Diet-induced obesity in the rat: a model for gestational diabetes mellitus

Trajectory of primordial follicle depletion is accelerated in obese mice in response to 7,12-dimethylbenz[a]anthracene exposure†

Both obesity and exposure to environmental genotoxicants, such as 7,12-dimethylbenz[a]anthracene, negatively impair female reproductive health. Hyperphagic lean KK.Cg-a/a (n = 8) and obese KK.Cg-Ay/J (n = 10) mice were exposed to corn oil as vehicle control (CT) or 7,12-dimethylbenz[a]anthracene (1 mg/kg/day) for 7d intraperitoneally, followed by a recovery period. Obesity increased liver and spleen weight (P < 0.05), and 7,12-dimethylbenz[a]anthracene exposure decreased uterine weight (P < 0.05) in obese mice. Primordial follicle loss (P < 0.05) caused by 7,12-dimethylbenz[a]anthracene exposure was observed in obese mice only. Primary (lean P < 0.1; obese P < 0.05) and secondary (lean P < 0.05, obese P < 0.1) follicle loss initiated by 7,12-dimethylbenz[a]anthracene exposure continued across recovery. Reduced pre-antral follicle number in lean mice (P < 0.05), regardless of 7,12-dimethylbenz[a]anthracene exposure, was evident with no effect on antral follicles or corpora lutea number. Immunofluorescence staining of DNA damage marker, γH2AX, did not indicate ongoing DNA damage but TRP53 abundance was decreased in follicles (P < 0.05) of 7,12-dimethylbenz[a]anthracene-exposed obese mice. In contrast, increased (P < 0.05) superoxide dismutase was observed in the corpora lutea of 7,12-dimethylbenz[a]anthracene-exposed obese mice and reduced (P < 0.05) TRP53 abundance was noted in preantral and antral follicles of 7,12-dimethylbenz[a]anthracene-exposed obese mice. This study indicates that obesity influences ovotoxicity caused by a genotoxicant, potentially involving accelerated primordial follicle activation and hampering normal follicular dynamics.

Pharmacological Action of Baicalin on Gestational Diabetes Mellitus in Pregnant Animals Induced by Streptozotocin via AGE-RAGE Signaling Pathway

OBJECTIVE

Baicalin (BC) is a flavonoid reported to have various pharmacological activities, including antioxidant, anti-cancer, anti-inflammatory, anti-allergy, immune regulation, and anti-diabetic. This study examines the probable mechanism for gestational diabetes mellitus (GDM) brought on by streptozotocin (STZ) and the impact of BC on fetal development via AGEs (advanced serum glycation end products) and RAGE (the role of advanced glycation end products).

MATERIAL AND METHOD

STZ has been used in the current experimental study to induce diabetes mellitus in pregnant animals (gestational diabetes mellitus). GDM pregnant animals were separated into five groups and were treated with BC in a dose-dependent pattern for 19 days. At the end of the experiment, the fetus and blood samples were drawn from all the pregnant rats to assess the biochemical parameter as well as AGE-RAGE.

RESULT

Administration of BC at varying doses leads to enhancement in the weight of the fetus body and placenta while gestational diabetic pregnant animals induced by STZ had a lower weight of the fetus body and placenta. The dose-dependent pattern of BC also enhanced fasting insulin (FINS), high-density lipoprotein (HDL), serum insulin, and hepatic glycogen. It also significantly enhanced the content of the antioxidant profile and pro-inflammatory cytokines and modulated the gene expression (VCAM- 1, p65, EGFR, MCP-1, 1NOX2, and RAGE) in various tissues in gestational diabetes mellitus pregnant rats.

CONCLUSION

Baicalin demonstrated the potential impact on the embryo's development via the AGE-RAGE signaling pathway in STZ-induced GDM pregnant animals.

Puberty as a DOHaD programming window: high-fat diet induces long-term hepatic dysfunction in male rats

The aim of this study was to evaluate whether high-fat (HF) diet intake during puberty can program obesity as well as generate glucose imbalance and hepatic metabolic dysfunctions in adult life. Male Wistar rats were randomly assigned into two groups: rats fed standard chow (NF) and rats fed a HF from postnatal 30-day-old (PND30) until PND60. Then, both groups were fed a standard chow from PND60 until PND120. Euthanasia and samples collections occurred at PND120. HF animals were overweight (+11%) and had increased adiposity, hyperphagia (+12%), hyperglycaemia (+13%), hyperinsulinemia (+69%), and hypertriglyceridemia (+34%). Plasma glucose levels during intravenous glucose tolerance test (ivGTT) and intraperitoneal insulin tolerance test (ipITT) were also higher in the HF group, whereas Kitt was significantly lower (-34%), suggesting reduced insulin sensitivity. In the same sense, HF animals present pancreatic islets hypertrophy and high β-cell mass. HF animals also had a significant increase in blood glucose levels during pyruvate tolerance test, indicating increased gluconeogenesis. Hepatic morphology analyses showed an increase in lipid inclusion in the HF group. Moreover, PEPCK and FAS protein expression were higher in the livers of the HF animals (+79% and + 37%, respectively). In conclusion, HF during puberty causes obese phenotype leading to glucose dyshomeostasis and nonalcoholic fatty liver disease, which can be related to the overexpression of proteins PEPCK and FAS.

Impact of Normal and Overweight Pregnancy in GLUT4 and Glucose-Dependent Vascular Contractility

INTRODUCTION

Obesity during pregnancy can contribute to hypertensive complications through changes in glucose utilization. We investigated the impact of vascular glucose uptake, GLUT4 density, and endothelium on agonist-induced vasoconstriction in the aortas of overweight pregnant rats.

METHODS

Isolated aortic rings with or without endothelium from pregnant or nonpregnant rats fed a standard (SD) or hypercaloric diet (HD) were contracted with phenylephrine or serotonin (10-9 to 10-4M) using standard (11 mm) or without (0 mm) glucose Krebs solution. GLUT4 density in the aortas was measured using the en face method.

RESULTS

Aortas from overweight pregnant animals (PHD) showed increased Phe-induced vasoconstriction (p < 0.05 vs. pregnant standard diet [PSD]), which was endothelium-independent. The contraction decreased significantly in the absence of glucose. In contrast, vessels from pregnant SD rats maintained their contraction in glucose-free Krebs solution. 5-HT increases PHD aortic contraction only in the absence of glucose. The fetal aortas from PHD mothers showed blunted vasoconstriction. Overweight significantly reduced GLUT4 expression in maternal and fetal aortas (p < 0.05 vs. PSD).

CONCLUSIONS

Aortic contractility is independent of glucose uptake during healthy pregnancy. In contrast, overweight pregnancy increases contractility. This increase depends directly on smooth muscle glucose uptake and inversely on GLUT-4 density. The increased contraction observed in the vasculature of overweight mothers was inverted in the fetal aortas.

Transgenerational effects of zinc, selenium and chromium supplementation on glucose homeostasis in female offspring of gestational diabetes rats

Clinical studies have demonstrated that maternal gestational diabetes mellitus (GDM) increases the offspring's risk of developing glucose intolerance. Our previous study reported that co-supplementation with zinc, selenium, and chromium improved insulin resistance in diet-induced GDM rats. Here, Transgenerational effects of supplementation with zinc (10 mg/kg.bw), selenium (20 μg/kg.bw), and chromium (20 μg/kg.bw) in F1 female offspring of both zinc, selenium and chromium (ZnSeCr)-treated, and untreated GDM rats daily by gavage from weaning to the postpartum were investigated in the present study. Glucose homeostasis in the F1 female offspring of GDM at different stages were evaluated. Maternal GDM did increase the birth mass of newborn F1 female offspring, as well as the serum glucose and insulin levels. Zinc, selenium and chromium supplementation attenuated the GDM-induced mass gain, increased serum glucose and insulin levels in the female neonates. The high fat and sucrose (HFS) diet-fed GDM-F1 offspring developed GDM, with glucose intolerance, hyperglycemia and insulin resistance during pregnancy. Moreover, endoplasmic reticulum (ER) stress-related protein levels were increased and the activation of insulin signaling pathways were reduced in the liver of HFS-fed GDM-F1 offspring. Whereas glucose homeostasis in parallel with insulin sensitivity was normalized in the female offspring of GDM by supplementation both F0 dams and F1 offspring with zinc, selenium and chromium, not in those either F0 or F1 elements supplemented offspring. Therefore, we speculate that zinc, selenium and chromium supplementation may have a potential beneficial transgenerational effect on the glucose homeostasis in the female offspring of GDM.

7,8-Dihydroxyflavone alleviates Endoplasmic Reticulum Stress in cafeteria diet-induced metabolic syndrome

AIMS

Prolonged Endoplasmic Reticulum Stress (ERS) is involved in the pathogenesis of metabolic syndrome, including type-2 diabetes mellitus, cardiovascular diseases, atherosclerosis, obesity, and fatty liver disease. There have been significant efforts to discover molecules to treat ERS and/or to ameliorate associate symptoms. In this study, we investigated the effect of 7,8-Dihydroxyflavone (7,8-DHF) on ERS in liver and pancreas tissues in a cafeteria (CAF) diet induced metabolic syndrome model.

MAIN METHODS

Male C57BL/6 mice were fed CAF diet for 16 weeks and 7,8-DHF was administered intraperitoneally (5 mg/kg/day) for last four weeks. 78-kDa glucose-regulated protein (GRP78) and C/EBP homologous protein (CHOP) in liver and pancreas tissues, insulin and interleukin-1β (IL-1β) in serum were analyzed by ELISA method and serum biochemistry parameters were analyzed with autoanalyzer. GRP78 and CHOP gene expression levels were determined by qRT-PCR. In addition, histopathological analyzes were performed on liver and pancreas tissues.

KEY FINDINGS

Findings revealed that CAF diet caused metabolic abnormalities, insulin resistance and inflammation in serum and triggered ERS in pancreas and liver tissues. 7,8-DHF treatment significantly reduced metabolic abnormalities by reducing serum biochemical parameters, HOMO-IR and IL-1β levels. qRT-PCR and ELISA results indicated that 7,8-DHF treatment down-regulated GRP78 and CHOP expression and protein levels in the liver and GRP78 expression in pancreas. Efficiency of 7,8-DHF in these tissues was also demonstrated by histopathological tests.

SIGNIFICANCE

In conclusion, CAF diet-induced metabolic syndrome model, 7,8-DHF suppressed ERS and ERS-induced metabolic disorders in both liver and pancreas. Therefore, 7,8-DHF may potentially be a novel therapeutic compound to ameliorate ERS and related metabolic symptoms.

The Protective Effects of Inulin-Type Fructans Against High-Fat/Sucrose Diet-Induced Gestational Diabetes Mice in Association With Gut Microbiota Regulation

Background

Inulin-type fructans (ITF) have been used as prebiotics to alleviate glucose and lipid metabolism disorders. However, few studies evaluated the microbial mechanism of ITF in improving maternal metabolic status during pregnancy.

Methods

C57BL/6J mice were fed a high-fat/sucrose diet (HFD) for 4 weeks before and throughout pregnancy to induce a model of gestational diabetes mellitus (GDM). Body weight, glycolipid metabolic parameters, and fecal short-chain fatty acids (SCFAs) were assessed in the experimental process. The effects of ITF on the fecal microbiota were analyzed by 16S rRNA gene amplicon sequencing.

Results

Pregnant HFD-fed mice displayed significant insulin resistance and dyslipidemia. ITF (3.33 g/kg/day) treatment improved glucose and lipid metabolism disorder parameters in HFD-induced GDM mice and alleviated fat accumulation and glucose intolerance. The alpha diversity of the gut microbial community was increased in ITF mice, while the beta diversity returned to the level of normal chow diet (NCD) mice. Interestingly, Verrucomicrobia, Bifidobacterium, and Akkermansia were obviously enriched, while Dubosiella was obviously lessened after inulin treatment. Further analysis indicated that Dubosiella was positively correlated with markers of glycolipid metabolism disorders, whereas the ITF-supplemented diet partially reversed the changes.

Conclusion

Our results suggest that the ITF treatment may alleviate glucose and lipid metabolism disorders with the mediation of gut microbiota.

Influence of High Energy Diet and Polygenic Predisposition for Obesity on Postpartum Health in Rat Dams

It is estimated that 30% of pregnant women worldwide are overweight or obese, leading to adverse health effects for both mother and child. Women with obesity during pregnancy are at higher risk for developing both metabolic and mental disorders, such as diabetes and depression. Numerous studies have used rodent models of maternal obesity to understand its consequences on the offspring, yet characterization of changes in the dams is rare, and most rodent models rely solely on a high fat diet to induce maternal obesity, without regarding genetic propensity for obesity. Here we present the influence of both peripartum high energy diet (HE) and obesity-proneness on maternal health using selectively bred diet-resistant (DR) and diet-induced obese (DIO) rat dams. Outbred Sprague-Dawley rats were challenged with HE diet prior to mating and bred according to their propensity to gain weight. The original outbred breeding dams (F0) were maintained on low-fat chow during pregnancy and lactation. By comparison, the F1 dams consuming HE diet during pregnancy and lactation displayed higher gestational body weight gain (P < 0.01), and HE diet caused increased meal size and reduced meal frequency (P < 0.001). Sensitivity to the hormone amylin was preserved during pregnancy, regardless of diet. After several rounds of selective breeding, DIO and DR dams from generation F3 were provided chow or HE during pregnancy and lactation and assessed for their postpartum physiology and behaviors. We observed strong diet and phenotype effects on gestational weight gain, with DIO-HE dams gaining 119% more weight than DR-chow (P < 0.001). A high-resolution analysis of maternal behaviors did not detect main effects of diet or phenotype, but a subset of DIO dams showed delayed nursing behavior (P < 0.05). In generation F6/F7 dams, effects on gestational weight gain persisted (P < 0.01), and we observed a main effect of phenotype during a sucrose preference test (P < 0.05), with DIO-chow dams showing lower sucrose preference than DR controls (P < 0.05). Both DIO and DR dams consuming HE diet had hepatic steatosis (P < 0.001) and exhibited reduced leptin sensitivity in the arcuate nucleus (P < 0.001). These data demonstrate that both diet and genetic obesity-proneness have consequences on maternal health.

Using the Isolated Rat Placenta to Assess Fetoplacental Hemodynamics

Placental health is critical to fetal growth and maternal health during gestation. However, investigating placental flow in an ex-vivo isolated system where inflow is independently controlled has yet to be developed in the rat. Here, we describe a novel technique, isolated perfused placenta technique that allows for analysis of placental pressure outflow pressure, placental flow in rats at gestational day 20. Using this method, we successfully perfused placentas from dams and were able to observe increases in outflow pressure and flow as the inflow pressure to the placenta was increased in a step wise fashion. This method will help to advance the functional analysis of placental flow and therefore placental resistance and efficiency.

TiO2 NPs induce the reproductive toxicity in mice with gestational diabetes mellitus through the effects on the endoplasmic reticulum stress signaling pathway

The effect of one of the most widely studied nanomaterials at present, TiO₂ nanoparticles (NPs), on pregnancy-related diseases is not clear. In this study, the adverse effects of TiO₂ NPs on mice with gestational diabetes mellitus (GDM) and their possible mechanism were investigated. GDM mice were orally administered 0, 10, 50 and 250 mg/kg TiO₂ NPs for 14 days. GDM reduced the weight of pregnant mice, destroyed the placental structure and caused abnormal fetal development. After exposure to increasing doses of TiO₂ NPs, blood glucose levels increased significantly and body weight further decreased in GDM mice. The accumulation of the Ti content was detected in the placenta and fetus, which may further damage the placental structure in GDM mice, thereby exacerbating abnormal fetal development. In addition, the MDA and SOD activities were obviously increased, and the expression of genes associated with endoplasmic reticulum stress (ERS) (PERK, eIF2α, AFT4, IRE1α, and XBP1s) and apoptosis (CHOP, JNK, Bax/Bcl-2, Caspase-12, Caspase-9, and Caspase-3) were also obviously increased in the placenta, which reflected the possible activation of apoptosis. It could be speculated that the reproductive toxicity of TiO₂ NPs in GDM mice triggered oxidative stress that subsequently activated ERS pathways to induce cell apoptosis.

Maternal High-Fat Diet Programs Renal Peroxisomes and Activates NLRP3 Inflammasome-Mediated Pyroptosis in the Rat Fetus

PURPOSE

Maternal obesity impairs kidney development and function of the offspring and leads to a greater risk of kidney disease in adulthood. The present study aimed to investigate the link between peroxisomes, oxidative stress (OS), and inflammasomes in the fetal kidney of maternal obesity rats and to explore the potential therapeutic effects of the antioxidant pyrroloquinoline quinone (PQQ).

METHODS

Maternal obesity rats were developed by administration of a high fat diet plus supplementation with PQQ (40 mg/kg body weight) as a potential therapy. Renal histology was observed by Periodic Acid-Schiff staining. The expression profiles of peroxins, fatty acid β-oxidation enzymes, antioxidants, and the regulators of the unfolded protein response (UPR) pathway and NLRP3 inflammasome were analyzed in the kidneys and tubular epithelial cells (TECs) from near-term fetuses (embryonic day 20).

RESULTS

The present work revealed that: 1) a maternal high fat diet (MHF) led to higher blood pressure in adult offspring; 2) MHF led to downregulation of peroxisome markers PEX3 and 14 in fetal kidneys; 3) the antioxidant SOD2 and catalase were decreased, and oxidative stress marker Ephx2 was increased; 4) MHF-induced activation of the UPR pathway; 5) the KEAP1-NRF2 pathway was activated; 6) activation of the NLRP3 inflammasome led to secretion of pro-inflammation factors; 7) in TECs, the changes in PEXs and NLRP3 are similar to tissues, but UPR and NRF2 pathways showed opposite trends; 8) and the antioxidant PQQ alleviated maternal lipotoxicity by decreasing ROS levels and inhibiting activation of ER stress and inflammasome in fetal kidney.

CONCLUSION

A maternal high fat diet decreased the number of peroxisomes, subsequently activated OS and inflammasomes, resulting in pyroptosis and apoptosis in fetal kidney. The antioxidant PQQ served a protective role against the effects of lipotoxicity on kidney programming and, thus, is a potential candidate to prevent maternal obesity-induced renal programming.

Zinc, selenium and chromium co-supplementation improves insulin resistance by preventing hepatic endoplasmic reticulum stress in diet-induced gestational diabetes rats

Gestational diabetes mellitus (GDM) is one of the most common pregnancy complications and results in adverse outcomes for pregnant women and their offspring. Endoplasmic reticulum (ER) stress is associated with insulin resistance and implicates in the development of GDM. Zinc, selenium and chromium have been shown to maintain glucose homeostasis via multiple mechanisms, but how these trace elements affect the insulin resistance and ER stress in GDM are largely unknown. To address this, a GDM rat model was induced by feeding female Sprague-Dawley rats a high-fat (45%) and sucrose diet, while zinc (10 mg/kg.bw), selenium (20 ug/kg.bw), chromium (20 ug/kg.bw) were daily supplemented alone or in combination from 6 weeks before mating to the end of lactation period. Maternal metabolic parameters, hepatic ER stress and insulin signaling were analyzed. The results showed that zinc, selenium and chromium co-supplementation dramatically alleviated high-fat and sucrose-induced glucose intolerance and oxidative stress during entire experiment period. Hepatic ER stress as well as the unfolded protein response was activated in GDM dams, characterized by the up-regulation of glucose-regulated protein 78, phosphorylated the protein kinase RNA-like endoplasmic reticulum kinase, and the inositol-requiring enzyme 1α. Zinc, selenium and chromium supplementation significantly prevented this activation, by which contributes to the promotion of the phosphorylated protein kinase B related insulin signaling and maintenance of glucose homeostasis. In conclusion, zinc, selenium and chromium supplementation may be a promising way to prevent the development of GDM by alleviating hepatic ER stress.

Prevention of Teratogenesis in Pregnancies of Obese Rats by Vitamin E Supplementation

Congenital malformations are a common adverse outcome in pregnancies complicated by pregestational obesity, although the underlying mechanisms are still unrevealed. Our aim was to study the effect of oxidative stress in obesity-induced teratogenesis. Wistar rats were fed a high-fat diet for 13 weeks, with (OE group) or without (O group) vitamin E supplementation. Then, rats were mated and sacrificed at day 11.5 of gestation. Embryos from O dams presented a 25.9 ± 3.5% rate of malformations (vs. 8.7 ± 3.4% in C rats), which was reduced in the OE group (11.5 ± 2.3%). Pregestational obesity induced hepatic protein and DNA oxidation and a decline in antioxidant enzymes. Importantly, glutathione content was also decreased, limiting the availability of this antioxidant in the embryos. Vitamin E supplementation efficiently maintained glutathione levels in the obese mothers, which could be used in their embryos to prevent oxidation-induced malformations. To test the effect of decreasing glutathione levels alone in a cell culture model of neuroepithelium, murine embryonic stem cells (ESC) were induced to form neuronal precursors and glutathione synthesis was inhibited with the gamma–glutamylcysteine synthesis inhibitor, buthionine sulfoximine (BSO). BSO inhibited the expression of Pax3, a gene required for neural tube closure that is also inhibited by oxidative stress. Taken together, our data indicate that obesity causes malformations through the depletion of maternal glutathione, thereby decreasing glutathione-dependent free radical scavenging in embryos, which can be prevented by vitamin E supplementation.

Associations between the chemical composition of PM2.5 and gestational diabetes mellitus

BACKGROUND

Fine particulate matter (PM_2.5) is a complex mixture of fine particulates with large spatiotemporal heterogeneities in chemical compositions. While PM_2.5 has been associated with gestational diabetes mellitus (GDM), little is known about the relationship between specific chemical components of PM_2.5 and GDM. We examined the associations between GDM and pregnancy exposures to PM_2.5 and its compositions, including sulfate (SO₄^2-), ammonium (NH₄⁺), nitrate (NO₃^-), organic matter (OM), black carbon (BC), mineral dust (DUST), and sea-salt (SS), and to identify critical windows of exposure.

METHODS

We used data from the 2005-2015 Florida Vital Statistics Birth Records. A well-validated geoscience-derived model was used to estimate women's pregnancy exposures to PM_2.5 and its compositions. Distributed lag models were used to examine the associations and to identify the critical windows of exposure.

RESULTS

A total of 2,078,669 women were included. In single-pollutant models, after controlling for potential confounders, positive associations between PM_2.5 and GDM were observed during the second trimester of pregnancy. We found positive associations between SO₄^2-, NH₄⁺, NO₃^-, OM and BC, with largest effect sizes observed in the 21-24 weeks of pregnancy. Negative associations were observed for DUST and SS. Consistent results for NH₄⁺, OM, DUST and SS were observed in the multi-pollutant models.

CONCLUSIONS

Exposures to PM_2.5 and its compositions (mainly NH₄⁺, OM) during the second trimester are positively associated with GDM, especially for exposures during the 21-24 weeks of pregnancy. Further studies are needed to confirm the findings and examine the underlying mechanisms.

Effects of maternal taurine supplementation on maternal dietary intake, plasma metabolites and fetal growth and development in cafeteria diet fed rats

BACKGROUND

Maternal obesity may disrupt the developmental process of the fetus during gestation in rats. Recent evidence suggests that taurine can exert protective role against detrimental influence of obesogenic diets. This study aimed to examine the effect of maternal cafeteria diet and/or taurine supplementation on maternal dietary intake, plasma metabolites, fetal growth and development.

METHODS

Female Wistar rats were fed a control diet (CON), CON supplemented with 1.5% taurine in drinking water (CONT), cafeteria diet (CAF) or CAF supplemented with taurine (CAFT) from weaning. After 8 weeks all animals were mated and maintained on the same diets during pregnancy and lactation.

RESULTS

Dietary intakes were significantly different between the groups. Both CAF and CAFT fed dams consumed less water in comparison to CON and CONT dams. Taurine supplementation only increased plasma taurine concentrations in CONT group. Maternal plasma adiponectin concentrations increased in CAF and CAFT fed dams compared to CON and CONT fed dams and there was no effect of taurine. Hyperleptinemia was observed in CAF fed dams but not in CAFT fed dams. Malondialdehyde was significantly increased only in CAF fed dams. Litter size, sex ratio and birth weight were similar between the groups. There was an increase in neonatal mortality in CONT group.

DISCUSSION

This study showed that maternal taurine supplementation exerted modest protective effects on cafeteria diet induced maternal obesity. The increased neonatal mortality in CONT neonates indicates possible detrimental effects of taurine supplementation in the setting of normal pregnancy. Therefore, future studies should investigate the optimal dose of taurine supplementation and long term potential effects on the offspring.

Divergent impact of gestational diabetes mellitus between the thoracic and abdominal rat aorta: Influence of endothelium and angiotensin II receptors

Gestational diabetes mellitus (GDM) affects 5-10% of pregnancies and increases the risk of fetal and maternal adverse outcomes. Interestingly, the vascular response to AngII is decreased by pregnancy while the response is increased by diabetes. It remains unclear how GDM affects vascular tone and how angiotensin II receptors contribute to these changes. In this work, we sought to establish the vascular impact of a hypercaloric diet-induced GDM through changes in AT1 and AT2 receptor's expression. Female rats fed for 7 weeks with standard (SD) or hypercaloric (HD) diet were divided at week 4. Half of the rats of each group were mated to become pregnant and those fed with a HD developed GDM. AngII-induced vasoconstriction was measured in thoracic or abdominal aorta rings using a conventional isolated organ bath and AT1 and AT2 receptors were searched by immunohistochemistry. Experiments where conducted on the pregnant standard diet group (PSD) and the pregnant hypercaloric-gestational diabetes mellitus group (PHD-GDM). Vasoconstriction was reduced in the thoracic aorta (P < 0.05 vs PSD) but increased in the abdominal aorta of PHD-GDM rats (P < 0.05 vs PSD). Blockade of AT2 receptors using PD123319 decreased vasoconstriction, particularly in the abdominal aorta of PHD-GDM animals (P < 0.05 vs PSD). PHD-GDM increased AT1 receptors expression (P < 0.05 vs PSD). Also, PHD-GDM reverted physiologic hypoglycemia and hypotension of healthy pregnancy. Findings provide new insight into the hypercaloric diet induced damage on the vasculature during pregnancy.

High NOV/CCN3 expression during high-fat diet pregnancy in mice affects GLUT3 expression and the mTOR pathway

We investigated the expression levels of nephroblastoma overexpressed [NOV or CCN3 (cellular communication network factor 3)] in the serum and placenta of pregnant women and of pregnant mice fed a high-fat diet (HFD), and its effect on placental glucose transporter 3 (GLUT3) expression, to examine its role in gestational diabetes mellitus (GDM). NOV/CCN3 expression was increased in the mouse serum during pregnancy. At gestational day 18, NOV/CCN3 protein expression was increased in the serum and placenta of the HFD mice compared with that of mice fed a normal diet. Compared with non-GDM patients, the patients with GDM had significantly increased serum NOV/CCN3 protein expression and placental NOV/CCN3 mRNA expression. Therefore, we hypothesized that NOV/CCN3 signaling may be involved in the pathogenesis of GDM. We administered NOV/CCN3 recombinant protein via intraperitoneal injections to pregnant mice fed HFD or normal diet. NOV/CCN3 overexpression led to glucose intolerance. Combined with the HFD, NOV/CCN3 exacerbated glucose intolerance and caused insulin resistance. NOV/CCN3 upregulates GLUT3 expression and affects the mammalian target of rapamycin (mTOR) pathway in the GDM environment in vivo and in vitro. In summary, our results demonstrate, for the first time, the molecular mechanism of NOV/CCN3 signaling in maternal metabolism to regulate glucose balance during pregnancy. NOV/CCN3 may be a potential target for detecting and treating GDM.NEW & NOTEWORTHY NOV/CCN3 regulates glucose homeostasis in mice during pregnancy. NOV/CCN3 upregulates GLUT3 expression and affects the mTOR pathway in the GDM environment in vivo and in vitro.

Therapeutic effect of ursolic acid on fetal development in pregnant rats with gestational diabetes mellitus via AGEs-RAGE signaling pathway

To investigate the effect of ursolic acid on the fetal development of gestational diabetes mellitus (GDM) caused by streptozotocin (STZ) and explore the potential mechanism for it. For the current experimental research, SD rats (pregnant animal) were used. STZ has been used to cause the diabetes mellitus in pregnant rats. Rats with evolved GDM were randomly divided and ursolic acid was given to pregnant rats in the experimental period up to 19 days in a dose-dependent manner. Blood samples and fetal rats of all group rats were collected at 19 days (pregnant rats), fetal rats and placental rats were weighted and the blood glucose, plasma insulin, C-peptide, and lipid parameters of pregnant women were estimated prior to delivery. Advanced serum glycation end-products (AGEs) were estimated at regular intervals in the heart and brain of pregnant rats. Monocyte Chemoattractant Protein-1 (MCP-1), NADPH oxidase 2 (Nox2), Role of advanced glycation end product (RAGE), Vascular endothelial growth factor (VEGF), p65, and vascular cell adhesion molecule 1 (VCAM-1) mRNA expression were estimated in the placenta. STZ-induced GDM pregnant rats showed significantly decreased placental weight and weight of fetal rats and dose-dependent ursolic acid treatment (p < .001) improved placental weight and weight of fetal rats at dose-dependent levels. After the ursolic acid treatment, serum blood glucose and lipid level were improved especially fasting blood glucose (FBG), high density lipoprotein (HDL), hepatic glycogen, fasting insulin (FINS), and serum insulin level and reached near to the normal control group rats. The antioxidant level of pancreas and liver were significantly (p < .001) reduced by the dose-dependent treatment of ursolic acid. Treatment with Ursolic acid moderately but not significantly decreases the risk of fetal development defects relative to the GDM group. The potential effect on fetal development in Pregnant Rats with Gestational Diabetes Mellitus via AGEs-RAGE signaling pathway was shown by Ursolic acid. PRACTICAL APPLICATIONS: As we know that the gestational diabetes mellitus increases worldwide day by day. In the current experimental study, we try to examine the gestational diabetic effect of ursolic acid. The finding of the current study showed the gestational diabetic protective effect in the female rats via AGEs-RAGE signaling pathway. The result showed the antioxidant, anti-inflammatory, and biochemical parameters. On the basis of the result, we can say that the ursolic acid can be the protective drug for treatment of gestational diabetes mellitus.

Pregnancy-induced changes in β-cell function: what are the key players?

Maternal metabolic adaptations during pregnancy ensure appropriate nutrient supply to the developing fetus. This is facilitated by reductions in maternal peripheral insulin sensitivity, which enables glucose to be available in the maternal circulation for transfer to the fetus for growth. To balance this process and avoid excessive hyperglycaemia and glucose intolerance in the mother during pregnancy, maternal pancreatic β-cells undergo remarkable changes in their function including increasing their proliferation and glucose-stimulated insulin secretion. In this review we examine how placental and maternal hormones work cooperatively to activate several signalling pathways, transcription factors and epigenetic regulators to drive adaptations in β-cell function during pregnancy. We also explore how adverse maternal environmental conditions, including malnutrition, obesity, circadian rhythm disruption and environmental pollutants, may impact the endocrine and molecular mechanisms controlling β-cell adaptations during pregnancy. The available data from human and experimental animal studies highlight the need to better understand how maternal β-cells integrate the various environmental, metabolic and endocrine cues and thereby determine appropriate β-cell adaptation during gestation. In doing so, these studies may identify targetable pathways that could be used to prevent not only the development of pregnancy complications like gestational diabetes that impact maternal and fetal wellbeing, but also more generally the pathogenesis of other metabolic conditions like type 2 diabetes.

The promise of placental extracellular vesicles: models and challenges for diagnosing placental dysfunction in utero†

Monitoring the health of a pregnancy is of utmost importance to both the fetus and the mother. The diagnosis of pregnancy complications typically occurs after the manifestation of symptoms, and limited preventative measures or effective treatments are available. Traditionally, pregnancy health is evaluated by analyzing maternal serum hormone levels, genetic testing, ultrasonographic imaging, and monitoring maternal symptoms. However, researchers have reported a difference in extracellular vesicle (EV) quantity and cargo between healthy and at-risk pregnancies. Thus, placental EVs (PEVs) may help to understand normal and aberrant placental development, monitor pregnancy health in terms of developing placental pathologies, and assess the impact of environmental influences, such as infection, on pregnancy. The diagnostic potential of PEVs could allow for earlier detection of pregnancy complications via noninvasive sampling and frequent monitoring. Understanding how PEVs serve as a means of communication with maternal cells and recognizing their potential utility as a readout of placental health have sparked a growing interest in basic and translational research. However, to date, PEV research with animal models lags behind human studies. The strength of animal pregnancy models is that they can be used to assess placental pathologies in conjunction with isolation of PEVs from fluid samples at different time points throughout gestation. Assessing PEV cargo in animals within normal and complicated pregnancies will accelerate the translation of PEV analysis into the clinic for potential use in prognostics. We propose that appropriate animal models of human pregnancy complications must be established in the PEV field.

Research Progress on the Experimental Animal Model of Gestational Diabetes Mellitus

Gestational diabetes mellitus (GDM) refers to different degrees of abnormal glucose metabolism during pregnancy, where blood glucose levels do not reach the level of overt diabetes, accounting for 80-90% of pregnancy with hyperglycemia. Hyperglycemia affects the pregnancy process, leading to a series of adverse maternal outcomes that have a profound impact on the future of the offspring. The establishing of an appropriate GDM model will provide theoretical basis for study GDM pathogenesis involves, the choice of resonable drugs and the observation the disease trends and outcomes. At present, there are many methods for establishing experimental GDM animal models and animal choices. This paper examines the different GDM models and their induction methods.

Dietary Options for Rodents in the Study of Obesity

Obesity and its associated metabolic diseases are currently a priority research area. The increase in global prevalence at different ages is having an enormous economic and health impact. Genetic and environmental factors play a crucial role in the development of obesity, and diet is one of the main factors that contributes directly to the obesogenic phenotype. Scientific evidence has shown that increased fat intake is associated with the increase in body weight that triggers obesity. Rodent animal models have been extremely useful in the study of obesity since weight gain can easily be induced with a high-fat diet. Here, we review the dietary patterns and physiological mechanisms involved in the dynamics of energy balance. We report the main dietary options for the study of obesity and the variables to consider in the use of a high-fat diet, and assess the progression of obesity and diet-induced thermogenesis.

Developmental origins of ovarian disorder: impact of maternal lean gestational diabetes on the offspring ovarian proteome in mice†

Gestational diabetes mellitus (GDM) is an obstetric disorder affecting approximately 10% of pregnancies. The four high-fat, high-sucrose (HFHS) mouse model emulates GDM in lean women. Dams are fed a HFHS diet 1 week prior to mating and throughout gestation resulting in inadequate insulin response to glucose in mid-late pregnancy. The offspring of HFHS dams have increased adiposity, thus, we hypothesized that maternal metabolic alterations during lean GDM would compromise ovarian function in offspring both basally and in response to a control or HFHS diet in adulthood. Briefly, DLPL were lean dams and control diet pups; DLPH were lean dams and HFHS pups; DHPL were HFHS dams and control diet pups; and DHPH were HFHS dams and HFHS pups. A HFHS challenge in the absence of maternal GDM (DLPL vs. DLPH) increased 3 and decreased 30 ovarian proteins. Maternal GDM in the absence of a dietary stress (DLPL vs. DHPL) increased abundance of 4 proteins and decreased abundance of 85 proteins in the offspring ovary. Finally, 87 proteins increased, and 4 proteins decreased in offspring ovaries due to dietary challenge and exposure to maternal GDM in utero (DLPL vs. DHPH). Canopy FGF signaling regulator 2, deleted in azoospermia-associated protein 1, septin 7, and serine/arginine-rich splicing factor 2 were altered across multiple offspring groups. Together, these findings suggest a possible impact on fertility and oocyte quality in relation to GDM exposure in utero as well as in response to a western diet in later life.

Perinatal exposure to maternal obesity: Lasting cardiometabolic impact on offspring

Evidence from epidemiological, clinical, and animal model studies clearly demonstrates that prenatal and lactational maternal obesity and high-fat diet consumption are associated with cardiometabolic morbidity in offspring. Fetal and offspring sex may be an important effect modifier. Adverse offspring cardiometabolic outcomes observed in the setting of maternal obesity include an increased risk for obesity, features of metabolic syndrome (hypertension, hyperglycemia and insulin resistance, hyperlipidemia, increased adiposity), and non-alcoholic fatty liver disease. This review article synthesizes human and animal data linking maternal obesity and high-fat diet consumption in pregnancy and lactation to adverse cardiometabolic outcomes in offspring. We review key mechanisms underlying skeletal muscle, adipose tissue, pancreatic, liver, and central brain reward programming in obesity-exposed offspring, and how such malprogramming contributes to offspring cardiometabolic morbidity.

Gestational Diabetes Mellitus: A Harbinger of the Vicious Cycle of Diabetes

Gestational diabetes mellitus (GDM), characterized by a transitory form of diabetes induced by insulin resistance and pancreatic β-cell dysfunction during pregnancy, has been identified as one of the major obstacles in achieving improved maternal and child health. Approximately 9-25% of pregnancies worldwide are impacted by the acute, long-term, and transgenerational health complications of this disease. Here, we discuss how GDM affects longstanding maternal and neonatal outcomes, as well as health risks that likely persist into future generations. In addition to the current challenges in the management and diagnosis of and the complications associated with GDM, we discuss current preclinical models of GDM to better understand the underlying pathophysiology of the disease and the timely need to increase our scientific toolbox to identify strategies to prevent and treat GDM, thereby advancing clinical care.

Lean maternal hyperglycemia alters offspring lipid metabolism and susceptibility to diet-induced obesity in mice†

We previously developed a model of gestational diabetes mellitus (GDM) in which dams exhibit glucose intolerance, insulin resistance, and reduced insulin response to glucose challenge only during pregnancy, without accompanying obesity. Here, we aimed to determine how lean gestational glucose intolerance affects offspring risk of metabolic dysfunction. One cohort of offspring was sacrificed at 19 weeks, and one at 31 weeks, with half of the second cohort placed on a high-fat, high-sucrose diet (HFHS) at 23 weeks. Exposure to maternal glucose intolerance increased weights of HFHS-fed offspring. Chow-fed offspring of GDM dams exhibited higher body fat percentages at 4, 12, and 20 weeks of age. At 28 weeks, offspring of GDM dams fed the HFHS but not the chow diet (CD) also had higher body fat percentages than offspring of controls (CON). Exposure to GDM increased the respiratory quotient (Vol CO2/Vol O2) in offspring. Maternal GDM increased adipose mRNA levels of peroxisome proliferator-activated receptor gamma (Pparg) and adiponectin (Adipoq) in 31-week-old CD-fed male offspring, and increased mRNA levels of insulin receptor (Insr) and lipoprotein lipase (Lpl) in 31-week-old male offspring on both diets. In liver at 31 weeks, mRNA levels of peroxisome proliferator-activated receptor alpha (Ppara) were elevated in CD-fed male offspring of GDM dams, and male offspring of GDM dams exhibited higher mRNA levels of Insr on both diets. Neither fasting insulin nor glucose tolerance was affected by exposure to GDM. Our findings show that GDM comprising glucose intolerance only during pregnancy programs increased adiposity in offspring, and suggests increased insulin sensitivity of subcutaneous adipose tissue.

Implications of early life stress on fetal metabolic programming of schizophrenia: A focus on epiphenomena underlying morbidity and early mortality

The fetal origin of adult disease hypothesis postulates that a stressful in utero environment can have deleterious consequences on fetal programming, potentially leading to chronic disease in later life. Factors known to impact fetal programming include the timing, intensity, duration and nature of the external stressor during pregnancy. As such, dynamic modulation of fetal programming is heavily involved in shaping health throughout the life course, possibly by influencing metabolic parameters including insulin action, hypothalamic-pituitary-adrenal activity and immune function. The ability of prenatal insults to program adult disease is likely to occur as a result of reduced functional capacity in key organs-a "thrifty" phenotype-where more resources are re-allocated to preserve critical organs such as the brain. Notably, it has been postulated that the manifestation of neuropsychiatric disorders in individuals priorly exposed to prenatal stress may arise from the interaction between hereditary factors and the intrauterine environment, which together precipitate disease onset by disrupting the trajectory of normal brain development. In this review we discuss the evidence linking prenatal programming to neuropsychiatric disorders, mainly schizophrenia, via a "Thrifty psychiatric phenotype" concept. We start by outlining the conception of the thrifty psychiatric phenotype. Next, we discuss the convergence of potential mechanistic pathways through which prenatal insults may trigger epigenetic changes that contribute to the increased morbidity and early mortality observed in neuropsychiatric disorders. Finally, we touch on the public health importance of fetal programming for these disorders. We conclude by providing a brief outlook on the future of this evolving field of research.

Possible mechanisms involved in the effect of the subchronic administration of rosuvastatin on endothelial function in rats with metabolic syndrome

Metabolic syndrome is a multifaceted condition associated with a greater risk of various disorders (e.g., diabetes and heart disease). In a rat model of metabolic syndrome, an acute in vitro application of rosuvastatin causes relaxation of aortic rings. Since the outcome of a subchronic rosuvastatin treatment is unknown, the present study explored its effect on acetylcholine-induced vasorelaxation of aortic rings from rats with metabolic syndrome. Animals were submitted to a 16-week treatment, including a standard diet, a cafeteria-style diet (CAF-diet), or a CAF-diet with daily rosuvastatin treatment (10 mg/kg). After confirming the development of metabolic syndrome in rats, aortic segments were extracted from these animals (those treated with rosuvastatin and untreated) and the acetylcholine-induced relaxant effect on the corresponding rings was evaluated. Concentration-response curves were constructed for this effect in the presence/absence of L-NAME, ODQ, KT 5823, 4-aminopyridine (4-AP), tetraethylammonium (TEA), apamin plus charybdotoxin, glibenclamide, indomethacin, clotrimazole, and cycloheximide pretreatment. Compared to rings from control rats, acetylcholine-induced vasorelaxation decreased in rings from animals with metabolic syndrome, and was maintained at a normal level in animals with metabolic syndrome plus rosuvastatin treatment. The effect of rosuvastatin was inhibited by L-NAME, ODQ, KT 5823, TEA, apamin plus charybdotoxin, but unaffected by 4-AP, glibenclamide, indomethacin, clotrimazole, or cycloheximide. In conclusion, the subchronic administration of rosuvastatin to rats with metabolic syndrome improved the acetylcholine-induced relaxant response, involving stimulation of the NO/cGMP/PKG/Ca2+-activated K+ channel pathway.

Exploring the causes and consequences of maternal metabolic maladaptations during pregnancy: Lessons from animal models

Pregnancy is a remarkable physiological state, during which the metabolic system of the mother adapts to ensure that nutrients are made available for transfer to the fetus for growth and development. Adaptations of maternal metabolism during pregnancy are influenced by the metabolic and nutritional status of the mother and the production of endocrine factors by the placenta that exert metabolic effects. Insufficient or inappropriate adaptations in maternal metabolism during pregnancy may lead to pregnancy complications with important short- and long-term effects for both the health of the child and mother. This is very evident in gestational diabetes, which is marked by greater glucose intolerance and insulin resistance above that expected of a normal pregnancy. Gestational diabetes is associated with increased fetal weight and/or increased adiposity, higher instrumented delivery rates and greater risks for both mother and child of developing type 2 diabetes in the long-term. However, despite the negative health impacts of such metabolic imbalances during pregnancy, the precise mechanisms responsible for orchestrating these changes remain largely unknown. The present review describes the dynamic pregnancy-specific changes that occur in the metabolic system of the mother during pregnancy. It also discusses findings using surgical, pharmacological, genetic and dietary methods in experimental animals that highlight the role of pathways in maternal tissues that lead to metabolic dysfunction, with a particular focus on gestational diabetes. Finally, it summarises the work largely employing gene targeting and hormone administration in rodents that have illuminated the involvement of placental endocrine function in driving maternal metabolic adaptations. While current animal models may not fully replicate what is observed in humans, these have been instrumental in showing that there is a dynamic interplay between changes in maternal metabolic physiology and the placental production of endocrine factors that govern the availability of nutrients to the growing fetus. However, more work is required to specifically identify the placenta-driven changes in maternal metabolic physiology that ensure the appropriate level of insulin production and action during pregnancy. In doing so, these studies may pave the way to understanding the development of pregnancy complications like gestational diabetes, as well as further our understanding of type-2 diabetes and the control of metabolic physiology more broadly.

In Vivo and In Vitro Models of Diabetes: A Focus on Pregnancy

Diabetes in pregnancy is associated with an increased risk of poor outcomes, both for the mother and her offspring. Although clinical and epidemiological studies are invaluable to assess these outcomes and the effectiveness of potential treatments, there are certain ethical and practical limitations to what can be assessed in human studies.Thus, both in vivo and in vitro models can aid us in the understanding of the mechanisms behind these complications and, in the long run, towards their prevention and treatment. This review summarizes the existing animal and cell models used to mimic diabetes, with a specific focus on the intrauterine environment. Summary of this review.

Obeticholic acid ameliorates dyslipidemia but not glucose tolerance in mouse model of gestational diabetes

Metabolism alters markedly with advancing gestation, characterized by progressive insulin resistance, dyslipidemia, and raised serum bile acids. The nuclear receptor farnesoid X receptor (FXR) has an integral role in bile acid homeostasis and modulates glucose and lipid metabolism. FXR is known to be functionally suppressed in pregnancy. The FXR agonist, obeticholic acid (OCA), improves insulin sensitivity in patients with type 2 diabetes with nonalcoholic fatty liver disease. We therefore hypothesized that OCA treatment during pregnancy could improve disease severity in a mouse model of gestational diabetes mellitus (GDM). C57BL/6J mice were fed a high-fat diet (HFD; 60% kcal from fat) for 4 wk before and throughout pregnancy to induce GDM. The impact of the diet supplemented with 0.03% OCA throughout pregnancy was studied. Pregnant HFD-fed mice displayed insulin resistance and dyslipidemia. OCA significantly reduced plasma cholesterol concentrations in nonpregnant and pregnant HFD-fed mice (by 22.4%, P < 0.05 and 36.4%, P < 0.001, respectively) and reduced the impact of pregnancy on insulin resistance but did not change glucose tolerance. In nonpregnant HFD-fed mice, OCA ameliorated weight gain, reduced mRNA expression of inflammatory markers in white adipose tissue, and reduced plasma glucagon-like peptide 1 concentrations (by 62.7%, P < 0.01). However, these effects were not evident in pregnant mice. OCA administration can normalize plasma cholesterol levels in a mouse model of GDM. However, the absence of several of the effects of OCA in pregnant mice indicates that the agonistic action of OCA is not sufficient to overcome many metabolic consequences of the pregnancy-associated reduction in FXR activity.

A mouse model of gestational glucose intolerance through exposure to a low protein diet during fetal and neonatal development

KEY POINTS

Pancreatic β-cell dysfunction is hypothesized to be the significant determinant of gestational diabetes pathogenesis, however pancreatic samples from patients are scarce. This study reports a novel mouse model of gestational glucose intolerance in pregnancy, originating from previous nutrition restriction in utero, in which glucose intolerance was restricted to late gestation as is seen in human gestational diabetes. Glucose intolerance was attributed to reduced β-cell proliferation, leading to impaired gestational β-cell mass expansion in maternal endocrine pancreas, in addition to reduced glucose-stimulated insulin secretion. This model reproduces some of the features of gestational diabetes and is suitable for testing safe therapeutic interventions that increase β-cell mass during pregnancy and prevent or reverse gestational glucose intolerance.

ABSTRACT

Gestational diabetes mellitus (GDM) is an increasingly prevalent form of diabetes that appears during pregnancy. Pathological studies link a failure to adaptively increase maternal pancreatic β-cell mass (BCM) in pregnancy to GDM. Due to the scarcity of pancreatic samples from GDM patients, we sought to develop a novel mouse model for impaired gestational glucose tolerance. Mature female C57Bl/6 mouse offspring (F1) born to dams fed either a control (C) or low-protein (LP) diet during gestation and lactation were randomly allocated into two subsequent study groups: pregnant (CP, LPP) or non-pregnant (CNP, LPNP). Glucose tolerance tests were performed at gestational day (GD) 9, 12 and 18. Subsequently, pancreata were removed for fluorescence immunohistochemistry to assess α-cell mass (ACM), BCM and β-cell proliferation. An additional group of animals was used to measure insulin secretion from isolated islets at GD18. LPP females displayed glucose intolerance compared to CP females at GD18 (P < 0.001). BCM increased threefold at GD18 in CP females. However, LPP females had reduced BCM expansion (P < 0.01) concurrent with reduced β-cell proliferation at GD12 (P < 0.05). LPP females also had reduced ACM expansion at GD18 (P < 0.01). LPP islets had impaired glucose-stimulated insulin secretion in vitro compared to CP islets (P < 0.01). Therefore, impaired glucose tolerance during pregnancy is associated with a failure to adequately adapt BCM, as a result of reduced β-cell proliferation, in addition to lower glucose-stimulated insulin secretion. This model could be used to evaluate novel interventions during pregnancy to increase BCM or function as a strategy to prevent/reverse GDM.

Late Cognitive Consequences of Gestational Diabetes to the Offspring, in a New Mouse Model

Gestational diabetes mellitus (GD) is a form of insulin resistance triggered during gestation, which affects approximately 10% of pregnant women. Although previously considered a transient condition with few long-term consequences, growing evidence suggest that GD may be linked to permanent metabolic and neurologic changes in the offspring. Currently available GD models fail to recapitulate the full spectrum of this disease, thus providing limited information about the true burden of this condition. Here, we describe a new mouse model of GD, based on the administration of an insulin receptor antagonist (S961, 30 nmol/kg s.c. daily) during pregnancy. Pregnant mice developed increased fasting glycemia and glucose intolerance in the absence of maternal obesity, with a return to normoglycemia shortly after parturition. Moreover, we showed that the adult offspring of GD dams presented pronounced metabolic and cognitive dysfunction when exposed to short-term high-fat diet (HFD). Our data demonstrate that S961 administration to pregnant mice comprises a valuable approach to study the complex pathophysiology of GD, as well as strategies focused on prevention and treatment of both the mother and the offspring. Our findings suggest that the offspring of GD mothers are more susceptible to metabolic and cognitive impairments when exposed to high-fat diet later in life, thus indicating that approaches to prevent and treat these late effects should be pursued.

Renal dysfunction in a mouse model of GDM is prevented by metformin through MAPKs

Gestational diabetes mellitus (GDM) incidence is increasing worldwide. In the present study, the effects of metformin on high fat diet (HFD)‑induced renal dysfunction were investigated in GDM mice. In addition, the molecular mechanisms underlying metformin function were examined. GDM was induced by feeding pregnant mice a HFD, and mice were treated with two different doses of metformin (300 and 600 mg/kg/day) or PBS between embryonic day 11.5 (E11.5) and E17.5. The pregnant mice at E18.5 were utilized to analyze the effects of metformin on renal dysfunction. Renal function and the protein expression levels of inflammatory cytokines and factors of the mitogen‑activated protein kinase (MAPK) signaling pathway in the kidneys of pregnant mice were assessed by ELISA and western blotting. Data obtained during late pregnancy suggested that metformin significantly decreased body weight and the levels of blood glucose in GDM mice, as assessed by the glucose tolerance test and the homeostatic model assessment for insulin resistance. The levels of microalbumin and serum β2‑microglobulin in GDM mice during late pregnancy were decreased following treatment with metformin. Furthermore, serum levels of interleukin (IL)‑6 and tumor necrosis factor (TNF)‑α, and phosphorylation of MAPK1/3, MAPK14 and MAPK8 in the kidneys were decreased in GDM mice following metformin treatment at E18.5, compared with the untreated GDM group. The present study suggested that inflammation may be associated with renal dysfunction in GDM mice, and that the MAPK signaling pathway may be involved in the protective effect of metformin on renal dysfunction in GDM mice.

Upregulation Of Renal GLUT2 And SGLT2 Is Involved In High-Fat Diet-Induced Gestational Diabetes In Mice

INTRODUCTION

Gestational diabetes mellitus (GDM) is a metabolic disorder during mid- to late-pregnancy characterized by hyperglycemia, insulin resistance and fetal mal-development. Glucose transporter type 2 (GLUT2) and sodium-coupled glucose cotransporters 2 (SGLT2) in the proximal tubules play a critical role in the reabsorption of glucose and have been linked to the occurrence of type 2 diabetes mellitus (T2DM). Our study was designed to investigate the role of GLUT2 and SGLT2 in the pathogenesis of GDM, which is considered a forerunner of T2DM, and investigate the related molecular mechanism.

METHODS

High-fat diet (HFD) was utilized to build a GDM mouse model that closely induces metabolic abnormalities similar to human GDM. Body weight, blood glucose and serum insulin were recorded in the experimental process. Glucose tolerance was determined by the use of an intraperitoneal glucose tolerance test (IPGTT). In addition, levels of GLUT2 and SGLT2 were evaluated to further explore the underlying mechanism of GDM.

RESULTS

HFD feeding induced abnormal glucose metabolism as manifested by increased levels of blood glucose and insulin and prominent glucose intolerance. Additionally, fetal mice from mother feed on HFD showed higher mean body weight. Furthermore, HFD feeding led to an increase in the number of positive cells of GLUT2 and SGLT2 in the renal proximal tubule and the expressions of renal GLUT2 and SGLT2 mRNA and proteins in mice. However, no obvious change was observed in renal morphology.

CONCLUSION

Our study demonstrates a potential involvement of renal GLUT2 and SGLT2 in GDM pathology in an HFD-induced GDM mouse model, which further supports the role of renal GLUT2 and SGLT2 not only in T1DM and T2DM but also in GDM.

Association of vascular endothelial growth factor expression and polymorphisms with the risk of gestational diabetes mellitus

OBJECTIVE

To study the associations of vascular endothelial growth factor (VEGF) expression and its gene polymorphisms with the risk of gestational diabetes mellitus (GDM).

METHODS

A total of 239 GDM patients (GDM group) and 275 healthy pregnant women (Control group) were included in this study. VEGF genotypes (including rs2146323, rs2010963, rs3025039, rs3025010, and rs833069) were analyzed by TaqMan assay. ELISA was used to determine the serum VEGF levels. The software SHEsis was performed to analyze haplotypes.

RESULTS

The carrier with the rs2146323 AA, CA+AA genotypes, and A allele, as well as the rs3025039 CT, TT, CT+TT genotypes, and T allele showed the increased risk of GDM (all P < 0.05), but the distributions of genotype and allele at rs2010963, rs3025010, and rs833069 were not significantly different between GDM patients and controls (all P > 0.05). Notably, the frequency of rs2010963-rs833069-rs2146323-rs3025010 haplotypes CAAC, CAAT, CACC, CACT, GACT, and GGCT was found statistically different between GDM patients and controls (all P < 0.05). The patients with rs3025039 CT+TT genotype had higher VEGF levels than those with CC genotype (all P < 0.05). Besides, age, family histories of diabetes, previous GDM, hypertension, pre-pregnancy body mass index, fasting plasma glucose, fasting insulin, homeostasis model assessment (HOMA)-IR, rs2146323 CA+AA, rs3025039 CT+TT, and VEGF expression level were independent risk factors, while HOMA-β was an independent protective factor for GDM (all P < 0.05).

CONCLUSION

VEGF rs2146323 and rs3025039 polymorphisms and its expression were significantly correlated with the risk of GDM, providing a great clinical value for GDM assessment and diagnosis.

Maternal overnutrition by hypercaloric diets programs hypothalamic mitochondrial fusion and metabolic dysfunction in rat male offspring

Background

Maternal overnutrition including pre-pregnancy, pregnancy and lactation promotes a lipotoxic insult leading to metabolic dysfunction in offspring. Diet-induced obesity models (DIO) show that changes in hypothalamic mitochondria fusion and fission dynamics modulate metabolic dysfunction. Using three selective diet formula including a High fat diet (HFD), Cafeteria (CAF) and High Sugar Diet (HSD), we hypothesized that maternal diets exposure program leads to selective changes in hypothalamic mitochondria fusion and fission dynamics in male offspring leading to metabolic dysfunction which is exacerbated by a second exposure after weaning.

Methods

We exposed female Wistar rats to nutritional programming including Chow, HFD, CAF, or HSD for 9 weeks (pre-mating, mating, pregnancy and lactation) or to the same diets to offspring after weaning. We determined body weight, food intake and metabolic parameters in the offspring from 21 to 60 days old. Hypothalamus was dissected at 60 days old to determine mitochondria-ER interaction markers by mRNA expression and western blot and morphology by transmission electron microscopy (TEM). Mitochondrial-ER function was analyzed by confocal microscopy using hypothalamic cell line mHypoA-CLU192.

Results

Maternal programming by HFD and CAF leads to failure in glucose, leptin and insulin sensitivity and fat accumulation. Additionally, HFD and CAF programming promote mitochondrial fusion by increasing the expression of MFN2 and decreasing DRP1, respectively. Further, TEM analysis confirms that CAF exposure after programing leads to an increase in mitochondria fusion and enhanced mitochondrial-ER interaction, which partially correlates with metabolic dysfunction and fat accumulation in the HFD and CAF groups. Finally, we identified that lipotoxic palmitic acid stimulus in hypothalamic cells increases Ca²⁺ overload into mitochondria matrix leading to mitochondrial dysfunction.

Conclusions

We concluded that maternal programming by HFD induces hypothalamic mitochondria fusion, metabolic dysfunction and fat accumulation in male offspring, which is exacerbated by HFD or CAF exposure after weaning, potentially due to mitochondria calcium overflux.

Developmental Programming of Ovarian Functions and Dysfunctions

The pathophysiological mechanisms underlying the origin of several ovarian pathologies remain unclear. In addition to the genetic basis, developmental insults are gaining attention as a basis for the origin of these pathologies. Such early insults include maternal over or under nutrition, stress, and exposure to environmental chemicals. This chapter reviews the development and physiological function of the ovary, the known ovarian pathologies, the developmental check points of ovarian differentiation impacted by developmental insults, the role played by steroidal and metabolic factors as mediaries, the epigenetic mechanisms via which these mediaries induce their effects, and the knowledge gaps for targeting future studies to ultimately aid in the development of improved treatments.

Female offspring born to obese and insulin-resistant dams are not at increased risk for obesity and metabolic dysfunction during early development

The percentage of women who are obese at the time of conception or during pregnancy is increasing, with animal and human studies demonstrating that offspring born to obese dams or mothers are at increased risk for obesity and the metabolic syndrome. Our goal was to confirm in an experimental model of metabolic syndrome in the dam, whether the offspring would be at increased risk of obesity. Conversely, we observed that male offspring born to dams with metabolic syndrome had no alterations in their body mass profiles, whereas female offspring born to dams with metabolic syndrome were heavier at weaning, but exhibited no perturbations in energy metabolism. Moreover, they gained weight at a reduced rate versus female offspring born to healthy dams, and thus weighed less at study completion. Hence, our findings suggest that factors other than increased adiposity and insulin resistance during pregnancy are responsible for the increased risk of obesity in children born to obese mothers.

Evidence of changes in alpha-1/AT1 receptor function generated by diet-induced obesity

To study whether hypercaloric diet-induced obesity deteriorates vascular contractility of rat aorta through functional changes in α₁ adrenergic and/or AT1 Angiotensin II receptors. Angiotensin II- or phenylephrine-induced contraction was tested on isolated aorta rings with and without endothelium from female Wistar rats fed for 7 weeks with hypercaloric diet or standard diet. Vascular expression of Angiotensin II Receptor type 1 (AT1R), Angiotensin II Receptor type 2 (AT2R), Cyclooxygenase-1 (COX-1), Cyclooxygenase-2 (COX-2), inducible Nitric Oxide Synthase (iNOS) and endothelial Nitric Oxide Synthase (eNOS), as well as blood pressure, glucose, insulin and angiotensin II blood levels were measured. Diet-induced obesity did not significantly change agonist-induced contractions (Emax and pD₂ hypercaloric diet vs standard diet n.s.d.) of both intact (e+) or endothelium free (e-) vessels but significantly decrease both phenylephrine and angiotensin II contraction (Emax p < 0.01 hypercaloric diet vs standard diet) in the presence of both prazosin and losartan but only in endothelium-intact vessels. Diet-induced obesity did not change angiotensin II AT1, AT2 receptor proteins expression but reduced COX-1 and NOS2 ( p < 0.05 vs standard diet). Seven-week hypercaloric diet-induced obesity produces alterations in vascular adrenergic and angiotensin II receptor dynamics that suggest an endothelium-dependent adrenergic/angiotensin II crosstalk. These changes reflect early-stage vascular responses to obesity.

A Western-style obesogenic diet alters maternal metabolic physiology with consequences for fetal nutrient acquisition in mice

KEY POINTS

In the Western world, obesogenic diets containing high fat and high sugar (HFHS) are commonly consumed during pregnancy, although their effects on the metabolism of the mother, in relation to feto-placental glucose utilization and growth, are unknown. In the present study, the consumption of an obesogenic HFHS diet compromised maternal glucose tolerance and insulin sensitivity in late pregnancy in association with dysregulated lipid and glucose handling by the dam. These maternal metabolic changes induced by HFHS feeding were related to altered feto-placental glucose metabolism and growth. A HFHS diet during pregnancy therefore causes maternal metabolic dysfunction with consequences for maternal nutrient allocation for fetal growth. These findings have implications for the health of women and their infants, who consume obesogenic diets during pregnancy.

ABSTRACT

In the Western world, obesogenic diets containing high fat and high sugar (HFHS) are commonly consumed during pregnancy. However, the impacts of a HFHS diet during pregnancy on maternal insulin sensitivity and signalling in relation to feto-placental growth and glucose utilization are unknown. The present study examined the effects of a HFHS diet during mouse pregnancy on maternal glucose tolerance and insulin resistance, as well as, on feto-placental glucose metabolism. Female mice were fed a control or HFHS diet from day (D) 1 of pregnancy (term = D20.5). At D16 or D19, dams were assessed for body composition, metabolite and hormone concentrations, tissue abundance of growth and metabolic signalling pathways, glucose tolerance and utilization and insulin sensitivity. HFHS feeding perturbed maternal insulin sensitivity in late pregnancy; hepatic insulin sensitivity was higher, whereas sensitivity of the skeletal muscle and white adipose tissue was lower in HFHS than control dams. These changes were accompanied by increased adiposity and reduced glucose production and glucose tolerance of HFHS dams. The HFHS diet also disturbed the hormone and metabolite milieu and altered expression of growth and metabolic signalling pathways in maternal tissues. Furthermore, HFHS feeding was associated with impaired feto-placental glucose metabolism and growth. A HFHS diet during pregnancy therefore causes maternal metabolic dysfunction with consequences for maternal nutrient allocation for fetal growth. These findings have implications for the health of women and their infants, who consume HFHS diets during pregnancy.

Antidiabetic Activity of a Lotus Leaf Selenium (Se)-Polysaccharide in Rats with Gestational Diabetes Mellitus

A selenium (Se)-containing polysaccharide, lotus leaf selenium (Se)-polysaccharide (LLP), was isolated from a lotus leaf. The effects of LLP on antioxidant enzyme activities and insulin resistance in pregnant rats with gestational diabetes mellitus (GDM) were investigated. LLP administered orally at two doses (50 and 100 mg/kg) could significantly reverse the weight loss of pregnant rats before the delivery, fetal rats, and placentas in GDM rats (P < 0.05). Furthermore, LLP treatment induced a decrease of fasting blood glucose (FBG) and fasting blood insulin (FINS) levels in GDM rats, but an increase of hepatic glycogen content, when compared with those in GDM rats (P < 0.05). Also, oral administrations of LLP markedly improved the lipid profile of GDM rats, as evidenced by a reduction of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) cholesterol levels except for the high-density lipoprotein (HDL) cholesterol level. Additionally, antioxidant enzyme levels, such as superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glutathione (GSH), in liver tissues of the GDM group were lower than those of the other groups, and following treatment of LLP, these indexes in liver tissues were equivalent to those of the control group (P > 0.05). All the data indicated that LLP may be a promising drug candidate or a healthcare food for GDM therapy or protection.

Absence of a gestational diabetes phenotype in the LepRdb/+ mouse is independent of control strain, diet, misty allele, or parity

Treatment options for gestational diabetes (GDM) are limited. In order to better understand mechanisms and improve treatments, appropriate animal models of GDM are crucial. Heterozygous db mice (db/+) present with glucose intolerance, insulin resistance, and increased weight gain during, but not prior to, pregnancy. This makes them an ideal model for GDM. However, several recent studies have reported an absence of GDM phenotype in their colony. We investigated several hypotheses for why the phenotype may be absent, with the aim of re-establishing it and preventing further resources being wasted on an ineffective model. Experiments were carried out across two laboratories in two countries (New Zealand and China), and were designed to assess type of control strain, diet, presence of the misty allele, and parity as potential contributors to the lost phenotype. While hyperleptinemia and pre-pregnancy weight gain were present in all db/+mice across the four studies, we found no consistent evidence of glucose intolerance or insulin resistance during pregnancy. In conclusion, we were unable to acquire the GDM phenotype in any of our experiments, and we recommend researchers do not use the db/+ mouse as a model of GDM unless they are certain the phenotype remains in their colony.

Association of temporal distribution of fine particulate matter with glucose homeostasis during pregnancy in women of Chiayi City, Taiwan

BACKGROUND

To investigate the effects of fine particulate matter (PM_2.5) on the indicators of glucose homeostasis during pregnancy.

METHODS

A total of 3589 non-diabetic pregnant women who underwent a 3-h 100-g oral glucose tolerance test (OGTT) were enrolled from a tertiary teaching hospital in Chiayi City, Taiwan between 2006 and 2014. Fasting, 1-h, 2-h, and 3-h glucose levels after an OGTT were used as indicators of glucose homeostasis. PM_2.5 and other air pollution data were obtained from one fixed-site monitoring station (Chiayi City station) operated by Taiwan Environmental Protection Administration (EPA). We used mixed models for indicators of glucose homeostasis to estimate the effects of PM_2.5. The models were adjusted for individual-specific effects (nulliparous status, age, body mass index, season, and year) and the moving averages of temperature and relative humidity in the corresponding study period.

RESULTS

There were significant relationships between PM_2.5 and the glucose homeostasis indicators, including fasting, 1-h, 2-h, and 3-h glucose levels in the single-pollutant covariate-adjusted model. The pre-screening 1-month to 1-year moving averages of IQR increases in PM_2.5 were significantly associated with elevated fasting OGTT glucose levels (1.32-5.87mg/dL). The two-pollutant covariate-adjusted models had similar results.

CONCLUSIONS

We found positive associations between PM_2.5 and OGTT glucose levels during pregnancy. The association was especially pronounced for the fasting and 1-h glucose levels. PM_2.5 exposure in the second trimester may enhance this effect. Exposure to PM_2.5 was associated with glucose homeostasis during pregnancy.

Adverse Effect of High-Fat Diet on Metabolic Programming in Offspring Born to a Murine Model of Maternal Hypertension

BACKGROUND

We previously reported that offspring heterozygous mice partially lacking endothelial nitric oxide synthase (eNOS) gene, and born to hypertensive eNOS-/- Knockout mother, are hypertensive. We hypothesized that those offspring when placed on high-fat diet (HFD) will undergo altered metabolic programming increasing their risk for developing metabolic syndrome.

METHODS

eNOS-/-KO and wild-type mice (eNOS+/+WT) were cross-bred to produce heterozygous offspring: maternal heterozygous (Mat, eNOS-/+), born from hypertensive eNOS-/-KO mothers; and paternal heterozygous (Pat, eNOS-/+), born from normotensive WT mothers. Mat, eNOS-/+ and Pat, eNOS-/+ female were allocated to HFD or control diet (CD) until 8 weeks of age. Then a metabolic profile was obtained: weight, glucose/insulin tolerance test (GTT, ITT), systolic blood pressure (SBP), serum fasting levels of insulin, adiponectin, leptin, and a lipid panel.

RESULTS

Weight was not different between all offspring within each diet. GTT curve was higher in Mat, eNOS-/+ vs. Pat, eNOS-/+ offspring on both diet (P < 0.001). In ITT, glucose level at 15 minutes was higher in Mat, eNOS-/+ on HFD. Insulin level was increased in Mat, eNOS-/+ vs. Pat, eNOS-/+ on either diet. SBP was elevated in Mat, eNOS-/+ vs. Pat, eNOS-/+ on CD and was further raised in Mat, eNOS-/+ offspring on HFD (P < 0.001). No other differences were seen except for lower high-density lipoprotein levels in Mat, eNOS-/+ fed HFD (P < 0.003).

CONCLUSIONS

Mat, eNOS-/+ offspring exposed in utero to maternal hypertension and fed HFD postnatally have increased susceptibility for metabolic abnormalities. Thus, maternal HTN is a risk factor for altered fetal metabolic programming.

Maternal Fat Feeding Augments Offspring Nephron Endowment in Mice

Increasing consumption of a high fat 'Western' diet has led to a growing number of pregnancies complicated by maternal obesity. Maternal overnutrition and obesity have health implications for offspring, yet little is known about their effects on offspring kidney development and renal function. Female C57Bl6 mice were fed a high fat diet (HFD, 21% fat) or matched normal fat diet (NFD, 6% fat) for 6 weeks prior to pregnancy and throughout gestation and lactation. HFD dams were overweight and glucose intolerant prior to mating but not in late gestation. Offspring of NFD and HFD dams had similar body weights at embryonic day (E)15.5, E18.5 and at postnatal day (PN)21. HFD offspring had normal ureteric tree development and nephron number at E15.5. However, using unbiased stereology, kidneys of HFD offspring were found to have 20-25% more nephrons than offspring of NFD dams at E18.5 and PN21. Offspring of HFD dams with body weight and glucose profiles similar to NFD dams prior to pregnancy also had an elevated nephron endowment. At 9 months of age, adult offspring of HFD dams displayed mild fasting hyperglycaemia but similar body weights to NFD offspring. Renal function and morphology, measured by transcutaneous clearance of FITC-sinistrin and stereology respectively, were normal. This study demonstrates that maternal fat feeding augments offspring nephron endowment with no long-term consequences for offspring renal health. Future studies assessing the effects of a chronic stressor on adult mice with augmented nephron number are warranted, as are studies investigating the molecular mechanisms that result in high nephron endowment.

The effects of prenatal metformin on obesogenic diet-induced alterations in maternal and fetal fatty acid metabolism

Background

Maternal obesity may program the fetus and increase the susceptibility of the offspring to adult diseases. Metformin crosses the placenta and has been associated with decreased inflammation and reversal of fatty liver in obese leptin-deficient mice. We investigated the effects of metformin on maternal and fetal lipid metabolism and hepatic inflammation using a rat model of diet-induced obesity during pregnancy.

Methods

Female Wistar rats (6–7 weeks old) were fed normal or high calorie diets for 5 weeks. After mating with normal-diet fed males, half of the high calorie-fed dams received metformin (300 mg/kg, daily); dams (8 per group) continued diets through gestational day 19. Maternal and fetal livers and fetal brains were analyzed for fatty acids and for fatty acid metabolism-related gene expression. Data were analyzed by ANOVA followed by Dunnett’s post hoc testing.

Results

When compared to control-lean maternal livers, obesogenic-diet-exposed maternal livers showed significantly higher saturated fatty acids (14:0 and 16:0) and monounsaturated fatty acids (16:1n7 and 18:1n9) and lower polyunsaturated (18:2n6 and 20:4n6 [arachidonic acid]) and anti-inflammatory n3 polyunsaturated fatty acids (18:3n3 and 22:6n3 [docosahexaenoic acid]) (p < 0.05). Metformin did not affect diet-induced changes in maternal livers. Fetal livers exposed to the high calorie diet showed significantly increased saturated fatty acids (18:0) and monounsaturated fatty acids (18:1n9 and 18:1n7) and decreased polyunsaturated fatty acids (18:2n6, 20:4n6 and 22:6n3) and anti-inflammatory n3 polyunsaturated fatty acids, along with increased gene expression of fatty acid metabolism markers (Fasn, D5d, D6d, Scd1, Lxrα). Metformin significantly attenuated diet-induced inflammation and 18:1n9 and 22:6n3 in fetal livers, as well as n3 fatty acids (p < 0.05). Prenatal obesogenic diet exposure significantly increased fetal liver IFNγ levels (p < 0.05), which was reversed by maternal metformin treatment (p < 0.05).

Conclusions

Consumption of a high calorie diet significantly affected maternal and fetal fatty acid metabolism. It reduced anti-inflammatory polyunsaturated fatty acids in maternal and fetal livers, altered gene expression of fatty acid metabolism markers, and induced inflammation in the fetal livers. Prenatal metformin attenuated some diet-induced fatty acid changes and inflammation in the fetal livers without affecting maternal livers, suggesting that maternal metformin may impact fetal/neonatal fatty acid/lipid metabolism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12986-016-0115-9) contains supplementary material, which is available to authorized users.

Creatine supplementation and glycemic control: a systematic review

The focus of this review is the effects of creatine supplementation with or without exercise on glucose metabolism. A comprehensive examination of the past 16 years of study within the field provided a distillation of key data. Both in animal and human studies, creatine supplementation together with exercise training demonstrated greater beneficial effects on glucose metabolism; creatine supplementation itself demonstrated positive results in only a few of the studies. In the animal studies, the effects of creatine supplementation on glucose metabolism were even more distinct, and caution is needed in extrapolating these data to different species, especially to humans. Regarding human studies, considering the samples characteristics, the findings cannot be extrapolated to patients who have poorer glycemic control, are older, are on a different pharmacological treatment (e.g., exogenous insulin therapy) or are physically inactive. Thus, creatine supplementation is a possible nutritional therapy adjuvant with hypoglycemic effects, particularly when used in conjunction with exercise.