PPARδ and its activator PGI2 are reduced in diabetic embryopathy: involvement of PPARδ activation in lipid metabolic and signalling pathways in rat embryo early organogenesis

Maternal diabetes increases FOXO1 activation during embryonic cardiac development

Maternal diabetes is known to affect heart development, inducing the programming of cardiac alterations in the offspring's adult life. Previous studies in the heart of adult offspring have shown increased activation of FOXO1 (a transcription factor involved in a wide variety of cellular functions such as apoptosis, cellular proliferation, reactive oxygen species detoxification, and antioxidant and pro-inflammatory processes) and of target genes related to inflammatory and fibrotic processes. In this work, we aimed to evaluate the effects of maternal diabetes on FOXO1 activation as well as on the expression of target genes relevant to the formation of the cardiovascular system during organogenesis (day 12 of gestation). The embryonic heart from diabetic rats showed increased active FOXO1 levels, reduced protein levels of mTOR (a nutrient sensor regulating cell growth, proliferation and metabolism) and reduced mTORC2-SGK1 pathway, which phosphorylates FOXO1. These alterations were related to increases in the levels of 4-hydroxynonenal (an oxidative stress marker) and increased mRNA levels of inducible nitric oxide synthase, angiopoietin-2 and matrix metalloproteinase-2 (MMP2) (all FOXO1 target genes relevant for cardiac development). Results also showed increased extracellular and intracellular immunolocalization of MMP2 in the myocardium and its projection into the lumen of the cavity (trabeculations) together with decreased immunostaining of connexin 43, a protein relevant for cardiac function that is target of MMP2. In conclusion, increases in active FOXO1 induced by maternal diabetes initiate early during embryonic heart development and are related to increases in markers of oxidative stress and of proinflammatory cardiac development, as well to an altered expression of proteolytic enzymes that regulate connexin 43. These alterations may lead to an altered programming of cardiovascular development in the embryonic heart of diabetic rats.

Dysregulated glycolysis underpins high-fat-associated endometrial decidualization impairment during early pregnancy in mice

Pregnancy complications are more likely to occur in obese women because of defective decidualization. However, the specific mechanism of glycolysis in decidual modulation associated with obesity remains unknown. Therefore, we explored the role of glycolysis in the endometrium of obese pregnant mice during decidualization. C57BL/6J mice were fed a high-fat diet (HFD) to induce obesity. All obesity related parameters were significantly higher in the HFD mice than control. Furthermore, the HFD mice had fewer implantation sites, a smaller decidual area growth, and decreased decidualization marker protein expression than control. The HFD mice also had significantly decreased lactate production and glycolytic enzyme expression. To confirm the functional role of glycolysis during the decidual period in obese pregnant mice, we extracted endometrial stromal cells (ESCs) and treated them with oleic acid (OA) and palmitic acid (PA) to mimic a high-fat environment. Decidualization and glycolysis were significantly restricted in the OA-and PA-treated groups. Moreover, we administered a glycolytic inhibitor, 2-DG, and an agonist, pioglitazone. 2-DG treatment considerably decreased the cells' glycolysis and decidualization. However, pioglitazone treatment improved glycolysis and alleviated defective decidualization. In conclusion, obesity-induced endometrial glycolysis modifications and key glycolytic enzyme downregulation during early pregnancy might cause abnormal decidualization, leading to an unsustainable pregnancy.

The Role of Peroxisome Proliferator-Activated Receptors in Preeclampsia

Preeclampsia is a common pregnancy-related hypertensive disorder. Often presenting as preexisting or new-onset hypertension complicated by proteinuria and/or end-organ dysfunction, preeclampsia significantly correlates with maternal and perinatal morbidity and mortality. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptor proteins that regulate gene expression. In order to investigate the role of PPARs in the pathophysiology of preeclampsia, we conducted a literature review using the MEDLINE and LIVIVO databases. The search terms "peroxisome proliferator-activated receptor", "PPAR", and "preeclampsia" were employed and we were able to identify 35 relevant studies published between 2002 and 2022. Different study groups reached contradictory conclusions in terms of PPAR expression in preeclamptic placentae. Interestingly, PPARγ agonists alone, or in combination with well-established pharmaceutical agents, were determined to represent novel, potent anti-preeclamptic treatment alternatives. In conclusion, PPARs seem to play a significant role in preeclampsia.

Peroxisome proliferator-activated receptor pathways in diabetic rat decidua early after implantation: regulation by dietary polyunsaturated fatty acids

RESEARCH QUESTION

Are peroxisome proliferator-activated receptor (PPAR) pathways and moieties involved in histotrophic nutrition altered in the decidua of diabetic rats? Can diets enriched in polyunsaturated fatty acids (PUFA) administered early after implantation prevent these alterations? Can these dietary treatments improve morphological parameters in the fetus, decidua and placenta after placentation?

DESIGN

Streptozotocin-induced diabetic Albino Wistar rats were fed a standard diet or diets enriched in n3- or n6-PUFAs early after implantation. Decidual samples were collected on day 9 of pregnancy. Fetal, decidual and placental morphological parameters were evaluated on day 14 of pregnancy.

RESULTS

On gestational day 9, PPARδ levels showed no changes in the diabetic rat decidua compared with controls. In diabetic rat decidua, PPARα levels and the expression of its target genes Aco and Cpt1 had reduced. These alterations were prevented by the n6-PUFA-enriched diet. Levels of PPARγ, the expression of its target gene Fas, lipid droplet number and perilipin 2 and fatty acid binding protein 4 levels increased in the diabetic rat decidua compared with controls. Diets enriched with PUFA prevented PPARγ increase, but not the increased lipid-related PPARγ targets. On gestational day 14, fetal growth, decidual and placental weight reduced in the diabetic group, and alterations prevented by the maternal diets were enriched in PUFAs.

CONCLUSION

When diabetic rats are fed diets enriched in n3- and n6-PUFAs early after implantation, PPAR pathways, lipid-related genes and proteins, lipid droplets and glycogen content in the decidua are modulated. This influences decidual histotrophic function and later feto-placental development.

The Potential Role of PPARs in the Fetal Origins of Adult Disease

The fetal origins of adult disease (FOAD) hypothesis holds that events during early development have a profound impact on one’s risk for the development of future adult disease. Studies from humans and animals have demonstrated that many diseases can begin in childhood and are caused by a variety of early life traumas, including maternal malnutrition, maternal disease conditions, lifestyle changes, exposure to toxins/chemicals, improper medication during pregnancy, and so on. Recently, the roles of Peroxisome proliferator-activated receptors (PPARs) in FOAD have been increasingly appreciated due to their wide variety of biological actions. PPARs are members of the nuclear hormone receptor subfamily, consisting of three distinct subtypes: PPARα, β/δ, and γ, highly expressed in the reproductive tissues. By controlling the maturation of the oocyte, ovulation, implantation of the embryo, development of the placenta, and male fertility, the PPARs play a crucial role in the transition from embryo to fetus in developing mammals. Exposure to adverse events in early life exerts a profound influence on the methylation pattern of PPARs in offspring organs, which can affect development and health throughout the life course, and even across generations. In this review, we summarize the latest research on PPARs in the area of FOAD, highlight the important role of PPARs in FOAD, and provide a potential strategy for early prevention of FOAD.

Modulation of PPAR signaling disrupts pancreas development in the zebrafish, Danio rerio

Peroxisome Proliferator Activated Receptors (PPARs) are transcription factors that regulate processes such as lipid and glucose metabolism. Synthetic PPAR ligands, designed as therapeutics for metabolic disease, provide a tool to assess the relationship between PPAR activity and pancreas development in vivo, an area that remains poorly characterized. Here, we aim to assess the effects of PPAR agonists and antagonists on gene expression, embryonic morphology and pancreas development in transgenic zebrafish embryos. To evaluate developmental perturbations, we assessed gross body and pancreas morphology at 4 days post fertilization (dpf) in response to developmental exposures with PPARα, PPARγ, and PPARβ/δ agonists and antagonists at 0, 0.01, 0.1, 1, and 10 μM concentrations. All ligand exposures, with the exception of the PPARα agonist, resulted in significantly altered fish length and yolk sac area. PPARγ agonist and antagonist had higher incidence of darkened yolk sac and craniofacial deformities, whereas PPARα antagonist had higher incidence of pericardial edema and death. Significantly reduced endocrine pancreas area was observed in both PPARγ ligands and PPARα agonist exposed embryos, some of which also exhibited aberrant endocrine pancreas morphology. Both PPARβ/δ ligands caused reduced exocrine pancreas length and novel aberrant phenotype, and disrupted gene expression of pancreatic targets pdx1, gcga, and try. Lipid staining was performed at 8 dpf and revealed altered lipid accumulation consistent with isoform function. These data indicate chronic exposure to synthetic ligands may induce morphological and pancreatic defects in zebrafish embryos.

Ameliorative effects of quercetin on the preimplantation embryos development in diabetic pregnant mice

AIM

Maternal diabetes adversely retards the development of preimplantation embryos. Quercetin is a flavonoid belonging to phytoestrogens family and may be useful in treatment of reproductive disorders. The aim of this study was investigation of the ameliorative effects of quercetin administration on preimplantation embryo development in diabetic pregnancy.

METHODS

Diabetic and healthy female mice were treated with 30 mg/kg/day quercetin 4 weeks before conception. Blastocysts were recovered at the 4th day of pregnancy for protein and mRNA expression changes. Plasma sex-steroid levels were also analyzed.

RESULTS

Quercetin significantly decreased blood glucose levels in diabetic mice. Embryos retrieved from diabetic mice exhibited a considerable delay in morphological development. In diabetic mice with quercetin treatment, morphological distribution was shifted considerably to the well-developed stages. Serum estradiol level reduced in diabetic mice but, treatment with quercetin significantly increased serum estradiol level. While IGF1R, integrin αvβ3, and Cox2 mRNA expression in the blastocyst of diabetic mice decreased significantly, quercetin treatment caused increasing expression levels of these genes. Expression of the Caspase3 gene increased dramatically in the collected blastocysts from diabetic mice and reduced following quercetin treatment. Besides, the inactive β-catenin protein level in the blastocysts of diabetic mice was higher than that in normal mice, while treatment with quercetin decreased the level of inactive β-catenin protein in the blastocyst of diabetic mice.

CONCLUSION

Quercetin protects preimplantation embryos from destructive effects of diabetes. The amelioration of sex hormones disturbance in early pregnancy may help to treat reproductive disorders in diabetic women. Quercetin can be considered as a novel solution to the improvement of reproductive disorders in the diabetic females.

Effect of the antioxidant idebenone on maternal diabetes-induced embryo alterations during early organogenesis

RESEARCH QUESTION

Can maternal treatments with idebenone, a structural analogue of coenzyme Q10, prevent alterations on markers of proinflammatory-prooxidant processes, on the expression of genes involved in mitochondrial biogenesis and function, and on the apoptotic rate in embryos from mild diabetic rats?

DESIGN

A mild diabetic rat model was induced by neonatal-streptozotocin administration (90 mg/kg subcutaneously). Female diabetic rats and controls were mated with healthy males. From day 1 of pregnancy, control and diabetic rats were orally treated with idebenone (100 mg/kg daily). On day 10.5 of gestation, the embryos were explanted and prepared for immunohistochemical studies, for the evaluation of gene expression by reverse transcription polymerase chain reaction and for TdT (terminal deoxynucleotidyl transferase)-mediated dUDP nick-end-labelling assay analysis.

RESULTS

Embryos from mild diabetic rats showed increased levels of nitrated proteins, 4-hydroxynonenal and matrix metalloproteinase 9, which were prevented by idebenone administration. We also found a decreased embryonic expression of cytochrome c oxidase and reduced mRNA levels of peroxisome proliferator activated receptor-γ coactivator-1-α and nuclear respiratory factor-1, both of which were prevented by idebenone administration to the diabetic pregnant rats. Embryos from mild diabetic rats also showed an increased apoptotic rate, which was diminished by idebenone treatment.

CONCLUSION

Maternal idebenone treatment ameliorates altered parameters related to the prooxidant-proinflammatory environment found in embryos from mild diabetic rats, suggesting a putative treatment to prevent diabetes-induced embryo alterations.

Effects of maternal dietary olive oil on pathways involved in diabetic embryopathy

Maternal diabetes induces a pro-oxidant/pro-inflammatory intrauterine environment related to the induction of congenital anomalies. Peroxisome proliferator activated receptors (PPARs) are transcription factors that regulate antioxidant and anti-inflammatory pathways. We investigated whether maternal diets supplemented with olive oil, enriched in oleic acid, a PPAR agonist, can regulate the expression of PPAR system genes, levels of lipoperoxidation and activity of matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs) in embryos and decidua from diabetic rats. The embryos and decidua from diabetic rats showed reduced expression of PPARs and increased concentration of lipoperoxidation, MMPs and TIMPs, whereas the maternal treatments enriched in olive oil increased PPARδ in embryos and PPARγ and PPARγ-coactivator-1α expression in decidua, and increased TIMPs concentrations and decreased lipoperoxidation and MMPs activity in both tissues. Thus, maternal diets enriched in olive oil can regulate embryonic and decidual PPAR system genes expression and reduce the pro-oxidant/pro-inflammatory environment during rat early organogenesis.

Role of Peroxisome Proliferator-Activated Receptor (PPAR)δ in Embryonic Stem Cell Proliferation

The peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that belong to the nuclear receptor family. It is well known that PPARs function as regulators of lipid and lipoprotein metabolism and glucose homeostasis, as well as influence cellular proliferation, differentiation and apoptosis. However, the role of the PPARs with regard to embryonic stem (ES) cells remains unknown. We will review the function of the PPARδ, one of the three PPAR isoforms, α, δ (also called β/δ), and γ, in ES cells and its role in embryo development. In addition, pluripotent mouse ES cells can be expanded in large numbers in vitro due to the process of symmetrical self-renewal. Here we describe how PPARδ sustains ES cell proliferation.

PPAR activation as a regulator of lipid metabolism, nitric oxide production and lipid peroxidation in the placenta from type 2 diabetic patients

Peroxisome proliferator activated receptors (PPARs) are ligand activated transcription factors with crucial functions in lipid homeostasis, anti-inflammatory processes and placental development. Maternal diabetes induces a pro-inflammatory environment and alters placental development. We investigated whether PPARs regulate lipid metabolism and nitric oxide (NO) production in placental explants from healthy and type 2 diabetic (DM2) patients. We found decreased PPARα and PPARγ concentrations, no changes in PPARδ concentrations, and increased lipids, lipoperoxides and NO production in placentas from DM2 patients. PPARα agonists reduced placental concentrations of triglycerides and both PPARα and PPARδ agonists reduced concentrations of phospholipids, cholesteryl esters and cholesterol. PPARγ agonists increased lipid concentrations in placentas from DM2 patients and more markedly in placentas from healthy patients. Endogenous ligands for the three PPAR isotypes reduced NO production and lipoperoxidation in placentas from DM2 patients. We conclude that PPARs play a role in placental NO and lipid homeostasis and can regulate NO production, lipid concentrations and lipoperoxidation in placentas from DM2 patients.

Ethanol neurotoxicity in the developing cerebellum: underlying mechanisms and implications

Ethanol is the main constituent of alcoholic beverages that exerts toxicity to neuronal development. Ethanol affects synaptogenesis and prevents proper brain development. In humans, synaptogenesis takes place during the third trimester of pregnancy, and in rodents this period corresponds to the initial few weeks of postnatal development. In this period neuronal maturation and differentiation begin and neuronal cells start migrating to their ultimate destinations. Although the neuronal development of all areas of the brain is affected, the cerebellum and cerebellar neurons are more susceptible to the damaging effects of ethanol. Ethanol’s harmful effects include neuronal cell death, impaired differentiation, reduction of neuronal numbers, and weakening of neuronal plasticity. Neuronal development requires many hormones and growth factors such as retinoic acid, nerve growth factors, and cytokines. These factors regulate development and differentiation of neurons by acting through various receptors and their signaling pathways. Ethanol exposure during development impairs neuronal signaling mechanisms mediated by the N-methyl-d-aspartate (NMDA) receptors, the retinoic acid receptors, and by growth factors such as brain-derived neurotrophic factor (BDNF), insulin-like growth factor 1 (IGF-I), and basic fibroblast growth factor (bFGF). In combination, these ethanol effects disrupt cellular homeostasis, reduce the survival and migration of neurons, and lead to various developmental defects in the brain. Here we review the signaling mechanisms that are required for proper neuronal development, and how these processes are impaired by ethanol resulting in harmful consequences to brain development.

Molecular mechanisms regulating the vascular prostacyclin pathways and their adaptation during pregnancy and in the newborn

Prostacyclin (PGI(2)) is a member of the prostanoid group of eicosanoids that regulate homeostasis, hemostasis, smooth muscle function and inflammation. Prostanoids are derived from arachidonic acid by the sequential actions of phospholipase A(2), cyclooxygenase (COX), and specific prostaglandin (PG) synthases. There are two major COX enzymes, COX1 and COX2, that differ in structure, tissue distribution, subcellular localization, and function. COX1 is largely constitutively expressed, whereas COX2 is induced at sites of inflammation and vascular injury. PGI(2) is produced by endothelial cells and influences many cardiovascular processes. PGI(2) acts mainly on the prostacyclin (IP) receptor, but because of receptor homology, PGI(2) analogs such as iloprost may act on other prostanoid receptors with variable affinities. PGI(2)/IP interaction stimulates G protein-coupled increase in cAMP and protein kinase A, resulting in decreased [Ca(2+)](i), and could also cause inhibition of Rho kinase, leading to vascular smooth muscle relaxation. In addition, PGI(2) intracrine signaling may target nuclear peroxisome proliferator-activated receptors and regulate gene transcription. PGI(2) counteracts the vasoconstrictor and platelet aggregation effects of thromboxane A(2) (TXA(2)), and both prostanoids create an important balance in cardiovascular homeostasis. The PGI(2)/TXA(2) balance is particularly critical in the regulation of maternal and fetal vascular function during pregnancy and in the newborn. A decrease in PGI(2)/TXA(2) ratio in the maternal, fetal, and neonatal circulation may contribute to preeclampsia, intrauterine growth restriction, and persistent pulmonary hypertension of the newborn (PPHN), respectively. On the other hand, increased PGI(2) activity may contribute to patent ductus arteriosus (PDA) and intraventricular hemorrhage in premature newborns. These observations have raised interest in the use of COX inhibitors and PGI(2) analogs in the management of pregnancy-associated and neonatal vascular disorders. The use of aspirin to decrease TXA(2) synthesis has shown little benefit in preeclampsia, whereas indomethacin and ibuprofen are used effectively to close PDA in the premature newborn. PGI(2) analogs have been used effectively in primary pulmonary hypertension in adults and have shown promise in PPHN. Careful examination of PGI(2) metabolism and the complex interplay with other prostanoids will help design specific modulators of the PGI(2)-dependent pathways for the management of pregnancy-related and neonatal vascular disorders.

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.

Animal models in diabetes and pregnancy

The worldwide increase in the incidence of diabetes, the increase in type 2 diabetes in women at reproductive ages, and the cross-generation of the intrauterine programming of type 2 diabetes are the bases for the growing interest in the use of experimental diabetic models in order to gain insight into the mechanisms of induction of developmental alterations in maternal diabetes. In this scenario, experimental models that present the most common features of diabetes in pregnancy are highly required. Several important aspects of human diabetic pregnancies such as the increased rates of spontaneous abortions, malformations, fetoplacental impairments, and offspring diseases in later life can be approached by using the appropriate animal models. The purpose of this review is to give a practical and critical guide into the most frequently used experimental models in diabetes and pregnancy, discuss their advantages and limitations, and describe the aspects of diabetes and pregnancy for which these models are thought to be adequate. This review provides a comprehensive view and an extensive analysis of the different models and phenotypes addressed in diabetic animals throughout pregnancy. The review includes an analysis of the surgical, chemical-induced, and genetic experimental models of diabetes and an evaluation of their use to analyze early pregnancy defects, induction of congenital malformations, placental and fetal alterations, and the intrauterine programming of metabolic diseases in the offspring's later life.

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.

Congenital anomalies in diabetic pregnancy

Congenital malformations are more common in infants of diabetic women than in children of non-diabetic women. The etiology, pathogenesis and prevention of the diabetes-induced malformations have spurred considerable clinical and basic research efforts. The ultimate aim of these studies has been to obtain an understanding of the teratogenic process, which may enable precise preventive therapeutic measures in diabetic pregnancies. The results of the clinical and basic studies support the view of an early gestational induction of the malformations in diabetic pregnancy by a teratogenic process of multifactorial etiology. There may be possible targets for new therapeutic efforts revealed by the research work. Thus, future additions to the therapeutic efforts may include supplementation with antioxidants and/or folic acid, although more research is needed to delineate the dosages and compounds to be used. As the research into genetic predisposition for the teratogenic induction of malformations by maternal diabetes starts to reveal new genes and gene products involved in the etiology of the malformations, a set of new targets for intervention may arise.

Development of a European human embryonic stem cell registry

The number of human embryonic stem cell (hESC) lines that are available and that are subsequently being used in numerous research projects is increasing steadily. However, there is little coordination of hESC line derivation, and comparative information on the characteristics and quality of these cells is sparse. Obtaining consistent information on hESCs is hampered further by legislative fragmentation, particularly in Europe. Recognizing these obstacles, the European Commission has set up a Human Embryonic Stem Cell Registry (hESCreg) to make hESCs and their characterizing information accessible and to ensure that the results of research become more quickly available to the public. The primary objectives of hESCreg are to provide freely accessible information on existing hESC lines, their derivation, molecular characteristics, use and quality. Successful research with listed hESC lines will be used to evaluate clinical potential and thus directly influence policy decisions. The developing integration with other initiatives, such as characterization projects, registries and cell banks, is expected to lead to a common and internationally accepted central reference. The hESCreg provides a first step in this direction and might grow into an internationally funded and administered project.

Peroxisome proliferator-activated receptor alpha activation regulates lipid metabolism in the feto-placental unit from diabetic rats

Maternal diabetes promotes an overaccumulation of lipids in the feto-placental unit and impairs feto-placental development and growth. Here, we investigated the role played by the nuclear receptor peroxisome proliferator-activated receptor (PPAR)alpha in lipid metabolism in fetuses and placentas from control and neonatal streptozotocin-induced diabetic rats. Placentas and fetuses were studied on day 13.5 of gestation. The concentrations of PPARalpha (by Western blot) and its endogenous agonist leukotriene B(4) (LTB(4)) (by enzyme immunoassay) were analysed. Placental explants and fetuses were cultured with LTB(4) or clofibrate, and then lipid metabolism analysed (concentrations and synthesis from (14)C-acetate of triglycerides, phospholipids, cholesterol and cholesteryl esters; release of glycerol and free fatty acids (FFAs)). We found that maternal diabetes led to increases in placental concentrations of triglycerides and cholesteryl esters, and fetal concentrations of phospholipids. PPARalpha agonists downregulated fetal and placental lipid concentrations in control and diabetic rats. The synthesis of lipids was reduced in the diabetic placenta but increased in fetuses from diabetic animals. PPARalpha agonists reduced the synthesis of lipids in control placenta and in the fetuses from control and diabetic rats. Glycerol and FFA release was enhanced in the diabetic placenta and in control placenta cultured with PPARalpha agonists. Maternal diabetes led to reductions in fetal and placental LTB(4) concentrations and to increases in placental PPARalpha concentrations. Overall, these data support a novel role of PPARalpha as a regulator of lipid metabolism in the feto-placental unit, relevant in maternal diabetes where fetal and placental PPARalpha, LTB(4) and lipid concentrations are altered.