Early Postnatal Overfeeding Research Articles

Citrus aurantium L. and synephrine improve brown adipose tissue function in adolescent mice programmed by early postnatal overfeeding.

Obesity is a multifactorial condition with high health risk, associated with important chronic disorders such as diabetes, dyslipidemia, and cardiovascular dysfunction. Citrus aurantium L. (C. aurantium) is a medicinal plant, and its active component, synephrine, a β-3 adrenergic agonist, can be used for weight loss. We investigated the effects of C. aurantium and synephrine in obese adolescent mice programmed by early postnatal overfeeding. Three days after birth, male Swiss mice were divided into a small litter (SL) group (3 pups) and a normal litter (NL) group (9 pups). At 30 days old, SL and NL mice were treated with C. aurantium standardized to 6% synephrine, C. aurantium with 30% synephrine, isolated synephrine, or vehicle for 19 days. The SL group had a higher body weight than the NL group. Heart rate and blood pressure were not elevated. The SL group had hyperleptinemia and central obesity that were normalized by C. aurantium and synephrine. In brown adipose tissue, the SL group showed a higher lipid droplet sectional area, less nuclei, a reduction in thermogenesis markers related to thermogenesis (UCP-1, PRDM16, PGC-1α and PPARg), and mitochondrial disfunction. C. aurantium and synephrine treatment normalized these parameters. Our data indicates that the treatment with C. aurantium and synephrine could be a promising alternative for the control of some obesity dysfunction, such as improvement of brown adipose tissue dysfunction and leptinemia.

Overfeeding in the early postnatal period aggravates inflammation and hepatic insulin sensitivity in the 5α-dihydrotestosterone-induced animal model of PCOS.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age and is closely associated with chronic low-grade inflammation and insulin resistance. To clarify the contribution of prepubertal weight gain to the development of insulin resistance in PCOS, we investigated the effects of early postnatal overfeeding on inflammatory and energy-sensing pathways as well as on markers of insulin signaling in the liver of the PCOS rat model. Obesity induced by overfeeding was achieved by reducing litter size, while the PCOS-like condition was developed by treatment with 5α-dihydrotestosterone (DHT). Western blot and qPCR were used to analyze the expression of pro-inflammatory transcription factors and cytokines, as well as markers of the energy sensing and insulin signaling pathways. The results showed that hepatic insulin sensitivity was impaired only in DHT-treated rats raised in small litters, as evidenced by increased phosphorylation of IRS1 on Ser307 and decreased expression of total IRS1. Postnatal overfeeding stimulated JNK1 activation independent of hyperandrogenemia; nevertheless, the synergistic effect of both factors triggered NLRP3 activation and increased IL1β expression in the small litter DHT-treated group. This pro-inflammatory state was accompanied by decreased activatory phosphorylation of AMPK and reduced levels of its protein targets. Overfeeding in the early postnatal period leads to a decrease in hepatic insulin sensitivity in the rat model of PCOS, which is associated with decreased activation of AMPK and stimulation of the hepatic NLRP3-IL1β signaling pathway. Accordingly, the inhibition of NLRP3 activation could provide a basis for the development of new therapeutic strategies for the treatment of insulin resistance in women with PCOS.

AMPK Activation as a Protective Mechanism to Restrain Oxidative Stress in the Insulin-Resistant State in Skeletal Muscle of Rat Model of PCOS Subjected to Postnatal Overfeeding.

Polycystic ovary syndrome (PCOS) is a common endocrinopathy in women of reproductive age, often associated with obesity and insulin resistance. Childhood obesity is an important predisposing factor for the development of PCOS later in life. Being particularly interested in the interplay between prepubertal obesity and hyperandrogenemia, we investigated the effects of early postnatal overfeeding, accomplished by reducing litter size during the period of suckling, on energy sensing and insulin signaling pathways in the gastrocnemius muscle of a rat model of PCOS-induced by 5α-dihydrotestosterone (DHT). The combination of overfeeding and DHT treatment caused hyperinsulinemia and decreased systemic insulin sensitivity. Early postnatal overfeeding induced defects at critical nodes of the insulin signaling pathway in skeletal muscle, which was associated with reduced glucose uptake in the presence of hyperandrogenemia. In this setting, under a combination of overfeeding and DHT treatment, skeletal muscle switched to mitochondrial β-oxidation of fatty acids, resulting in oxidative stress and inflammation that stimulated AMP-activated protein kinase (AMPK) activity and its downstream targets involved in mitochondrial biogenesis and antioxidant protection. Overall, a combination of overfeeding and hyperandrogenemia resulted in a prooxidative and insulin-resistant state in skeletal muscle. This was accompanied by the activation of AMPK, which could represent a potential therapeutic target in insulin-resistant PCOS patients.

Dietary curcumin supplementation promotes browning and energy expenditure in postnatal overfed rats

BackgroundEarly postnatal overfeeding could result in metabolic imprinting that decreases energy expenditure following white adipose tissue (WAT) gain throughout life. This research investigated whether curcumin (CUR) supplementation could promote WAT browning and activate thermogenesis in postnatal overfed rats.Methods and resultsThis study adjusted the size of litters to three (small litters, SL) or ten (normal litters, NL) to mimic early postnatal overfeeding or normal feeding from postnatal day 3. From postnatal week 3 (weaning period), SL rats were fed a standard diet (SL) or a diet supplemented with 1% (SL1% CUR) or 2% (SL2% CUR) CUR for ten weeks. At postnatal week 13, SL rats with 1% or 2% CUR supplementation had lower body weight and less WAT gain and had an increased lean mass ratio, and their glucose tolerance and blood lipid levels had recovered to normal when compared to SL rats that did not receive the supplement. Moreover, the increased heat generation were consistent with the expression levels of uncoupling protein 1 (UCP1) and other browning-related genes in the subcutaneous adipose tissue (SAT) of the SL2% CUR rats but not in the SL1% CUR rats. In addition, 2% CUR dietary supplementation enhanced the serum norepinephrine levels in SL rats, with upregulated mRNA levels of β3-adrenergic receptor (β3-AR) in SAT.ConclusionDietary CUR supplementation attenuates body fat gain and metabolic disorders in SL, which might be induced by promoting browning of SAT and energy expenditure. Moreover, the benefits were more obvious in SL with 2% CUR supplementation.

Lean in one way, in obesity another: effects of moderate exercise in brown adipose tissue of early overfed male Wistar rats.

Early postnatal overfeeding (PO) induces long-term overweight and reduces brown adipose tissue (BAT) thermogenesis. Exercise has been suggested as a possible intervention to increase BAT function. In this study, we investigated chronical effects of moderate-intensity exercise in BAT function in postnatal overfed male Wistar rats METHODS: Litters' delivery was on postnatal-day 0 - PN0. At PN2, litters were adjusted to nine (normal litter - NL) or three pups (small litter - SL) per dam. Animals were weaned on PN21 and in PN30 randomly divided into sedentary (NL-Sed and SL-Sed) or exercised (NL-Exe and SL-Exe), N of 14 litters per group. Exercise protocol started (PN30) with an effort test; training sessions were performed three times weekly at 60% of the VO2max achieved in effort test, until PN80. On PN81, a temperature transponder was implanted beneath the interscapular BAT, whose temperature was assessed in periods of lights-on and -off from PN87 to PN90. Sympathetic nerve activation of BAT was registered at PN90. Animals were euthanized at PN91 and tissues collected RESULTS: PO impaired BAT thermogenesis in lights-on (pPO < 0.0001) and -off (pPO < 0.01). Exercise increased BAT temperature in lights-on (pExe < 0.0001). In NL-Exe, increased BAT activity was associated with higher sympathetic activity (pExe < 0.05), β3-AR (pExe < 0.001), and UCP1 (pExe < 0.001) content. In SL-Exe, increasing BAT thermogenesis is driven by a combination of tissue morphology remodeling (pExe < 0.0001) with greater effect in increasing UCP1 (pExe < 0.001) and increased β3-AR (pExe < 0.001) content. Moderate exercise chronically increased BAT thermogenesis in both, NL and SL groups. In NL-Exe by increasing Sympathetic activity, and in SL-Exe by a combination of increased β3-AR and UCP1 content with morphologic remodeling of BAT. Chronically increasing BAT thermogenesis in obese subjects may lead to higher overall energy expenditure, favoring the reduction of obesity and related comorbidities.

Renal Programming by Transient Postnatal Overfeeding: The Role of Senescence Pathways.

BackgroundEarly nutrition influences the risk of chronic kidney diseases (CKDs) development in adulthood. Mechanisms underlying the early programming of altered renal function remain incompletely understood. This study aims at characterizing the role of cell senescence pathways in early programming of CKD after transient postnatal overfeeding.Materials and MethodsReduced litters of 3 mice pups and standard litters of 9 mice pups were obtained to induce overfed animals during lactation and control animals, respectively. Animals were sacrificed at 24 days (weaning) or at 7 months of life (adulthood). Body weight, blood pressure, kidney weight, and glomerular count were assessed in both groups. Senescence pathways were investigated using β-Galactosidase staining and Western blotting of P16, P21, P53, P-Rb/Rb, and Sirtuin 1 (Sirt1) proteins.ResultsEarly overfed animals had a higher body weight, a higher blood pressure at adulthood, and a higher glomerular number endowment compared to the control group. A higher β-Galactosidase activity, a significant increase in P53 protein expression (p = 0.0045) and a significant decrease in P-Rb/Rb ratio (p = 0.02), were observed at weaning in animals who underwent early postnatal overfeeding. Protein expression of Sirt1, a protective factor against accelerated stress-induced senescence, was significantly decreased (p = 0.03) at weaning in early overfed animals.ConclusionEarly postnatal overfeeding by litter size reduction is associated with increased expression of factors involved in cellular senescence pathways, and decreased expression of Sirt 1 in the mouse kidney at weaning. These alterations may contribute to CKD programming after early postnatal overfeeding.

Postnatal overfeeding induces hepatic microRNA-221 expression and impairs the PI3K/AKT pathway in adult male rats.

Increasing evidence suggests that postnatal overfeeding induces childhood obesity, which is strongly associated with metabolic syndrome. Insulin resistance is a risk factor for metabolic syndrome. MicroRNA-221 (miR-221) is involved in the development of obesity and has been reported to negatively regulate insulin sensitivity. However, the underlying mechanism remains unclear. Rats raised in small litters (SLs, three pups/dam, n = 10) and normal litters (NLs, 10 pups/dam, n = 10) were used to model early postnatal overfeeding and act as controls, respectively. miR-221 and proteins related to the phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT) pathway were assessed in the liver. Early postnatal overfeeding significantly increased body weight, visceral fat index, blood glucose, serum triglycerides, and the homeostasis model assessment of insulin resistance at 9 weeks. Real-time polymerase chain reaction (PCR) and western blot analysis revealed that postnatal overfeeding induced insulin receptor and insulin receptor substrate 2 expression, but decreased PI3K and AKT phosphorylation in the liver. Quantitative real-time PCR showed that hepatic miR-221 was significantly overexpressed in the SL group. These results indicate that postnatal overfeeding induces hepatic miR-221 overexpression and impairs the PI3K/AKT signal pathway, which may cause insulin resistance. We first report postnatal overfeeding induces hepatic miR-221 expression. Postnatal overfeeding impairs PI3K/AKT pathway in the liver of adult rats. Postnatal overfeeding induces obesity and high blood glucose. Avoidance of overfeeding during early postnatal life may prevent obesity and T2DM.

Effects of Obesity on Pulmonary Inflammation and Remodeling in Experimental Moderate Acute Lung Injury.

Obese patients are at higher risk of developing acute respiratory distress syndrome (ARDS); however, their survival rates are also higher compared to those of similarly ill non-obese patients. We hypothesized that obesity would not only prevent lung inflammation, but also reduce remodeling in moderate endotoxin-induced acute lung injury (ALI). Obesity was induced by early postnatal overfeeding in Wistar rats in which the litter size was reduced to 3 pups/litter (Obese, n = 18); Control animals (n = 18) were obtained from unculled litters. On postnatal day 150, Control, and Obese animals randomly received E. coli lipopolysaccharide (ALI) or saline (SAL) intratracheally. After 24 h, echocardiography, lung function and morphometry, and biological markers in lung tissue were evaluated. Additionally, mediator expression in neutrophils and macrophages obtained from blood and bronchoalveolar lavage fluid (BALF) was analyzed. Compared to Control-SAL animals, Control-ALI rats showed no changes in echocardiographic parameters, increased lung elastance and resistance, higher monocyte phagocytic capacity, collagen fiber content, myeloperoxidase (MPO) activity, and levels of interleukin (IL-6), tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β, and type III (PCIII), and I (PCI) procollagen in lung tissue, as well as increased expressions of TNF-α and monocyte chemoattractant protein (MCP)-1 in blood and BALF neutrophils. Monocyte (blood) and macrophage (adipose tissue) phagocytic capacities were lower in Obese-ALI compared to Control-ALI animals, and Obese animals exhibited reduced neutrophil migration compared to Control. Obese-ALI animals, compared to Obese-SAL, exhibited increased interventricular septum thickness (p = 0.003) and posterior wall thickness (p = 0.003) and decreased pulmonary acceleration time to pulmonary ejection time ratio (p = 0.005); no changes in lung mechanics, IL-6, TNF-α, TGF-β, PCIII, and PCI in lung tissue; increased IL-10 levels in lung homogenate (p = 0.007); reduced MCP-1 expression in blood neutrophils (p = 0.009); decreased TNF-α expression in blood (p = 0.02) and BALF (p = 0.008) neutrophils; and increased IL-10 expression in monocytes (p = 0.004). In conclusion, after endotoxin challenge, obese rats showed less deterioration of lung function, secondary to anti-inflammatory and anti-fibrotic effects, as well as changes in neutrophil and monocyte/macrophage phenotype in blood and BALF compared to Control rats.

Effects of overfeeding in breastfeeding period on blood pressure and vascular endothelial dilation function of rats

Objective To study the effects of postnatal overfeeding and high-fat diet on blood pressure of rats, and to explore the pathophysiological mechanism underlying hypertension induced by continuous early postnatal overfeeding. Methods Male Sprague-Dawley rats were randomly divided into normal feeding group (10/litter) and overfeeding group (3/litter) on postnatal day 3 with a random number table. After weaning at postnatal week 3, the rats were randomly given standard chow or high-fat (HF) diet until week 16. Hence four groups were analyzed, namely normal feeding group, breastfed overfeeding group, post-weaning overfeeding group, and continuous overfeeding group. Body weight was continuously monitored in each week. Visceral fat pad(retroperitoneal and perigenital), systolic pressure, and heart rate were observed at week 3 and week 16. Thoracic aorta was sampled for measurement of vascular endothelial dilation function. Histological morphology was observed with HE staining, nitric oxide content of thoracic aorta was detected with nitrate reductase method. The mRNA expression of endothelial nitric oxide synthase (eNOS) in thoracic aorta was determined by real-time polymerase chain reaction. The protein expressions of eNOS and phosphorylated eNOS were determined by Western blot. Results At week 3, breastfed overfeeding rats displayed significantly larger body weight [(77.80±0.57) g vs. (62.80±0.85)g, t=14.576, P<0.01] and visceral fat [retroperitoneal: (8.19±0.49)mg/g vs. (4.92±0.31)mg/g, t=5.629, P<0.01; perigenital: (3.50±0.29)mg/g vs. (2.08±0.13)mg/g, t=4.552, P<0.01] compared with normal feedindg rats, and the protein expression of phosphorylated eNOS in aortic tissues was significantly reduced to week 16 (F=15.215, P<0.01); high-fat diet feeding after weaning further increased the body weight and fat mass in breastfed overfeeding rats. At week 16, continuous overfeeding rats showed hypertension [(149±1.94)mmHg (1 mmHg=0.133 kPa), F=22.834, P<0.01], impaired vascular endothelial dilation function (F=7.648, P<0.05), and reduced protein expression of phosphorylated eNOS(F=15.215, P<0.01), while the post-weaning overfeeding group only had elevated blood pressure. Conclusions Overfeeding in breastfeeding period and high-fat diet after weaning leads to hypertension. The continuous decrease in phosphorylated eNOS in vascular tissues may be an important molecular process participating in the occurrence of vascular endothelial dysfunction in adults induced by postnatal overfeeding. Key words: Early postnatal overfeeding; Vascular endothelial dilation function; Hypertension; Nitric oxide; Phosphorylated endothelial nitric oxide synthase

Perinatal overnutrition exacerbates adipose tissue inflammation caused by high-fat feeding in C57BL/6J mice.

Obesity causes white adipose tissue (WAT) inflammation and insulin resistance in some, but not all individuals. Here, we used a mouse model of early postnatal overfeeding to determine the role of neonatal nutrition in lifelong WAT inflammation and metabolic dysfunction. C57BL/6J mice were reared in small litters of 3 (SL) or normal litters of 7 pups (NL) and fed either regular chow or a 60% high fat diet (HFD) from 5 to 17 weeks. At weaning, SL mice did not develop WAT inflammation despite increased fat mass, although there was an up-regulation of WAT Arg1 and Tlr4 expression. On HFD, adult SL mice had greater inguinal fat mass compared to NL mice, however both groups showed similar increases in visceral fat depots and adipocyte hypertrophy. Despite the similar levels of visceral adiposity, SL-HFD mice displayed greater impairments in glucose homeostasis and more pronounced hepatic steatosis compared to NL-HFD mice. In addition, WAT from SL mice fed a HFD displayed greater crown-like structure formation, increased M1 macrophages, and higher cytokine gene expression. Together, these data suggest that early postnatal overnutrition may be a critical determinant of fatty liver and insulin resistance in obese adults by programming the inflammatory capacity of adipose tissue.

Litter size reduction alters insulin signaling in the ventral tegmental area and influences dopamine-related behaviors in adult rats

Postnatal overfeeding is a well-known model of early-life induced obesity and glucose intolerance in rats. However, little is known about its impact on insulin signaling in specific brain regions such as the mesocorticolimbic system, and its putative effects on dopamine-related hedonic food intake in adulthood. For this study, rat litters were standardized to 4 (small litter – SL) or 8 pups (control – NL) at postnatal day 1. Weaning was at day 21, and all tests were conducted after day 60 of life in male rats. In Experiment 1, we demonstrated that the SL animals were heavier than the NL at all time points and had decreased AKT/pAKT ratio in the Ventral Tegmental Area (VTA), without differences in the skeletal muscle insulin signaling in response to insulin injection. In Experiment 2, the standard rat chow intake was addressed using an automated system (BioDAQ, Research Diets®), and showed no differences between the groups. On the other hand, the SL animals ingested more sweet food in response to the 1min tail-pinch challenge and did not develop conditioned place preference to sweet food. In Experiment 3 we showed that the SL rats had increased VTA TH content but had no difference in this protein in response to a sweet food challenge, as the NL had. The SL rats also showed decreased levels of dopamine D2 receptors in the nucleus accumbens. Here we showed that early postnatal overfeeding was linked to an altered functioning of the mesolimbic dopamine pathway, which was associated with altered insulin signaling in the VTA, suggesting increased sensitivity, and expression of important proteins of the dopaminergic system.

Overweight, hypertension and renal dysfunction in adulthood of neonatally overfed rats

Accelerated growth in early infancy has been associated with later cardiovascular and metabolic diseases. We investigated the influence of overnutrition during neonatal periods on the development of renal pathophysiological changes in adult offspring rats. Three or 10 male pups per mother were assigned to either the small litter (SL) or normal litter (NL) control groups during the first 21 days of life. The effects of early postnatal overnutrition on body weight, blood pressure and renal changes were determined at 3 and 6 months. Pups in the SL group weighed more than controls between 7 days and 6 months of age (P<.05). In the SL group, serum creatinine levels were higher at 3 and 6 months (P<.05), and at 6 months, blood pressure levels were higher than those of the controls (P<.05). The number of ED-1 positive macrophages in renal cortex and glomerulosclerosis index increased in the SL group at 3 and 6 months (P<.05). Additionally, cortical apoptotic cells increased in the SL group at 6 months (P<.05). Immunoblotting and immunohistochemistry showed that matrix metalloproteinase (MMP)-9 protein expressions decreased and tissue inhibitor of MMP-1, tumor necrosis factor-α, osteopontin and adiponectin expressions increased in the SL group at 3 months (P<.05). However, at 6 months, MMP-9 expression was elevated, and osteopontin expression remained elevated in the SL group (P<.05). Early postnatal overfeeding can lead to lasting overweight, hypertension and renal dysfunction and place a greater burden on the kidney.

Intrauterine protein restriction combined with early postnatal overfeeding was not associated with adult-onset obesity but produced glucose intolerance by pancreatic dysfunction

We investigated if whether intrauterine protein restriction in combination with overfeeding during lactation would cause adult-onset obesity and metabolic disorders. After birth, litters from dams fed with control (17% protein) and low protein (6% protein) diets were adjusted to a size of four (CO and LO groups, respectively) or eight (CC and LC groups, respectively) pups. All of the offspring were fed a diet containing 12% protein from the time of weaning until they were 90 d old. Compared to the CC and LC groups, the CO and LO groups had higher relative and absolute food intakes, oxygen consumption and carbon dioxide production; lower brown adipose tissue weight and lipid content and greater weight gain and absolute and relative white adipose tissue weight and absolute lipid content. Compared with the CO and CC rats, the LC and LO rats exhibited higher relative food intake, brown adipose tissue weight and lipid content, reduced oxygen consumption, carbon dioxide production and spontaneous activity, increased relative retroperitoneal adipose tissue weight and unaltered absolute white adipose tissue weight and lipid content. The fasting serum glucose was similar among the groups. The area under the glucose curve was higher in the LO and CO rats than in the LC and CC rats. The basal insulinemia and homeostasis model assessment of insulin resistance (HOMA-IR) were lower in the LO group than in the other groups. The total area under the insulin curve for the LO rats was similar to the CC rats, and both were lower than the CO and LC rats. Kitt was higher in the LO, LC and CO groups than in the CC group. Thus, intrauterine protein restriction followed by overfeeding during lactation did not induce obesity, but produced glucose intolerance by impairing pancreatic function in adulthood.

Severe hyperglycemia during pregnancy and early overfeeding induce metabolic syndrome in adult offsprings in rats

Objective To explore the metabolic phenotype of the adult offspring rats with maternal severe hyperglycemia during pregnancy and overfeeding in early life. Methods The adult Wistar rats were administered intraperitoneally with 20% Streptozotocin （STZ, 50 rng/kg） on day 5 of pregnancy to induce severely gestational diabetes mellitus （SDM） model （blood glucose 20 mmol/L）. Early postnatal overfeeding models were established through reduction of the number of newborn rats fed by one mother rat. Offsprings were divided into 3 groups according to maternal blood glucose level during the pregnancy and feeding patterns during the lactation period （1） control pups （CP） ：maternal euglycemia was achieved during pregnancy and eight pups fed by one mother rat;（2） SDM-normal feeding group： SDM mothers and 8 pups fed by one mother rat; （3） SDM-overfeeding group：SDM mother and 4 pups fed by one mother rat. All pups were fed by standard laboratory chow adlibitum after weaning at 3 weeks of age. The body weight of all pups were measured weekly after weaning. At the age of 26 weeks, the systolic blood pressure （SBP）, diastolic blood pressure （DBP）, heart rate （HR） and metabolic markers, including fasting plasma glucose （FPG）, fasting insulin （FINS）, total triglyceride （TG）, total cholesterol （TC） , low density lipoprotein-cholestrol （LDL C） and high density lipoprotein-cholestrol （HDL C） were measured in all 3 groups. ANOVA and LSD test were applied in statistical analysis. Results The average plasma glucose level was significantly higher in the SDM mothers than in the controls [（28. 3±5.14） mmol/L vs （6.25±1.41） retool/L, P〈0. 05]. After weaning at 3 weeks, the weight of SDM-overfeeding group and SDM-normal feeding group was lighter than that of CP group [（43.63±4.83） g, （31.45±10.21） g vs （55.75±8.41） g, P〈0. 05], meanwhile, that of the SDM-overfeeding group were heavier than that of the SDM-normal feeding group （P〈 0.05）. Pups in SDM-overfeeding group exhibited catchup growth during the lactation period, and those in SDM normal group showed catchup growth at both lactation period and childhood. At 26 weeks of age, the systolic blood pressure and TG level of pups in SDM-normal feeding and overfeeding group were （153.31±13.91） mm Hg and （147.21± 12.29） mm Hg, and （0.73±0.22） mmol/L and （0.71±0.49） mmol/L, respectively, which were higher than those of the CP group[（132.21± 11.26） mm Hg, and （0.37 ± 0.08） mmol/L, P〈0.05], but no significant difference was found between the two SDM groups （P〉0.05）. There was no difference in FPG levels among the three groups, but the FINS level and HOMA IR in the SDM-overfeeding group were higher than in theSDM normal feeding and CP group [（12.552±3.260） mU/L vs （9.067±1.782） mU/L and （8. 590 ±0.806） mU/L, 2. 400 ± 0.624 vs 1. 797 ± 0.508 and 1.729 ± 0.246; P〈0.05]. Conclusions Fetal exposure to maternal severe hyperglycemia during pregnancy may lead to low birth weight infant who will exhibit postnatal catch-up growth. This may lead to the increased risk of metabolic syndrome in the offspings when they grow up, and this process would be accelerated by early overfeeding. Key words: Pregnancy complications; Hyperglycemia; Breast feeding; Rat; Metabolic syndrome X

Effects of severe hyperglycaemia in pregnancy and early overfeeding on islet development and insulin resistance

Study the effects of early overfeeding in the adult offspring of mother with severely hyperglycaemia in pregnancy to islet development and insulin resistance. Thirty healthy female Wistar rats were mated with 10 male Wistar rats and the morning on which sperm were found in three different visual fields of the vaginal smear was designated pregnancy day 1. The pregnant rats were intraperitoneally administered with Streptozotocin (STZ, 50 mg/L) on 5th day of pregnancy, and blood glucose exceeded 20 mmol/L to induce severely gestational diabetes mellitus (SDM) model. The pregnant Wistar rats were assigned to two experimental groups: SDM (n = 16) and control (n = 8). Litter size reduction in the lactation period induced early postnatal overfeeding model. Offspring were divided into three groups according to the level of blood glucose in pregnancy and feeding patterns in lactation: (1) control group (CG): euglycemia in pregnancy, eight pups in lactation; (2) severely gestational diabetes mellitus-normal feeding (SDM-N): severely gestational diabetes mellitus, eight pups in lactation; (3) severely gestational diabetes mellitus-overfeeding (SDM-O): severely gestational diabetes mellitus, four pups lactation. At the end of the lactation period, all pups were fed standard laboratory chow adlibitum until the date of the experiments. Offspring body weight was measured weekly after ablactation. Serum insulin was measured by enzyme-linked immunosorbent assay (ELISA) and pancreatic islet morphology was analyzed by immunohistochemistry (IHC) in all three groups at 26 weeks of age. (1) Blood glucose of pregnant Wistar rats: SDM (28.3 ± 5.1) mmol/L was statistically higher than control (6.3 ± 1.4) mmol/L (P < 0.05). (2) Growth rates of body weight in 3-7 weeks and 3-9 weeks: SDM-N: (4.6 ± 1.3)% and (6.8 ± 2.5)%, SDM-O: (3.2 ± 0.7)% and (4.6 ± 1.2)%, CG: (2.9 ± 0.6)% and (4.1 ± 0.8)%. The growth rates of body weight in SDM-N and SDM-O were both significantly higher than those in CG (P < 0.05). (3) Body weight at 26 weeks: CG: (486 ± 132) g, SDM-N: (387 ± 115) g, SDM-O: (382 ± 122) g. There was no statistical difference among the three groups (P > 0.05). (4) Fasting plasma glucose (FPG), fasting insulin (FINS), homeostasis model of insulin resistance (HOMA-IR) and insulin sensitivity index (ISI): at 26 weeks, the SDM-offspring has normal FPG, but more insulin was needed to keep it normal. The insulin level of SDM-O [(12.6 ± 3.3) mU/L] was statistically higher than those of SDM-N [(10.9 ± 3.3) mU/L] and CG [(8.6 ± 0.8) mU/L] (P < 0.05). The ISI of SDM-O (0.020 ± 0.006) was significantly smaller than its HOMA-IR (2.40 ± 0.62, P < 0.05). (5) The morphological change of pancreatic islet: The islets of CG and SDM-N were round or ellipse and have clear boundary between endocrine and exocrine parts and the β cells distributed equally. However, SDM-O islets were not of uniform size and most of islets were hyperplasia and hypertrophy. (6) Relative β cell area of pancreas, β-cell area and islet size: SDM-O: (1.81 ± 0.31)%, (57.1 ± 3.2)% and (39,067 ± 3308) µm(2); SDM-N:(1.34 ± 0.43)%, (60.9 ± 0.6)% and (30,570 ± 4824) µm(2); CG: (1.11 ± 0.26)%, (63.7 ± 2.7)% and (26,443 ± 4431) µm(2). SDM-O has significantly increasing β-cell mass, hypertrophic islet size and slightly decreasing β-cell percentage compared with other two groups (P < 0.05). The exposure of severely hyperglycemia in pregnancy induces low weight infant and postnatal catch-up growth leading to the possibility of insulin resistance (IR) in adult and early postnatal overfeeding will accelerate such course. Islet morphology of SDM-N has no significant change, indicating that maternal diabetes mainly affected β-cell function but not islet morphological features. SDM overfeeding results in early impairment of islet morphology and function, indicating that the compensation ability of islets has already been impaired and the risk of further development of impaired glucose tolerance (IGT) and diabetes. In conclusion, the nutritional environment in early life (duration of pregnancy and lactation) participate in the metabolic programming in adulthood.

Early postnatal overfeeding induces early chronic renal dysfunction in adult male rats

Low birth weight is associated with an increased risk of hypertension and renal dysfunction at adulthood. Such an association has been shown to involve a reduction of nephron endowment and to be enhanced by accelerated postnatal growth in humans. However, while low-birth-weight infants often undergo catch-up growth, little is known about the long-term vascular and renal effects of accelerated postnatal growth. We surimposed early postnatal overfeeding (OF; reduction of litter size during the suckling period) to appropriate-birth-weight (NBW+OF) and intrauterine growth restriction (IUGR; IUGR+OF) pups, obtained after a maternal gestational low-protein diet. Blood pressure (systolic blood pressure; SBP) and renal function (glomerular filtration rate; GFR) were measured in young and aging offspring. Glomerulosclerosis and nephron number were determined in aging offspring (22 mo). Nephron number was reduced in both IUGR and IUGR+OF male offspring (by 24 and 26%). GFR was reduced by 40% in 12-mo-old IUGR+OF male offspring, and both NBW+OF and IUGR+OF aging male offspring had sustained hypertension (+25 mmHg) and glomerulosclerosis, while SBP and renal function were unaffected in IUGR aging offspring. Female offspring were unaffected. In conclusion, in this experimental model, early postnatal OF in the neonatal period has major long-lasting effects. Such effects are gender dependent. Reduced nephron number alone, associated with IUGR, may not be sufficient to induce long-lasting physiological alterations, and early postnatal OF acts as a "second hit." Early postnatal OF is a suitable model with which to study the long-term effects of postnatal growth in the pathogenesis of vascular disorders and renal disease.

Obesity and enhanced diabetes and cardiovascular risk in adult rats due to early postnatal overfeeding.

To investigate possible permanent consequences of an early postnatal overfeeding, the following experimental model was used: Male Wistar rats were divided into three groups after birth: (1) Small litters with 3-4 newborns (overnutrition), (2) normal litters with 12 animals (normonutrition), and (3) large litters with 20-24 newborn rats (undernutrition). After weaning all animals had free access to tap water and standard pellet diet. The serum insulin level of animals from small litters on day 15 of life was highly significantly increased as compared to the other groups. These overfed hyperinsulinaemic rats showed a higher body weight gain during the suckling period trough juvenile life until adulthood, associated with enhanced mean food intake and resulting in an increased relative body weight (per body length) as a sign of obesity. The obesity was found to be correlated with basal hyperinsulinaemia and increased systolic blood pressure in the small-litter-adults. Moreover, the early postnatally overnourished animals developed an increased type I-like diabetes susceptibility to a "subdiabetogenic" dose of streptozotocin in adulthood. These results suggest once more that hyperinsulinism during brain differentiation, in the present experiment induced by early postnatal overnutrition, may represent a predisposing factor for the development of obesity, of increased diabetes susceptibility and also of increased cardiovascular risk in later life.

060. OVER FEEDING EARLY IN LIFE AND RISK OF OBESITY: INSIGHT FROM THE RODENT

While adult lifestyle factors undoubtedly contribute to the incidence of obesity and its attendant disorders, mounting evidence suggests that programming of obesity may occur following over-nutrition during development. As hypothalamic control of appetite and energy expenditure is set early in life and can be perturbed by certain exposures such as under-nutrition and altered metabolic and hormonal signals, in utero exposure to maternal obesity related changes may contribute to programming of obesity in offspring. Data from animal studies indicate both intrauterine and postnatal environments are critical determinants of the development of pathways regulating energy homeostasis. Experimental evidence in rat studies from our laboratory points to an additive detrimental impact of high fat diet consumption after weaning in animals born of obese mothers. Deleterious effects of high fat diet during pregnancy on metabolic profile, adiposity and cardiac hypertrophy were enhanced by postnatal over consumption. Even modest early postnatal overfeeding induced by litter size reduction leads to increased adiposity. Studies are needed to determine to what extent the effect of maternal and early nutritional changes persist. This presentation summarizes recent evidence of the impact of maternal obesity on subsequent obesity risk, paying particular attention to the hypothalamic regulation of appetite, and markers of metabolic control. There is an urgent need to investigate the mechanisms underlying the trans-generational effects of maternal obesity due to an extraordinary rise in the rates of maternal obesity.

A matter of insulin: Developmental programming of body weight regulation

Alterations of the intrauterine and early postnatal nutritional, metabolic and hormonal environment may cause a predisposition for disorders and diseases throughout later life. Studies in offspring of diabetic mothers (ODM) have decisively contributed to this perception and our understanding of causal mechanisms. Hormones in particular are environment-dependent organizers of the developing organism. When they are present in non-physiological concentrations during critical periods of early development, they can dose-dependently lead to a permanent malprogramming of fundamental regulatory systems. Worthy of note, fetal and neonatal hyperinsulinism is the pathognomic feature in ODM. Epidemiological, clinical, as well as experimental data obtained by our group during the past two decades indicate that insulin itself, when occurring in elevated concentrations during perinatal life, may program the development of obesity and diabetes. Similarly, this may occur due to general increase of fetal food supply, e.g., in overweight pregnant women and neonatal overfeeding. From a clinical point of view, universal screening and therapy for all types of diabetes during pregnancy as well as avoidance of early postnatal overfeeding, especially by promoting breast feeding, are, therefore, recommended. These measures might serve as causal approaches to a genuine primary prevention.

Low expression of insulin signaling molecules impairs glucose uptake in adipocytes after early overnutrition

Experimental and clinical studies have demonstrated that early postnatal overnutrition represents a risk factor for later obesity and associated metabolic and cardiovascular disturbance. In the present study, we assessed the levels of glucose transporter 4 (GLUT-4), GLUT-1, insulin receptor (IR), IR substrate 1 (IRS-1), phosphatidylinositol 3-kinase (PI3K) and Akt expression, as well as insulin-stimulated glucose transport and Akt activity in adipocytes from adult rats previously raised in small litters (SL). The normal litter (NL) served as control group. We also investigated glycemia, insulinemia, plasma lipid levels, and glucose tolerance. Our data demonstrated that early postnatal overfeeding induced a persistent hyperphagia accompanied by a significant increase in body weight until 90 days of age. The SL group also presented a significant increase ( approximately 42%) in epidydimal fat weight. Blood glucose, plasma insulin, and lipid levels were similar among the animals from the SL and NL groups. While insulin-stimulated glucose uptake was approximately twofold higher in adipocytes from the NL group, no stimulatory effect was observed in the SL group. The impaired insulin-stimulated glucose transport in adipose cells from the SL rats was associated with a significant decrease in GLUT-4, IRS-1 and PI3K expression, and Akt activity. In contrast, IR and Akt expression in adipocytes was not different between the SL and NL groups. Despite these alterations, our results showed no differences in glucose tolerance test in rats raised under different feeding conditions. Our findings reinforce a potent and long-term effect of neonatal overfeeding, which can program major changes in the metabolic regulatory mechanisms.