Englitazone administration to late pregnant rats produces delayed body growth and insulin resistance in their fetuses and neonates

Dose-dependent effects of prenatal exposure of pioglitazone, the PPARγ agonist, on the hippocampus development and learning and memory performance of rat offspring

It is known that pioglitazone, defined as a PPARγ agonist, has neuron-protective properties in nervous system disorders. The aim of this study is to investigate the effects of pioglitazone administration at different doses during prenatal period on the neurons, glial cells and learning-memory levels in the hippocampus of rat offspring. Pregnant rats were divided into three groups; Low-Dose Pioglitazone (LDP), High-Dose Pioglitazone (HDP) and control (C) (n = 3). Pregnant rats in the HDP and LDP groups were given pioglitazone at 30 mg/kg and 5 mg/kg doses, respectively, by gavage once a day during their pregnancy. No procedure was applied to the rats in the control group. Morris water tank test was applied to offspring obtained from postnatal 24th to 28th day. The offspring were sacrificed on the 29th postal day and their brain tissues removed. Stereological, histopathological and immunohistochemical techniques were used to analyze brain tissues. As a result of the analysis, it was observed that there were delays in learning and memory, the number of pyramidal neurons decreased, and the density of cells stained with glial fibrillar acidic protein (GFAP) positive increased in the HDP group compared to the other groups (p < 0.05). No significant difference was found between the LDP and control groups in terms of these parameters (p > 0.05). Our results showed that pioglitazone administered in the prenatal period had an effect on the hippocampus development and learning and memory performance of rats, depending on the dose.

Connecting Metainflammation and Neuroinflammation Through the PTN-MK-RPTPβ/ζ Axis: Relevance in Therapeutic Development

Inflammation is a common factor of pathologies such as obesity, type 2 diabetes or neurodegenerative diseases. Chronic inflammation is considered part of the pathogenic mechanisms of different disorders associated with aging. Interestingly, peripheral inflammation and the associated metabolic alterations not only facilitate insulin resistance and diabetes but also neurodegenerative disorders. Therefore, the identification of novel pathways, common to the development of these diseases, which modulate the immune response and signaling is key. It will provide highly relevant information to advance our knowledge of the multifactorial process of aging, and to establish new biomarkers and/or therapeutic targets to counteract the underlying chronic inflammatory processes. One novel pathway that regulates peripheral and central immune responses is triggered by the cytokines pleiotrophin (PTN) and midkine (MK), which bind its receptor, Receptor Protein Tyrosine Phosphatase (RPTP) β/ζ, and inactivate its phosphatase activity. In this review, we compile a growing body of knowledge suggesting that PTN and MK modulate the immune response and/or inflammation in different pathologies characterized by peripheral inflammation associated with insulin resistance, such as aging, and in central disorders characterized by overt neuroinflammation, such as neurodegenerative diseases and endotoxemia. Evidence strongly suggests that regulation of the PTN and MK signaling pathways may provide new therapeutic opportunities particularly in those neurological disorders characterized by increased PTN and/or MK cerebral levels and neuroinflammation. Importantly, we discuss existing therapeutics, and others being developed, that modulate these signaling pathways, and their potential use in pathologies characterized by overt neuroinflammation.

Downregulation of peroxisome proliferator-activated receptor gamma in the placenta correlates to hyperglycemia in offspring at young adulthood after exposure to gestational diabetes mellitus

AIMS/INTRODUCTION

Children who are exposed to gestational diabetes mellitus (GDM) in utero are at high risk of developing related illnesses, such as type 2 diabetes mellitus in young adulthood, but the underlying mechanism and related predictive biomarkers are not known.

MATERIALS AND METHODS

The present study identified the related biomarkers of hyperglycemia in young adults from the relationship between fetal blood glucose and placental lipid transporters at messenger ribonucleic acid (mRNA) and protein expression levels. We recruited patients from a prospective cohort, and determined the mRNA and protein levels of placental fatty acid transporters. Diet-induced mouse models of GDM were established, and the mRNA and protein levels of the same transporters in placentas were validated.

RESULTS

Only the mRNA levels of peroxisome proliferator-activated receptor gamma correlated with the levels of neonatal blood glucose in GDM patients using linear regression and Spearman's correlation analyses (r = 0.774, P = 0.001). The mRNA levels of peroxisome proliferator-activated receptor gamma, matrix metalloproteinase-2 and fatty acid transport protein-6 correlated with blood glucose levels in mouse offspring (r = 0.82, P = 0.001, r = 0.737, P = 0.006 and r = -0.891, P = 0.001, respectively) at young adulthood using the same analyses. Notably, we observed significantly higher blood glucose levels in GDM offspring at 12 weeks-of-age compared with the control and rosiglitazone-supplemented groups (P < 0.05).

CONCLUSIONS

The downregulation of peroxisome proliferator-activated receptor gamma in the placenta might predict hyperglycemia in offspring at young adulthood.

The Role of Metformin in Metabolic Disturbances during Pregnancy: Polycystic Ovary Syndrome and Gestational Diabetes Mellitus

Maintenance of gestation implicates complex function of multiple endocrine mechanisms, and disruptions of the global metabolic environment prompt profound consequences on fetomaternal well-being during pregnancy and postpartum. Polycystic Ovary Syndrome (PCOS) and gestational diabetes mellitus (GDM) are very frequent conditions which increase risk for pregnancy complications, including early pregnancy loss, pregnancy-induced hypertensive disorders, and preterm labor, among many others. Insulin resistance (IR) plays a pivotal role in the pathogenesis of both PCOS and GDM, representing an important therapeutic target, with metformin being the most widely prescribed insulin-sensitizing antidiabetic drug. Although traditional views neglect use of oral antidiabetic agents during pregnancy, increasing evidence of safety during gestation has led to metformin now being recognized as a valuable tool in prevention of IR-related pregnancy complications and management of GDM. Metformin has been demonstrated to reduce rates of early pregnancy loss and onset of GDM in women with PCOS, and it appears to offer better metabolic control than insulin and other oral antidiabetic drugs during pregnancy. This review aims to summarize key aspects of current evidence concerning molecular and epidemiological knowledge on metformin use during pregnancy in the setting of PCOS and GDM.

Fructose during pregnancy affects maternal and fetal leptin signaling

Fructose intake from added sugars correlates with the epidemic rise in obesity, metabolic syndrome and cardiovascular diseases. Fructose intake also causes features of metabolic syndrome in laboratory animals. Therefore, we have investigated whether fructose modifies lipidemia in pregnant rats and produces changes in their fetuses. Thus, fructose administration (10% wt/vol.) in the drinking water of rats throughout gestation leads to maternal hypertriglyceridemia. This change was not observed in glucose-fed rats, although both carbohydrates produced similar changes in liver triglycerides and in the expression of transcription factors and enzymes involved in lipogenesis. After fasting overnight, mothers fed with carbohydrates were found to be hyperleptinemic. However, after a bolus of glucose, leptinemia in fructose-fed mothers showed no response, whereas it increased in parallel in glucose-fed and control mothers. Fetuses from fructose-fed mothers showed hypotriglyceridemia and a higher hepatic triglyceride content than fetuses from control or glucose-fed mothers. A higher expression of genes related to lipogenesis and a lower expression of fatty acid catabolism genes were also found in fetuses from fructose-fed mothers. Moreover, although hyperleptinemic, these fetuses exhibited increased tyrosine phosphorylation of the signal transducer and activator of transcription-3 (STAT-3) protein, without a parallel increase in the serine phosphorylation of STAT-3 nor in the suppressor of cytokine signaling-3 protein levels whose expression is regulated by leptin through STAT-3 activation. Thus, fructose intake during gestation provoked a diminished maternal leptin response to fasting and refeeding and an impairment in the transduction of the leptin signal in the fetuses, which could be responsible for their hepatic steatosis.

Oral Hypoglycemic Agents in pregnancy: An Update

INTRODUCTION

Traditionally, insulin has been the gold standard in the management of Type 2 diabetes in pregnancy and gestational diabetes. However, insulin therapy can be inconvenient because of the needs for multiple injections, its associated cost, pain at the injection site, need for refrigeration, and skillful handling of the syringes. This has led to the exploration of oral hypoglycemic agents as an alternative to insulin therapy.

OBJECTIVES

This review examines and evaluates the evidences on the efficacy, safety, and current recommendations of oral hypoglycemic agents.

CONCLUSION

The evidence of this study supports the use of glyburide and metformin in the management of Type 2 diabetes and gestational diabetes with no increased risk of neonatal hypoglycemia or congenital anomalies. The safety of these oral hypoglycemic agents are limited to the prenatal period and more randomized controlled trials are required to provide information on the long-term follow up on neonatal and cognitive development.

Pioglitazone therapy in mouse offspring exposed to maternal obesity

OBJECTIVE

Pioglitazone (PIO), an antidiabetic drug of the thiazolidinedione family, improves glucose and lipid metabolism in muscle, adipose, and liver tissues via peroxisome proliferator-activated receptor gamma activation. We hypothesize that PIO therapy will improve the metabolic status of offspring exposed to maternal obesity in a mouse model developmentally programmed for metabolic syndrome.

STUDY DESIGN

CD-1 female mice were fed a high-fat diet for 3 months prior to breeding and throughout pregnancy and lactation. The pups were weaned to a standard-fat diet. Offspring were randomly assigned to receive 40 mg/kg of PIO in 0.5% of methyl cellulose or 0.5% methyl cellulose by daily oral gavage for 2 weeks. The pre- and posttreatment total body weights of the pups were recorded. Visceral and subcutaneous adipose tissue were evaluated using microcomputed tomography. Serum analytes were measured. After treatment, minimally invasive microendoscopic fluorescence confocal imaging and intraperitoneal glucose tolerance tests were performed. The data were analyzed using appropriate statistical tests (significance, P < .05).

RESULTS

PIO therapy resulted in lower total body weight and lower visceral adipose tissue gain and increased subcutaneous adipose tissue. PIO significantly lowered triglycerides, insulin levels, and homeostasis model assessment of insulin resistance in males and fasting glucose in females. There was a trend toward larger adipocyte size.

CONCLUSION

Short-term PIO therapy in the offspring of obese mothers attenuates metabolic changes associated with the developmental programming of metabolic syndrome. These novel data suggest a potential role for drugs that activate peroxisome proliferator-activated receptor gamma receptors to prevent metabolic syndrome in the adult offspring at risk to develop metabolic alterations.

Thiazolidinediones and Fertility in Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most frequent cause of female infertility. The treatment of PCOS patients with insulin sensitizers, such as metformin or thiazolidinediones, increases the ovulation rate and the number of successful pregnancies. The positive action of the insulin-sensitizing treatments could be explained by a decrease in the peripheral insulin resistance but also by a direct action at the ovarian level. We report in this review different hypotheses of thiazolidinediones actions to improve PCOS (steroid secretion by ovarian cells ; insulin sensitivity in muscle and adipocyte and fat redistribution).

Childhood obesity and environmental chemicals

Childhood and adolescent rates of obesity and overweight are continuing to increase in much of the world. Risk factors such as diet composition, excess caloric intake, decreased exercise, genetics, and the built environment are active areas of etiologic research. The obesogen hypothesis, which postulates that prenatal and perinatal chemical exposure can contribute to risk of childhood and adolescent obesity, remains relatively underexamined. This review surveys numerous classes of chemicals for which this hypothesis has been explored. We focus on human data where they exist and also discuss the findings of rodent and cell culture studies. Organochlorine chemicals as well as several classes of chemicals that are peroxisome proliferator-activated receptor agonists are identified as possible risk factors for obesity. Recommendations for future epidemiologic and experimental research on the chemical origins of obesity are also given.

Effects of prepartum 2,4-thiazolidinedione on metabolism and performance in transition dairy cows

Thiazolidinediones (TZD) are potent synthetic ligands for peroxisome proliferator-activated receptor-gamma that have been shown previously to reduce plasma nonesterified fatty acids and increase peripartal dry matter intake (DMI) in dairy cows. Data from Holstein cows (n = 36) entering their second or greater lactation were used to determine whether late prepartum administration of TZD would affect periparturient metabolism, milk production, and ovarian activity. Cows were administered 0, 2.0, or 4.0 mg of TZD/kg of BW by intrajugular infusion once daily from 21 d before expected parturition until parturition. Plasma samples were collected daily from 22 d before expected parturition through 21 d postpartum and twice weekly from wk 4 through 9 postpartum. In response to increasing TZD dosage, plasma nonesterified fatty acid concentrations decreased linearly during the postpartum period (d 0 to +21: 348, 331, 268 +/- 31 microEq/L, respectively). Plasma concentrations of glucose were highest in cows administered 4.0 mg of TZD/kg of BW during the peripartum and postpartum periods (d -7 to +7: 57.9, 57.8, 61.1 +/- 0.8 mg/dL and d 0 to +21: 51.6, 49.3, 54.7 +/- 1.1 mg/dL, respectively). Plasma concentrations of beta-hydroxybutyrate were increased during the peripartum period by TZD administration (9.6, 9.9, 10.2 +/- 0.3 mg/dL) but were not affected during the postpartum period. Plasma insulin was not affected by treatment during any time period. Postpartum liver triglyceride content was decreased linearly (11.0, 10.4, 4.2 +/- 1.6%) and glycogen content was increased linearly (2.16, 2.38, 2.79 +/- 0.19%) by prepartum TZD administration. Prepartum TZD administration linearly increased DMI during the peripartum period (d -7 to +7: 16.1, 17.2, 17.3 +/- 0.5 kg/d). Cows administered TZD prepartum maintained higher postpartum body condition scores than control cows (wk 1 through 9: 2.77, 2.89, 3.02 +/- 0.05). There was no effect of prepartum TZD on milk yield; however, yields of 3.5% fat-corrected milk (52.2, 54.6, 48.0 +/- 1.6 kg/d) and most other milk components were decreased in cows that received 4.0 mg of TZD/kg of BW prepartum. Prepartum TZD administration linearly decreased the number of days to first ovulation (29.3, 28.3, 19.0 +/- 3.6 d). These results suggest that prepartum administration of TZD improves metabolic health and DMI of periparturient dairy cows and may decrease reliance on body fat reserves during early lactation.

The effects of maternal dietary treatments with natural PPAR ligands on lipid metabolism in fetuses from control and diabetic rats

Maternal diabetes impairs fetal development and growth. We studied the effects of maternal diets enriched in unsaturated fatty acids capable of activating peroxisome proliferator-activated receptors (PPARs) on the concentrations of 15deoxyDelta12,14PGJ2 (15dPGJ2), lipid mass, and the de novo lipid synthesis in 13.5-day fetuses from control and diabetic rats. Diabetes was induced by neonatal streptozotocin administration (90 mg/kg). Rats were treated with a standard diet supplemented or not with 6% olive oil or 6% safflower oil from days 0.5 to 13.5 of gestation. Fetuses from diabetic rats fed with the standard diet showed reduced 15dPGJ2 concentrations, whereas maternal treatments with olive and safflower oils increased 15dPGJ2 concentrations. Fetuses from diabetic rats showed increased concentrations of phospholipids and increased synthesis of triglycerides, phospholipids, cholesterol and free fatty acids. Diabetic rat treatments with olive and safflower oils reduced phospholipids, cholesterol, and free fatty acid concentrations and the de novo lipid synthesis in the fetuses. These effects were different from those observed in fetuses from control rats, and seem not to involve PPARgamma activation. In conclusion, olive oil- and safflower oil-supplemented diets provide beneficial effects in maternal diabetes, as they prevent fetal impairments in 15dPGJ2 concentrations, lipid synthesis and lipid accumulation.

Oral anti-hyperglycemic agents for the management of gestational diabetes mellitus

The purpose of this review is to provide a brief overview for understanding the management guidelines of gestational diabetes. The rationale for the use of oral antidiabetic drugs is provided based on validation by appropriately conducted research trials. Concerns over teratogenicity due to possible placental transfer, neonatal and maternal outcome, and basic pharmacologic benefits are addressed.

Prepartum 2,4-Thiazolidinedione Alters Metabolic Dynamics and Dry Matter Intake of Dairy Cows

Thiazolidinediones (TZD) are potent, synthetic ligands for peroxisome proliferator activated receptor-gamma (PPAR-gamma) that reduce plasma nonesterified fatty acids (NEFA) and potentiate the action of insulin in peripheral tissues of several species. Holstein cows (n = 9) entering their second or greater lactation were used to determine whether late prepartum administration of TZD would affect periparturient metabolism and milk production. Cows were limit-fed a total mixed ration (TMR) during the prepartum period to provide no more than 130% of predicted energy requirements. During the postpartum period cows were fed a common TMR for ad libitum intake. Cows were administered either 2,4-TZD (4.0 mg/kg of body weight) or saline (control) by intrajugular infusion once daily from 25 d before expected parturition until parturition. Plasma samples were collected daily from 26 d before expected parturition through 7 d postpartum. Plasma NEFA concentrations decreased during the prepartum period (d -21 to -1; 70 vs. 83 +/- 4 microEq/L) and tended to be decreased during the peripartum period (d -7 to d +7; 113 vs. 205 +/- 32 microEq/L) due to prepartum TZD administration. Plasma concentrations of glucose were not affected by treatment; however, plasma beta-hydroxybutyrate concentrations decreased in TZD-treated cows (8.6 vs. 10.7 +/- 1.7 mg/dL) as parturition approached, and plasma insulin concentrations increased during the peripartum period (0.65 vs. 0.38 +/- 0.07 ng/mL). Postpartum liver triglyceride and glycogen content was not affected by treatment. Prepartum TZD administration tended to increase dry matter intake during the peripartum and postpartum periods (16.6 vs. 14.6 +/- 0.8 kg/d and 20.0 vs. 17.2 +/- 1.2 kg/d, respectively). Milk yield for the first 30 d postpartum and milk composition measured on d 8 postpartum were not affected by treatment. There was no effect of prepartum TZD administration on insulin-dependent glucose utilization assessed using insulin challenge during either the prepartum or postpartum periods. These results suggest that administration of TZD during the late prepartum period has the potential to improve metabolic health and DMI of periparturient dairy cows and warrants further investigation.

Ligand-activated peroxisome proliferator activated receptor gamma alters placental morphology and placental fatty acid uptake in mice

The nuclear receptor peroxisome proliferator activated receptor gamma (PPARgamma) is essential for murine placental development. We previously showed that activation of PPARgamma in primary human trophoblasts enhances the uptake of fatty acids and alters the expression of several proteins associated with fatty acid trafficking. In this study we examined the effect of ligand-activated PPARgamma on placental development and transplacental fatty acid transport in wild-type (wt) and PPARgamma(+/-) embryos. We found that exposure of pregnant mice to the PPARgamma agonist rosiglitazone for 8 d (embryonic d 10.5-18.5) reduced the weights of wt, but not PPARgamma(+/-) placentas and embryos. Exposure to rosiglitazone reduced the thickness of the spongiotrophoblast layer and the surface area of labyrinthine vasculature, and altered expression of proteins implicated in placental development. The expression of fatty acid transport protein 1 (FATP1), FATP4, adipose differentiation related protein, S3-12, and myocardial lipid droplet protein was enhanced in placentas of rosiglitazone-treated wt embryos, whereas the expression of FATP-2, -3, and -6 was decreased. Additionally, rosiglitazone treatment was associated with enhanced accumulation of the fatty acid analog 15-(p-iodophenyl)-3-(R, S)-methyl pentadecanoic acid in the placenta, but not in the embryos. These results demonstrate that in vivo activation of PPARgamma modulates placental morphology and fatty acid accumulation.