Maternal hyperinsulinemia predisposes rat fetuses for hyperinsulinemia, and adult-onset obesity and maternal mild food restriction reverses this phenotype

We have previously shown that artificial rearing of newborn female rat pups on a high-carbohydrate (HC) milk formula resulted in chronic hyperinsulinemia and adult-onset obesity (HC phenotype) and that the maternal HC phenotype was transmitted to their progeny (2-HC rats) because of fetal development in the HC female rat. The aims of this study were to investigate 1) the fetal adaptations that predisposed the progeny for the expression of the HC phenotype in adulthood and 2) whether the transfer of the HC phenotype to the progeny could be reversed by maternal food restriction. Fetal parameters such as plasma insulin and glucose levels, mRNA level of preproinsulin gene, pancreatic insulin content, and islet insulin secretory response in vitro were determined. On gestational day 21, 2-HC fetuses were hyperinsulinemic, had increased insulin content and mRNA level of the preproinsulin gene in their pancreata and demonstrated an altered glucose-stimulated insulin secretory response by isolated islets. Modification of the intrauterine environment in HC female rats was achieved by pair feeding them to the amount of diet consumed by age-matched control rats from the time of their weaning. This mild dietary restriction reversed their HC phenotype and also prevented the development of the HC phenotype in their progeny. These findings show that mal-programming of the progeny of the hyperinsulinemic-obese HC female for the expression of the HC phenotype is initiated in utero and that normalization of the maternal environment in HC female rats by mild food restriction resulted in the normal phenotype in their progeny.     

Programmed metabolic syndrome: prenatal undernutrition and postweaning overnutrition

Maternal nutrient restriction results in intrauterine growth restriction (IUGR) newborns that develop obesity despite normal postweaning diet. The epidemic of metabolic syndrome is attributed to programmed "thrifty phenotype" and exposure to Western diets. We hypothesized that programmed IUGR newborns would demonstrate greater susceptibility to obesity and metabolic abnormalities in response to high-fat diet. From day 10 to term gestation and lactation, control pregnant rats received ad libitum (AdLib) food, whereas study rats were 50% food restricted (FR). Cross-fostering techniques resulted in three offspring groups: control (AdLib/AdLib), FR during pregnancy (FR/AdLib), and FR during lactation (AdLib/FR). At 3 weeks, offspring were weaned to laboratory chow or high-fat calorie diet (9% vs. 17% calorie as fat). Body composition, appetite hormones, and glucose and lipid profiles were determined in 9-mo-old male and female offspring. High-fat diet had no effect on body weight of AdLib/AdLib, but significantly increased weights of FR/AdLib and AdLib/FR offspring. High-fat diet significantly increased body fat, reduced lean body mass, and accentuated plasma leptin but not ghrelin levels in both sexes in all groups. In males, high-fat diet caused a significant increase in glucose levels in all three groups with increased insulin levels in AdLib/AdLib and AdLib/FR, but not in FR/AdLib. In females, high-fat diet had no effect on glucose but significantly increased basal insulin among all three groups. High-fat diet caused hypertriglyceridemia in all three groups although only food-restricted females exhibited hypercholesterolemia. Sex and offspring phenotype-associated effects of high-fat diet indicate differing pathophysiologic mechanisms that require specific therapeutic approaches.     

Prevention of diet-induced obesity and impaired glucose tolerance in rats following administration of leptin to their mothers

Absence of leptin is known to disrupt the development of energy balance regulatory mechanisms. We investigated whether administration of leptin to normally nourished rats affects energy balance in their offspring. Leptin (2 mg.kg(-1).day(-1)) was administered from day 14 of pregnancy and throughout lactation. Male and female offspring were fed either on chow or on high-fat diets that elicited similar levels of obesity in the sexes from 6 wk to 15 mo of age. Treatment of the dams with leptin prevented diet-induced increases in the rate of weight gain, retroperitoneal fat pad weight, area under the intraperitoneal glucose tolerance curve, and fasting plasma insulin concentration in female offspring. In the male offspring, the diet-induced increase in weight gain was prevented and increased fat pad weight was reduced. Energy intake per rat was higher in response to the obesogenic diet in male offspring of saline-treated but not leptin-treated dams. A similar trend was seen in 3-mo-old female offspring. Energy expenditure at 3 mo of age was higher for a given body weight in female offspring of leptin-treated compared with saline-treated dams when these animals were fed on the obesogenic diet. A similar trend was seen for male rats fed on the obesogenic diet. Thus leptin levels during pregnancy and lactation can affect the development of energy balance regulatory systems in their offspring.     

Effects of fructose and glucose on plasma leptin, insulin, and insulin resistance in lean and VMH-lesioned obese rats

To determine the influence of dietary fructose and glucose on circulating leptin levels in lean and obese rats, plasma leptin concentrations were measured in ventromedial hypothalamic (VMH)-lesioned obese and sham-operated lean rats fed either normal chow or fructose- or glucose-enriched diets (60% by calories) for 2 wk. Insulin resistance was evaluated by the steady-state plasma glucose method and intravenous glucose tolerance test. In lean rats, glucose-enriched diet significantly increased plasma leptin with enlarged parametrial fat pad, whereas neither leptin nor fat-pad weight was altered by fructose. Two weeks after the lesions, the rats fed normal chow had marked greater body weight gain, enlarged fat pads, and higher insulin and leptin compared with sham-operated rats. Despite a marked adiposity and hyperinsulinemia, insulin resistance was not increased in VMH-lesioned rats. Fructose brought about substantial insulin resistance and hyperinsulinemia in both lean and obese rats, whereas glucose led to rather enhanced insulin sensitivity. Leptin, body weight, and fat pad were not significantly altered by either fructose or glucose in the obese rats. These results suggest that dietary glucose stimulates leptin production by increasing adipose tissue or stimulating glucose metabolism in lean rats. Hyperleptinemia in VMH-lesioned rats is associated with both increased adiposity and hyperinsulinemia but not with insulin resistance. Dietary fructose does not alter leptin levels, although this sugar brings about hyperinsulinemia and insulin resistance, suggesting that hyperinsulinemia compensated for insulin resistance does not stimulate leptin production.     

Long-term consequences of maternal high-fat feeding on hypothalamic leptin sensitivity and diet-induced obesity in the offspring

Epidemiological and animal studies suggest that the alteration of hormonal and metabolic environment during fetal and neonatal development can contribute to development of metabolic syndrome in adulthood. In this paper, we investigated the impact of maternal high-fat (HF) diet on hypothalamic leptin sensitivity and body weight gain of offspring. Adult Wistar female rats received a HF or a control normal-fat (C) diet for 6 wk before gestation until the end of the suckling period. After weaning, pups received either C or HF diet during 6 wk. Body weight gain and metabolic and endocrine parameters were measured in the eight groups of rats formed according to a postweaning diet, maternal diet, and gender. To evaluate hypothalamic leptin sensitivity in each group, STAT-3 phosphorylation was measured in response to leptin or saline intraperitoneal bolus. Pups exhibited similar body weights at birth, but at weaning, those born to HF dams weighed significantly less (-12%) than those born to C dams. When given the HF diet, males and females born to HF dams exhibited smaller body weight and feed efficiency than those born to C dams, suggesting increased energy expenditure programmed by the maternal HF diet. Thus, maternal HF feeding could be protective against adverse effects of the HF diet as observed in male offspring of control dams: overweight (+17%) with hyperleptinemia and hyperinsulinemia. Furthermore, offspring of HF dams fed either C or HF diet exhibited an alteration in hypothalamic leptin-dependent STAT-3 phosphorylation. We conclude that maternal high-fat diet programs a hypothalamic leptin resistance in offspring, which, however, fails to increase the body weight gain until adulthood.     

Maternal diet-induced obesity during suckling period programs offspring obese phenotype and hypothalamic leptin/insulin resistance

During the early post-natal period, offspring are vulnerable to environmental insults, such as nutritional and hormonal changes, which increase risk to develop metabolic diseases later in life. Our aim was to understand whether maternal obesity during lactation programs offspring to metabolic syndrome and obese phenotype, in addition we aimed to assess the peripheral glucose metabolism and hypothalamic leptin/insulin signaling pathways. At delivery, female Wistar rats were randomly divided in two groups: Control group (CO), mothers fed a standard rodent chow (Nuvilab); and Diet-induced obesity group (DIO), mothers who had free access to a diet performed with 33% ground standard rodent chow, 33% sweetened condensed milk (Nestlé), 7% sucrose and 27% water. Maternal treatment was performed throughout suckling period. All offspring received standard rodent chow from weaning until 91-day-old. DIO dams presented increased total body fat and insulin resistance. Consequently, the breast milk from obese dams had altered composition. At 91-day-old, DIO offspring had overweight, hyperphagia and higher adiposity. Furthermore, DIO animals had hyperinsulinemia and insulin resistance, they also showed pancreatic islet hypertrophy and increased pancreatic β-cell proliferation. Finally, DIO offspring showed low ObRb, JAK2, STAT-3, IRβ, PI3K and Akt levels, suggesting leptin and insulin hypothalamic resistance, associated with increased of hypothalamic NPY level and decreased of POMC. Maternal obesity during lactation malprograms rat offspring to develop obesity that is associated with impairment of melanocortin system. Indeed, rat offspring displayed glucose dyshomeostasis and both peripheral and central insulin resistance.     

Hepatic insulin binding following in utero exposure to ethanol

Insulin binding to liver membranes has been studied in term fetuses of rats fed ethanol-containing liquid diet during pregnancy . Pair-fed and ad libitum-fed controls received liquid diet in which maltose-dextrins were substituted isocalorically for ethanol. Food consumption and body weigh gain of ethanol- imbibing dams were 35% and 70% less than their ad libitum counterparts respectively. Ethanol-fed rats also exhibited less gain in body weight than pair-fed controls despite isocalorically equivalent food intake. The number of live pups was not different among the various groups; however, liver weight of fetuses exposed to ethanol in utero was 47% less than those of the pups of ad libitum control dams and 28% less than those of the offspring of pair-fed control rats. Insulin binding to liver membranes of fetuses exposed to ethanol in utero was lower than that of ad libitum controls but was not significantly different from that of the pair-fed control animals. Average affinity profiles showed a reduction in K at all levels of receptor occupancy in the fetuses of ethanol-fed rats. For fetuses of the pair-fed group, K was reduced only at fractional occupancy below 20% but not at higher fractional occupancy. Because of the similarity of insulin binding in the fetuses of the ethanol-fed rats and their pair-fed counterparts, effects of ethanol on insulin binding cannot account for the reduced hepatic glycogen stores previously reported in term fetuses.     

Perigestational suppression of weight gain with central leptin gene therapy results in lower weight F1 generation

The efficacy of central leptin therapy on weight homeostasis through various phases of reproduction, pregnancy outcome and postnatal, prepubertal and pubertal growth of offspring was assessed. Enhanced leptin transgene expression after a single intracerebroventricular injection of recombinant adeno-associated virus vector encoding the leptin gene (rAAV-lep) decreased calorie intake and weight in adult nulliparous female rats. rAAV-lep treated rats conceived normally, displayed unremarkable pregnancy rate, parturition and delivered normal sized litters. Significantly lower weight was maintained through gestation, lactation, and post-lactation periods. The maintenance of a modest weight reduction was accompanied by voluntarily reduced calorie intake, increased thermogenic energy expenditure, decreased adiposity as reflected by drastically reduced leptin levels, and suppressed insulin and insulin-like growth factor 1 levels through lactation and post-lactation in rAAV-lep treated dams. The offspring at birth weighed significantly less than those of controls and this lower weight range was sustained during postnatal, prepubertal, pubertal and adult (3 months old) periods, contemporaneous with metabolic circulating hormones in the normal range. For the first time we show the persistent efficacy of central leptin gene therapy to suppress weight gain through all phases of reproduction, lactation and post-lactation in dams and reveal the potential imprinting link to producing lower weight in the F1 generation.     

Maternal high-fat diet consumption results in fetal malprogramming predisposing to the onset of metabolic syndrome-like phenotype in adulthood

Chronic consumption of a high-fat (HF) diet by female rats in their postweaning period resulted in significant increases in body weight and plasma levels of insulin, glucose, and triglycerides during pregnancy compared with female rats consuming a standard rodent laboratory chow (LC). On gestational day 21, plasma insulin levels and the insulin secretory response of islets to various secretogogues were significantly increased in HF fetuses. The HF male progeny weaned onto LC (HF/LC) demonstrated increases in body weight from postnatal day 60 onward. In adulthood, HF/LC male rats were significantly heavier than controls, had increased plasma levels of insulin, glucose, free fatty acids, and triglycerides, and demonstrated glucose intolerance. HF/LC male islets secreted increased amounts of insulin in response to low glucose concentrations, but their response to a high glucose concentration was similar to that of LC/LC islets. In another set of experiments, when the male progeny of HF female rats were weaned onto a high-sucrose diet (HF/HSu), their metabolic profile was further worsened. These results indicate that chronic consumption of a HF diet by female rats malprograms the male progeny for glucose intolerance and development of increased body weight in adulthood. The long-term high-fat feeding to female rats employed in this study bears resemblance to the dietary habits in Western societies. The results of this study implicate dietary practices of women in the etiology of the present epidemic of human obesity and related disorders.     

Autonomic involvement in the permanent metabolic programming of hyperinsulinemia in the high-carbohydrate rat model

Exposure to a high-carbohydrate (HC) milk formula during the suckling period results in permanent metabolic programming of hyperinsulinemia in HC rats. Previous studies have shown that hyperinsulinemia in HC rats involves a programmed hyperresponsiveness to glucose. However, the immediate onset and persistence of enhanced insulin secretion throughout life suggests a role for numerous factors that control insulin secretion. Present in vivo and in vitro studies have shown a role for altered autonomic activity, including increased parasympathetic and decreased sympathetic activities, in the maintenance of hyperinsulinemia in 100-day-old HC rats. HC rats were shown to be more sensitive to cholinergic-induced potentiation of glucose-stimulated insulin secretion (GSIS) in response to acetylcholine and showed increased sensitivity to blockade of cholinergic-induced insulin secretion by the muscarinic-type 3 receptor-specific antagonist 4-diphenylacetoxy-N-methylpiperidine. In addition, HC rats were less sensitive to adrenergic-induced inhibition of insulin secretion by oxymetazoline, whereas treatment with yohimbine resulted in increased GSIS. Furthermore, HC rats showed greater reductions in plasma insulin levels after vagotomy, as well as an attenuation of yohimbine-induced potentiation of GSIS, suggesting that yohimbine-mediated changes are mediated by parasympathetic activity. Changes in autonomic regulation of GSIS are supported by increased mRNA levels of the parasympathetic signaling molecules muscarinic-type 3 receptor, phospholipase Cbeta1, and protein kinase C-alpha and decreased levels of alpha(2a)-adrenergic receptors in islets from adult HC rats. In conclusion, metabolic programming of hyperinsulinemia throughout adulthood of HC rats involves changes in autonomic activity in response to the HC dietary intervention in the suckling period.     

Role of the autonomic nervous system in the development of hyperinsulinemia by high-carbohydrate formula feeding to neonatal rats

An early dietary intervention in the form of a high-carbohydrate (HC) milk formula in neonatal rat pups results in immediate onset of hyperinsulinemia. While increased insulin secretion in HC rats has been shown to be related to hypersensitivity to glucose, the immediate onset of hyperinsulinemia and its persistence throughout the suckling period suggest involvement of multiple systems that enhance insulin secretion in response to increased demand. Evidence presented here in 12-day-old HC rats indicates that altered activity of the autonomic nervous system contributes to enhanced insulin secretory responses to glucose stimulation through increased parasympathetic and decreased sympathetic signaling. Both in vivo and in vitro studies have shown that HC rats secrete significantly higher levels of insulin in response to glucose in the presence of acetylcholine, a cholinergic agonist, while sensitivity to inhibition of insulin secretion by oxymetazoline, an alpha(2a)-adrenergic receptor (alpha(2a)AR) agonist, was reduced. In addition, HC rats showed increased sensitivity to blockade of cholinergic-induced insulin secretion by the muscarinic type 3 receptor (M3R) antagonist 4-diphenylacetoxy-N-methylpiperidine methobromide, as well as increased potentiation of glucose-stimulated insulin secretion by treatment with yohimbine. Increases in islets levels of M3R, phospholipase C-beta1, and protein kinase Calpha mRNAs, as well as decreased alpha(2a)AR mRNA, in 12-day-old HC rats provide a mechanistic connection to the changes in insulin secretion seen in HC rats. In conclusion, altered autonomic regulation of insulin secretion, due to the HC nutritional intervention, contributes to the development of hyperinsulinemia in 12-day-old HC rats.     

Excess of Methyl Donor in the Perinatal Period Reduces Postnatal Leptin Secretion in Rat and Interacts with the Effect of Protein Content in Diet

Methionine, folic acid, betaine and choline interact in the one-carbon metabolism which provides methyl groups for methylation reactions. An optimal intake of these nutrients during pregnancy is required for successful completion of fetal development and evidence is growing that they could be involved in metabolic long-term programming. However, the biological pathways involved in the action of these nutrients are still poorly known. This study investigated the interaction between methyl donors and protein content in maternal diet during the preconceptual, pregnancy and lactation periods and the consequences on the rat offspring in the short and long term. Methyl donor supplementation reduced leptin secretion in offspring, whereas insulin levels were mostly affected by protein restriction. The joint effect of protein restriction and methyl donor excess strongly impaired postnatal growth in both gender and long term weight gain in male offspring only, without affecting food intake. In addition, rats born from protein restricted and methyl donor supplemented dams gained less weight when fed a hypercaloric diet. Methylation of the leptin gene promoter in adipose tissue was increased in methyl donor supplemented groups but not affected by protein restriction only. These results suggest that maternal methyl donor supplementation may influence energy homeostasis in a gender-dependent manner, without affecting food intake. Moreover, we showed that macronutrients and micronutrients in maternal diet interact to influence the programming of the offspring.     

Effect of high-fat diet during gestation, lactation, or postweaning on physiological and behavioral indexes in borderline hypertensive rats

Maternal obesity is becoming more prevalent. We used borderline hypertensive rats (BHR) to investigate whether a high-fat diet at different stages of development has adverse programming consequences on metabolic parameters and blood pressure. Wistar dams were fed a high- or low-fat diet for 6 wk before mating with spontaneously hypertensive males and during the ensuing pregnancy. At birth, litters were fostered to a dam from the same diet group as during gestation or to the alternate diet condition. Female offspring were weaned on either control or "junk food" diets until about 6 mo of age. Rats fed the high-fat junk food diet were hyperphagic relative to their chow-fed controls. The junk food-fed rats were significantly heavier and had greater fat pad mass than those rats maintained on chow alone. Importantly, those rats suckled by high-fat dams had heavier fat pads than those suckled by control diet dams. Fasting serum leptin and insulin levels differed as a function of the gestational, lactational, and postweaning diet histories. Rats gestated in, or suckled by high-fat dams, or maintained on the junk food diet were hyperleptinemic compared with their respective controls. Indirect blood pressure did not differ as a function of postweaning diet, but rats gestated in the high-fat dams had lower mean arterial blood pressures than those gestated in the control diet dams. The postweaning dietary history affected food-motivated behavior; junk food-fed rats earned less food pellets on fixed (FR) and progressive (PR) ratio cost schedules than chow-fed controls. In conclusion, the effects of maternal high-fat diet during gestation or lactation were mostly small and transient. The postweaning effects of junk food diet were evident on the majority of the parameters measured, including body weight, fat pad mass, serum leptin and insulin levels, and operant performance.     

F-DIO obesity-prone rat is insulin resistant before obesity onset

We previously created a novel F-DIO rat strain derived by crossing rats selectively bred for the diet-induced obesity (DIO) phenotype with obesity-resistant Fischer F344 rats. The offspring retained the DIO phenotype through 3 backcrosses with F344 rats but also had exaggerated insulin responses to oral glucose before they became obese on a 31% fat high-energy (HE) diet. Here, we demonstrate that chow-fed rats from the subsequent randomly bred progeny required 57% lower glucose infusions to maintain euglycemia during a hyperinsulinemic clamp in association with 45% less insulin-induced hepatic glucose output inhibition and 80% lower insulin-induced glucose uptake than F344 rats. The DIO phenotype and exaggerated insulin response to oral glucose in the nonobese, chow-fed state persisted in the F6 generation. Also, compared with F344 rats, chow-fed F-DIO rats had 68% higher arcuate nucleus proopiomelanocortin mRNA expression which, unlike the increase in F344 rats, was decreased by 26% on HE diet. Further, F-DIO lateral hypothalamic orexin expression was 18% lower than in F344 rats and was increased rather than decreased by HE diet intake. Finally, both maternal obesity and 30% caloric restriction during the third week of gestation produced F-DIO offspring which were heavier and had higher leptin and insulin levels than lean F-DIO dam offspring. Third-gestational week dexamethasone also produced offspring with higher leptin and insulin levels but with lower body weight. Thus F-DIO rats represent a novel and potentially useful model for the study of DIO, insulin resistance, and perinatal factors that influence the development and persistence of obesity.     

Abnormal glucose homeostasis in adult female rat offspring after intrauterine ethanol exposure

Adverse events during pregnancy, including prenatal ethanol (EtOH) exposure, are associated with insulin-resistant diabetes in male rat offspring, but it is unclear whether this is true for female offspring. We investigated whether prenatal EtOH exposure alters glucose metabolism in adult female rat offspring and whether this is associated with reduced in vivo insulin signaling in skeletal muscle. Female Sprague-Dawley rats were given EtOH, 4 g.kg(-1).day(-1) by gavage throughout pregnancy. Glucose tolerance test and hyperinsulinemic euglycemic clamp were performed, and insulin signaling was investigated in skeletal muscle, in adult female offspring. We gave insulin intravenously to these rats and determined the association of glucose transporter-4 with plasma membranes, as well as the phosphorylation of phosphoinositide-dependent protein kinase-1 (PDK1), Akt, and PKCzeta. Although EtOH offspring had normal birth weight, they were overweight as adults and had fasting hyperglycemia, hyperinsulinemia, and reduced insulin-stimulated glucose uptake. After insulin treatment, EtOH-exposed rats had decreased membrane glucose transporter-4, PDK1, Akt, and PKCzeta in the gastrocnemius muscle, compared with control rats. Insulin stimulation of PDK1, Akt, and PKCzeta phosphorylation was also reduced. In addition, the expression of the protein tribbles-3 and the phosphatase enzyme activity of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), which prevent Akt activation, were increased in muscle from EtOH-exposed rats. Female rat offspring exposed to EtOH in utero develop insulin-resistant diabetes in association with excessive PTEN and tribbles-3 signaling downstream of the phosphatidylinositol 3-kinase pathway in skeletal muscle, which may be a mechanism for the abnormal glucose tolerance.     

Postnatal early overfeeding induces hypothalamic higher SOCS3 expression and lower STAT3 activity in adult rats

Postnatal early overnutrition (EO) is a risk factor for future obesity and metabolic disorders. Rats raised in small litters (SLs) develop overweight, hyperphagia, hyperleptinemia, hyperinsulinemia and hypertension when adults. As obesity is related to hyperleptinemia, leptin resistance and metabolic syndrome, we aimed to investigate body composition, plasma hormone levels, glucose tolerance and the leptin signaling pathway in hypothalamus from early overfed animals at weaning and adulthood. To induce postnatal EO, we reduced litter size to three pups/litter (SL), and the groups with normal litter size (10 pups/litter) were used as control. Rats had free access to standard diet and water postweaning. Body weight and food intake were monitored daily, and offspring were killed at 21 (weaning) and 180 days old (adulthood). Postnatal EO group had higher body weight and total and visceral fat mass at both periods. Lean mass and serum high-density lipoprotein cholesterol (HDL-C) were higher at 21 days and lower at 180 days. Small litter rats presented higher levels of globulins at both periods, while albumin levels were higher at weaning and lower at adulthood. There was higher leptin, insulin and glucose serum concentrations at 21 days old, while no glucose intolerance was observed in adulthood. Leptin signaling pathway was unaffected at weaning. However, postnatal EO induced lower JAK2 and p-STAT3, and higher SOCS3 expression in adult animals, indicating central leptin resistance in adulthood. In conclusion, postnatal EO induces obesity, higher total and visceral fat mass, lower HDL-C and central leptin resistance in adult life.     

Association between maternal and child leptin levels 9 years after pregnancy complicated by gestational diabetes.

Obesity is a state of relative leptin resistance, and obesity in childhood is associated with an increased incidence of type 2 diabetes in later life. Offspring of mothers with gestational diabetes mellitus (GDM) are at increased risk of obesity. A cohort consisting of 64 mothers, 33 GDM and 31 controls screened for diabetes during the index pregnancy together with their 9-year-old offspring were studied. Our hypotheses were: 1) an elevated child leptin is associated with elevated maternal leptin in GDM mothers 9 years post delivery; and 2) child leptin at 9 years serves as a marker for incipient insulin resistance. By univariate analyses, child leptins were only significantly correlated with maternal leptins among the offspring of GDMs (OGDM) (r = 0.59; p = 0.001). By multivariate analyses, child leptin for the total study group was significantly associated with child body mass index (BMI) (R(2) = 0.65; p < 0.0001), child fasting insulin (R(2) = 0.08; p = 0.03), and female gender (R(2) = 0.28; p = 0.001). In addition, among OGDM child leptin was associated with maternal leptin (R(2) = 0.14; p = 0.005). Our results suggest that there is an association between maternal and child leptin levels 9 years after a pregnancy complicated by gestational diabetes.     

Protein calorie restriction has opposite effects on glucose metabolism and insulin gene expression in fetal and adult rat endocrine pancreas

We previously demonstrated that fetuses from undernourished pregnant rats exhibited increased beta-cell mass and hyperinsulinemia, whereas keeping food restriction until adult age caused reduced beta-cell mass, hypoinsulinemia, and decreased insulin secretion. Because these alterations can be related to insulin availability, we have now investigated early and long-term effects of protein calorie food restriction on insulin mRNA levels as well as the possible mechanisms that could modulate the endogenous insulin mRNA content. We used fetuses at 21.5 days of gestation proceeding from food-restricted rats during the last week of pregnancy and 70-day-old rats undernourished from day 14 of gestation until adult age and with respective controls. Insulin mRNA levels, glucose transporters, and total glycolysis and mitochondrial oxidative fluxes were evaluated. We additionally analyzed undernutrition effects on signals implicated in glucose-mediated insulin gene expression, especially pancreatic duodenal homeobox-1 (PDX-1), stress-activated protein kinase-2 (p38/SAPK2), and phosphatidylinositol 3-kinase. Undernourished fetuses showed increased insulin mRNA, oxidative glucose metabolism, and p38/SAPK2 levels, whereas undernutrition until adult age provoked a decrease in insulin gene expression, oxidative glucose metabolism, and PDX-1 levels. The results indicate that food restriction caused changes in insulin gene expression and content leading to alterations in glucose-stimulated insulin secretion. The molecular events, increased p38/SAPK2 levels in fetuses and decreased PDX-1 levels in adults, seem to be the responsible for the altered insulin mRNA expression. Moreover, because PDX-1 activation appears to be regulated by glucose-derived metabolite(s), the altered glucose oxidation caused by undernutrition could in some manner affect insulin mRNA expression.