N-Acetylcysteine Resolves Placental Inflammatory-Vasculopathic Changes in Mice Consuming a High-Fat Diet.

The mechanism by which poor maternal nutrition can affect the long-term health of offspring is poorly understood. In mice, we previously found that maternal high-fat diet (HFD) exposure results in reduced fetal growth regardless of maternal genotype. We tested our hypothesis that maternal HFD-induced inflammation contributes to metabolic disease susceptibility of the offspring via alterations in the placenta. The effect of maternal genotype, diet, and treatment with the anti-inflammatory compound N-acetylcysteine (NAC) on placental morphologic features was investigated. Placentas from wild-type dams maintained on a HFD but not those heterozygous (+/-) for Glut4 (Slc2a4) on the same diet had an increase in decidual inflammation and vasculopathy occurring together. NAC administration resulted in amelioration of HFD-induced decidual vasculopathy independent of offspring genotype and sex. Consistent with these morphologic improvements, placentas from HFD dams treated with NAC had decreased mRNA and immunostaining of IL-1ß and monocyte chemoattractant protein-1, decreased mRNA of inflammatory genes, and increased mRNA of Vegfa. These results strongly suggest consumption of an HFD results in vascular changes in placenta reflected by alterations in expression of pivotal vascular developmental markers and inflammatory genes all of which are ameliorated by NAC. These placental changes play a key role in the increased programed metabolic disease of HFD-exposed offspring.

CARMIL2-related immunodeficiency manifesting with photosensitivity.

We report a case of a newly recognized primary immunodeficiency due to biallelic mutations in CARMIL2 manifesting as an actinic prurigo-like photodermatitis, allergic diathesis and recurrent infections in a child. We present this case to highlight a rare phenotype seen in this T-cell immunodeficiency and provide an overview of other dermatologic manifestations among published reports of this condition.

Animal models of in utero exposure to a high fat diet: a review.

The incidence of metabolic disease, including type 2 diabetes and obesity, has increased to epidemic levels in recent years. A growing body of evidence suggests that the intrauterine environment plays a key role in the development of metabolic disease in offspring. Among other perturbations in early life, alteration in the provision of nutrients has profound and lasting effects on the long term health and well being of offspring. Rodent and non-human primate models provide a means to understand the underlying mechanisms of this programming effect. These different models demonstrate converging effects of a maternal high fat diet on insulin and glucose metabolism, energy balance, cardiovascular function and adiposity in offspring. Furthermore, evidence suggests that the early life environment can result in epigenetic changes that set the stage for alterations in key pathways of metabolism that lead to type 2 diabetes or obesity. Identifying and understanding the causal factors responsible for this metabolic dysregulation is vital to curtailing these epidemics. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.

Critical periods of increased fetal vulnerability to a maternal high fat diet.

BACKGROUND: Fetal adaptations to high fat (HF) diet in utero (IU) that may predispose to Metabolic Syndrome (MetS) in adulthood include changes in fetal hepatic gene expression. Studies were performed to determine whether maternal exposure to HF diet at different stages during pregnancy had different effects on the fetus, including hepatic gene expression. METHODS: Female wild type mice were fed either a HF or breeding chow (C) for 2 wks prior to mating. The experimental groups were composed of embryonic day (e) 18.5 fetuses obtained from WT female mice that were fed HF (HF, 35.5% fat) or breeding chow (C, 9.5% fat) for 2 wk before mating until e9.5 of pregnancy (periconception-midpregnancy). At e9.5 dams were switched to the opposite diet (C-HF or HF-C). RESULTS: Exposure to HF diet throughout pregnancy reduced maternal weight gain compared to C diet (p < 0.02 HF vs. C). HF-C dams had significantly decreased adiponectin levels and litter size when compared to C-HF (p < 0.02 HF-C vs C-HF). Independent of the timing of exposure to HF, fetal weight and length were significantly decreased when compared to C diet (HF, C-HF and HF-C vs. C p < 0.02). HF diet during the second half of pregnancy increased expression of genes in the fetal liver associated with fetal growth (C-HF vs C p < 0.001), glucose production (C-HF vs C p < 0.04), oxidative stress and inflammation (C-HF vs C p < 0.01) compared to C diet. CONCLUSIONS: This model defines that there are critical periods during gestation in which the fetus is actively shaped by the environment. Early exposure to a HF diet determines litter size while exposure to HF during the second half of pregnancy leads to dysregulation of expression of key genes responsible for fetal growth, hepatic glucose production and oxidative stress. These findings underscore the importance of future studies designed to clarify how these critical periods may influence future risk of developing MetS later in life.

In utero exposure to a maternal high-fat diet alters the epigenetic histone code in a murine model.

OBJECTIVE: Data from animal models show that in utero exposure to a maternal high-fat diet (HFD) renders susceptibility of these offspring to the adult onset of metabolic syndrome. We and others have previously shown that epigenetic modifications to histones may serve as a molecular memory of the in utero exposure, rendering the risk of adult disease. Because mice heterozygous for the Glut4 gene (insulin sensitive glucose transporter) born to wild-type (WT) mothers demonstrate exacterbated metabolic syndrome when exposed to an HFD in utero, we sought to analyze the genome-wide epigenetic changes that occur in the fetal liver in susceptible offspring. STUDY DESIGN: WT and Glut4(+/-) (G4(+/-)) offspring of WT mothers that were exposed either to a control or an HFD in utero were studied. Immunoblotting was used to measure hepatic histone modifications of fetal and 5-week animals. Chromatin immunoprecipitation (ChIP) followed by hybridization to chip arrays (ChIP-on-chip) was used to detect genome-wide changes of histone modifications with HFD exposure. RESULTS: We found that levels of hepatic H3K14ac and H3K9me3 significantly increased with HFD exposure in WT and G4(+/-) fetal and 5-week offspring. Pathway analysis of our ChIP-on-chip data revealed differential H3K14ac and H3K9me3 enrichment along pathways that regulate lipid metabolism, specifically in the promoter regions of Pparg, Ppara, Rxra, and Rora. CONCLUSION: We conclude that HFD exposure in utero is associated with functional alterations to fetal hepatic histone modifications in both WT and G4(+/-) offspring, some of which persist up to 5 weeks of age.

SARS-CoV-2 Infection in Unvaccinated High-Risk Pregnant Women in the Bronx, NY, USA Is Associated with Decreased Apgar Scores and Placental Villous Infarcts.

Babies born to severe acute respiratory syndrome corona virus-2 (SARS-CoV-2)-infected mothers are at greater risk for perinatal morbidity and more likely to receive a neurodevelopmental diagnosis in the first year of life. However, the effect of maternal infection on placental function and neonatal outcomes varies depending upon the patient population. We set out to test our hypothesis that maternal SARS-CoV-2 infection in our underserved, socioeconomically disadvantaged, mostly unvaccinated, predominantly African American and Latina population in the Bronx, NY would have effects evident at birth. Under IRB approval, 56 SARS-CoV-2-positive patients infected during the "first wave" of the pandemic with alpha and beta strains of the virus, 48 patients infected during the "second wave" of the pandemic with delta and omicron strains and 61 negative third-trimester high-risk patients were randomly selected from Montefiore Medical Center (MMC), Bronx, NY. In addition, two positive cases from Yale New Haven Hospital, CT were included as controls. All 104 placentas delivered by SARS-CoV-2-positive mothers were uninfected by the virus, based on immunohistochemistry, in situ hybridization, and qPCR analysis. However, placental villous infarcts were significantly increased in first-wave cases compared to second-wave cases or negative controls. Significantly lower Apgar scores at 1 min and 5 min were observed in neonates born to infected mothers with severe symptoms. These findings suggest that even without entering the placenta, SARS-CoV-2 can affect various systemic pathways, culminating in altered placental development and function, which may adversely affect the fetus, especially in a high-risk patient population such as ours. These results underline the importance of vaccination among pregnant women, particularly in low-resource areas.

Antioxidant Effects of N-Acetylcysteine Prevent Programmed Metabolic Disease in Mice.

An adverse maternal in utero and lactation environment can program offspring for increased risk for metabolic disease. The aim of this study was to determine whether N-acetylcysteine (NAC), an anti-inflammatory antioxidant, attenuates programmed susceptibility to obesity and insulin resistance in offspring of mothers on a high-fat diet (HFD) during pregnancy. CD1 female mice were acutely fed a standard breeding chow or HFD. NAC was added to the drinking water (1 g/kg) of the treatment cohorts from embryonic day 0.5 until the end of lactation. NAC treatment normalized HFD-induced maternal weight gain and oxidative stress, improved the maternal lipidome, and prevented maternal leptin resistance. These favorable changes in the in utero environment normalized postnatal growth, decreased white adipose tissue (WAT) and hepatic fat, improved glucose and insulin tolerance and antioxidant capacity, reduced leptin and insulin, and increased adiponectin in HFD offspring. The lifelong metabolic improvements in the offspring were accompanied by reductions in proinflammatory gene expression in liver and WAT and increased thermogenic gene expression in brown adipose tissue. These results, for the first time, provide a mechanistic rationale for how NAC can prevent the onset of metabolic disease in the offspring of mothers who consume a typical Western HFD.

The Unique Role of 11-Oxygenated C19 Steroids in Both Premature Adrenarche and Premature Pubarche.

INTRODUCTION: Recent studies have shown 11-oxygenated androgens (11oAs) are the dominant androgens in premature adrenarche (PA). Our objective was to compare 11oAs and conventional androgens in a well-defined cohort of children with PA or premature pubarche (PP) and correlate these androgens with metabolic markers. METHODS: A prospective cross-sectional study was conducted at a university hospital. Fasting early morning serum steroids (including 11oAs) and metabolic biomarkers were compared and their correlations determined in children ages 3-8 years (F) or 3-9 years (M) with PA or PP (5 M and 15 F) and healthy controls (3 M and 8 F). RESULTS: There were no differences between PA, PP, and controls or between PA and PP subgroups for sex, BMI z-score, or criteria for childhood metabolic syndrome. Dehydroepiandrosterone sulfate (DHEAS) was elevated only in the PA subgroup, as defined. 11oAs were elevated versus controls in PA and PP although no differences in 11oAs were noted between PA and PP. Within the case cohort, there was high correlation of T and A4 with 11-ketotestosterone and 11ß-hydroxyandrostenedione. While lipids did not differ, median insulin and HOMA-IR were higher but not statistically different in PA and PP. CONCLUSIONS: PA and PP differ only by DHEAS and not by 11oAs or insulin sensitivity, consistent with 11oAs - rather than DHEAS - mediating the phenotypic changes of pubarche. Case correlations suggest association of 11oAs with T and A4. These data are the first to report the early morning steroid profiles including 11oAs in a well-defined group of PA, PP, and healthy children.

Pancreatic beta-cell overexpression of the glucagon receptor gene results in enhanced beta-cell function and mass.

In addition to its primary role in regulating glucose production from the liver, glucagon has many other actions, reflected by the wide tissue distribution of the glucagon receptor (Gcgr). To investigate the role of glucagon in the regulation of insulin secretion and whole body glucose homeostasis in vivo, we generated mice overexpressing the Gcgr specifically on pancreatic beta-cells (RIP-Gcgr). In vivo and in vitro insulin secretion in response to glucagon and glucose was increased 1.7- to 3.9-fold in RIP-Gcgr mice compared with controls. Consistent with the observed increase in insulin release in response to glucagon and glucose, the glucose excursion resulting from both a glucagon challenge and intraperitoneal glucose tolerance test (IPGTT) was significantly reduced in RIP-Gcgr mice compared with controls. However, RIP-Gcgr mice display similar glucose responses to an insulin challenge. beta-Cell mass and pancreatic insulin content were also increased (20 and 50%, respectively) in RIP-Gcgr mice compared with controls. When fed a high-fat diet (HFD), both control and RIP-Gcgr mice developed similar degrees of obesity and insulin resistance. However, the severity of both fasting hyperglycemia and impaired glucose tolerance (IGT) were reduced in RIP-Gcgr mice compared with controls. Furthermore, the insulin response of RIP-Gcgr mice to an IPGTT was twice that of controls when fed the HFD. These data indicate that increased pancreatic beta-cell expression of the Gcgr increased insulin secretion, pancreatic insulin content, beta-cell mass, and, when mice were fed a HFD, partially protected against hyperglycemia and IGT.

Neonatal exendin-4 treatment reduces oxidative stress and prevents hepatic insulin resistance in intrauterine growth-retarded rats.

Intrauterine growth retardation (IUGR) has been linked to the development of type 2 diabetes in adulthood. We have developed an IUGR model in the rat whereby the animals develop diabetes later in life. Previous studies demonstrate that administration of the long-acting glucagon-like-peptide-1 agonist, exendin-4, during the neonatal period prevents the development of diabetes in IUGR rats. IUGR animals exhibit hepatic insulin resistance early in life (prior to the onset of hyperglycemia), characterized by blunted suppression of hepatic glucose production (HGP) in response to insulin. Basal HGP is also significantly higher in IUGR rats. We hypothesized that neonatal administration of exendin-4 would prevent the development of hepatic insulin resistance. IUGR and control rats were given exendin-4 on days 1-6 of life. Hyperinsulinemic-euglycemic clamp studies showed that Ex-4 significantly reduced basal HGP by 20% and normalized insulin suppression of HGP in IUGR rats. While Ex-4 decreased body weight and fat content in both Control and IUGR animals, these differences were only statistically significant in Controls. Exendin-4 prevented development of oxidative stress in liver and reversed insulin-signaling defects in vivo, thereby preventing the development of hepatic insulin resistance. Defects in glucose disposal and suppression of hepatic glucose production in response to insulin were reversed. Similar results were obtained in isolated Ex-4-treated neonatal hepatocytes. These results indicate that exposure to exendin-4 in the newborn period reverses the adverse consequences of fetal programming and prevents the development of hepatic insulin resistance.

Relationship between adiponectin and ambulatory blood pressure in obese adolescents.

Obesity is associated with elevated blood pressure (BP), insulin resistance, and altered plasma adiponectin levels; the relationship between the biochemical features of obesity and 24-h ambulatory blood pressure (24-h ABP) parameters in adolescents remains unknown. Anthropometric measurements and 24-h ABP monitoring were obtained on 41 obese adolescents with and without type 2 diabetes mellitus (T2DM). Serum adiponectin, high sensitivity C-reactive protein (hs-CRP), lipid profile, insulin, fasting glucose, liver enzymes, Hb A1c (HbA1c), and two random urine samples were obtained for creatinine and microalbumin measurements. The determinants of 24-h systolic (SBP) and diastolic (DBP) BP were examined using multivariate linear regression models with BP parameters as outcome variables. Forty-one obese adolescents were studied. Adiponectin levels were reduced and hs-CRP levels were elevated, and were inversely and significantly correlated (rho = -0.3, p = 0.05). ABP showed blunted nocturnal SBP dipping. Twenty-four hour SBP and DBP indexes were significantly (p < 0.05) and inversely correlated with adiponectin (rho = -0.4 and -0.42), respectively. In multivariate models, lower adiponectin level was independently associated with 24-h SBP and DBP. Adiponectin inversely correlate with ABP parameters in obese adolescents. Larger studies are needed to examine the relationship between adiponectin and mechanisms of BP regulation.

Maternal substrate utilization programs the development of the metabolic syndrome in male mice exposed to high fat in utero.

Studies were conducted to determine whether maternal substrate utilization during pregnancy affects fetal growth and predisposes offspring to metabolic disease. Female wild-type (WT) and glucose transporter 4 heterozygous mice (G4+/-, a model of altered peripheral substrate utilization) were fed high-fat diet (HFD, 35.5% fat) or control chow (C, 9.5% fat) for 2 wk before mating, throughout pregnancy and lactation (IU/L). WT HFD females exhibited increased serum nonesterified fatty acid and lactate levels and increased hepatic mRNA expression of peroxisome proliferator-activated receptor gamma coactivator-1-beta and SREBP-1c, consistent with increased lipogenesis. G4+/- HFD females exhibited enhanced lipid clearance, and exposure to HFD did not increase hepatic gene expression. HFD independent of maternal genotype decreased fetal growth and birth weight. WT offspring were weaned onto a low-fat diet (5.6% fat). Male offspring of WT mothers exposed to HFD exhibited "catch-up" growth accompanied by increased adiposity, impaired glucose tolerance, and insulin sensitivity. In contrast, male offspring of G4+/- HFD mothers did not exhibit any characteristics of metabolic syndrome. These data suggest that differences in maternal substrate utilization influence offspring metabolic phenotype.

Deficits in Bone Geometry in Growth Hormone-Deficient Prepubertal Boys Revealed by High-Resolution Peripheral Quantitative Computed Tomography.

INTRODUCTION: Although growth hormone (GH) is essential for attainment of peak bone mass, bone health in prepubertal children with GH deficiency is not routinely evaluated. The objective of this study was to evaluate bone microarchitecture in GH-deficient (GHD) boys using high-resolution peripheral quantitative computed tomography (HR-pQCT). METHODS: Fifteen control and fifteen GHD, GH naïve pre-pubertal boys were recruited for a case-control study at a major academic center. Subjects with panhypopituitarism, chromosomal pathology, chronic steroids, or stimulant use were excluded. Volumetric bone mineral density (vBMD; total, cortical, and trabecular), bone geometry (total, cortical and trabecular cross-sectional area, cortical perimeter), bone microarchitecture, and estimated bone strength of the distal radius and tibia were assessed by HR-pQCT. Areal BMD and body composition were assessed by DXA. Insulin-like growth factor 1 (IGF-1), osteocalcin, C telopeptide, and P1NP levels were measured. RESULTS: GHD subjects had a significantly smaller cortical perimeter of the distal radius compared to controls (p < 0.001), with the difference in cortical perimeter persisting after adjusting for height z score, age, lean mass, and 25-hydroxyvitamin D level (p < 0.05).No significant differences were found in vBMD. No significant differences were found in microarchitecture, estimated strength, areal BMD, body composition, or bone turnover markers. Analysis showed significant positive correlations between IGF-1 levels and cortical parameters. DISCUSSION/CONCLUSIONS: Prepubertal GHD boys had deficits in bone geometry not evident with DXA. Larger prospective/longitudinal HR-pQCT studies are needed to determine the extent of these deficits, the need for routine bone evaluation, and the timing of GH replacement for prevention or restoration of these deficits.

Animal models for small for gestational age and fetal programming of adult disease.

Fetal growth retardation is a fetal adaptation in response to inadequate supply of oxygen and/or nutrients. Animal models of intrauterine growth retardation are an invaluable tool to question the genetic, molecular and cellular events that determine fetal growth and development. Rodent and non-litter bearing animals are mammalian system with similar embryology,anatomy and physiology to humans. Utilization of these systems has led to a greater understanding of the pathophysiology and consequences of intrauterine growth retardation. These observations are comparable to that observed in humans born small for gestational age, and are of interest because of the known association between poor fetal growth and development of adult disease. All the experimental manipulations described here have altered a number of metabolic and physiological variables, but the pattern of alterations seems to vary with the procedure and species employed. This review describes animal models for intrauterine growth retardation and assesses their potentials and limitations at aiming to improve strategies for the prevention of adult disease.

In Utero Exposure to a High-Fat Diet Programs Hepatic Hypermethylation and Gene Dysregulation and Development of Metabolic Syndrome in Male Mice.

Exposure to a high-fat (HF) diet in utero is associated with increased incidence of cardiovascular disease, diabetes, and metabolic syndrome later in life. However, the molecular basis of this enhanced susceptibility for metabolic disease is poorly understood. Gene expression microarray and genome-wide DNA methylation analyses of mouse liver revealed that exposure to a maternal HF milieu activated genes of immune response, inflammation, and hepatic dysfunction. DNA methylation analysis revealed 3360 differentially methylated loci, most of which (76%) were hypermethylated and distributed preferentially to hotspots on chromosomes 4 [atherosclerosis susceptibility quantitative trait loci (QTLs) 1] and 18 (insulin-dependent susceptibility QTLs 21). Interestingly, we found six differentially methylated genes within these hotspot QTLs associated with metabolic disease that maintain altered gene expression into adulthood (Arhgef19, Epha2, Zbtb17/Miz-1, Camta1 downregulated; and Ccdc11 and Txnl4a upregulated). Most of the hypermethylated genes in these hotspots are associated with cardiovascular system development and function. There were 140 differentially methylated genes that showed a 1.5-fold increase or decrease in messenger RNA levels. Many of these genes play a role in cell signaling pathways associated with metabolic disease. Of these, metalloproteinase 9, whose dysregulation plays a key role in diabetes, obesity, and cardiovascular disease, was upregulated 1.75-fold and hypermethylated in the gene body. In summary, exposure to a maternal HF diet causes DNA hypermethylation, which is associated with long-term gene expression changes in the liver of exposed offspring, potentially contributing to programmed development of metabolic disease later in life.

Ablation of the glucagon receptor gene increases fetal lethality and produces alterations in islet development and maturation.

Although glucagon (GLU) plays a pivotal role in glucose homeostasis, its role in the regulation of fetal growth and maturation is poorly understood. These issues were examined in a line of mice with a global deletion of the GLU receptor (Gcgr-/-), which are characterized by lower blood glucose levels and by alpha- and delta-cell hyperplasia in adults. Ablation of Gcgr was deleterious to fetal survival; it delayed beta-cell differentiation and perturbed the proportion of beta- to alpha-cells in embryonic islets. In adults, the mutation inhibited the progression of alpha-cells to maturity, affected the expression of several beta-cell-specific genes, and resulted in an augmentation of the alpha-, beta-, and delta-cell mass. This increase was due to an augmentation in both islet number and in the rate of proliferation of cells expressing GLU or insulin. These findings suggest that GLU participates in a feedback loop that regulates the proportion of the different endocrine cell types in islets, the number of islets per pancreas, and development of the mature alpha-cell phenotype.

Blockade of glucagon signaling prevents or reverses diabetes onset only if residual ß-cells persist.

Glucagon secretion dysregulation in diabetes fosters hyperglycemia. Recent studies report that mice lacking glucagon receptor (Gcgr(-/-)) do not develop diabetes following streptozotocin (STZ)-mediated ablation of insulin-producing ß-cells. Here, we show that diabetes prevention in STZ-treated Gcgr(-/-) animals requires remnant insulin action originating from spared residual ß-cells: these mice indeed became hyperglycemic after insulin receptor blockade. Accordingly, Gcgr(-/-) mice developed hyperglycemia after induction of a more complete, diphtheria toxin (DT)-induced ß-cell loss, a situation of near-absolute insulin deficiency similar to type 1 diabetes. In addition, glucagon deficiency did not impair the natural capacity of α-cells to reprogram into insulin production after extreme ß-cell loss. α-to-ß-cell conversion was improved in Gcgr(-/-) mice as a consequence of α-cell hyperplasia. Collectively, these results indicate that glucagon antagonism could i) be a useful adjuvant therapy in diabetes only when residual insulin action persists, and ii) help devising future ß-cell regeneration therapies relying upon α-cell reprogramming.

Lack of glucagon receptor signaling and its implications beyond glucose homeostasis.

Glucagon action is transduced by a G protein-coupled receptor located in liver, kidney, intestinal smooth muscle, brain, adipose tissue, heart, pancreatic ß-cells, and placenta. Genetically modified animal models have provided important clues about the role of glucagon and its receptor (Gcgr) beyond glucose control. The PubMed database was searched for articles published between 1995 and 2014 using the key terms glucagon, glucagon receptor, signaling, and animal models. Lack of Gcgr signaling has been associated with: i) hypoglycemic pregnancies, altered placentation, poor fetal growth, and increased fetal-neonatal death; ii) pancreatic glucagon cell hyperplasia and hyperglucagonemia; iii) altered body composition, energy state, and protection from diet-induced obesity; iv) impaired hepatocyte survival; v) altered glucose, lipid, and hormonal milieu; vi) altered metabolic response to prolonged fasting and exercise; vii) reduced gastric emptying and increased intestinal length; viii) altered retinal function; and ix) prevention of the development of diabetes in insulin-deficient mice. Similar phenotypic findings were observed in the hepatocyte-specific deletion of Gcgr. Glucagon action has been involved in the modulation of sweet taste responsiveness, inotropic and chronotropic effects in the heart, satiety, glomerular filtration rate, secretion of insulin, cortisol, ghrelin, GH, glucagon, and somatostatin, and hypothalamic signaling to suppress hepatic glucose production. Glucagon (α) cells under certain conditions can transdifferentiate into insulin (ß) cells. These findings suggest that glucagon signaling plays an important role in multiple organs. Thus, treatment options designed to block Gcgr activation in diabetics may have implications beyond glucose homeostasis.

Effects of genetics and in utero diet on murine pancreatic development.

Intrauterine (IU) malnutrition could alter pancreatic development. In this study, we describe the effects of high-fat diet (HFD) during pregnancy on fetal growth and pancreatic morphology in an 'at risk' animal model of metabolic disease, the glucose transporter 4 (GLUT4) heterozygous mouse (G4+/-). WT female mice mated with G4+/- males were fed HFD or control diet (CD) for 2 weeks before mating and throughout pregnancy. At embryonic day 18.5, fetuses were killed and pancreata isolated for analysis of morphology and expression of genes involved in insulin (INS) cell development, proliferation, apoptosis, glucose transport and function. Compared with WT CD, WT HFD fetal pancreata had a 2.4-fold increase in the number of glucagon (GLU) cells (P=0.023). HFD also increased GLU cell size by 18% in WT pancreata compared with WT CD. Compared with WT CD, G4+/- CD had an increased number of INS cells and decreased INS and GLU cell size. Compared with G4+/- CD, G4+/- HFD fetuses had increased pancreatic gene expression of Igf2, a mitogen and inhibitor of apoptosis. The expression of genes involved in proliferation, apoptosis, glucose transport, and INS secretion was not altered in WT HFD compared with G4+/- HFD pancreata. In contrast to WT HFD pancreata, HFD exposure did not alter pancreatic islet morphology in fetuses with GLUT4 haploinsufficiency; this may be mediated in part by increased Igf2 expression. Thus, interactions between IU diet and fetal genetics may play a critical role in the developmental origins of health and disease.