Regulation of postnatal pancreatic Pdx1 and downstream target genes after gestational exposure to protein restriction in rats

The study carried out in our laboratory demonstrated that protein restriction (low protein, LP) during fetal and neonatal life alters pancreatic development and impairs glucose tolerance later in life. In this study, we examined the role of the transcription factor Pdx1, a master regulator of β-cell differentiation and function along with its downstream target genes insulin, Glut2 and glucokinase (GK). The role(s) of these genes and protein products on the pancreata of male offspring from mothers exposed to LP diets were assessed during gestation, weaning, and adult life. Pregnant rats were allocated to two dietary treatments: control (C) 20% protein diet or LP, 8%protein diet. At birth, offspring were divided into four groups: C received control diet all life, LP1 received LP diet all life, LP2 changed the LP diet to C at weaning, and LP3 switched to C after being exposed to LP during gestation only. Body weights (bw) were significantly (P\u3c0.001) decreased in all LP groups at birth. At weaning, only the LP3 offspring had their body weight restored to control levels. Pdx1 or any of the Pdx1-target genes were similar in all diets at day 21. However, at d130 Pdx1 mRNA expression and protein abundance were significantly decreased (P\u3c0.05) in all LP groups. In addition, insulin mRNA and protein were decreased in LP1 and LP3 groups compared with C, Glut2 mRNA and GLUT2 protein levels were decreased in LP3 and GK did not change between groups. Intraperitoneal glucose tolerance test revealed impaired glucose tolerance in LP3 males, concomitant with decreased β-cell mass, islet area, and PDX1 nuclear protein localization. Collectively, this study suggests that restoring proteins in the diet after birth in LP offspring dramatically impairs glucose homeostasis in early adulthood, by altering Pdx1 expression and downstream-target genes increasing the risk to develop type 2 diabetes

Maternal Protein Restriction Elevates Cholesterol in Adult Rat Offspring Due to Repressive Changes in Histone Modifications at the Cholesterol 7α-Hydroxylase Promoter

Adverse events in utero, such as intrauterine growth restriction (IUGR), can permanently alter epigenetic mechanisms leading to the metabolic syndrome, which encompasses a variety of symptoms including augmented cholesterol. The major site for cholesterol homeostasis occurs via the actions of hepatic cholesterol 7α-hydroxylase (Cyp7a1), which catabolizes cholesterol to bile acids. To determine whether posttranslational histone modifications influence the long-term expression of Cyp7a1 in IUGR, we used a protein restriction model in rats. This diet during pregnancy and lactation led to IUGR offspring with decreased liver to body weight ratios, followed by increased circulating and hepatic cholesterol levels in both sexes at d 21 and exclusively in the male offspring at d 130. The augmented cholesterol was associated with decreases in the expression of Cyp7a1. Chromatin immunoprecipitation revealed that this was concomitant with diminished acetylation and enhanced methylation of histone H3 lysine 9 [K9,14], markers of chromatin silencing, surrounding the promoter region of Cyp7a1. These epigenetic modifications originate in part due to dietary-induced decreases in fetal hepatic Jmjd2a expression, a histone H3 [K9] demethylase. Collectively, these findings suggest that the augmented cholesterol observed in low-protein diet-derived offspring is due to permanent repressive posttranslational histone modifications at the promoter of Cyp7a1. Moreover, this is the first study to demonstrate that maternal undernutrition leads to long-term cholesterol dysregulation in the offspring via epigenetic mechanisms. (Molecular Endocrinology 25: 785–798, 2011

The effects of low protein during gestation on mouse pancreatic development and beta cell regeneration

Beta cells are partially replaced in neonatal rodents after deletion with streptozotocin (STZ). Exposure of pregnant rats to a low protein (LP) diet impairs endocrine pancreas development in the offspring, leading to glucose intolerance in adulthood. Our objective was to determine whether protein restriction has a similar effect on the offspring in mice, and if this alters the capacity for beta cell regeneration after STZ. Pregnant Balb/c mice were fed a control (C) (20% protein) or an isocaloric LP (8% protein) diet during gestation. Pups were given 35 mg/kg STZ (or vehicle) from d 1 to 5 for each dietary treatment. Histologic analysis showed that C-fed offspring had largely replaced beta cell mass (BCM) after STZ by d 30, but this was not sustained over time. Female LP-fed offspring showed an initial increase in BCM by d 14 but developed glucose intolerance by d 130. In contrast, male LP offspring showed no changes in BCM or glucose tolerance. However, LP exposure limited the capacity for recovery of BCM in both genders after STZ treatment. Copyright © 2010 International Pediatric Research Foundation, Inc

Insulin-positive, Glut2-low cells present within mouse pancreas exhibit lineage plasticity and are enriched within extra-islet endocrine cell clusters

ABSTRACT: Regeneration of insulin-producing β-cells from resident pancreas progenitors requires an understanding of both progenitor identity and lineage plasticity. One model suggested that a rare β-cell sub-population within islets demonstrated multi-lineage plasticity. We hypothesized that β-cells from young mice (postnatal day 7, P7) exhibit such plasticity and used a model of islet dedifferentiation toward a ductal epithelial-cell phenotype to test this theory. RIPCre;Z/AP+/+ mice were used to lineage trace the fate of β-cells during dedifferentiation culture by a human placental alkaline phosphatase (HPAP) reporter. There was a significant loss of HPAP-expressing β-cells in culture, but remaining HPAP+ cells lost insulin expression while gaining expression of the epithelial duct cell marker cytokeratin-19 (Ck19). Flow cytometry and recovery of β-cell subpopulations from whole pancreas vs. islets suggest that the HPAP+Ck19+ cells had derived from insulin-positive, glucose-transporter-2-low (Ins+Glut2LO) cells, representing 3.5% of all insulin-expressing cells. The majority of these cells were found outside of islets within clusters of \u3c5 β-cells. These insulin+Glut2LO cells demonstrated a greater proliferation rate in vivo and in vitro as compared to insulin+Glut2+ cells at P7, were retained into adulthood, and a subset differentiated into endocrine, ductal, and neural lineages, illustrating substantial plasticity. Results were confirmed using RIPCre;ROSA- eYFP mice. Quantitative PCR data indicated these cells possess an immature β-cell phenotype. These Ins+Glut2LO cells may represent a resident population of cells capable of forming new, functional β-cells, and which may be potentially exploited for regenerative therapies in the future

Correction to: Role of Delayed Neuroglial Activation in Impaired Cerebral Blood Flow Restoration Following Comorbid Injury (Cellular and Molecular Neurobiology, (2020), 40, 3, (369-380), 10.1007/s10571-019-00735-y)

The original version of this article contained a random order of part labels for Fig. 4. The correct caption of Fig. 4 with correct order of part labels is given below

Acetone ingestion mimics a fasting state to improve glucose tolerance in a mouse model of gestational hyperglycemia

Gestational diabetes mellitus results, in part, from a sub‐optimal β‐cell mass (BCM) during pregnancy. Artemisinins were reported to increase BCM in models of diabetes by α‐ to β‐cell conversion leading to enhanced glucose tolerance. We used a mouse model of gestational glucose intolerance to compare the effects of an artemisinin (artesunate) on glycemia of pregnant mice with vehicle treatment (acetone) or no treatment. Animals were treated daily from gestational days (GD) 0.5 to 6.5. An intraperitoneal glucose tolerance test was performed prior to euthanasia at GD18.5 or post‐partum. Glucose tolerance was significantly improved in both pregnant and non‐pregnant mice with both artesunate and vehicle‐alone treatment, suggesting the outcome was primarily due to the acetone vehicle. In non‐pregnant, acetone‐treated animals, improved glucose tolerance was associated with a higher BCM and a significant increase in bihormonal insulin and glucagon‐con-taining pancreatic islet cells, suggesting α‐ to β‐cell conversion. BCM did not differ with treatment during pregnancy or post‐partum. However, placental weight was higher in acetone‐treated animals and was associated with an upregulation of apelinergic genes. Acetone‐treated animals had reduced weight gain during treatment despite comparable food consumption to non‐treated mice, suggesting transient effects on nutrient uptake. The mean duodenal and ileum villus height was reduced following exposure to acetone. We conclude that acetone treatment may mimic transient fasting, resulting in a subsequent improvement in glucose tolerance during pregnancy

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 PPARa expression, lipid metabolism, lipoperoxidation, andnitricoxide(NO) productionare alteredinthe fetal hearts of diabetic rats, and to analyze the putative effects of in vivo PPARactivation on these parameters. We found decreased PPARa expression in the hearts ofmale but not female fetuses of diabetic rats when compared with controls. Fetal treatments with the PPARa ligand leukotriene B4upregulated 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 with6%oliveoil or6%safflower oil,enrichedinunsaturatedfatty acids that canactivate PPARs, led to few changes in lipid concentrations, but up-regulated PPARa 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 ofmale fetuses in the diabetic group, was reduced by thematernal treatments supplementedwithsaffloweroil. In conclusion, impaired PPARa expression, altered lipid metabolism, and increased oxidative and nitridergic pathways were evidenced in hearts of fetuses of diabetic rats and were regulated in a genderdependent manner by treatments enriched with PPAR ligands

Olive oil diet in mild pre-gestational diabetes impacts offspring β-cell development.

Maternal diabetes impairs fetal development and increases the risk of metabolic diseases in the offspring. Previously, we showed maternal dietary supplementation with 6% of olive oil prevents diabetes-induced embryo and fetal defects, in part, through the activation of peroxisome proliferator-activated receptors (PPARs). In this study we examined the effects of this diet on neonatal and adult pancreatic development in both male and female offspring. A mild diabetic model was developed by injecting neonatal rats with streptozotocin (90 mg/kg). During pregnancy these dams were fed a chow diet supplemented or not with 6% olive oil. Dual immunohistochemistry was performed to detect α and β cells in islets at post-natal day 2 and at 5 months of age. Morphometric analysis was carried out to determine the number of islets, α and β cell clusters and β-cell mass. At 5 months, male offspring of diabetic mothers had reduced β-cell mass. Moreover, this β-cell pancreatic deficit was prevented by the maternal supplementation with olive oil. While no changes in PPARα expression was detected in the pancreas, both PPARβ/δ and PPARγ expression were reduced in 5-month-old male offspring of diabetic rats. Interestingly, the reduction in PPAR β/δ expression was prevented by maternal olive-oil supplementation. To further explore the direct effects on PPARs, INS-1E (β) and αTC1-6 (α) cell lines were treated with oleic acid. Interestingly PPARβ/δ expression is highly expressed in INS-1E. Collectively, these findings suggest that olive oil supplementation in utero may prevent diabetes-induced β cell loss in postnatal life by modulating pancreatic PPARs

Addition of olive oil to diet of rats with mild pre-gestational diabetes impacts offspring β-cell development

Maternal diabetes impairs fetal development and increases the risk of metabolic diseases in the offspring. Previously, we demonstrated that maternal dietary supplementation with 6% of olive oil prevents diabetes-induced embryo and fetal defects, in part, through the activation of peroxisome proliferator-activated receptors (PPARs). In this study, we examined the effects of this diet on neonatal and adult pancreatic development in male and female offspring of mothers affected with pre-gestational diabetes. A mild diabetic model was developed by injecting neonatal rats with streptozotocin (90 mg/kg). During pregnancy, these dams were fed a chow diet supplemented or not with 6% olive oil. Offspring pancreata was examined at day 2 and 5 months of age by immunohistochemistry followed by morphometric analysis to determine number of islets, α and β cell clusters and β-cell mass. At 5 months, male offspring of diabetic mothers had reduced β-cell mass that was prevented by maternal supplementation with olive oil. PPARα and PPARγ were localized mainly in α cells and PPARβ/δ in both α and β cells. Although Pparβ/δ and Pparγ RNA expression showed reduction in 5-month-old male offspring of diabetic rats, Pparβ/δ expression returned to control levels after olive-oil supplementation. Interestingly, in vitro exposure to oleic acid (major component of olive oil) and natural PPAR agonists such as LTB4, CPC and 15dPGJ2 also significantly increased expression of all Ppars in αTC1–6 cells. However, only oleic acid and 15dPGJ2 increased insulin and Pdx-1 expression in INS-1E cells suggesting a protective role in β-cells. Olive oil may be considered a dietary supplement to improve islet function in offspring of affected mothers with pre-gestational diabetes.Fil: Taqui, Bushra. Western University; CanadáFil: Asadi, Farzad. Western University; CanadáFil: Capobianco, Evangelina Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Hardy, Daniel Barry. Western University; CanadáFil: Jawerbaum, Alicia Sandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Arany, Edith Juliana. Western University; Canad

Maternal exposure to Δ9-tetrahydrocannabinol impairs female offspring glucose homeostasis and endocrine pancreatic development in the rat.

Recent reports indicate that 7% of pregnant mothers in North America use cannabis. This is concerning given that in utero exposure to Δ9-tetrahydrocannabinol (Δ9-THC), the main psychoactive component in cannabis, causes fetal growth restriction and may alter replication and survival of pancreatic β-cells in the offspring. Accordingly, we hypothesized that maternal exposure to Δ9-THC during pregnancy would impair postnatal glucometabolic health of offspring. To test this hypothesis, pregnant Wistar rats were treated with daily intraperitoneal injections of either 3 mg/kg Δ9-THC or vehicle from gestational day 6 to birth. Offspring were subsequently challenged with glucose and insulin at 5 months of age to assess glucose tolerance and peripheral muscle insulin sensitivity. Female offspring exposed to Δ9-THC in utero were glucose intolerant, associated with blunted insulin response in muscle and increased serum insulin concentration 15 min after glucose challenge. Additionally, pancreata from male and female offspring were harvested at postnatal day 21 and 5 months of age for assessment of endocrine pancreas morphometry by immunostaining. This analysis revealed that gestational exposure to Δ9-THC reduced the density of islets in female, but not male, offspring at postnatal day 21 and 5 months, culminating in reduced β-cell mass at 5 months. These results demonstrate that fetal exposure to Δ9-THC causes female-specific impairments in glucose homeostasis, raising concern regarding the metabolic health of offspring, particularly females, exposed to cannabis in utero