Review: Effects of PPAR activation in the placenta and the fetus: Implications in maternal diabetes

Metabolic and molecular effects of dietary extra virgin olive oil in blood and placenta of women with GDM

Gestational diabetes mellitus (GDM) increases the risks of maternal, placental, and neonatal complications. Previously, we found that a diet enriched in extra virgin olive oil (EVOO) prevents increased maternal triglyceridemia and placental proinflammatory markers in a cohort of GDM patients. The aim of this work was to evaluate maternal circulating markers of insulin resistance, placental collagen, glycogen and lipid levels, and placental levels of proteins, mRNAs, and a microRNA involved in the endocytic pathway in the same cohort of control women and women with GDM who received or did not receive a diet enriched in EVOO (36 g/day) from weeks 24 to 28 of pregnancy until term.

Results

At term, the TG/HDL cholesterol ratio, fatty acid binding protein 4 circulating levels, and maternal BMI were increased in the GDM patients, alterations prevented by the maternal diet enriched in EVOO. Although there were no changes in placental lipid levels and lipid profile, GDM placentas were thicker than controls and showed increased glycogen and collagen content, alterations prevented by the EVOO enriched diet. GDM placentas showed increases in megalin levels, in the expression of several genes involved in the endocytic pathway, and in miR-199, which targets these genes, alterations prevented by the maternal diet enriched in EVOO.

Conclusions

We identified novel beneficial effects of an EVOO-enriched diet in GDM women, a diet capable of regulating maternal insulin resistance, the structure and metabolism of the placenta, and the placental endocytic pathway, suggesting effects that may be beneficial for fetal development.

Toward assessing the role of dietary fatty acids in lamb's neurological and cognitive development

Understanding and measuring sheep cognition and behavior can provide us with measures to safeguard the welfare of these animals in production systems. Optimal neurological and cognitive development of lambs is important to equip individuals with the ability to better cope with environmental stressors. However, this development can be affected by nutrition with a special role from long-chain fatty acid supply from the dam to the fetus or in lamb's early life. Neurological development in lambs takes place primarily during the first two trimesters of gestation. Through late fetal and early postnatal life, the lamb brain has a high level of cholesterol synthesis. This rate declines rapidly at weaning and remains low throughout adulthood. The main polyunsaturated fatty acids (PUFA) in the brain are ω-6 arachidonic acid and ω-3 docosahexaenoic acid (DHA), which are elements of plasma membranes' phospholipids in neuronal cells. DHA is essential for keeping membrane integrity and is vital for normal development of the central nervous system (CNS), and its insufficiency can damage cerebral functions and the development of cognitive capacities. In sheep, there is evidence that supplying PUFA during gestation or after birth may be beneficial to lamb productive performance and expression of species-specific behaviors. The objective of this perspective is to discuss concepts of ruminant behavior and nutrition and reflect on future research directions that could help to improve our knowledge on how dietary fatty acids (FA) relate to optimal neurological and cognitive development in sheep.

Metabolic signature of spent culture media shows lipid metabolism as a determinant of pregnancy outcomes

In the present study, we investigated the spent culture media of in vitro produced (IVP) bovine embryos which did (group Pregnant) or did not (group Non-pregnant) establish pregnancy after transfer. For that purpose, IVP embryos on D5 were transferred to individual droplets for the last 48 h of culture. Embryos at the blastocyst stage were then transferred to synchronized recipients, while respective culture media drops were collected and evaluated individually. The list of metabolites present in spent culture media was obtained by electrospray ionization mass spectrometry (ESI-MS) and analysed with Metaboanalyst® to characterize the metabolic profile of each group. The spectrometric analysis showed that pathways related to lipid metabolism, particularly fatty acids degradation via beta-oxidation, were more present in the Pregnant group whereas no significant pathway was identified in the group Non-pregnant. By using this method, we were able to identify a metabolic signature in culture media that allows for a better comprehension of preferential metabolic routes taken by the most viable embryos. These findings offer great insights into the biochemistry of embryo development and reveal a potential target for the development of better-quality IVP systems, as well as tools to identify bovine embryos with greater chances to establish and maintain pregnancy.

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.

Lipid metabolism and endometrial receptivity

BACKGROUND

Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms, especially the roles of lipid metabolism in endometrial receptivity, remain largely elusive.

OBJECTIVE AND RATIONALE

This review summarizes current evidence on the impacts of several major lipids and lipid-derived mediators on the embryonic implantation process. Emerging methods for evaluating endometrial receptivity, for example transcriptomic and lipidomic analysis, are also discussed.

SEARCH METHODS

The PubMed and Embase databases were searched using the following keywords: (lipid or fatty acid or prostaglandin or phospholipid or sphingolipid or endocannabinoid or lysophosphatidic acid or cholesterol or progesterone or estrogen or transcriptomic or lipidomic or obesity or dyslipidemia or polycystic ovary syndrome) AND (endometrial receptivity or uterine receptivity or embryo implantation or assisted reproductive technology or in vitro fertilization or embryo transfer). A comprehensive literature search was performed on the roles of lipid-related metabolic pathways in embryo implantation published between January 1970 and March 2022. Only studies with original data and reviews published in English were included in this review. Additional information was obtained from references cited in the articles resulting from the literature search.

OUTCOMES

Recent studies have shown that a fatty acids-related pro-inflammatory response in the embryo-endometrium boundary facilitates pregnancy via mediation of prostaglandin signaling. Phospholipid-derived mediators, for example endocannabinoids, lysophosphatidic acid and sphingosine-1-phosphate, are associated with endometrial receptivity, embryo spacing and decidualization based on evidence from both animal and human studies. Progesterone and estrogen are two cholesterol-derived steroid hormones that synergistically mediate the structural and functional alterations in the uterus ready for blastocyst implantation. Variations in serum cholesterol profiles throughout the menstrual cycle imply a demand for steroidogenesis at the time of window of implantation (WOI). Since 2002, endometrial transcriptomic analysis has been serving as a diagnostic tool for WOI dating. Numerous genes that govern lipid homeostasis have been identified and, based on specific alterations of lipidomic signatures differentially expressed in WOI, lipidomic analysis of endometrial fluid provides a possibility for non-invasive diagnosis of lipids alterations during the WOI.

WIDER IMPLICATIONS

Given that lipid metabolic dysregulation potentially plays a role in infertility, a better understanding of lipid metabolism could have significant clinical implications for the diagnosis and treatment of female reproductive disorders.

Placental lipid transport and content in response to maternal overweight and gestational diabetes mellitus in human term placenta

BACKGROUND AND AIMS

Placental lipid transport is altered in women with high prepregnancy body mass index (pre-BMI) or gestational diabetes (GDM), which consequently affects foetal growth. However, the interaction of maternal overweight (OW) and GDM on placental lipid metabolism and possible adaptations are less studied. We aimed to examine whether maternal OW or GDM is the main factor disrupting placental lipid processing in human term placenta.

METHODS AND RESULTS

A total of 152 lean (18.5 ≤ pre-BMI ≤ 23.9 kg/m²) and OW (24 ≤ pre-BMI ≤ 27.9 kg/m²) pregnant women with or without GDM with a scheduled delivery by caesarean section were recruited. Maternal venous blood samples were used to measure metabolic parameters during pregnancy. Term placentas and cord blood were collected at delivery to determine placental lipid metabolism and foetal circulating lipid levels. Maternal OW significantly increased the placental mRNA expression of genes involved in lipid metabolism (FAT/CD36, FATP1, FATP4, FATP6, and PPAR-α), elevated placental lipid content (triglyceride, cholesterol), enhanced placental mTORC1-rpS6 and ERK1/2 signalling, increased cord blood insulin levels and birth weight. Neonatal birth weight was positively correlated with maternal pre-BMI, placental ERK1/2 signalling and cord blood insulin. There was an interaction between OW and GDM in regulating key placental fuel transport and storage gene expression (LPL, FATP6, FABP7, PPAR-α, PPAR-β, PPAR-γ, IR-β, GLUT1, SNAT2, SNAT4, and LAT1).

CONCLUSION

Maternal OW mainly affects placental lipid metabolism, which may contribute to foetal overgrowth and may impact long-term offspring health. GDM plays a less significant role in affecting placental lipid transfer and other mechanisms may be involved.

Unsaturated Fatty Acid Intake During Periconception and Incidence of Achieving Pregnancy: A Systematic Review and Meta-Analysis

Background: Previous studies suggest that maternal diets enriched in unsaturated fatty acids may have a positive effect on pregnancy success. The aim of the present study was to conduct a systematic review and meta-analysis to evaluate whether increased dietary intake of polyunsaturated fatty acids (PUFAs) or monounsaturated fatty acids (MUFAs) during the periconception period has beneficial effects on the achievement of pregnancy in women.

Methods: The electronic databases PubMed, Medline and Cochrane Central Register, as well as references in related review articles, were searched to find studies assessing the effects of unsaturated fatty acid dietary intake during the periconception period on the achievement of pregnancy in women. Pregnancy was confirmed by high levels of hCG (biochemical means) and ultrasound confirmation of a gestational sac and heartbeat (clinical means).

Results: For the meta-analysis evaluating the effects of periconceptional diets enriched in PUFAs on pregnancy, four articles, providing data on 2,121 patients, were included. Results showed that periconceptional intake of PUFAs has no significant effects on achieving pregnancy compared to controls, according to both the fixed effects and random effects models (RR = 0.99, 95% CI 0.98–1.00). Further secondary analysis considering ω-6 and ω-3 PUFAs separately showed no significant effects on achieving pregnancy compared to controls. On the other hand, for the meta-analysis evaluating the effects of periconceptional diets enriched in MUFAs on achieving pregnancy, five articles, providing data on 2,473 patients, were included. Results showed that periconceptional dietary intake of MUFAs has significant effects on achieving pregnancy compared to controls according to the fixed effects model (RR = 1.03, 95% CI 1.01–1.06, p < 0.02) but not to the random effects model, due to heterogeneity. A secondary meta-analysis excluding one study which led to heterogeneity showed significant effects of MUFAs on achieving pregnancy compared to controls, according to both the fixed effects and random effects models (RR = 1.03, 95% CI 1.01–1.05, p < 0.02).

Conclusion: The meta-analysis of published clinical studies suggests that diets enriched in MUFAs, although not those enriched in PUFAs, may have a positive effect on pregnancy success as determined by HCG and ultrasonography.

Systematic Review Registration:https://www.crd.york.ac.uk/PROSPERO/display_record.php?ID=CRD42021239355, identifier: CRD42021239355.

Maternal yeast-based nucleotide supplementation decreased stillbirth by regulating nutrient metabolism

BACKGROUND

As an enzymatic product of yeast, yeast-based nucleotide (YN) is rich in nucleotides. To test the effects of maternal dietary supplementation with YN during late pregnancy on placental nutrient transport and nutrient metabolism in neonatal piglets, 64 pregnant sows (day 85 ± 3) were assigned into two groups: (i) control (CON) and (ii) treatment (YN; 4 g kg^-1 ). Blood, placenta and liver samples of neonates during delivery were collected.

RESULTS

The results showed that maternal YN supplementation decreased stillbirth rate and intra-uterine growth restriction rate (P < 0.05). In addition, maternal YN supplementation increased total serum protein, albumin and total cholesterol (P < 0.05). Furthermore, in neonatal piglets in the YN group, both serum amino acidand nucleotide profiles were affected, as well as liver amino acid, and fatty acid profiles were regulated (P < 0.05). Moreover, maternal YN supplementation increased liver mRNA expression of SLC28A3, SLC29A1, SLC29A2, PC, PCK1, FBP1, SREBP1c, HSL and CYP7a1 of neonatal piglets (P < 0.05). Meanwhile, there was a decrease in placental gene expression of EAAT2, EAAT3, LAT1 and PAT1, as well as lower protein expression of peroxisome proliferator-activated receptor (PPAR)γ, AKT, phosphorylated-AKT, phosphorylated-mammalian target of rapamycin (mTOR) and Raptor, in the YN group (P < 0.05).

CONCLUSION

Taken together, these results indicate that maternal YN supplementation regulates placental nutrient transport by regulating the mTOR complex 1-PPAR pathway, and affects the liver metabolism of nucleotides, amino acids and fatty acids in neonatal piglets, thereby improving the reproductive performance of sow to a certain extent. © 2020 Society of Chemical Industry.

Endocrine disrupting chemicals (EDCs) and placental function: Impact on fetal brain development

Pregnancy is a critical time of vulnerability for the development of the fetal brain. Exposure to environmental pollutants at any point in pregnancy can negatively impact many aspects of fetal development, especially the organization and differentiation of the brain. The placenta performs a variety of functions that can help protect the fetus and sustain brain development. However, disruption of any of these functions can have negative impacts on both the pregnancy outcome and fetal neurodevelopment. This review presents current understanding of how environmental exposures, specifically to endocrine disrupting chemicals (EDCs), interfere with placental function and, in turn, neurodevelopment. Some of the key differences in placental development between animal models are presented, as well as how placental functions such as serving as a xenobiotic barrier and exchange organ, immune interface, regulator of growth and fetal oxygenation, and a neuroendocrine organ, could be vulnerable to environmental exposure. This review illustrates the importance of the placenta as a modulator of fetal brain development and suggests critical unexplored areas and possible vulnerabilities to environmental exposure.

Intergenerational effects of the antioxidant Idebenone on the placentas of rats with gestational diabetes mellitus

Experimental models of maternal diabetes lead to the intrauterine programming of Gestational Diabetes Mellitus (GDM) in the offspring, together with an intrauterine proinflammatory environment, feto-placental metabolic alterations and fetal overgrowth. The aim of this work was to evaluate the effect of the mitochondrial antioxidant Idebenone given to F0 mild pregestational diabetic rats on the development of GDM in their F1 offspring and the intergenerational programming of a pro-oxidant/proinflammatory environment that affects the placentas of F2 fetuses. Control and mild pregestational diabetic female rats (F0) were mated with control males, and Idebenone or vehicle was administered to diabetic rats from day 1 of gestation to term. The F1 female offspring were mated with control males and maternal and fetal plasma samples were obtained for metabolic determinations at term. The F2 fetuses and placentas were weighed, and placental protein levels and peroxynitrite-induced damage (immunohistochemistry), mRNA levels (PCR), nitric oxide production (Griess reaction), and number of apoptotic cells (TUNEL) were evaluated. The F1 offspring of F0 diabetic rats (treated or not with Idebenone) developed GDM. The placentas of GDM rats showed a decrease in the mRNA levels of manganese superoxide dismutase and an increase in the production of nitric oxide, peroxynitrite-induced damage, and connective tissue growth factor levels, alterations that were prevented by the maternal Idebenone treatment in F0 rats. In conclusion, the maternal treatment with Idebenone in pregestational diabetic F0 rats ameliorates the pro-oxidant/proinflammatory environment that affects the placentas of F2 fetuses, although it does not prevent F1 rats from developing GDM.

Peroxisome Proliferator-Activated Receptors (PPAR), fatty acids and microRNAs: Implications in women delivering low birth weight babies

Low birth weight (LBW) babies are associated with neonatal morbidity and mortality and are at increased risk for noncommunicable diseases (NCDs) in later life. However, the molecular determinants of LBW are not well understood. Placental insufficiency/dysfunction is the most frequent etiology for fetal growth restriction resulting in LBW and placental epigenetic processes are suggested to be important regulators of pregnancy outcome. Early life exposures like altered maternal nutrition may have long-lasting effects on the health of the offspring via epigenetic mechanisms like DNA methylation and microRNA (miRNA) regulation. miRNAs have been recognized as major regulators of gene expression and are known to play an important role in placental development. Angiogenesis in the placenta is known to be regulated by transcription factor peroxisome proliferator-activated receptor (PPAR) which is activated by ligands such as long-chain-polyunsaturated fatty acids (LCPUFA). In vitro studies in different cell types indicate that fatty acids can influence epigenetic mechanisms like miRNA regulation. We hypothesize that maternal fatty acid status may influence the miRNA regulation of PPAR genes in the placenta in women delivering LBW babies. This review provides an overview of miRNAs and their regulation of PPAR gene in the placenta of women delivering LBW babies.Abbreviations: AA - Arachidonic Acid; Ago2 - Argonaute2; ALA - Alpha-Linolenic Acid; ANGPTL4 - Angiopoietin-Like Protein 4; C14MC - Chromosome 14 miRNA Cluster; C19MC - Chromosome 19 miRNA Cluster; CLA - Conjugated Linoleic Acid; CSE - Cystathionine γ-Lyase; DHA - Docosahexaenoic Acid; EFA - Essential Fatty Acids; E2F3 - E2F transcription factor 3; EPA - Eicosapentaenoic Acid; FGFR1 - Fibroblast Growth Factor Receptor 1; GDM - Gestational Diabetes Mellitus; hADMSCs - Human Adipose Tissue-Derived Mesenchymal Stem Cells; hBMSCs - Human Bone Marrow Mesenchymal Stem Cells; HBV - Hepatitis B Virus; HCC - Hepatocellular Carcinoma; HCPT - Hydroxycamptothecin; HFD - High-Fat Diet; Hmads - Human Multipotent Adipose-Derived Stem; HSCS - Human Hepatic Stellate Cells; IUGR - Intrauterine Growth Restriction; LA - Linoleic Acid; LBW - Low Birth Weight; LCPUFA - Long-Chain Polyunsaturated Fatty Acids; MEK1 - Mitogen-Activated Protein Kinase 1; MiRNA - MicroRNA; mTOR - Mammalian Target of Rapamycin; NCDs - NonCommunicable Diseases; OA - Oleic Acid; PASMC - Pulmonary Artery Smooth Muscle Cell; PLAG1 - Pleiomorphic Adenoma Gene 1; PPAR - Peroxisome Proliferator-Activated Receptor; PPARα - PPAR alpha; PPARγ - PPAR gamma; PPARδ - PPAR delta; pre-miRNA - precursor miRNA; RISC - RNA-Induced Silencing Complex; ROS - Reactive Oxygen Species; SAT - Subcutaneous Adipose Tissue; WHO - World Health Organization.

Maternal Supply of Fatty Acids during Late Gestation on Offspring's Growth, Metabolism, and Carcass Characteristics in Sheep

Lambs born from dams supplemented with different sources of fatty acids (FA) during late gestation have a different growth rate and plasma glucose concentration. The main objectives of this experiment were to evaluate the effect of supplementing different sources of FA during late gestation on offspring plasma metabolite concentrations, growth, and on a glucose tolerance test (GTT) during the finishing phase. Fifty-four lambs (18 pens, 3 lambs/pen) were born from ewes supplemented during late gestation with one of three treatments: (1) no FA (NF); (2) a source of monounsaturated FA (PDS, 1.01% of Ca salts); or (3) a source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (EDS, 1.01% of Ca salts containing). At birth (day 0), supplementation ceased, and all ewes and lambs were placed in a common pen. On day 60, lambs were weaned, grouped by sex, blocked by body weight (BW), and placed on a common finishing diet for 54 days (FP). One lamb per pen was used for the GTT after the FP. There was a tendency for FA × Sex × Day interaction (p = 0.08) on lamb growth during the finishing period, with PDS females being heavier than PDS males, while EDS males were heavier than EDS females at day 60. There was a tendency for FA × Sex interaction (p = 0.06) for plasma insulin concentration for the GTT. Plasma insulin concentration of wethers increased as FA unsaturation degree increased during the GTT; the opposite happened with the plasma insulin concentration of female lambs. In conclusion, FA supplementation during late gestation tended to modified growth and insulin response to a GTT; these changes differed with the degree of FA unsaturation of the supplement and lamb sex.

A Comparative Transcriptomic Analysis of Human Placental Trophoblasts in Response to Pathogenic and Probiotic Enterococcus faecalis Interaction

With the ability to cross placental barriers in their hosts, strains of Gram-positive Enterococcus faecalis can exhibit either beneficial or harmful properties. However, the mechanisms underlying these effects have yet to be determined. A comparative transcriptomic analysis of human placental trophoblasts in response to pathogenic or probiotic E. faecalis was performed in order to investigate the molecular basis of different traits. Results indicated that both E. faecalis Symbioflor 1 and V583 could pass through the placental barrier in vitro with similar levels of invasion ability. In total, 2353 (1369 upregulated and 984 downregulated) and 2351 (1233 upregulated and 1118 downregulated) DEGs were identified in Symbioflor 1 and V583, respectively. Furthermore, 1074 (671 upregulated and 403 downregulated) and 1072 (535 upregulated and 537 downregulated) DEGs were only identified in Symbioflor 1 and V583 treatment groups, respectively. KEGG analysis showed that 6 and 9 signaling pathways were associated with interactions between Symbioflor 1 and V583. GO analysis revealed that these DEGs were mainly related to cellular and metabolic processes and biological regulation. However, 28 and 44 DEGs were classified into terms associated with placental and embryonic development in Symbioflor 1 and V583 treatment groups, respectively. Notably, 9 and 25 unique DEGs were identified only in Symbioflor 1 and V583 treatment groups, respectively. A large proportion of transcriptional responses differed when compared between pathogenic and probiotic E. faecalis interaction, and several unique DEGs and signal pathways were identified in the two different groups. These data enhance our understanding of how different traits can be affected by pathogenic and probiotic E. faecalis and the mechanisms underlying these effects.

Role of Dietary Amino Acids and Nutrient Sensing System in Pregnancy Associated Disorders

Defective implantation is related to pregnancy-associated disorders such as spontaneous miscarriage, intrauterine fetal growth restriction and others. Several factors proclaimed to be involved such as physiological, nutritional, environmental and managemental that leads to cause oxidative stress. Overloading of free radicals promotes oxidative stress, and the internal body system could not combat its ability to encounter the damaging effects and subsequently leading to pregnancy-related disorders. During pregnancy, essential amino acids display important role for optimum fetal growth and other necessary functions for continuing fruitful pregnancy. In this context, dietary amino acids have received much attention regarding the nutritional concerns during pregnancy. Arginine, glutamine, tryptophan and taurine play a crucial role in fetal growth, development and survival while ornithine and proline are important players for the regulation of gene expression, protein synthesis and angiogenesis. Moreover, amino acids also stimulate the mammalian target of rapamycin (mTOR) signaling pathway which plays a central role in the synthesis of proteins in placenta, uterus and fetus. This review article explores the significances of dietary amino acids in pregnancy development, regulation of nutrient-sensing pathways such as mTOR, peroxisome proliferator-activated receptors (PPARs), insulin/insulin-like growth factor signaling pathway (IIS) and 5' adenosine monophosphate-activated protein kinase (AMPK) which exhibit important role in reproduction and its related problems. In addition, the antioxidant function of dietary amino acids against oxidative stress triggering pregnancy disorders and their possible outcomes will also be enlightened. Dietary supplementation of amino acids during pregnancy could help mitigate reproductive disorders and thereby improving fertility in animals as well as humans.

Nutritional modulation of leptin expression and leptin action in obesity and obesity-associated complications

In obesity, an elevated accumulation and dysregulation of adipose tissue, due to an imbalance between energy intake and energy expenditure, usually coexists with the loss of responsiveness to leptin in central nervous system, and subsequently with hyperleptinemia. Leptin, a peptide hormone mainly produced by white adipose tissue, regulates energy homeostasis by stimulating energy expenditure and inhibiting food intake. Human obesity is characterized by increased plasma leptin levels, which have been related with different obesity-associated complications, such as chronic inflammatory state (risk factor for diabetes, cardiovascular and autoimmune diseases), as well as infertility and different types of cancer. Besides, leptin is also produced by placenta, and high leptin levels during pregnancy may be related with some pathological conditions such as gestational diabetes. This review focuses on the current insights and emerging concepts on potentially valuable nutrients and food components that may modulate leptin metabolism. Notably, several dietary food components, such as phenols, peptides, and vitamins, are able to decrease inflammation and improve leptin sensitivity by up- or down-regulation of leptin signaling molecules. On the other hand, some food components, such as saturated fatty acids may worsen chronic inflammation increasing the risk for pathological complications. Future research into nutritional mechanisms that restore leptin metabolism and signals of energy homeostasis may inspire new treatment options for obesity-related disorders.

Effects of maternal dietary omega-3 polyunsaturated fatty acids and methionine during late gestation on fetal growth, DNA methylation, and mRNA relative expression of genes associated with the inflammatory response, lipid metabolism and DNA methylation in placenta and offspring's liver in sheep

BACKGROUND

Omega-3 PUFA or methionine (Met) supply during gestation alters offspring physiology. However, the effect of both nutrients on fetal development has not been explored. Our objective was to determine the effects of supplementation of these two nutrients during late gestation on fetal growth, DNA methylation, and mRNA expression of genes associated with the inflammatory response, and DNA methylation. Ewes (n = 5/treatment) were fed from day 100 to 145 of gestation one of the following treatments: 1) basal diet (NS) without fatty acids (FS) or methionine (MS) supplementation; 2) FS (10 g/kg Ca salts, source omega-3 PUFA); 3) MS (1 g/kg rumen protected methionine); and 4) FS and MS (FS-MS). On day 145, ewes were euthanized, and data from dams and fetus was recorded. Placenta (cotyledon), fetal liver, and blood samples were collected.

RESULTS

A treatments interaction on fetal liver weight, ewe body weight and body condition score (BCS) was observed; FS-MS were heavier (P <  0.01) than FS and MS, and FS-MS ewes had a better (P = 0.02) BCS than NS. Methionine increased (P = 0.03) ewe plasma glucose concentration. Fetal liver global DNA methylation increased (P <  0.01) in FS and MS. Dietary treatments modify the mRNA relative expression on some of the genes evaluated. In the fetal liver, FS increased (P = 0.04) the mRNA relative expression of arachidonate-5-lipoxygenase-activating-protein and tended to decrease (P = 0.06) methionine-adenosyltransferase-1A. Moreover, MS decreased (P = 0.04) DNA-methyltransferase-1 and tended to decrease (P = 0.08) free-fatty-acid-receptor-1 mRNA relative expression. Furthermore, FS-MS decreased mRNA relative expression of tumor-necrosis-factor-alpha (P = 0.05), peroxisome-proliferator-activated-receptor-delta (P = 0.03) and gamma (P = 0.04), tended to decrease (P ≤ 0.09) interleukin-6, fatty-acid-transport-protein-1, and delta-5-desaturase, and increased adenosylhomocysteinase (P = 0.04) mRNA relative expression. In cotyledon, FS tended to decrease fatty acid binding protein 4 (P = 0.09) mRNA relative expression.

CONCLUSION

Omega-3 PUFA and Met supplementation improves dam's performance in late gestation, which was positively correlated with an increase in offspring's liver development. Moreover, FS-MS decreased mRNA relative expression of proinflammatory cytokines, and lipogenic genes, and increased the expression on an enzyme that has an important role in methylation.

An extra virgin olive oil-enriched diet improves maternal, placental, and cord blood parameters in GDM pregnancies

AIMS

To address the effect of a diet enriched in extra virgin olive oil (EVOO) on maternal metabolic parameters and placental proinflammatory markers in Gestational diabetes mellitus (GDM) patients.

METHODS

Pregnant women at 24-28 weeks of gestation were enrolled: 33 GDM patients which were randomly assigned or not to the EVOO-enriched group and 17 healthy controls. Metabolic parameters were determined. Peroxisome proliferator activated receptor (PPAR) γ and PPARα protein expression, expression of microRNA (miR)-130a and miR-518d (which respectively target these PPAR isoforms) and levels of proinflammatory markers were evaluated in term placentas. Matrix metalloproteinases (MMPs) activity was evaluated in term placentas and umbilical cord blood.

RESULTS

GDM patients that received the EVOO-enriched diet showed reduced pregnancy weight gain (GDM-EVOO:10.3 ± 0.9, GDM:14.2 ± 1.4, P = .03) and reduced triglyceridemia (GDM-EVOO:231 ± 14, GDM:292 ± 21, P = .02) compared to the non-EVOO-enriched GDM group. In GDM placentas, the EVOO-enriched diet did not regulate PPARγ protein expression or miR-130a expression, but prevented the reduced PPARα protein expression (P = .02 vs GDM) and the increased miR-518d expression (P = .009 vs GDM). Increased proinflammatory markers (interleukin-1β, tumour necrosis factor-α and nitric oxide overproduction) in GDM placentas were prevented by the EVOO-enriched diet (respectively P = .001, P = .001 and P = .01 vs GDM). MMPs overactivity was prevented in placenta and umbilical cord blood in the EVOO-enriched GDM group (MMP-9: respectively P = .01 and P = .001 vs GDM).

CONCLUSIONS

A diet enriched in EVOO in GDM patients reduced maternal triglyceridemia and weight gain and has antiinflammatory properties in placenta and umbilical cord blood, possibly mediated by the regulation of PPAR pathways.

Leptin and Nutrition in Gestational Diabetes

Leptin is highly expressed in the placenta, mainly by trophoblastic cells, where it has an important autocrine trophic effect. Moreover, increased leptin levels are found in the most frequent pathology of pregnancy: gestational diabetes, where leptin may mediate the increased size of the placenta and the fetus, which becomes macrosomic. In fact, leptin mediates the increased protein synthesis, as observed in trophoblasts from gestational diabetic subjects. In addition, leptin seems to facilitate nutrients transport to the fetus in gestational diabetes by increasing the expression of the glycerol transporter aquaporin-9. The high plasma leptin levels found in gestational diabetes may be potentiated by leptin resistance at a central level, and obesity-associated inflammation plays a role in this leptin resistance. Therefore, the importance of anti-inflammatory nutrients to modify the pathology of pregnancy is clear. In fact, nutritional intervention is the first-line approach for the treatment of gestational diabetes mellitus. However, more nutritional intervention studies with nutraceuticals, such as polyphenols or polyunsaturated fatty acids, or nutritional supplementation with micronutrients or probiotics in pregnant women, are needed in order to achieve a high level of evidence. In this context, the Mediterranean diet has been recently found to reduce the risk of gestational diabetes in a multicenter randomized trial. This review will focus on the impact of maternal obesity on placental inflammation and nutrients transport, considering the mechanisms by which leptin may influence maternal and fetal health in this setting, as well as its role in pregnancy pathologies.

Proinflammation in maternal and fetal livers and circulating miR-122 dysregulation in a GDM rat model induced by intrauterine programming

In gestational diabetes mellitus (GDM) pregnancies, a compromised fetal liver may impact offspring's metabolic health. Here, we aimed to address prooxidant, proinflammatory and profibrotic markers in the livers from GDM rats and their fetuses, and to analyze the expression of miR-122 (a relevant microRNA in liver pathophysiology) in fetal and maternal plasma of GDM rats, as well as in the fetal livers of neonatal streptozotocin-induced (nSTZ) diabetic rats, the rats that generate GDM through intrauterine programming. GDM and nSTZ rats were evaluated on day 21 of pregnancy. We found increased nitric oxide production and lipoperoxidation in the livers from GDM rats and their fetuses compared to controls. Livers from GDM fetuses also showed increased levels of connective tissue growth factor and matrix metalloproteinase-2. The expression of miRNA-122 was downregulated in the plasma from GDM rats and their male fetuses, as well as in the livers from male fetuses of nSTZ diabetic rats. miR-122 levels were regulated both in vitro through PPARγ activation and in vivo through a maternal diet enriched in PPAR ligands. Our findings revealed a prooxidant/proinflammatory environment in the livers from GDM rats and their fetuses and a dysregulation of miR-122, likely relevant in the programming of offspring's diseases.

Olive oil supplementation prevents extracellular matrix deposition and reduces prooxidant markers and apoptosis in the offspring´s heart of diabetic rats

Maternal diabetes induces fetal programming of cardiovascular diseases. Diabetes induced-cardiac fibrosis is a process that may start in utero and may be related to the prooxidant/proinflammatory environment. The aim of this study was to investigate the effect of a maternal diet enriched in olive oil on the levels of components and regulators of the extracellular matrix, on prooxidant markers and on apoptosis rate in the heart of 21-day-old offspring of diabetic rats. Maternal diabetes was induced by neonatal administration of streptozotocin. During pregnancy, diabetic and control rats were fed with diets supplemented or not with 6% olive oil. The heart of the offspring was studied at 21 days of age. We found increased deposition of collagen IV and fibronectin in the offspring´s heart of diabetic rats, which was prevented by the maternal diets enriched in olive oil. Increases in connective tissue growth factor were also prevented by the maternal diets enriched in olive oil. Prooxidant markers as well as apoptosis, which were increased in the heart of the offspring of diabetic rats, were prevented by the maternal olive oil dietary treatment. Our findings identified powerful effects of a maternal diet enriched in olive oil on the prevention of increased extracellular matrix deposition and increased prooxidant markers in the heart of 21-day-old offspring of diabetic rats.

Association of Proteins Modulating Immune Response and Insulin Clearance During Gestation with Antenatal Complications in Patients with Gestational or Type 2 Diabetes Mellitus

Background: The purpose of the study is to establish and quantitatively assess protein markers and their combination in association with insulin uptake that may be have value for early prospective recognition of diabetic fetopathy (DF) as a complication in patients with diabetes mellitus during gestation. Methods: Proteomic surveying and accurate quantitative measurement of selected proteins from plasma samples collected from the patients with gestational diabetes mellitus (GDM) and type 2 diabetes mellitus (T2DM) who gave birth of either healthy or affected by maternal diabetes newborns was performed using mass spectrometry. Results: We determined and quantitatively measured several proteins, including CRP, CEACAM1, CNDP1 and Ig-family that were significantly differed in patients that gave birth of newborns with signs of DF. We found that patients with newborns associated with DF are characterized by significantly decreased CEACAM1 (113.18 ± 16.23 ng/mL and 81.09 ± 10.54 ng/mL in GDM and T2DM, p < 0.005) in contrast to control group (515.6 ± 72.14 ng/mL, p < 0.005). On the contrary, the concentration of CNDP1 was increased in DF-associated groups and attained 49.3 ± 5.18 ng/mL and 37.7 ± 3.34 ng/mL (p < 0.005) in GDM and T2DM groups, respectively. Among other proteins, dramatically decreased concentration of IgG4 and IgA2 subclasses of immunoglobulins were noticed. Conclusion: The combination of the measured markers may assist (AUC = 0.893 (CI 95%, 0.785–0.980) in establishing the clinical finding of the developing DF especially in patients with GDM who are at the highest risk of chronic insulin resistance.

Maternal diets enriched in olive oil regulate lipid metabolism and levels of PPARs and their coactivators in the fetal liver in a rat model of gestational diabetes mellitus

In a rat model of gestational diabetes mellitus (GDM) programmed in the offspring of neonatal streptozotocin-induced (nSTZ) diabetic rats, lipids are accumulated in the fetal liver in a sex-dependent way. Here, we evaluated whether maternal diets enriched in olive oil in rats that will develop GDM ameliorate lipid metabolic impairments in the fetal livers. Pregnant offspring of control and nSTZ diabetic rats (F0) were fed a 6% olive oil-supplemented diet throughout the F1 gestation. We evaluated maternal metabolic parameters as well as lipid content, expression of lipid metabolizing enzymes and protein expression of PLIN2, PPARs and PPAR coactivators in the fetal livers. The offspring of nSTZ diabetic rats developed GDM regardless of the maternal treatment. Hypertriglyceridemia in GDM rats was prevented by the olive oil-enriched maternal treatment. In the livers of male fetuses of GDM rats, the maternal olive oil-supplemented diet prevented lipid overaccumulation and prevented the increase in PPARγ and PPARδ levels. In the livers of female fetuses of GDM rats, the maternal olive oil supplementation prevented the increase in PPARδ levels and the reduction in PGC1α levels, but did not prevent the reduced lipid content. Control and GDM rats showed a reduction of lipid metabolic enzymes in the fetal livers, which was associated with reduced levels of the PPAR coactivators PGC-1α and SRC-1 in males and of SRC-1 in females. These results suggest powerful effects of a maternal olive oil-supplemented diet in the fetal liver, possibly providing benefits in the fetuses and offspring from GDM rats.

Critical role of mTOR, PPARγ and PPARδ signaling in regulating early pregnancy decidual function, embryo viability and feto-placental growth

STUDY QUESTION

What are the consequences of inhibiting mTOR, the mechanistic target of rapamycin (mTOR), and the peroxisome proliferator activated receptor gamma (PPARγ) and PPARδ pathways in the early post-implantation period on decidual function, embryo viability and feto-placental growth in the rat?

SUMMARY ANSWER

mTOR inhibition from Days 7 to 9 of pregnancy in rats caused decidual PPARγ and PPARδ upregulation on Day 9 of pregnancy and resulted in embryo resorption by Day 14 of pregnancy. PPARγ and PPARδ inhibition differentially affected decidual mTOR signaling and levels of target proteins relevant to lipid histotrophic nutrition and led to reduced feto-placental weights on Day 14 of pregnancy.

WHAT IS KNOWN ALREADY

Although mTOR, PPARγ and PPARδ are nutrient sensors important during implantation, the role of these signaling pathways in decidual function and how they interact in the early post-implantation period are unknown. Perilipin 2 (PLIN2) and fatty acid binding protein 4 (FABP4), two adipogenic proteins involved in lipid histotrophic nutrition, are targets of mTOR and PPAR signaling pathways in a variety of tissues.

STUDY DESIGN, SIZE, DURATION

Rapamycin (mTOR inhibitor, 0.75 mg/kg, sc), T0070907 (PPARγ inhibitor, 0.001 mg/kg, sc), GSK0660 (PPARδ inhibitor, 0.1 mg/kg, sc) or vehicle was injected daily to pregnant rats from Days 7 to 9 of pregnancy and the studies were performed on Day 9 of pregnancy (n = 7 per group) or Day 14 of pregnancy (n = 7 per group).

PARTICIPANTS/MATERIALS, SETTING, METHODS

On Day 9 of pregnancy, rat decidua were collected and prepared for western blot and immunohistochemical studies. On Day 14 of pregnancy, the resorption rate, number of viable fetuses, crown-rump length and placental and decidual weights were determined.

MAIN RESULTS AND THE ROLE OF CHANCE

Inhibition of mTOR in the early post-implantation period led to a reduction in FABP4 protein levels, an increase in PLIN2 levels and an upregulation of PPARγ and PPARδ in 9-day-pregnant rat decidua. Most embryos were viable on Day 9 of pregnancy but had resorbed by Day 14 of pregnancy. This denotes a key function of mTOR in the post-implantation period and suggests that activation of PPAR signaling was insufficient to compensate for impaired nutritional/survival signaling induced by mTOR inhibition. Inhibition of PPARγ signaling resulted in decreased decidual PLIN2 and FABP4 protein expression as well as in inhibition of decidual mTOR signaling in Day 9 of pregnancy. This treatment also reduced feto-placental growth on Day 14 of pregnancy, revealing the relevance of PPARγ signaling in sustaining post-implantation growth. Moreover, following inhibition of PPARδ, PLIN2 levels were decreased and mTOR complex 1 and 2 signaling was altered in decidua on Day 9 of pregnancy. On Day 14 of pregnancy, PPARδ inhibition caused reduced feto-placental weight, increased decidual weight and increased resorption rate, suggesting a key role of PPARδ in sustaining post-implantation development.

LARGE SCALE DATA

Not applicable.

LIMITATIONS, REASONS FOR CAUTION

This is an in vivo animal study and the relevance of the results for humans remains to be established.

WIDER IMPLICATIONS OF THE FINDINGS

The early post-implantation period is a critical window of development and changes in the intrauterine environment may cause embryo resorption and lead to placental and fetal growth restriction. mTOR, PPARγ and PPARδ signaling are decidual nutrient sensors with extensive cross-talk that regulates adipogenic proteins involved in histotrophic nutrition and important for embryo viability and early placental and fetal development and growth.

STUDY FUNDING/COMPETING INTEREST(S)

Funding was provided by the Agencia Nacional de Promoción Científica y Tecnológica de Argentina (PICT 2014-411 and PICT 2015-0130), and by the International Cooperation (Grants CONICET-NIH-2014 and CONICET-NIH-2017) to A.J. and T.J. The authors have no conflicts of interest.

Comparative Analysis of the Transcriptome and Proteome during Mouse Placental Development

The condition of the placenta is a determinant of the short- and long-term health of the mother and the fetus. However, critical processes occurring in early placental development, such as trophoblast invasion and establishment of placental metabolism, remain poorly understood. To gain a better understanding of the genes involved in regulating these processes, we utilized a multiomics approach, incorporating transcriptome, proteome, and phosphoproteome data generated from mouse placental tissue collected at two critical developmental time points. We found that incorporating information from both the transcriptome and proteome identifies genes associated with time point-specific biological processes, unlike using the proteome alone. We further inferred genes upregulated on the basis of the proteome data but not the transcriptome data at each time point, leading us to identify 27 genes that we predict to have a role in trophoblast migration or placental metabolism. Finally, using the phosphoproteome data set, we discovered novel phosphosites that may play crucial roles in the regulation of placental transcription factors. By generating the largest proteome and phosphoproteome data sets in the developing placenta, and integrating transcriptome analysis, we uncovered novel aspects of placental gene regulation.

Diet Enriched with Olive Oil Attenuates Placental Dysfunction in Rats with Gestational Diabetes Induced by Intrauterine Programming

SCOPE

Offspring from rats with mild diabetes develop gestational diabetes mellitus (GDM). We tested the hypothesis that an olive oil-supplemented diet attenuates placental oxidative stress/inflammation, activation of mTOR signaling, and inhibition of peroxisome proliferator-activated receptor γ (PPARγ) and fetal overgrowth in GDM offspring from mild diabetic rats.

METHODS AND RESULTS

Female offspring from rats with mild diabetes (group that developed GDM) and controls were fed with either a standard diet or a 6% olive oil-supplemented diet during pregnancy. On day 21 of pregnancy, plasma glucose levels in mothers and fetuses were increased in the GDM group independently of the diet. Fetal overgrowth and activation of placental mTOR signaling were partially prevented in the olive oil-treated GDM group. Placental PPARγ protein expression was decreased in GDM rats, independently of the diet. However, increases in placental lipoperoxidation, connective tissue growth factor, and matrix metalloproteinase 2 levels were prevented by the olive oil-enriched diet.

CONCLUSION

Diets enriched with olive oil attenuate placental dysfunction and fetal overgrowth in rats with GDM induced by intrauterine programming.

Diabetes in pregnancy: a new decade of challenges ahead

Every 10 years, the Diabetic Pregnancy Study Group, a study group of the EASD, conducts an audit meeting to review the achievements of the preceding decade and to set the directions for research and clinical practice improvements for the next decade. The most recent meeting focused on the following areas: improving pregnancy outcomes for women with pregestational type 1 diabetes and type 2 diabetes; the influence of obesity and gestational diabetes on pregnancy outcomes; the determinants and assessment of fetal growth and development; and public health issues, including consideration of transgenerational consequences and economic burden. The audit meeting also considered the likely impact of 'omics' on research within the field and the potential of these technologies to enable precision-medicine approaches to management. Through sharing of the findings and ideas of audit meeting participants, the DPSG hopes to promote networking, research and advances in clinical care, to improve outcomes for all women and their offspring affected by diabetes and obesity in pregnancy.

Hypertriglyceridemia and adverse outcomes during pregnancy

Introducción. Durante el embarazo, los niveles séricos de triglicéridos maternos aumentan como un mecanismo de adaptación fisiológica para suplir las necesidades del feto en desarrollo. Pese a que el incremento excesivo se ha asociado a preeclampsia, macrosomía y parto pretérmino, no se han establecido de manera contundente los niveles a partir de los cuales se deben tomar medidas en cada trimestre para prevenir complicaciones.Objetivo. Hacer una revisión sobre fisiopatología, efectos en madre e hijo, valores esperados en cada trimestre e intervenciones terapéuticas en hipertrigliceridemia gestacional.Materiales y métodos. Se realizó una revisión con la búsqueda de artículos en las bases de datos ScienceDirect, PubMed, Scopus, LILACS, Cochrane y SciELO con los términos: Pregnancy; Hypertriglyceridemia; Maternal-Fetal Exchange; Fetal Development; Pregnancy Complications y sus equivalentes en español.Resultados. Se encontraron 59 artículos que cumplieron los criterios de búsqueda y daban respuesta a los objetivos.Conclusiones. El número limitado y la gran variabilidad de los datos indican la necesidad de realizar más investigaciones que establezcan los rangos de normalidad de los triglicéridos durante los tres trimestres del embarazo y así determinar riesgos e intervenciones eficaces antes de la gestación y reducir la morbimortalidad materno-infantil.

Placental lipid processing in response to a maternal high-fat diet and diabetes in rats

BackgroundDiabetes and obesity during pregnancy have an impact on the health of both mothers and developing babies. Prevention focuses on glycemic control, but increasing evidence implicates a role for lipids. Using a rat model, we showed that a maternal high-fat (HF) diet increased perinatal morbidity and mortality, but lipid processing across the maternal-placental-fetal triad remained unstudied. We hypothesized that HF diet would disrupt placental lipid processing to exaggerate fuel-mediated consequences of diabetic pregnancy.MethodsWe compared circulating lipid profiles, hormones, and inflammatory markers in dams and rat offspring from normal, diabetes-exposed, HF-diet-exposed, and combination-exposed pregnancies. Placentae were examined for lipid accumulation and expression of fuel transporters.ResultsMaternal HF diet exaggerated hyperlipidemia of pregnancy, with diabetes marked dyslipidemia developed in dams but not in offspring. Placentae demonstrated lipid accumulation and lower expression of fatty acid (FA) transporters. Diet-exposed offspring had a lower fraction of circulating essential FAs. Pregnancy loss was significantly higher in diet-exposed but not in diabetes-exposed pregnancies, which could not be explained by differences in hormone production. Although not confirmed, inflammation may play a role.ConclusionMaternal hyperlipidemia contributes to placental lipid droplet accumulation, perinatal mortality, and aberrant FA profiles that may influence the health of the developing offspring.

Sex-dependent changes in lipid metabolism, PPAR pathways and microRNAs that target PPARs in the fetal liver of rats with gestational diabetes

Gestational diabetes mellitus (GDM) is a prevalent disease that impairs fetal metabolism and development. We have previously characterized a rat model of GDM induced by developmental programming. Here, we analyzed lipid content, the levels of the three PPAR isotypes and the expression of microRNAs that regulate PPARs expression in the liver of male and female fetuses of control and GDM rats on day 21 of pregnancy. We found increased levels of triglycerides and cholesterol in the livers of male fetuses of GDM rats compared to controls, and, oppositely, reduced levels of triglycerides, cholesterol, phospholipids and free fatty acids in the livers of female fetuses of GDM rats compared to controls. Although GDM did not change PPARα levels in male and female fetal livers, PPARγ was increased in the liver of male fetuses of GDM rats, a change that occurred in parallel to a reduction in the expression of miR-130, a microRNA that targets PPARγ. In livers of female fetuses of GDM rats, no changes in PPARγ and miR-130 were evidenced, but PPARδ was increased, a change that occurred in parallel to a reduction in the expression of miR-9, a microRNA that targets PPARδ, and was unchanged in the liver of male fetuses of GDM and control rats. These results show clear sex-dependent changes in microRNAs that target different PPAR isotypes in relation to changes in the levels of their targets and the differential regulation of lipid metabolism evidenced in fetal livers of GDM pregnancies.

Supplementation with polyunsaturated fatty acids in pregnant rats with mild diabetes normalizes placental PPARγ and mTOR signaling in female offspring developing gestational diabetes

Maternal diabetes impairs fetoplacental development and programs metabolic diseases in the offspring. We have previously reported that female offspring of pregnant rats with mild diabetes develop gestational diabetes mellitus (GDM) when they become pregnant. Here, we studied the effects of supplementation with polyunsaturated fatty acids (PUFAs) in pregnant mild diabetic rats (F0) by feeding a 6% safflower-oil-enriched diet from day 1 to 14 followed by a 6% chia-oil-enriched diet from day 14 of pregnancy to term. We analyzed maternal metabolic parameters and placental signaling at term in pregnant offspring (F1). The offspring of both PUFAs-treated and untreated mild diabetic rats developed GDM. Although gestational hyperglycemia was not prevented by dietary PUFAs treatment in F0, triglyceridemia and cholesterolemia in F1 mothers were normalized by F0 PUFAs dietary treatment. In the placenta of F1 GDM rats, PPARγ levels were reduced and lipoperoxidation was increased, changes that were prevented by the maternal diets enriched in PUFAs in the F0 generation. Moreover, fetal overgrowth and placental activation of mTOR signaling pathways were reduced in F1 GDM rats whose mothers were treated with PUFAs diets. These results suggest that F0 PUFAs dietary treatment in pregnancies with mild diabetes improves maternal dyslipidemia, fetal overgrowth and placental signaling in female offspring when they become pregnant. We speculate that an increased PUFAs intake in pregnancies complicated by diabetes may prove effective to ameliorate metabolic programming in the offspring, thereby improving the health of future generations.

Metabolic basis to Sherpa altitude adaptation

The Himalayan Sherpas, a human population of Tibetan descent, are highly adapted to life in the hypobaric hypoxia of high altitude. Mechanisms involving enhanced tissue oxygen delivery in comparison to Lowlander populations have been postulated to play a role in such adaptation. Whether differences in tissue oxygen utilization (i.e., metabolic adaptation) underpin this adaptation is not known, however. We sought to address this issue, applying parallel molecular, biochemical, physiological, and genetic approaches to the study of Sherpas and native Lowlanders, studied before and during exposure to hypobaric hypoxia on a gradual ascent to Mount Everest Base Camp (5,300 m). Compared with Lowlanders, Sherpas demonstrated a lower capacity for fatty acid oxidation in skeletal muscle biopsies, along with enhanced efficiency of oxygen utilization, improved muscle energetics, and protection against oxidative stress. This adaptation appeared to be related, in part, to a putatively advantageous allele for the peroxisome proliferator-activated receptor A (PPARA) gene, which was enriched in the Sherpas compared with the Lowlanders. Our findings suggest that metabolic adaptations underpin human evolution to life at high altitude, and could have an impact upon our understanding of human diseases in which hypoxia is a feature.

Modification of the fatty acid composition of an obesogenic diet improves the maternal and placental metabolic environment in obese pregnant mice

Peri-conceptional exposure to maternal obesogenic nutrition is associated with in utero programming of later-life overweight and metabolic disease in the offspring. We aimed to investigate whether dietary intervention with a modified fatty acid quality in an obesogenic high-calorie (HC) diet during the preconception and gestational phases can improve unfavourable effects of an adipogenic maternal environment. In NMRI mice, peri-conceptional and gestational obesity was induced by feeding a HC diet (controls), and they were compared with dams on a fat-modified (Fat-mod) HC diet of the same energy content but enriched with medium-chain fatty acids (MCFAs) and adjusted to a decreased ratio of n-6 to n-3 long-chain polyunsaturated fatty acids (LC-PUFAs). Effects on maternal and placental outcomes at delivery (day 17.5 post coitum) were investigated. Despite comparable energy assimilation between the two groups of dams, the altered fatty acid composition of the Fat-mod HC diet induced lower maternal body weight, weights of fat depots, adipocyte size, and hepatic fat accumulation compared to the unmodified HC diet group. Further, there was a trend towards lower fasting glucose, insulin and leptin concentrations in dams fed the Fat-mod HC diet. Phenotypic changes were accompanied by inhibition of transcript and protein expression of genes involved in hepatic de novo lipogenesis comprising PPARG2 and its target genes Fasn, Acaca, and Fabp4, whereas regulation of other lipogenic factors (Srebf1, Nr1h3, Abca1) appeared to be more complex. The modified diet led to a sex-specific placental response by upregulating PPARG-dependent fatty acid transport gene expression in female versus male placentae. Qualitative modification of the fatty acid spectrum of a high-energy maternal diet, using a combination of both MCFAs and n-3 LC-PUFAs, seems to be a promising interventional approach to ameliorate the adipogenic milieu of mice before and during gestation.

Maternal diabetes modulates offspring cell proliferation and apoptosis during odontogenesis via the TLR4/NF-κB signalling pathway

OBJECTIVES

Maternal gestational diabetes leads to an adverse in utero environment and increases the risk of malformations during embryo organogenesis. In the present study, we analysed the effects of maternal diabetes on tooth germ cell proliferation and apoptosis in offspring, and investigated their underlying mechanisms.

MATERIALS AND METHODS

A rat model of maternal diabetes was induced by intraperitoneal injection of streptozotocin and the pregnant rats were divided into three groups: controls, the diabetic group and diabetic group with insulin treatment. Offspring of the three groups were collected and cell proliferation and apoptosis in tooth germs were analysed. Primary dental papilla cells and dental epithelial stem cells were isolated and treated with high glucose in vitro, in an attempt to simulate maternal diabetes-induced hyperglycaemia in vivo.

RESULTS

Maternal diabetes significantly affected cell proliferation and apoptosis in offspring tooth germs. The TLR4/NF-ĸB signalling pathway was activated in the tooth germs of offspring of diabetic dams. High glucose treatment activated the TLR4/NF-ĸB signalling pathway in primary dental papilla cells and dental epithelial stem cells in vitro, resulting in suppression of cell proliferation and enhancement of apoptosis. TLR4 knockdown significantly reduced adverse effects induced by high glucose treatment.

CONCLUSIONS

Maternal gestational diabetes significantly impaired dental epithelial and mesenchymal cell proliferation and apoptosis in offspring, possibly by activation of the TLR4/NF-ĸB signalling pathway.

The peroxisome proliferator-activated receptors under epigenetic control in placental metabolism and fetal development

The placental metabolism can adapt to the environment throughout pregnancy to both the demands of the fetus and the signals from the mother. Such adaption processes include epigenetic mechanisms, which alter gene expression and may influence the offspring's health. These mechanisms are linked to the diversity of prenatal environmental exposures, including maternal under- or overnutrition or gestational diabetes. The peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that contribute to the developmental plasticity of the placenta by regulating lipid and glucose metabolism pathways, including lipogenesis, steroidogenesis, glucose transporters, and placental signaling pathways, thus representing a link between energy metabolism and reproduction. Among the PPAR isoforms, PPARγ appears to be the main modulator of mammalian placentation. Certain fatty acids and lipid-derived moieties are the natural activating PPAR ligands. By controlling the amounts of maternal nutrients that go across to the fetus, the PPARs play an important regulatory role in placenta metabolism, thereby adapting to the maternal nutritional status. As demonstrated in animal studies, maternal nutrition during gestation can exert long-term influences on the PPAR methylation pattern in offspring organs. This review underlines the current state of knowledge on the relationship between environmental factors and the epigenetic regulation of the PPARs in placenta metabolism and offspring development.

Could gestational diabetes mellitus be managed through dietary bioactive compounds? Current knowledge and future perspectives

Gestational diabetes mellitus (GDM) is a serious problem growing worldwide that needs to be addressed with urgency in consideration of the resulting severe complications for both mother and fetus. Growing evidence indicates that a healthy diet rich in fruit, vegetables, nuts, extra-virgin olive oil and fish has beneficial effects in both the prevention and management of several human diseases and metabolic disorders. In this review, we discuss the latest data concerning the effects of dietary bioactive compounds such as polyphenols and PUFA on the molecular mechanisms regulating glucose homoeostasis. Several studies, mostly based on in vitro and animal models, indicate that dietary polyphenols, mainly flavonoids, positively modulate the insulin signalling pathway by attenuating hyperglycaemia and insulin resistance, reducing inflammatory adipokines, and modifying microRNA (miRNA) profiles. Very few data about the influence of dietary exposure on GDM outcomes are available, although this approach deserves careful consideration. Further investigation, which includes exploring the ‘omics’ world, is needed to better understand the complex interaction between dietary compounds and GDM.

A novel rat model of gestational diabetes induced by intrauterine programming is associated with alterations in placental signaling and fetal overgrowth

A family history of diabetes predisposes to gestational diabetes mellitus (GDM). We hypothesized that female offspring of rats with pre-gestational diabetes will develop GDM, a pathology associated with fetal overgrowth and altered placental signaling. We found normal glycemia and insulinemia in the offspring from pre-gestational diabetic rats at three months of age. However, consistent with GDM, maternal hyperglycemia and hyperinsulinemia and increased fetal weight were evident when compared to controls. In this intrauterine programmed GDM model, the placentas showed alterations in mTOR pathway: unchanged phosphorylation of 4EBP-1 and PKCα despite reduced total expression of 4EBP-1 and PKCα, and increased phosphorylation of SGK1. GDM placentas also showed reduced expression of PPARα and PPARγ, and increased lipoperoxidation, nitric oxide production and peroxynitrite-induced damage. We conclude that exposure of maternal diabetes in utero programs GDM in the female offspring, leading to a GDM model associated with impaired placental signaling pathways, increased pro-oxidant/pro-inflammatory environment and fetal overgrowth.

In vitro evaluation of dual agonists for PPARγ/β from the flower of Edgeworthia gardneri (wall.) Meisn

ETHNOPHARMACOLOGICAL RELEVANCE

In Tibet, the flower of Edgeworthia gardneri (Wall.) Meisn., locally named "Lvluohua, [symbols: see text]", has been traditionally used to treat diabetes mellitus for many years.

AIM OF THIS STUDY

To evaluate the activity of dual agonists for PPARγ/β from the flower of E.gardneri in vitro.

MATERIALS AND METHODS

HeLa cells were transiently co-transfected with the re-constructed plasmids of pBIND-PPARγ-LBD or pBIND-PPARβ-LBD and rL4.35. The activities of crude extracts, secondary fractions and compounds from the flower of E.gardneri were evaluated with the transfected cells. Rosiglitazone (at 0.5 μg/mL) and L-165041 (at 0.5 μg/mL) were used as the positive controls for PPARγ and PPARβ respectively.

RESULTS

The results demonstrated that n-hexane, ethyl acetate and n-butanol extracts from the flower of E.gardneri were able to significantly activate PPARγ and PPARβ respectively, and the activity of ethyl acetate extract was much better. We further observed that, among the 11 secondary fractions of ethyl acetate extract, the fr. 9 could activate PPARγ and PPARβ significantly. Moreover, umbelliferone (from fr.9) and pentadecanoic acid could activate PPARγ and PPARβ at the same time.

CONCLUSIONS

The extracts from the flower of E.gardneri could significantly activate PPARγ and PPARβ. Besides, umbelliferone and pentadecanoic acid isolated from the flower of E.gardneri were the new agonists for PPARγ and PPARβ.

PPAR ligands improve impaired metabolic pathways in fetal hearts of diabetic rats

In maternal diabetes, the fetal heart can be structurally and functionally affected. Maternal diets enriched in certain unsaturated fatty acids can activate the nuclear receptors peroxisome proliferator-activated receptors (PPARs) and regulate metabolic and anti-inflammatory pathways during development. Our aim was to investigate whether PPARα expression, lipid metabolism, lipoperoxidation, and nitric oxide (NO) production are altered in the fetal hearts of diabetic rats, and to analyze the putative effects of in vivo PPAR activation on these parameters. We found decreased PPARα expression in the hearts of male but not female fetuses of diabetic rats when compared with controls. Fetal treatments with the PPARα ligand leukotriene B4 upregulated the expression of PPARα and target genes involved in fatty acid oxidation in the fetal hearts. Increased concentrations of triglycerides, cholesterol, and phospholipids were found in the hearts of fetuses of diabetic rats. Maternal treatments with diets supplemented with 6% olive oil or 6% safflower oil, enriched in unsaturated fatty acids that can activate PPARs, led to few changes in lipid concentrations, but up-regulated PPARα expression in fetal hearts. NO production, which was increased in the hearts of male and female fetuses in the diabetic group, and lipoperoxidation, which was increased in the hearts of male fetuses in the diabetic group, was reduced by the maternal treatments supplemented with safflower oil. In conclusion, impaired PPARα expression, altered lipid metabolism, and increased oxidative and nitridergic pathways were evidenced in hearts of fetuses of diabetic rats and were regulated in a gender-dependent manner by treatments enriched with PPAR ligands.

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.

Maternal dietary omega-3 fatty acids and placental function

The developing fetus requires substantial amounts of fatty acids to support rapid cellular growth and activity. Although the fatty acid composition delivered to the fetus is largely determined by maternal circulating levels, the placenta preferentially transfers physiologically important long-chain polyunsaturated fatty acids (LC-PUFAs), particularly omega-3 (n-3) PUFAs. Maternal dietary supplementation with n-3 PUFAs during pregnancy has been shown to increase gestation length, enhance fetal growth, and reduce the risk of pregnancy complications, although the precise mechanisms governing these effects remain uncertain. Omega-3 PUFAs are involved in several physiological pathways which could account for these effects, including anti-inflammatory, pro-resolving, and anti-oxidative pathways. Recent studies have shown that maternal dietary n-3 PUFA supplementation during rat pregnancy can reduce placental oxidative damage and increase placental levels of pro-resolving mediators, effects associated with enhanced fetal and placental growth. Because several placental disorders, such as intrauterine growth restriction, preeclampsia, and gestational diabetes mellitus, are associated with heightened placental inflammation and oxidative stress, there is considerable interest in the potential for dietary n-3 PUFAs as a therapeutic intervention for these disorders. In this study, we review the impact of dietary n-3 PUFAs on placental function, with particular focus on placental inflammation, inflammatory resolution, and oxidative stress.

Peroxisome proliferator-activated receptor ligands regulate lipid content, metabolism, and composition in fetal lungs of diabetic rats

Maternal diabetes impairs fetal lung development. Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors relevant in lipid homeostasis and lung development. This study aims to evaluate the effect of in vivo activation of PPARs on lipid homeostasis in fetal lungs of diabetic rats. To this end, we studied lipid concentrations, expression of lipid metabolizing enzymes and fatty acid composition in fetal lungs of control and diabetic rats i) after injections of the fetuses with Leukotriene B4 (LTB4, PPARα ligand) or 15deoxyΔ(12,14)prostaglandin J2 (15dPGJ2, PPARγ ligand) and ii) fed during pregnancy with 6% olive oil- or 6% safflower oil-supplemented diets, enriched with PPAR ligands were studied. Maternal diabetes increased triglyceride concentrations and decreased expression of lipid-oxidizing enzymes in fetal lungs of diabetic rats, an expression further decreased by LTB4 and partially restored by 15dPGJ2 in lungs of male fetuses in the diabetic group. In lungs of female fetuses in the diabetic group, maternal diets enriched with olive oil increased triglyceride concentrations and fatty acid synthase expression, while those enriched with safflower oil increased triglyceride concentrations and fatty acid transporter expression. Both olive oil- and safflower oil-supplemented diets decreased cholesterol and cholesteryl ester concentrations and increased the expression of the reverse cholesterol transporter ATP-binding cassette A1 in fetal lungs of female fetuses of diabetic rats. In fetal lungs of control and diabetic rats, the proportion of polyunsaturated fatty acids increased with the maternal diets enriched with olive and safflower oils. Our results revealed important changes in lipid metabolism in fetal lungs of diabetic rats, and in the ability of PPAR ligands to modulate the composition of lipid species relevant in the lung during the perinatal period.

Adiponectin inhibits insulin function in primary trophoblasts by PPARα-mediated ceramide synthesis

Maternal adiponectin (ADN) levels are inversely correlated with birth weight, and ADN infusion in pregnant mice down-regulates placental nutrient transporters and decreases fetal growth. In contrast to the insulin-sensitizing effects in adipose tissue and muscle, ADN inhibits insulin signaling in the placenta. However, the molecular mechanisms involved are unknown. We hypothesized that ADN inhibits insulin signaling and insulin-stimulated amino acid transport in primary human trophoblasts by peroxisome proliferator-activated receptor-α (PPARα)-mediated ceramide synthesis. Primary human term trophoblast cells were treated with ADN and/or insulin. ADN increased the phosphorylation of p38 MAPK and PPARα. ADN inhibited insulin signaling and insulin-stimulated amino acid transport. This effect was dependent on PPARα, because activation of PPARα with an agonist (GW7647) inhibited insulin signaling and function, whereas PPARα-small interfering RNA reversed the effects of ADN on the insulin response. ADN increased ceramide synthase expression and stimulated ceramide production. C2-ceramide inhibited insulin signaling and function, whereas inhibition of ceramide synthase (with Fumonisin B1) reversed the effects of ADN on insulin signaling and amino acid transport. These findings are consistent with the model that maternal ADN limits fetal growth mediated by activation of placental PPARα and ceramide synthesis, which inhibits placental insulin signaling and amino acid transport, resulting in reduced fetal nutrient availability.

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.

Maternal dietary omega-3 fatty acid intake increases resolvin and protectin levels in the rat placenta

Placental inflammation is associated with several pregnancy disorders. Inflammation is limited by anti-inflammatory and proresolving mechanisms, the latter partly mediated by resolvins and protectins derived from omega-3 polyunsaturated fatty acids (n-3PUFA). We examined effects of dietary n-3PUFAs on levels of resolvins, protectins, and lipoxygenase (ALOX) enzymes in the rat placenta. Rats consumed standard (Std) or high n-3PUFA (Hn3) diets from day 1 of pregnancy; tissues were collected on day 17 or 22 (term = day 23). Maternal Hn3 diet increased resolvin and protectin precursors, 18R/S-HEPE (P < 0.001), and 17R/S-HDHA (P < 0.01) at both days. Resolvins (17R-RvD1 and RvD1) increased at day 22 (P < 0.001) after Hn3 consumption, coincident with higher Alox15b and Alox5 mRNA expression, while RvD2 increased at both days (P < 0.05). Protectins, PD1, and 10S,17S-DiHDHA increased over late gestation (P < 0.001), coincident with higher Alox15 mRNA expression (P < 0.001) and further increased with Hn3 diet (P < 0.05). Maternal systemic and placental proinflammatory mediators were not suppressed by Hn3 diet; systemic IL1β, placental Il1β, and Il6 mRNA expression increased marginally with Hn3 at day 22 (P < 0.001), while Ptgs1 (Cox1) expression increased both days (P < 0.05). Our data indicate that maternal n-3PUFA supplementation enhances expression of enzymes in the n-3PUFA metabolic pathway and increases placental levels of resolvins and protectins.

Homeobox genes and down-stream transcription factor PPARγ in normal and pathological human placental development

The placenta provides critical transport functions between the maternal and fetal circulations during intrauterine development. Formation of this interface is controlled by nuclear transcription factors including homeobox genes. Here we summarize current knowledge regarding the expression and function of homeobox genes in the placenta. We also describe the identification of target transcription factors including PPARγ, biological pathways regulated by homeobox genes and their role in placental development. The role of the nuclear receptor PPARγ, ligands and target genes in human placental development is also discussed. A better understanding of these pathways will improve our knowledge of placental cell biology and has the potential to reveal new molecular targets for the early detection and diagnosis of pregnancy complications including human fetal growth restriction.