infant's weight and length were measured at birth. Multiple linear regression analyses were used to determine the association between maternal FM and FFM and birth weight adjusted for gestational age (BWt) and change in estimated foetal weight (ΔEFW), controlling for infant gender, maternal serum glucose, energy intake, parity, height and income.

RESULTS

Maternal FM, but not FFM, was positively associated with BWt (p = 0.02) and borderline with ΔEFW (p = 0.05). FM expressed as a percentage of body weight (%FM) showed a significant positive association with BWt (p < 0.001) and ΔEFW (p < 0.01). Using backward linear regression analysis, FM was a significant predictor of BWt (p < 0.001) and ΔEFW (p = 0.03), but not change in femur length.

CONCLUSION

In this small sample of normal and overweight/obese women, maternal FM at mid-pregnancy is associated with neonatal BW and foetal growth.

Effects of Intrauterine Growth Restriction During Late Pregnancy on the Development of the Ovine Fetal Thymus and the T-Lymphocyte Subpopulation

PROBLEM

The retarded development of fetal thymus in intrauterine growth restriction (IUGR) from maternal undernutrition during late pregnancy destroys the tridimensional structure and modifies the development of fetal T lymphocytes. The mechanisms, however, remain unclear. The objective of this study was to investigate the effect of IUGR during late pregnancy on the development of the ovine fetal thymus and the T-lymphocyte subpopulation.

METHOD OF STUDY

Eighteen time-mated ewes with singleton fetuses were allocated to three groups at day 90 of pregnancy: restricted group 1 (RG1, 0.18 MJ ME/BW(0.75) /day, n = 6), restricted group 2 (RG2, 0.33 MJ ME/BW(0.75) /day, n = 6) and a control group (CG, ad libitum, 0.67 MJ ME/BW(0.75) /day, n = 6). Fetuses were recovered at slaughter on day 140.

RESULTS

Fetuses in RG1 exhibited decreased (P < 0.05) thymic weight, cortical thickness, cortical:medullary, DNA content, total antioxidant capacity, and superoxide dismutase; intermediate changes were found in RG2 fetuses, including decreased thymic weight, cortical thickness, and DNA content (P < 0.05). The reductions (P < 0.05) of CD4(+) CD8(+) T cells, relative mRNA expression of keratin 8, recombination activating gene 1 (RAG1), and B-cell lymphoma 2 (Bcl-2) were found in both restricted groups. In addition, there was reduced mRNA expression (P < 0.05) of T-cell receptor, apoptosis antigen 1 ligand, and RAG2 in the RG1 group. In contrast, increases in glutathione peroxidase, malondialdehyde, caspase-3, Cytochrome c, and CD4(+) T cells were observed (P < 0.05), and higher mRNA expressions (P < 0.05) of protein 53, Bcl-2 associated X protein (Bax), and apoptosis antigen 1 (Fas) were found in RG1 fetuses; and thymuses of RG2 fetuses had increased caspase-3, and expression of Fas and Bax (P < 0.05), relative to control fetuses.

CONCLUSION

These results indicate that reduced cell proliferation, oxidative stress, and increased cell apoptosis were the potential mechanisms for impaired development and microenvironment of IUGR fetal thymus, and for modifying the maturation of CD4(+) CD8(+) thymocytes underlying their reduced numbers .

Fetal adrenal demedullation lowers circulating norepinephrine and attenuates growth restriction but not reduction of endocrine cell mass in an ovine model of intrauterine growth restriction

Placental insufficiency is associated with fetal hypoglycemia, hypoxemia, and elevated plasma norepinephrine (NE) that become increasingly pronounced throughout the third trimester and contribute to intrauterine growth restriction (IUGR). This study evaluated the effect of fetal adrenal demedullation (AD) on growth and pancreatic endocrine cell mass. Placental insufficiency-induced IUGR was created by exposing pregnant ewes to elevated ambient temperatures during mid-gestation. Treatment groups consisted of control and IUGR fetuses with either surgical sham or AD at 98 days gestational age (dGA; term = 147 dGA), a time-point that precedes IUGR. Samples were collected at 134 dGA. IUGR-sham fetuses were hypoxemic, hypoglycemic, and hypoinsulinemic, and values were similar in IUGR-AD fetuses. Plasma NE concentrations were ~5-fold greater in IUGR-sham compared to control-sham, control-AD, and IUGR-AD fetuses. IUGR-sham and IUGR-AD fetuses weighed less than controls. Compared to IUGR-sham fetuses, IUGR-AD fetuses weighed more and asymmetrical organ growth was absent. Pancreatic β-cell mass and α-cell mass were lower in both IUGR-sham and IUGR-AD fetuses compared to controls, however, pancreatic endocrine cell mass relative to fetal mass was lower in IUGR-AD fetuses. These findings indicate that NE, independently of hypoxemia, hypoglycemia and hypoinsulinemia, influence growth and asymmetry of growth but not pancreatic endocrine cell mass in IUGR fetuses.

Increased adrenergic signaling is responsible for decreased glucose-stimulated insulin secretion in the chronically hyperinsulinemic ovine fetus

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.

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

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.