Effect of food restriction and leptin supplementation on fetal programming in mice

A novel model of gestational diabetes: Acute high fat high sugar diet results in insulin resistance and beta cell dysfunction during pregnancy in mice

Gestational diabetes mellitus (GDM) affects 7-18% of all pregnancies. Despite its high prevalence, there is no widely accepted animal model. To address this, we recently developed a mouse model of GDM. The goal of this work was to further characterize this animal model by assessing insulin resistance and beta cell function. Mice were randomly assigned to either control (CD) or high fat, high sugar (HFHS) diet and mated 1 week later. At day 0 (day of mating) mice were fasted and intraperitoneal insulin tolerance tests (ipITT) were performed. Mice were then euthanized and pancreata were collected for histological analysis. Euglycemic hyperinsulinemic clamp experiments were performed on day 13.5 of pregnancy to assess insulin resistance. Beta cell function was assessed by glucose stimulated insulin secretion (GSIS) assay performed on day 0, 13.5 and 17.5 of pregnancy. At day 0, insulin tolerance and beta cell numbers were not different. At day 13.5, glucose infusion and disposal rates were significantly decreased (p<0.05) in Pregnant (P) HFHS animals (p<0.05) suggesting development of insulin resistance in P HFHS dams. Placental and fetal glucose uptake was significantly increased (p<0.01) in P HFHS dams at day 13.5 of pregnancy and by day 17.5 of pregnancy fetal weights were increased (p<0.05) in P HFHS dams compared to P CD dams. Basal and secreted insulin levels were increased in HFHS fed females at day 0, however at day 13.5 and 17.5 GSIS was decreased (p<0.05) in P HFHS dams. In conclusion, this animal model results in insulin resistance and beta cell dysfunction by mid-pregnancy further validating its relevance in studying the pathophysiology GDM.

Conditional knockout of leptin receptor in the female reproductive tract reduces fertility due to parturition defects in mice

Leptin is required for fertility, including initiation of estrous cycles. It is therefore challenging to assess the role of leptin signaling during pregnancy. While neuron-specific transgene approaches suggest that leptin signaling in the central nervous system is most important, experiments with pharmacologic inhibition of leptin in the uterus or global replacement of leptin during pregnancy suggest leptin signaling in the reproductive tract may be required. Here, conditional leptin receptor knockout (Lepr cKO) with a progesterone receptor-driven Cre recombinase was used to examine the importance of leptin signaling in pregnancy. Lepr cKO mice have almost no leptin receptor in uterus or cervix, and slightly reduced leptin receptor levels in corpus luteum. Estrous cycles and progesterone concentrations were not affected by Lepr cKO. Numbers of viable embryos did not differ between primiparous control and Lepr cKO dams on days 6.5 and 17.5 of pregnancy, despite a slight reduction in the ratio of embryos to corpora lutea, showing that uterine leptin receptor signaling is not required for embryo implantation. Placentas of Lepr cKO dams had normal weight and structure. However, over four parities, Lepr cKO mice produced 22% fewer live pups than controls, and took more time from pairing to delivery by their fourth parity. Abnormal birth outcomes of either dystocia or dead pups occurred in 33% of Lepr cKO deliveries but zero control deliveries, and the average time to deliver each pup after crouching was significantly increased. Thus, leptin receptor signaling in the reproductive tract is required for normal labor and delivery. Summary sentence. Mice lacking leptin receptor in the reproductive tract produce fewer live pups and have more adverse labor outcomes than controls, but normal numbers of embryos near term, showing that leptin receptor signaling is required for normal parturition.

Adrenomedullin and its receptors are expressed in mouse pancreatic β-cells and suppresses insulin synthesis and secretion

Gestational diabetes mellitus (GDM) is associated with defective pancreatic β-cell adaptation in pregnancy, but the underlying mechanism remains obscure. Our previous studies demonstrated that GDM women display increased plasma adrenomedullin (ADM) levels, and non-obese GDM mice show decreased serum concentrations of insulin and the number of β-cells in pancreas islets. The aims of this study is to examine if ADM and its receptors are expressed in female mouse pancreas, and if so, whether insulin secretion is regulated by ADM in mouse β-cell line, NIT-1 cells and isolated mouse pancreatic islets. Present study shows that ADM and its receptor components CRLR, RAMPs are present in mouse pancreatic islets and co-localized with insulin. The expressions of ADM, CRLR and RAMP2 in islets from pregnant mice are reduced compared to that of non-pregnant mice. NIT-1-β cells express ADM and its receptor mRNA, and glucose dose-dependently stimulates expressions. Furthermore, ADM inhibits NIT-1-β cell growth, and this inhibition is reversed by ADM antagonist, ADM22-52. The glucose-induced insulin secretion was suppressed by ADM in NIT-1-β cells and isolated pancreatic islets from pregnant mice. These inhibitory effects are accompanied by upregulation of endoplasmic reticulum (ER) stress biomarker genes in NIT-1-β cells. This study unveils that reduced ADM and its receptors may play a role in β-cell adaptation during pregnancy, while increased plasma ADM in GDM may contribute to the β-cells dysfunction, and blockade of ADM may reverse β-cell insulin production.

Influence of leptin administration to pregnant female mice on obesity development, taste preferences, and gene expression in the liver and muscles of their male and female offspring

. The consumption of food rich in sugar and fat provokes obesity. Prenatal conditions have an impact on taste preferences and metabolism in the adult offspring, and this impact may manifest differently in different sexes. An increase in blood leptin level in pregnant females reduces the risk of obesity and insulin resistance in the offspring, although the mechanisms mediating this effect are unknown. Neither is it known whether maternal leptin affects taste preferences. In this study, we investigated the effect of leptin administration to pregnant mice on the development of diet-induced obesity, food choice, and gene expression in the liver and muscles of the offspring with regard to sex. Leptin was administered to female mice on days 11, 12, and 13 of pregnancy. In male and female offspring, growth rate and intake of standard chow after weaning, obesity development, gene expression in the liver and muscles, and food choice when kept on a high-calorie diet (standard chow, lard, sweet cookies) were recorded. Leptin administration to pregnant females reduced body weight in the female offspring fed on the standard diet. When the offspring were given a high-calorie diet, leptin administration inhibited obesity development and reduced the consumption of cookies only in males. It also increased the consumption of standard chow and the mRNA levels of genes for the insulin receptor and glucose transporter type 4 in the muscles of both male and female offspring. The results demonstrate that an increase in blood leptin levels in pregnant females has a sex-specif ic effect on the metabolism of the offspring increasing resistance to obesity only in male offspring. The mechanism underlying this effect includes a shift in food preference in favor of a balanced diet and maintenance of insulin sensitivity in muscle tissues.

Morphology and gene expression in mouse placentas lacking leptin receptors

In the pregnant mouse, the hormone leptin is primarily produced by adipose tissue and does not significantly cross the placenta into fetal circulation. Nonetheless, leptin treatment during gestation affects offspring phenotypes. Leptin treatment also affects placental trophoblast cells in vitro, by altering proliferation, invasion and nutrient transport. The goal of the present study was to determine whether the absence of placental leptin receptors alters placental development and gene expression. Lepr^db-3j+ mice possessing only one functional copy of the leptin receptor were mated to obtain wildtype, Lepr^db-3j+ and Lepr^db-3j/db-3j conceptuses, which were then transferred to wildtype recipient dams. Placentas were collected at gestational d18.5 to examine placental morphology and gene expression. Placentas lacking functional leptin receptor had reduced weights, but were otherwise morphologically indistinguishable from control placentas. Relative mRNA levels, however, were altered in Lepr^db-3j/db-3j placentas, particularly transcripts related to amino acid and lipid metabolism and transport. Consistent with a previous in vitro study, leptin was found to promote expression of stathmin, a positive regulator of trophoblast invasion, and of serotonin receptors, potential mediators of offspring neurological development. Overall placental leptin receptor was found not to play a significant role in morphological development of the placenta, but to regulate placental gene expression, including in metabolic pathways that affect fetal growth.

Sex-specific effects of leptin administration to pregnant mice on the placentae and the metabolic phenotypes of offspring

Obesity during pregnancy has been shown to increase the risk of metabolic diseases in the offspring. However, the factors within the maternal milieu which affect offspring phenotypes and the underlying mechanisms remain unknown. The adipocyte hormone leptin plays a key role in regulating energy homeostasis and is known to participate in sex‐specific developmental programming. To examine the action of leptin on fetal growth, placental gene expression and postnatal offspring metabolism, we injected C57BL mice with leptin or saline on gestational day 12 and then measured body weights (BWs) of offspring fed on a standard or obesogenic diet, as well as mRNA expression levels of insulin‐like growth factors and glucose and amino acid transporters. Male and female offspring born to leptin‐treated mothers exhibited growth retardation before and a growth surge after weaning. Mature male offspring, but not female offspring, exhibited increased BWs on a standard diet. Leptin administration prevented the development of hyperglycaemia in the obese offspring of both sexes. The placentas of the male and female foetuses differed in size and gene expression, and leptin injection decreased the fetal weights of both sexes, the placental weights of the male foetuses and placental gene expression of the GLUT1 glucose transporter in female foetuses. The data suggest that mid‐pregnancy is an ontogenetic window for the sex‐specific programming effects of leptin, and these effects may be exerted via fetal sex‐specific placental responses to leptin administration.

Impact of adrenomedullin blockage on lipid metabolism in female mice exposed to high-fat diet

PURPOSE

Adrenomedullin (ADM) levels are elevated in gestational and type 2 diabetic patients. ADM also stimulates lipolysis in vitro. Disturbed lipid metabolism has been implicated in the pathogenesis of diabetes. Here, we explore whether blockade of ADM is beneficial for metabolic homeostasis in a diabetic mouse model.

METHODS

C57BL/6J female mice were placed on either a control or a high fat high sucrose (HFHS) diet for 8 weeks. At week 4, osmotic mini-pumps were implanted for constant infusion of either saline or ADM antagonist, ADM_22-52. Glucose tolerance tests were performed prior to infusion and 4 weeks after infusion began. Animals were then sacrificed and visceral adipose tissue collected for further analysis.

RESULTS

Mice fed HFHS displayed glucose intolerance, increased mRNA expressions in VAT for Adm and its receptor components, Crlr. HFHS fed mice also had increased basal and isoprenaline-induced glycerol release by VAT explants. ADM_22-52 did not significantly affect glucose intolerance. ADM_22-52 did suppress basal and isoprenaline-induced glycerol release by VAT explants. This alteration was associated with enhanced mRNA expression of insulin signaling factors Insr and Glut4, and adipogenic factor Pck1.

CONCLUSIONS

HFHS diet induces glucose intolerance and enhances ADM and its receptor expressions in VAT in female mice. ADM_22-52 treatment did not affect glucose intolerance in HFHS mice, but reduced both basal and isoprenaline-induced lipolysis, which is associated with enhanced expression of genes involved in adipogenesis. These results warrant further research on the effects of ADM blockade in improving lipid homeostasis in diabetic patients.

Maternal Lipid Concentrations during Early Pregnancy and Eating Behaviour and Energy Intake in the Offspring

Worldwide, childhood obesity is rapidly increasing, making it a pressing public health issue. Obesity is strongly linked to eating behaviour and energy intake but little is known about their prenatal determinants. In an exploratory study of data collected within the Amsterdam Born Children and their Development (ABCD) study, we hypothesized that intra-uterine exposure to increased lipids is associated with adverse eating behaviour and increased energy intake in the offspring at age 5. During early gestation, a non-fasting blood sample was taken from 1463 non-diabetic Dutch women, including: total cholesterol (TC), triglycerides (TG), free fatty acids (FFA), Apolipoprotein A1 (ApoA1) and Apolipoprotein B (ApoB). Eating behaviour, measured using the Children’s Eating Behaviour Questionnaire, included food approaching (enjoyment of food, food responsiveness) and food avoidant behaviour (satiety responsiveness, slowness of eating). Energy intake (total energy, fat and carbohydrate intake) was measured using a validated food frequency questionnaire. Associations were analysed using multivariable linear regression. Increased maternal TC concentrations were associated with lower enjoyment of food, higher satiety responsiveness and increased slowness of eating, as well as decreased kcal and fat intake in the offspring. Elevated ApoA1 was associated with increased slowness of eating, lower enjoyment of food and lower kcal, fat and carbohydrate intake. ApoB was positively associated with satiety responsiveness and slowness of eating. Higher TG concentrations were associated with higher food responsiveness. Maternal FFA did not show significant associations. Findings demonstrated that the maternal prenatal lipid profile was associated with offspring’s eating behaviour and energy intake, although not always in the hypothesized direction.

Maternal food restriction in rats of the F0 generation increases retroperitoneal fat, the number and size of adipocytes and induces periventricular astrogliosis in female F1 and male F2 generations

The present study investigated whether male offspring (F₂ generation) from female rats (F₁ generation) whose mothers (F₀ generation) were food restricted during gestation inherit a phenotypic transgenerational tendency towards being overweight and obese in the juvenile period, in the absence of food restriction in the F₁/F₂ generations. Dams of the F₀ generation were 40% food restricted during pregnancy. Bodyweight, the number and size of larger and small hypodermal adipocytes (HAs), total retroperitoneal fat (RPF) weight and the expression of glial fibrillary acidic protein (GFAP) in periventricular hypothalamic astrocytes (PHAs), as determined by immunohistochemistry, were evaluated in both generations. In the female F₁ generation, there was low bodyweight gain only during the juvenile period (30-65 days of age), a decrease in the size of small adipocytes, an increase in the number of small adipocytes, an increase in RPF weight and an increase in GFAP expression in PHAs at 90-95 days of age. In males of the F₂ generation at 50 days of age, there was increased bodyweight and RPF weight, and a small number of adipocytes and GFAP expression in PHAs. These data indicate that the phenotypic transgenerational tendency towards being overweight and obese was observed in females (F₁) from mothers (F₀) that were prenatally food restricted was transmitted to their male offspring.

GENDER-SPECIFIC INFLUENCE OF Aу MUTATION ON PROGENY METABOLIC PHENOTYPE, FETAL GROWTH AND PLACENTAL GENE EXPRESSION IN MICE

Obesity during pregnancy increases the risk of obesity in offspring. To correct the offspring development in obese mothers, it is necessary to reveal the molecular mechanisms that mediate the influence of the maternal environment on the offspring ontogenesis. Leptin levels increase with obesity. In C57Bl mice, the Ауmutation is associated with elevated blood levels of leptin in pregnant females and exerts a gender-specific effect on the metabolic phenotype of mature offspring. Aim: to study the influence of Ауmutation on sensitivity to diet-induced obesity in male and female offspring, on fetal and placental weight and on the expression of genes in the placentas of the fetuses of different sexes. Body weight and food intake on a standard and an obesogenic diet, fetal and placental weights on pregnancy days 13 and 18, and gene expression of glucose transporters (GLUT1, GLUT3), neutral amino acid transporters (SNAT1, SNAT2, SNAT4), insulin-like growth factor 2 IGF2 and its receptor IGF2R were measured in male and female offspring of и ɑ/ɑ (control) and Ау/ɑ mothers. Aymutation influenced the body weight only in male offspring, which consumed a standard diet, and did not influence obesity development in both male and female offspring. The weight of fetuses and placentas in Ау/ɑ as compared to ɑ/ɑ  females was reduced on day 13 of pregnancy and was not different on day 18. On day 13 of pregnancy, the mRNA levels of the examined genes did not differ in placentas of male and female fetuses in ɑ/ɑ  females. In Ау/ɑ females, the gene expression of GLUT1, GLUT3, SNAT1 and SNAT4 was reduced in female placentas compared to male placentas. The results suggest that the sex-specific transcription response of placentas to elevated leptin levels in pregnant Ау/ɑ females can mediate the gender-specific impact of Ауmutation on the offspring metabolism in postnatal life.

Effects of acute exposure to a high-fat, high-sucrose diet on gestational glucose tolerance and subsequent maternal health in mice

Gestational diabetes mellitus (GDM) is a common obstetric complication. Half of women who have GDM will go on to develop type 2 diabetes. Understanding the mechanisms by which this occurs requires an animal model of GDM without ongoing diabetes at conception. C57Bl/6J mice react acutely to a high-fat, high-sucrose (HFHS) challenge. Here, we hypothesized that a periconceptional HFHS challenge will induce glucose intolerance during gestation. C57Bl/6J female mice were placed on an HFHS either 1 or 3 weeks prior to mating and throughout pregnancy. Intraperitoneal glucose tolerance tests, insulin measurements, and histological analysis of pancreatic islets were used to assess the impact of acute HFHS. C57Bl/6J females fed HFHS beginning 1 week prior to pregnancy became severely glucose intolerant, with reduced insulin response to glucose, and decreased pancreatic islet expansion during pregnancy compared to control mice. These GDM characteristics did not occur when the HFHS diet was started 3 weeks prior to mating, suggesting the importance of acute metabolic stress. Additionally, HFHS feeding resulted in only mild insulin resistance in nonpregnant females. When the diet was discontinued at parturition, symptoms resolved within 3 weeks. However, mice that experienced glucose intolerance in pregnancy became glucose intolerant more readily in response to a HFHS challenge later in life than congenic females that experienced a normal pregnancy, or that were fed the same diet outside of pregnancy. Thus, acute HFHS challenge in C57Bl/6 mice results in a novel, nonobese, animal model that recapitulates the long-term risk of developing type 2 diabetes following GDM.

In Utero and Postnatal Exposure to High Fat, High Sucrose Diet Suppressed Testis Apoptosis and Reduced Sperm Count

Obesity affects male fertility and maternal diabetes affects the offspring sperm epigenome. However, the effects of in utero exposure to maternal glucose intolerance in combination with postnatal high fat, high sucrose (HFHS) diet consumption on offspring spermatogenesis is not clear. The present study was designed to test these effects. One week before and during pregnancy, dams were fed either control or HFHS diet to induce gestational glucose intolerance, and returned to standard diet during lactation. Male offspring from each maternal group were split into control and HFHS-fed groups for eight weeks prior to sacrifice at 11, 19 or 31 weeks of age, and reproductive tissues were harvested for analysis of testicular germ cell apoptosis and sperm output. Postnatal HFHS diet suppressed spermatogonia apoptosis in all age groups and maternal HFHS diet reduced testosterone levels at 11 weeks. At 31 weeks of age, the postnatal HFHS diet increased body weight, and reduced epididymis weight and sperm count. The combination of in utero and postnatal exposure impacted sperm counts most significantly. In summary, HFHS diet during pregnancy puts male offspring at greater risk of infertility, particularly when combined with postnatal high fat diet feeding.

A new model for fetal programming: maternal Ramadan-type fasting programs nephrogenesis

The effect of maternal Ramadan-type fasting (RTF) on the outcome of pregnancy, kidney development and nephron number in male rat offspring was investigated in current study. Pregnant rats were given food and water ad libitum during pregnancy (control) or restricted for 16 h per day (RTF). Kidney structure was examined during fetal life, at birth, and in early and late adulthood. Maternal body weight, food intake, relative food intake and plasma glucose levels were significantly lower (P<0.001) in the RTF group. Litter and pup weights also were significantly lower (P<0.05) in the RTF group at birth, with no difference in the litter size. The RTF group had a longer gestation, delayed nephrogenesis with less well-differentiated glomeruli, more connective tissue, fewer medullary rays, an increase in the nephrogenic zone/cortical zone ratio, and significant increase (P<0.001) in kidney apoptosis at birth. On the other hand, maternal fasting reduced nephron number (by ~31%) with unchanged kidney and total glomerular volumes. Mean glomerular volume was significantly higher in RTF offspring. Assessment of renal structure revealed mild glomerulosclerosis with enlarged lobulated glomeruli in the renal cortex and high interstitial fibrosis in the medulla of RTF kidneys. Taken together, gestational fasting delays nephrogenesis and reduces nephron number in the kidneys of the offspring, that could be partially owing to increased apoptosis.

Hypercaloric diet prevents sexual impairment induced by maternal food restriction

Prenatal undernutrition impairs copulatory behavior and increases the tendency to become obese/overweight, which also reduces sexual behavior. Re-feeding rats prenatally undernourished with a normocaloric diet can restore their physiological conditions and copulatory behavior. Thus, the present study investigated whether a hypercaloric diet that is administered in rats during the juvenile period prevents sexual impairments that are caused by maternal food restriction and the tendency to become overweight/obese. Female rats were prenatally fed a 40% restricted diet from gestational day 2 to 18. The pups received a hypercaloric diet from postnatal day (PND) 23 to PND65 (food restricted hypercaloric [FRH] group) or laboratory chow (food restricted control [FRC] group). Pups from non-food-restricted dams received laboratory chow during the entire experiment (non-food-restricted [NFR] group). During the juvenile period and adulthood, body weight gain was evaluated weekly. The day of balanopreputial separation, sexual behavior, sexual organ weight, hypodermal adiposity, striatal dopamine and serotonin, serum testosterone, and tumor necrosis factor α (TNF-α) were evaluated. The FRH group exhibited an increase in body weight on PND58 and PND65. The FRC group exhibited an increase in the latency to the first mount and intromission and an increase in serum TNF-α levels but a reduction of dopaminergic activity. The hypercaloric diet reversed all of these effects but increased adiposity. We concluded that the hypercaloric diet administered during the juvenile period attenuated reproductive impairments that were induced by maternal food restriction through increases in the energy expenditure but not the tendency to become overweight/obese.

In ovo leptin administration modulates glucocorticoid receptor mRNA expression specifically in the hypothalamus of broiler chickens

The glucocorticoid receptor (GR) is well documented to play a crucial role in the central control of energy homeostasis in mammals. However, the distribution and function of the GR in the chicken brain are less clear. Leptin is a key hormone regulating energy homeostasis in mammals, yet its action in the chicken is still under debate. In this study, the distribution of GR mRNA in the chicken brain and the effects of in ovo administration of leptin and its antagonist on early post-hatch growth and GR mRNA expression in different hypothalamic nuclei were investigated via in situ hybridization (ISH) and quantitative PCR. GR mRNA was widely expressed in the chicken brain, mainly in the corpus striatum, nucleus rotundus, dorsolateral nucleus, nucleus ovoidalis, nucleus reticularis superior and the hippocampus (Hp) and in the preoptic area of the hypothalamus. High doses of leptin (5.0μg) significantly promoted post-hatch growth, resulting in a significant high body weight increased by 24.64% at day (D) 21 of life. Meanwhile, hypothalamic expression of GR mRNA in the LL and HL groups was down-regulated significantly by 7.02% and 13.65% respectively (P<0.05). ISH revealed region-specific changes: GR mRNA was found to be significantly decreased (P<0.05) in the paraventricular nucleus, periventricular nucleus and ventromedial nucleus but not in the Hp, infundibular nucleus or lateral hypothalamus of D21 broiler chickens. The leptin antagonist was able to reverse the effect of leptin on the growth rate and hypothalamic GR mRNA expression. These results provide evidence that in ovo administration of leptin influences early post-hatch growth and the hypothalamic expression of GR mRNA in broiler chickens.

Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta

During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstn^tm1Sjl/+) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstn^tm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2^oim), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2^oim/+ offspring from natural mating of Mstn^tm1Sjl/+ dams to Col1a2^oim/+sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2^oim/+ dams to Col1a2^oim/+ sires. Finally, increased bone biomechanical strength of Col1a2^oim/+ offspring that had been transferred into Mstn^tm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta.

Maternal Hyperleptinemia Improves Offspring Insulin Sensitivity in Mice

Maternal obesity and gestational diabetes are prevalent worldwide. Offspring of mothers with these conditions weigh more and are predisposed to metabolic syndrome. A hallmark of both conditions is maternal hyperleptinemia, but the role of elevated leptin levels during pregnancy on developmental programming is largely unknown. We previously found that offspring of hyperleptinemic mothers weighed less and had increased activity. The goal of this study was to determine whether maternal leptin affects offspring insulin sensitivity by investigating offspring glucose metabolism and lipid accumulation. Offspring from two maternal hyperleptinemic models were compared. The first model of hyperleptinemia is the Lepr(db/+) mouse, which has a mutation in one copy of the gene that encodes the leptin receptor, resulting in a truncated long form of the receptor, and hyperleptinemia. Wild-type females served as the control for the Lepr(db/+) females. For the second hyperleptinemic model, wild-type females were implanted with miniosmotic pumps, which released leptin (350 ng/h) or saline (as the control) just prior to mating and throughout gestation. In the offspring of these dams, we measured glucose tolerance; serum leptin, insulin, and triglyceride levels; liver triglycerides; pancreatic α- and β-cell numbers; body composition; incidence of nonalcoholic fatty liver disease; and the expression of key metabolic genes in the liver and adipose tissue. We found that the offspring of hyperleptinemic dams exhibited improved glucose tolerance, reduced insulin and leptin concentrations, reduced liver triglycerides, and a lower incidence of nonalcoholic fatty liver disease. Overall, maternal hyperleptinemia was beneficial for offspring glucose and lipid metabolism.

Maternal Hyperleptinemia Is Associated with Male Offspring's Altered Vascular Function and Structure in Mice

Children of mothers with gestational diabetes have greater risk of developing hypertension but little is known about the mechanisms by which this occurs. The objective of this study was to test the hypothesis that high maternal concentrations of leptin during pregnancy, which are present in mothers with gestational diabetes and/or obesity, alter blood pressure, vascular structure and vascular function in offspring. Wildtype (WT) offspring of hyperleptinemic, normoglycemic, Leprdb/+ dams were compared to genotype matched offspring of WT-control dams. Vascular function was assessed in male offspring at 6, and at 31 weeks of age after half the offspring had been fed a high fat, high sucrose diet (HFD) for 6 weeks. Blood pressure was increased by HFD but not affected by maternal hyperleptinemia. On a standard diet, offspring of hyperleptinemic dams had outwardly remodeled mesenteric arteries and an enhanced vasodilatory response to insulin. In offspring of WT but not Leprdb/+ dams, HFD induced vessel hypertrophy and enhanced vasodilatory responses to acetylcholine, while HFD reduced insulin responsiveness in offspring of hyperleptinemic dams. Offspring of hyperleptinemic dams had stiffer arteries regardless of diet. Therefore, while maternal hyperleptinemia was largely beneficial to offspring vascular health under a standard diet, it had detrimental effects in offspring fed HFD. These results suggest that circulating maternal leptin concentrations may interact with other factors in the pre- and post -natal environments to contribute to altered vascular function in offspring of diabetic pregnancies.

Placental changes caused by food restriction during early pregnancy in mice are reversible

In a previous study, 50% calorie restriction in mice from d1.5 to 11.5 of pregnancy resulted in reduced placental weights and areas,relative sparing of labyrinth zone area compared to junctional zone area, and dramatic changes in global gene expression profiles.However, little lasting effect was seen on adult offspring of these pregnancies, with a slight reduction in adiposity in males and some changes in liver gene expression in both sexes. The goals of the present study were to determine whether the placental changes induced by caloric restriction in early pregnancy had permanent, irreversible effects on the placenta, and whether the changes in liver gene expression in adult offspring were present before birth. There were no differences in placental weights or areas, or the areas of individual placental zones near term in mice that had previously been food restricted. Global gene expression profiles at d18.5 were indistinguishable in placentas from control and previously food-restricted mothers. In fetuses from restricted dams at d18.5, liver expression of Gck, a key regulator of glycogen synthesis, was reduced, whereas its expression was increased in livers from adult offspring of restricted dams. Ppara expression was also reduced in fetal livers from restricted dams at d18.5, but not in adult offspring livers. We conclude that alterations in the placenta caused by nutrient restriction in early pregnancy are reversible, and that alterations in gene expression in livers of adult offspring are not a result of changes initiated during pregnancy and maintained through adulthood.

Hyperleptinemia During Pregnancy Decreases Adult Weight of Offspring and Is Associated With Increased Offspring Locomotor Activity in Mice

Pregnant women who are obese or have gestational diabetes mellitus have elevated leptin levels and their children have an increased risk for child and adult obesity. The goals of this study were to determine whether offspring weights are altered by maternal hyperleptinemia, and whether this occurs via behavioral changes that influence energy balance. We used 2 hyperleptinemic mouse models. The first was females heterozygous for a leptin receptor mutation (DB/+), which were severely hyperleptinemic, and that were compared with wild-type females. The second model was wild-type females infused with leptin (LEP), which were moderately hyperleptinemic, and were compared with wild-type females infused with saline (SAL). Total food consumption, food preference, locomotor activity, coordinated motor skills, and anxiety-like behaviors were assessed in wild-type offspring from each maternal group at 3 postnatal ages: 4-6, 11-13, and 19-21 weeks. Half the offspring from each group were then placed on a high-fat diet, and behaviors were reassessed. Adult offspring from both groups of hyperleptinemic dams weighed less than their respective controls beginning at 23 weeks of age, independent of diet or sex. Weight differences were not explained by food consumption or preference, because female offspring from hyperleptinemic dams tended to consume more food and had reduced preference for palatable, high-fat and sugar, food compared with controls. Offspring from DB/+ dams were more active than offspring of controls, as were female offspring of LEP dams. Maternal hyperleptinemia during pregnancy did not predispose offspring to obesity, and in fact, reduced weight gain.

An intrauterine catch-up growth regimen increases food intake and post-natal growth in rats

Nutritional conditions during the intrauterine stage are an important developmental programming factor that can affect the growth and metabolic status during foetal development and permanently alter the phenotypes of newborn offspring and adults. This study was performed to examine the effects of intrauterine catch-up growth (IUCG) on food intake, post-natal body growth and the metabolic status of offspring and growing rats. Control pregnant rats were fed ad libitum during the entire gestation period. For the IUCG regimen, pregnant rats were fed 50% of the food of the controls from pregnancy days 4 through 11 (8 days), followed by ad libitum feeding from pregnancy days 12 through parturition. The birth weight of offspring was not affected by the IUCG regimen. At weaning, offspring from each treatment group were assigned to two groups and given either a normal diet or high-fat diet (HFD) for 12 weeks until 103 days of age. In the normal diet group, the IUCG offspring showed a 9.0% increase (P < 0.05) in total food intake, were 11.2% heavier (p < 0.05) at 103 days of age and had an 11.0% greater (p < 0.05) daily weight gain compared with control offspring. The IUCG regimen did not affect body glucose and lipid metabolism. After exposure to the HFD, the IUCG regimen has not exacerbated metabolic disorders. In conclusion, our findings suggest that the IUCG nutritional regimen during pregnancy can increase the food intake and post-natal body growth of offspring without inducing metabolic disorders such as obesity and insulin resistance. The IUCG nutritional regimen might be used to improve the food intake and post-natal body growth of domestic animals.

Influence of abnormally high leptin levels during pregnancy on metabolic phenotypes in progeny mice

Maternal obesity increases the risk of obesity in offspring, and obesity is accompanied by an increase in blood leptin levels. The "yellow" mutation at the mouse agouti locus (A(y)) increases blood leptin levels in C57BL preobese pregnant mice without affecting other metabolic characteristics. We investigated the influence of the A(y) mutation or leptin injection at the end of pregnancy in C57BL mice on metabolic phenotypes and the susceptibility to diet-induced obesity (DIO) in offspring. In both C57BL-A(y) and leptin-treated mice, the maternal effect was more pronounced in male offspring. Compared with males born to control mothers, males born to A(y) mothers displayed equal food intake (FI) but decreased body weight (BW) gain after weaning, equal glucose tolerance, and enhanced FI-to-BW ratios on the standard diet but the same FI and BW on the high-fat diet. Males born to A(y) mothers were less responsive to the anorectic effect of exogenous leptin and less resistant to fasting (were not hyperphagic and gained less weight during refeeding after food deprivation) compared with males born to control mothers. However, all progeny displayed equal hypothalamic expression of Agouti gene-related protein (AgRP), neuropeptide Y (NPY), and proopiomelanocortin (POMC) and equal plasma leptin and glucose levels after food deprivation. Leptin injections in C57BL mice on day 17 of pregnancy decreased BW in both male and female offspring but inhibited FI and DIO only in male offspring. Our results show that hyperleptinemia during pregnancy has sex-specific long-term effects on energy balance regulation in progeny and does not predispose offspring to developing obesity.

Metabolic syndrome: role of maternal undernutrition and fetal programming

Development of metabolic syndrome is attributed to genes, dietary intake, physical activity and environmental factors. Fetal programming due to maternal nutrition is also an important factor especially in developing countries where intrauterine growth retardation followed by excess nutrition postnatally is causing mismatch predisposing individuals to development of metabolic syndrome and its components. Several epidemiological and animal studies have provided evidence for the link between intrauterine growth retardation and adult metabolic diseases. Deficiency of macronutrients, protein and carbohydrates, during pregnancy and gestation results in lower infant birth weight, a surrogate marker of fetal growth and subsequently insulin resistance, glucose intolerance, hypertension and adiposity in adulthood. The role of micronutrients is less extensively studied but however gaining attention with several recent studies focusing on this aspect. Several mechanisms have been proposed to explain the developmental origin of adult diseases important among them being alteration of hypothalamic pituitary axis, epigenetic regulation of gene expression and oxidative stress. All of these mechanisms may be acting at different time during gestation and contributing to development of metabolic syndrome in adulthood.

Sex differences in adipose tissue: It is not only a question of quantity and distribution

Obesity and its associated secondary complications are active areas of investigation in search of effective treatments. As a result of this intensified research numerous differences between males and females at all levels of metabolic control have come to the forefront. These differences include not only the amount and distribution of adipose tissue, but also differences in its metabolic capacity and functions between the sexes. Here, we review some of the recent advances in our understanding of these dimorphisms and emphasize the fact that these differences between males and females must be taken into consideration in hopes of obtaining successful treatments for both sexes.

Leptin and the placental response to maternal food restriction during early pregnancy in mice

Several studies have demonstrated that maternal undernutrition or overnutrition during pregnancy can have negative consequences for the health of children born to these pregnancies, but the physiological mechanisms by which this occurs are not completely understood. During periods of food restriction, concentrations of leptin decline, whereas leptin is elevated in obesity, suggesting that it may play a role in the response to altered nutrition during pregnancy. This study compares placental development and global placental gene expression profiles at Day 11.5 in pregnant control mice, mice that were undernourished, and mice that were undernourished but given leptin. Placentas from mothers exposed to food restriction preserved the placental labyrinth zone at the expense of the junctional zone, an effect abrogated in the restricted plus leptin group, which had a significant decrease in the labyrinth zone area compared with controls. Similarly, there were more significant differences in gene expression between placentas from control and restricted plus leptin mothers (1128 differentially expressed genes) than between placentas of control and restricted mothers (281 differentially expressed genes). We conclude that the presence of high concentrations of circulating leptin during food restriction disrupts the normal adaptive response of the placenta to reduced energy availability.