Folic acid supplementation affects ROS scavenging enzymes, enhances Vegf-A, and diminishes apoptotic state in yolk sacs of embryos of diabetic rats

Aberrant lipid accumulation in the mouse visceral yolk sac resulting from maternal diabetes and obesity

Maternal diabetes and obesity in pregnancy are well-known risk factors for structural birth defects, including neural tube defects and congenital heart defects. Progeny from affected pregnancies are also predisposed to developing cardiometabolic disease in later life. Based upon in vitro embryo cultures of rat embryos, it was postulated that nutrient uptake by the yolk sac is deficient in diabetic pregnancies. In contrast, using two independent mouse models of maternal diabetes, and a high-fat diet-feeding model of maternal obesity, we observed excessive lipid accumulation at 8.5 days in the yolk sac. The numbers as well as sizes of intracellular lipid droplets were increased in yolk sacs of embryos from diabetic and obese pregnancies. Maternal metabolic disease did not affect expression of lipid transporter proteins, including ApoA1, ApoB and SR-B1, consistent with our earlier report that expression of glucose and fatty acid transporter genes was also unchanged in diabetic pregnancy-derived yolk sacs. Colocalization of lipid droplets with lysosomes was significantly reduced in the yolk sacs from diabetic and obese pregnancies compared to yolk sacs from normal pregnancies. We therefore conclude that processing of lipids is defective in pregnancies affected by maternal metabolic disease, which may lead to reduced availability of lipids to the developing embryo. The possible implications of insufficient supply of lipids -and potentially of other nutrients-to the embryos experiencing adverse pregnancy conditions are discussed.

The Use of Bioactive Compounds in Hyperglycemia- and Amyloid Fibrils-Induced Toxicity in Type 2 Diabetes and Alzheimer’s Disease

It has become increasingly apparent that defective insulin signaling may increase the risk for developing Alzheimer’s disease (AD), influence neurodegeneration through promotion of amyloid formation or by increasing inflammatory responses to intraneuronal β-amyloid. Recent work has demonstrated that hyperglycemia is linked to cognitive decline, with elevated levels of glucose causing oxidative stress in vulnerable tissues such as the brain. The ability of β-amyloid peptide to form β-sheet-rich aggregates and induce apoptosis has made amyloid fibrils a leading target for the development of novel pharmacotherapies used in managing and treatment of neuropathological conditions such as AD-related cognitive decline. Additionally, deposits of β-sheets folded amylin, a glucose homeostasis regulator, are also present in diabetic patients. Thus, therapeutic compounds capable of reducing intracellular protein aggregation in models of neurodegenerative disorders may prove useful in ameliorating type 2 diabetes mellitus symptoms. Furthermore, both diabetes and neurodegenerative conditions, such as AD, are characterized by chronic inflammatory responses accompanied by the presence of dysregulated inflammatory biomarkers. This review presents current evidence describing the role of various small bioactive molecules known to ameliorate amyloidosis and subsequent effects in prevention and development of diabetes and AD. It also highlights the potential efficacy of peptide–drug conjugates capable of targeting intracellular targets.

Verbascoside-enriched fraction from Buddleja cordata Kunth ameliorates the effects of diabetic embryopathy in an animal model

BACKGROUND

The deleterious effects of diabetes mellitus (DM) over development are apparently due to an increase in oxidative stress. Some antioxidants could prevent developmental alterations produced by diabetic state. Extracts of plants of the genus Buddleja are used traditionally for Mexican indigens to ameliorate some diseases. The purpose of this work was to evaluate the effect of the extract of Buddleja cordata over diabetic embryopathy.

METHODS

Two experimental approaches were used: an in vivo study and an in vitro model. In the first, rats were treated with streptozotocin, streptozotocin plus methanolic extract of B. cordata, or none. Females were sacrificed at gestational day (GD) 19, and biochemical clinical parameters were measured; also, the fetuses were obtained and morphologically analyzed. In the in vitro model, a verbascoside-enriched fraction (VEF) of the extract was used in whole embryo culture in order to search for the mechanisms for embryoprotection effect over hyperglycemia-induced malformations.

RESULTS

In the in vivo experiments, B. cordata extract reduces the frequency and severity of fetal malformations produced by chemically induced diabetes, and additionally partially ameliorates the diabetic condition; in the in vitro model, both severity and frequency of embryo dysmorphogenesis were reduced by the VEF; also, this fraction reduces lipoperoxidation without affecting the activity of the antioxidant enzymes.

CONCLUSION

The results suggest that verbascoside of methanolic extract and enriched fraction can directly affect the redox state, and thus, prevents the embryotoxicity mediated by oxidative stress, in embryos of diabetic pregnancy.

Bcl-2 expression in a diabetic embryopathy model in presence of polyamines

The frequency of congenital malformations is 3-5 times higher in mothers with pregestational diabetes mellitus than in general population. Apparently, this problem is due to change in the expression of apoptotic and antiapoptotic genes induced by the oxidative stress derived from the diabetes/hyperglycemia. One of these genes is Bcl-2, which is associated with the control and inhibition of apoptosis. The purpose of the present work was to study the effect of polyamine addition over expression of Bcl-2 gene in a model of diabetic embryopathy. For this, gestational day 10.5 (GD10.5) rat embryos were incubated at 37°C for 24 h in control medium, medium with high glucose, or medium with high glucose and supplemented with spermidine or spermine. Post-cultured embryos were harvested and observed to obtain morphological scores; some of them were subjected to molecular biology studies: DNA isolation plus conventional PCR or RNA isolation plus RT-PCR; other embryos were fixed with paraformaldehyde and used for immunohistochemical detection of Bcl-2 protein. Although Bcl-2 mRNA was similarly expressed in all rat embryo treatments, Bcl-2 protein was found only in control-incubated embryos. In conclusion, it seems that the inhibition of Bcl-2 gene expression induced by glucose was not reversed by polyamines.

The effect of folic acid administration on cardiac tissue matrix metalloproteinase activity and hepatorenal biomarkers in diabetic rats 1

Diabetes mellitus (DM) is a metabolic disorder that causes severe complications. Thus, the aims of this study were to investigate the influence of DM and folic acid treatment on liver and renal biomarkers, and heart remodeling through evaluation of cardiac matrix metalloproteinase (MMP) activity. There were 4 groups: control (physiological saline 1 mL/kg, i.p., 28 days), DM (streptozotocin [STZ] 100 mg/kg in physiological saline, i.p., 1 day), folic acid (FA; 5 mg/kg, i.p., 28 days), and DM+FA (STZ 100 mg/kg, i.p., 1 day and folic acid 5 mg/kg, i.p., 28 days). Our results demonstrated increased aminotransferase and alkaline phosphatase activity, urea and creatinine concentration, and decreased albumin and fibrinogen concentration in the DM group. MMP-2 relative activity was elevated in the DM and FA groups; MMP-9 was decreased in the DM and increased in the FA group. The folic acid treatment of diabetic rats did not change aminotransferase activity; it alleviated the increase in alkaline phosphatase and the decrease in albumin and fibrinogen concentration, and reduced MMP-2 activity; however, it increased urea and creatinine concentration. In conclusion, folic acid treatment of diabetic rats has cardio- and hepato-protective effects. However, its dosing should be carefully considered because of possible renal damage.

Therapies for gestational diabetes and their implications for maternal and offspring health: Evidence from human and animal studies

Obesity prior to and during pregnancy is associated with an increased risk of complications during pregnancy. One of the most common complications of pregnancy is gestational diabetes mellitus (GDM), a condition characterized by hyperglycemia and insulin resistance that is diagnosed in the third trimester of pregnancy. GDM predisposes both mothers and their children to increased obesity and cardiometabolic disorders, namely type 2 diabetes and cardiovascular disease. Current treatments include lifestyle changes and insulin injections, but oral anti-diabetic drugs such as metformin and glyburide are increasingly prescribed as they do not require injections. However, the long-term implications of therapies for diabetes during pregnancy on mothers and their offspring are not fully understood. In this review, we describe current treatments for GDM, including the first line lifestyle interventions such as exercise as well as insulin, glyburides and metformin. We also review selected natural health products that are sometimes used by individuals during pregnancy that could also be an effective therapeutic in pregnancies characterized by obesity or GDM. We focus on both the short- and long-term effects of treatments on the health of mothers and their offspring. We review the current literature from clinical research and animal studies.

Arsenic toxicity and epimutagenecity: the new LINEage

Global methylation pattern regulates the normal functioning of a cell. Research have shown arsenic alter these methylation landscapes within the genome leading to aberrant gene expression and inducts various pathophysiological outcomes. Long interspersed nuclear elements (LINE-1) normally remains inert due to heavy methylation of it's promoters, time and various environmental insults, they lose these methylation signatures and begin retro-transposition that has been associated with genomic instability and cancerous outcomes. Of the various high throughput technologies available to detect global methylation profile, development of LINE-1 methylation index shall provide a cost effect-screening tool to detect epimutagenic events in the wake of toxic exposure in a large number of individuals. In the present review, we tried to discuss the state of research and whether LINE-1 methylation can be considered as a potent epigenetic signature for arsenic toxicity.

Streptozotocin-Induced Maternal Hyperglycemia Increases the Expression of Antioxidant Enzymes and Mast Cell Number in Offspring Rat Ventral Prostate

Gestational diabetes mellitus (GDM) has increased in recent years. Although the cellular and molecular mechanisms involved in GDM-increased risk factors to offspring remained poorly understood, some studies suggested an association between an increase in oxidative stress induced by maternal hyperglycemia and complications for both mothers and newborns. Here, we investigated the impact of maternal hyperglycemia followed by maternal insulin replacement during lactation on the expression of antioxidant enzymes and mast cell number in offspring ventral prostate (VP) at puberty. Pregnant rats were divided into three groups: control (CT); streptozotocin-induced maternal hyperglycemia (MH); and MH plus maternal insulin replacement during lactation (MHI). Male offspring were euthanized at postnatal day (PND) 60 and the VP was removed and processed for histology and Western blotting analyses. Maternal hyperglycemia delayed prostate maturation, and increased mast cell number catalase (CAT), superoxide dismutase (SOD), glutatione-s-transferase (GST-pi), and cyclooxygenase-2 (Cox-2) expression in the offspring of hyperglycemic dams. Maternal insulin replacement restored VP structure, mast cell number and antioxidant protein expression, except for Cox-2, which remained higher in the MHI group. Thus, an increase in oxidative stress induced by intrauterine hyperglycemia impacts prostate development and maturation, which persists until puberty. The overall improvement of maternal metabolism after insulin administration contributes to the restoration of prostate antioxidant enzymes and secretory function. Taken together, our results highlighted that imbalanced physiological maternal-fetal interaction contributes to the impairment of reproductive performance of the offspring from diabetic mothers. Anat Rec, 300:291-299, 2017. © 2016 Wiley Periodicals, Inc.

Decoding the oxidative stress hypothesis in diabetic embryopathy through proapoptotic kinase signaling

Maternal diabetes-induced birth defects occur in 6-10% of babies born to mothers with pregestational diabetes, representing a significant maternal-fetal health problem. Currently, these congenital malformations represent a significant maternal-fetal medicine issue, but are likely to create an even greater public health threat as 3 million women of reproductive age (19-44 years) have diabetes in the United States alone, and this number is expected to double by 2030. Neural tube defects (NTDs) and congenital heart defects are the most common types of birth defects associated with maternal diabetes. Animal studies have revealed that embryos under hyperglycemic conditions exhibit high levels of oxidative stress resulting from enhanced production of reactive oxygen species and impaired antioxidant capability. Oxidative stress activates a set of proapoptotic kinase signaling intermediates leading to abnormal cell death in the embryonic neural tube, which causes NTD formation. Work in animal models also has revealed that maternal diabetes triggers a series of signaling intermediates: protein kinase C (PKC) isoforms, PKCα, βII and δ; apoptosis signal-regulating kinase 1; c-Jun-N-terminal kinase (JNK)1/2; caspase; and apoptosis. Specifically, maternal diabetes in rodent models activates the proapoptotic unfolded protein response and endoplasmic reticulum (ER) stress. A reciprocal causation between JNK1/2 activation and ER stress exists in diabetic embryopathy. Molecular studies further demonstrate that deletion of the genes for Prkc, Ask1, Jnk1, or Jnk2 abolishes maternal diabetes-induced neural progenitor apoptosis and ameliorates NTD formation. Similar preventive effects are also observed when apoptosis signal-regulating kinase 1, JNK1/2, or ER stress is inhibited. Cell membrane stabilizers and antioxidant supplements are also effective in prevention of diabetes-induced birth defects. Mechanistic studies have revealed important insights into our understanding the cause of diabetic embryopathy and have provided a basis for future interventions against birth defects or other pregnancy complications associated with maternal diabetes. The knowledge of a molecular pathway map identified in animal studies has created unique opportunities to identify molecular targets for therapeutic intervention.

Pregestational diabetes induces fetal coronary artery malformation via reactive oxygen species signaling

Hypoplastic coronary artery disease is a congenital coronary artery malformation associated with a high risk of sudden cardiac death. However, the etiology and pathogenesis of hypoplastic coronary artery disease remain undefined. Pregestational diabetes increases reactive oxygen species (ROS) levels and the risk of congenital heart defects. We show that pregestational diabetes in mice induced by streptozotocin significantly increased 4-hydroxynonenal production and decreased coronary artery volume in fetal hearts. Pregestational diabetes also impaired epicardial epithelial-to-mesenchymal transition (EMT) as shown by analyses of the epicardium, epicardial-derived cells, and fate mapping. Additionally, the expression of hypoxia-inducible factor 1α (Hif-1α), Snail1, Slug, basic fibroblast growth factor (bFgf), and retinaldehyde dehydrogenase (Aldh1a2) was decreased and E-cadherin expression was increased in the hearts of fetuses of diabetic mothers. Of note, these abnormalities were all rescued by treatment with N-acetylcysteine (NAC) in diabetic females during gestation. Ex vivo analysis showed that high glucose levels inhibited epicardial EMT, which was reversed by NAC treatment. We conclude that pregestational diabetes in mice can cause coronary artery malformation through ROS signaling. This study may provide a rationale for further clinical studies to investigate whether pregestational diabetes could cause hypoplastic coronary artery disease in humans.

Growth factors in preeclampsia: a vascular disease model. A failed vasodilation and angiogenic challenge from pregnancy onwards?

Preeclampsia is the major cause of maternofetal and neonatal morbi-mortality including intrauterine growth retardation, miscarriages and stillbirths. Inadequate vascular dilation and angiogenesis represent the crucial underlying defect of gravidic hypertension, denoting a failed response to the vasodilatory and pro-angiogenic challenge imposed by pregnancy, especially if multifetal. A similar pathogenesis appears involved in gestational diabetes. In this review we aimed to provide a hint on understanding the deeply involved angiogenic disorders which eventually culminate in utero-placental failure. The key players in these complex processes may be found in an intricate network of growth factors (GFs) and GF inhibitors, controlled by several vascular risk factors modulated by environment and genes, which eventually impact on early and late cardiovascular outcomes of mother and fetus.

New concepts in diabetic embryopathy

Diabetes mellitus is responsible for nearly 10% of fetal anomalies in diabetic pregnancies. Although aggressive perinatal care and glycemic control are available in developed countries, the birth defect rate in diabetic pregnancies remains higher than that in the general population. Major cellular activities (ie, proliferation and apoptosis) and intracellular metabolic conditions (ie, nitrosative, oxidative, and endoplasmic reticulum stress) have been shown to be associated with diabetic embryopathy using animal models. Translating advances made in animal studies into clinical applications in humans requires collaborative efforts across the basic research, preclinical, and clinical communities.

Folic acid supplementation changes the fate of neural progenitors in mouse embryos of hyperglycemic and diabetic pregnancy

Folic acid has been shown to decrease the incidence of neural tube defects (NTDs) in normal and hyperglycemic conditions, but the influence of folic acid on the development of central nervous system is not fully understood. Here, we aimed to explore the effects of folic acid, especially high dose of folic acid, on the characteristics of neural progenitors in embryos of hyperglycemic and diabetic mouse. Hyperglycemic and diabetic pregnant mice were given 3 mg/kg or 15 mg/kg folic acid from embryonic day 0.5 (E0.5) and were euthanased on E11.5, E13.5 or E18.5. The incidence of NTDs at E13.5 was counted. The proliferation, apoptosis and differentiation of neural progenitors and neuronal migration were determined using BrdU incorporation assay, TUNEL assay, immunofluorescence, Western blot and real-time reverse transcriptase polymerase chain reaction. Both normal and high doses of folic acid decreased the incidence of NTDs, promoted proliferation and reduced apoptosis of neuroepithelial cells in embryos of hyperglycemic and diabetic mice. Importantly, folic acid, especially at high dose, might affect the premature differentiation of neural progenitors in embryos of hyperglycemic and diabetic pregnancy. This may be attributed to changes of messenger RNA expression levels of some basic-helix-loop-helix transcription factors. In addition, folic acid might be involved in regulating neuronal migration in embryos of hyperglycemic and diabetic pregnancy. These findings suggest that periconceptional supplementation of folic acid, especially at high dose, may be a double-edged sword because it may result in undesirable outcomes affecting both the neuronal and glial differentiation in hyperglycemic and diabetic pregnancy.

Down regulation of the proliferation and apoptotic pathways in the embryonic brain of diabetic rats

Compelling evidence shows that the offspring subjected to uncontrolled hyperlycemia during gestation display behavioral, neurochemical, and cellular abnormalities during adulthood. However, the molecular mechanisms underlying these defects remain elusive. Previous studies have shown an increased rate of apoptosis and a decreased index of neuronal proliferation associated with diabetic embryopathy. The aim of the present study was to determine whether impairments in apoptotic related proteins also occur in the developing central nervous system from non-malformed embryos exposed to uncontrolled gestational hyperglycemia. Pregnant rats injected with either streptozotocin or vehicle were killed on gestational day 19. Offspring brains were quickly removed to evaluate protein expression by Western blotting. Embryonic brains from diabetic rats exhibited a decrease in the cell survival p-Akt expression (52.83 ± 24.35%) and in the pro-apoptotic protein Bax (56.16 ± 6.47%). Moreover, the anti-apoptotic protein Bcl-2 showed a non-significant increase while there were no changes in Procaspase 3 or cleaved Caspase 3 proteins. The cytoskeleton proteins NF-200 and GFAP were also examined. Neither NF-200 nor GFAP showed differences in embryonic brains from diabetic rats compared to controls. Altogether, these results indicate that both proliferation and apoptotic pathways are decreased in the brain from the developing offspring of diabetic rats. Since selective neuronal apoptosis, as well as selective cell proliferation, are specifically involved in brain organogenesis, it is possible that simultaneous impairments during the perinatal period contribute to the long lasting alterations observed in the adult brain.

Autophagy mechanism of right ventricular remodeling in murine model of pulmonary artery constriction

Although right ventricular failure (RVF) is the hallmark of pulmonary arterial hypertension (PAH), the mechanism of RVF is unclear. Development of PAH-induced RVF is associated with an increased reactive oxygen species (ROS) production. Increases in oxidative stress lead to generation of nitro-tyrosine residues in tissue inhibitor of metalloproteinase (TIMPs) and liberate active matrix metalloproteinase (MMPs). To test the hypothesis that an imbalance in MMP-to-TIMP ratio leads to interstitial fibrosis and RVF and whether the treatment with folic acid (FA) alleviates ROS generation, maintains MMP/TIMP balance, and regresses interstitial fibrosis, we used a mouse model of pulmonary artery constriction (PAC). After surgery mice were given FA in their drinking water (0.03 g/l) for 4 wk. Production of ROS in the right ventricle (RV) was measured using oxidative fluorescent dye. The level of MMP-2, -9, and -13 and TIMP-4, autophagy marker (p62), mitophagy marker (LC3A/B), collagen interstitial fibrosis, and ROS in the RV wall was measured. RV function was measured by Millar catheter. Treatment with FA decreased the pressure to 35 mmHg from 50 mmHg in PAC mice. Similarly, RV volume in PAC mice was increased compared with the Sham group. A robust increase of ROS was observed in RV of PAC mice, which was decreased by treatment with FA. The protein level of MMP-2, -9, and -13 was increased in RV of PAC mice in comparison with that in the sham-operated mice, whereas supplementation with FA abolished this effect and mitigated MMPs levels. The protein level of TIMP-4 was decreased in RV of PAC mice compared with the Sham group. Treatment with FA helped PAC mice to improve the level of TIMP-4. To further support the claim of mitophagy occurrence during RVF, the levels of LC3A/B and p62 were measured by Western blot and immunohistochemistry. LC3A/B was increased in RV of PAC mice. Similarly, increased p62 protein level was observed in RV of PAC mice. Treatment with FA abolished this effect in PAC mice. These results suggest that FA treatment improves MMP/TIMP balance and ameliorates mitochondrial dysfunction that results in protection of RV failure during pulmonary hypertension.

Linkage study of embryopathy-polygenic inheritance of diabetes-induced skeletal malformations in the rat

We developed an inbred rat model of diabetic embryopathy, in which the offspring displays skeletal malformations (agnathia or micrognathia) when the mother is diabetic, and no malformations when she is not diabetic. Our aim was to find genes controlling the embryonic maldevelopment in a diabetic environment. We contrasted the fetal outcome in inbred Sprague-Dawley L rats (20% skeletal malformations in diabetic pregnancy) with that of inbred Wistar Furth rats (denotedW, no skeletal malformations in diabetic pregnancy). We used offspring from the backcross F(1)×L to probe for the genetic basis for malformation of the mandible in diabetic pregnancy. A set of 186 fetuses (93 affected, 93 unaffected) was subjected to a whole genome scan with 160 micro satellites. Analysis of genotype distribution indicated 7 loci on chromosome 4, 10 (3 loci), 14, 18, and 19 in the teratogenic process (and 14 other loci on 12 chromosomes with less strong association to the malformations), several of which contained genes implicated in other experimental studies of diabetic embryopathy. These candidate genes will be scrutinized in further experimentation. We conclude that the genetic involvement in rodent diabetic embryopathy is polygenic and predisposing for congenital malformations.

Folic acid and safflower oil supplementation interacts and protects embryos from maternal diabetes-induced damage

Maternal diabetes increases the risk of embryo malformations. Folic acid and safflower oil supplementations have been shown to reduce embryo malformations in experimental models of diabetes. In this study we here tested whether folic acid and safflower oil supplementations interact to prevent embryo malformations in diabetic rats, and analyzed whether they act through the regulation of matrix metalloproteinases (MMPs), their endogenous inhibitors (TIMPs), and nitric oxide (NO) and reactive oxygen species production. Diabetes was induced by streptozotocin administration prior to mating. From Day 0.5 of pregnancy, rats did or did not receive folic acid (15 mg/kg) and/or a 6% safflower oil-supplemented diet. Embryos and decidua were explanted on Day 10.5 of gestation for further analysis of embryo resorptions and malformations, MMP-2 and MMP-9 activities, TIMP-1 and TIMP-2 levels, NO production and lipid peroxidation. Maternal diabetes induced resorptions and malformations that were prevented by folic acid and safflower oil supplementation. MMP-2 and MMP-9 activities were increased in embryos and decidua from diabetic rats and decreased with safflower oil and folic acid supplementations. In diabetic animals, the embryonic and decidual TIMPs were increased mainly with safflower oil supplementation in decidua and with folic acid in embryos. NO overproduction was decreased in decidua from diabetic rats treated with folic acid alone and in combination with safflower oil. These treatments also prevented increases in embryonic and decidual lipid peroxidation. In conclusion, folic acid and safflower oil supplementations interact and protect the embryos from diabetes-induced damage through several pathways related to a decrease in pro-inflammatory mediators.

The role of oxidative stress in the pathophysiology of gestational diabetes mellitus

Normal human pregnancy is considered a state of enhanced oxidative stress. In pregnancy, it plays important roles in embryo development, implantation, placental development and function, fetal development, and labor. However, pathologic pregnancies, including gestational diabetes mellitus (GDM), are associated with a heightened level of oxidative stress, owing to both overproduction of free radicals and/or a defect in the antioxidant defenses. This has important implications on the mother, placental function, and fetal well-being. Animal models of diabetes have confirmed the important role of oxidative stress in the etiology of congenital malformations; the relative immaturity of the antioxidant system facilitates the exposure of embryos and fetuses to the damaging effects of oxidative stress. Of note, there are only a few clinical studies evaluating the potential beneficial effects of antioxidants in GDM. Thus, whether or not increased antioxidant intake can reduce the complications of GDM in both mother and fetus needs to be explored. This review provides an overview and updated data on our current understanding of the complications associated with oxidative changes in GDM.

The effects of homocysteine and folic acid on angiogenesis and VEGF expression during chicken vascular development

Homocysteine (Hcy) has been implicated in the development of cardiovascular developmental defects. Additionally, in experimental studies, vasculotoxic properties of Hcy have been described. Although Hcy has been identified as a vascular pathogen, little is known about the direct effects Hcy exerts during early embryonic vascular development. Angiogenesis is a critical process involved in embryo survival and development. There are limited studies on the effects of Hcy on early embryonic vasculogenesis and angiogenesis. Folic acid (FA) is a B vitamin essential in embryo development, and FA supplementation may lead to reduced Hcy levels. Therefore, the purpose of our study was to explore the effects of Hcy and FA on early embryonic vascular development. Embryonic day (E) 3.5 chicken embryos were treated with a sham, Hcy or FA solution. We developed a computational program for systematic analysis of microscopic images obtained from the extra embryonic vascular beds. These results were combined with real-time PCR data on the expression of VEGF-A and its receptor in these vascular beds. Our data show that Hcy exposure inhibits early vascular development, displayed by a significant reduction of vessel area and altered composition of the vascular beds. Vascular beds of Hcy embryos for the greater part consisted of vessels of the smallest diameters, compared to middle size vessels in control and FA embryos. Hcy also reduced expression of VEGF-A and VEGFR-2. No significant effects of FA were found. We conclude that Hcy exposure causes impaired early extra embryonic vascular development, shown by altered composition of the vascular beds as well as reduced expression of VEGF-A and VEGFR-2. These effects of Hcy, and the consecutive cascade of events, may be involved in the development of cardiovascular developmental defects.

Understanding diabetic teratogenesis: where are we now and where are we going?

Maternal pregestational diabetes (type 1 or type 2) poses an increased risk for a broad spectrum of birth defects. To our knowledge, this problem first came to the attention of the Teratology Society at the 14th Annual Meeting in Vancouver, B.C. in 1974, with a presentation by Lewis Holmes, "Etiologic heterogeneity of neural tube defects". Although advances in the control of diabetes in the decades since the discovery of insulin in the 1920's have reduced the risk for birth defects during diabetic pregnancy, the increasing incidence of diabetes among women of childbearing years indicates that this cause of birth defects is a growing public health concern. Major advances in understanding how a disease of maternal fuel metabolism can interfere with embryogenesis of multiple organ systems have been made in recent years. In this review, we trace the history of the study of diabetic teratogenesis and discuss a model in which tissue-specific developmental control genes are regulated at specific times in embryonic development by glucose metabolism. The major function of such genes is to suppress apoptosis, perhaps to preserve proliferative capability, and inhibit premature senescence.

Maternal diet modulates the risk for neural tube defects in a mouse model of diabetic pregnancy

Pregnancies complicated by maternal diabetes have long been known to carry a higher risk for congenital malformations, such as neural tube defects. Using the FVB inbred mouse strain and the Streptozotocin-induced diabetes model, we tested whether the incidence of neural tube defects in diabetic pregnancies can be modulated by maternal diet. In a comparison of two commercial mouse diets, which are considered nutritionally replete, we found that maternal consumption of the unfavorable diet was associated with a more than 3-fold higher rate of neural tube defects. Our results demonstrate that maternal diet can act as a modifier of the risk for abnormal development in high-risk pregnancies, and provide support for the possibility that neural tube defects in human diabetic pregnancies might be preventable by optimized maternal nutrition.

Diabetes and apoptosis: neural crest cells and neural tube

Birth defects resulting from diabetic pregnancy are associated with apoptosis of a critical mass of progenitor cells early during the formation of the affected organ(s). Insufficient expression of genes that regulate viability of the progenitor cells is responsible for the apoptosis. In particular, maternal diabetes inhibits expression of a gene, Pax3, that encodes a transcription factor which is expressed in neural crest and neuroepithelial cells. As a result of insufficient Pax3, cardiac neural crest and neuroepithelial cells undergo apoptosis by a process dependent on the p53 tumor suppressor protein. This, then provides a cellular explanation for the cardiac outflow tract and neural tube and defects induced by diabetic pregnancy.

Can we prevent diabetic birth defects with micronutrients?

Congenital malformations are more common in infants of diabetic women than in children of non-diabetic women. The mechanisms behind diabetes-induced congenital anomalies are not known. Disturbed micronutrient metabolism, in concert with oxidative stress, has been suggested as a cause of diabetes-induced malformations by several studies. In experimental work, administration of inositol, arachidonic acid and several antioxidative compounds, as well as folic acid, to the embryo, has proven to attenuate the teratogenic effects of a diabetic environment. Future therapeutic efforts may include supplementation with antioxidants or micronutrients, such as folic acid, to the pregnant diabetic woman, although exact compounds and doses need to be determined.

Caspase-8: a key role in the pathogenesis of diabetic embryopathy

Maternal diabetes causes neural tube defects in embryos, which are associated with increased apoptosis in the neuroepithelium. Many factors, including effector caspases, have been shown to be involved in the events. However, the key regulators have not been identified and the underlying mechanisms remain to be addressed. Caspase-8, an initiator caspase, has been shown to be altered in diabetic embryopathy, suggesting a role as an upstream apoptotic regulator. Using mouse embryos as a model system, this study demonstrates that caspase-8 is required for the production of hyperglycemia-associated embryonic malformations. Caspase-8 was shown to be expressed in the developing neural tube. Its activity, as evidenced by enhanced cleavage, was increased by hyperglycemia. These changes were associated with increased formation of the active cleavage of Bid. Inhibition of caspase-8 activity in high glucose-challenged embryos reduced the rate of embryonic malformation and this was associated with decreased apoptosis in the neuroepithelium of the neural tube. Inhibition of caspase-8 activity also reduced hyperglycemia-induced Bid activation and caspase-9 cleavage. These data suggest that caspase-8 may control diabetic embryopathy-associated apoptosis via regulation of the Bid-stimulated mitochondrion/caspase-9 pathway.