Programming of islet functions in the progeny of hyperinsulinemic/obese rats

Early introduction of exercise prevents insulin resistance in postnatal overfed rats

Early childhood obesity increases the risk of developing metabolic diseases. We examined the early introduction of exercise in small-litter obese-induced rats (SL) on glucose metabolism in the epididymal adipose tissue (AT) and soleus muscle (SM). On day 3 post-birth, pups were divided into groups of ten or three (SL). On day 22, rats were split into sedentary (S and SLS) and exercise (E and SLE) groups. The rats swam three times/week carrying a load for 30 min. In the first week, they swam without a load; in the 2nd week, they carried a load equivalent to 2% of their body weight; from the 3rd week to the final week, they carried a 5% body load. At 85 days of age, an insulin tolerance test was performed in some rats. At 90 days of age, rats were killed, and blood was harvested for plasma glucose, cholesterol, and triacylglycerol measurements. Mesenteric, epididymal, retroperitoneal, and brown adipose tissues were removed and weighed. SM and AT were incubated in the Krebs-Ringer bicarbonate buffer, 5.5 mM glucose for 1 h with or without 10 mU/mL insulin. Comparison between the groups was performed by 3-way ANOVA followed by the Tukey post-hoc test. Sedentary, overfed rats had greater body mass, more visceral fat, lower lactate production, and insulin resistance. Early introduction of exercise reduced plasma cholesterol and contained the deposition of white adipose tissue and insulin resistance. In conclusion, the early introduction of exercise prevents the effects of obesity on glucose metabolism in adulthood in this rat model.

The genetic basis of high-carbohydrate and high-monosodium glutamate diet related to the increase of likelihood of type 2 diabetes mellitus: a review

Diabetes is one of the most common metabolic diseases. Aside from the genetic factor, previous studies stated that other factors such as environment, lifestyle, and paternal-maternal condition play critical roles in diabetes through DNA methylation in specific areas of the genome. One of diabetic cases is caused by insulin resistance and changing the homeostasis of blood glucose control so glucose concentration stood beyond normal rate (hyperglycemia). High fat diet has been frequently studied and linked to triggering diabetes. However, most Asians consume rice (or food with high carbohydrate) and food with monosodium glutamate (MSG). This habit could lead to pathophysiology of type 2 diabetes mellitus (T2D). Previous studies showed that high-carbohydrate or high-MSG diet could change gene expression or modify protein activity in body metabolism. This imbalanced metabolism can lead to pleiotropic effects of diabetes mellitus. In this study, the authors have attempted to relate various changes in genes expression or protein activity to the high-carbohydrate and high-MSG-induced diabetes. The authors have also tried to relate several genes that contribute to pathophysiology of T2D and proposed several ideas of genes as markers and target for curing people with T2D. These are done by investigating altered activities of various genes that cause or are caused by diabetes. These genes are selected based on their roles in pathophysiology of T2D.

Morphofunctional renal alterations in rats induced by intrauterine hyperglycemic environment

INTRODUCTION

The renal development of rats begins in intrauterine life, finishing by 15 days after birth. Diabetes and other diseases during pregnancy can cause systemic changes in the offspring. We evaluated the structural and functional renal alterations of the offspring from diabetic mothers.

MATERIAL AND METHODS

Pregnant rats were separated and 1, 7, 30 and 90 days-old (DO) pups were divided into groups according to the treatment that the mothers received: G1: control, G2: untreated diabetic and G3: insulin-treated diabetic. The kidneys from offspring at 1, 7 and 30 DO were removed for immunohistochemical and histological studies. Furthermore, blood and urine samples were collected from animals at 30 DO to determine the glomerular filtration rate (GFR) by creatinine clearance, and the animals at 90 DO were subjected to blood pressure measurement by plethysmography.

RESULTS

Our results show an increase of PCNA(+) glomerular cells at 7 DO and a reduction in 30 DO animals as well as increased α-smooth muscle actin (α-SMA) tubulointerstitial expression at 1 and 7 DO in animals from G2, when compared with controls. The adult offspring from G2 showed reduced GFR and increased blood pressure.

CONCLUSIONS

Maternal diabetes may have induced programming of renal damage in offspring of hyperglycemic mothers, which may have contributed to the impairment of renal function.

High fat programming of beta cell compensation, exhaustion, death and dysfunction

Programming refers to events during critical developmental windows that shape progeny health outcomes. Fetal programming refers to the effects of intrauterine (in utero) events. Lactational programming refers to the effects of events during suckling (weaning). Developmental programming refers to the effects of events during both fetal and lactational life. Postnatal programming refers to the effects of events either from birth (lactational life) to adolescence or from weaning (end of lactation) to adolescence. Islets are most plastic during the early life course; hence programming during fetal and lactational life is most potent. High fat (HF) programming is the maintenance on a HF diet (HFD) during critical developmental life stages that alters progeny metabolism and physiology. HF programming induces variable diabetogenic phenotypes dependent on the timing and duration of the dietary insult. Maternal obesity reinforces HF programming effects in progeny. HF programming, through acute hyperglycemia, initiates beta cell compensation. However, HF programming eventually leads to chronic hyperglycemia that triggers beta cell exhaustion, death and dysfunction. In HF programming, beta cell dysfunction often co-presents with insulin resistance. Balanced, healthy nutrition during developmental windows is critical for preserving beta cell structure and function. Thus early positive nutritional interventions that coincide with the development of beta cells may reduce the overwhelming burden of diabetes and metabolic disease.

Swimming training prevents metabolic imprinting induced by hypernutrition during lactation

BACKGROUND & AIMS

Reduction in litter size during lactation induces hypernutrition of the offspring culminating with altered metabolic programming during adult life. Overnourished rats present alterations in the endocrine pancreas and major predisposition to the development of type 2 diabetes. Our study evaluated the impact of swimming training on insulin secretion control in overnourished rats.

METHODS

At postnatal day 3 male rat pup litters were redistributed randomly into Small Litters (SL, 3 pups) or Normal Litters (NL, 9 pups) to induce early overfeeding during lactation. Both groups were subjected to swimming training (3 times/week/30 min) post-weaning (21 days) for 72 days. At 92 days of life pancreatic islets were isolated using collagenase technique and incubated with glucose in the presence or absence of acetylcholine (Ach, 0.1-1000 μM) or glucagon-like peptide 1 (GLP1, 10 nM). Adipose tissue depots (white and brown) and endocrine pancreas samples were examined by histological analysis. Food intake and body weight were measured. Blood biochemical parameters were also evaluated.

RESULTS

Swimming training prevented metabolic program alteration by hypernutrition during lactation. Exercise reduced obesity and hyperglycemia in overnourished rats. Pancreatic islets isolated from overnourished rats showed a reduction in glucose-induced insulin secretion and cholinergic responses while the insulinotropic action of GLP1 was increased. Physical training effectively restored glucose-induced insulin secretion and GLP1-stimulated action in pancreatic islets from overnourished rats. However, swimming training did not correct the weak cholinergic response in pancreatic islets isolated from overnourished rats.

CONCLUSIONS

Swimming training avoids obesity development, corrects glucose-induced insulin secretion, as well as, GLP1 insulinotropic response in overnourished rats.

Is carbohydrate intake in the first years of life related to future risk of NCDs?

Studies on children's carbohydrate intake, especially fibre intake, and its associations with later health are rare. The current recommendations for fibre intake in children are based on average assumptions and data extrapolated from intakes in adults. Generally, increase in whole-grain consumption and decrease in sucrose intake are considered healthy. Due to fibre's high bulk volume however, excessive dietary fibre has been feared to decrease energy density have effects on growth, at least in developing countries and in children consuming very restricted diets. Furthermore, it has been speculated that if fats are reduced from the diet, it may become high in sucrose. In STRIP study, which is a long-term, randomized controlled trial designed to decrease the exposure of children to known risk factors of atherosclerosis, carbohydrate intakes have been investigated in detail in children aged 13 months to 9 years. The intervention was successful in decreasing saturated fat intake and cholesterol concentrations throughout childhood and adolescence. The study results also show that a higher than average fibre intake does not displace energy or disturb growth in children and that children with high fibre intake have better dietary quality than those with low fibre intake. Dietary fibre intake associated with lower serum total cholesterol concentrations whereas increases in total carbohydrate, sucrose and fructose intakes associated with increases in serum triglyceride concentrations. In conclusion, from the point of view of CHD risk factor prevention, efforts aiming at increasing the fibre intake while restricting that of refined sugar seem justified in the child population in developed countries.

CLINICAL TRIAL REGISTRATION INFORMATION

NCT00223600.

Metabolic programming in the immediate postnatal life

The metabolic programming effects of nutritional modifications in the immediate postnatal life are increasingly recognized to independently contribute to the development of metabolic syndrome in later life. Adjustment of litter size in rodents has been used to induce either under- or overnourishment in the immediate postnatal life of the offspring. While undernourishment led to growth retardation in the offspring, overnourishment produced increased body weight gains, hyperinsulinemia and hyperleptinemia. Overnourishment during the suckling period induced several adaptations in the energy circuitry in the hypothalamus of the offspring predisposing them for the onset of obesity later in life. Another approach for a nutritional modification in the immediate postnatal period is the artificial rearing of newborn rat pups on a high-carbohydrate (HC) milk formula without changes in the total calorie availability. Hyperinsulinemia, immediately evident in the HC pups, persisted in the post-weaning period even after withdrawal of the HC milk. Significant alterations in pancreatic islets supported chronic hyperinsulinemia in the HC rats. Alterations in the gene expression of hypothalamic neuropeptides predisposing to hyperphagia were evident during the period of the HC dietary modification. The persistence of these hypothalamic adaptations supported the obese phenotype in adult HC rats. A transgenerational effect gave rise to the development of chronic hyperinsulinemia and adult-onset obesity in the offspring of the HC female rats. Other studies have shown that lactation by a diabetic, obese or malnourished mother resulted in predisposition for the onset of metabolic disorders in the offspring. These observations from animal studies on the metabolic programming effects due to altered nutritional experiences in the immediate postnatal life strongly suggest that altered feeding practices for infants (formula feeding and early introduction of infant foods) could contribute to the rising incidence of overweight/obesity in children and adults.

Does consumption of processed foods explain disparities in the body weight of individuals? The case of Guatemala

Overweight/obesity, caused by the 'nutrition transition', is identified as one of the leading risk factors for non-communicable mortality. The nutrition transition in developing countries is associated with a major shift from the consumption of staple crops and whole grains to highly and partially processed foods. This study examines the contribution of processed foods consumption to the prevalence of overweight/obesity in Guatemala using generalized methods of moments (GMM) regression. The results show that all other things remaining constant, a 10% point increase in the share of partially processed foods from the total household food expenditure increases the BMI of family members (aged 10 years and above) by 3.95%. The impact of highly processed foods is much stronger. A 10% point increase in the share of highly processed food items increases the BMI of individuals by 4.25%, ceteris paribus. The results are robust when body weight is measured by overweight/obesity indicators. These findings suggest that increasing shares of partially and highly processed foods from the total consumption expenditure could be one of the major risk factors for the high prevalence of overweight/obesity in the country.

Maternal diabetes programs hypertension and kidney injury in offspring

We investigated whether maternal diabetes programs the offspring to develop hypertension and kidney injury in adulthood and examined potential underlying mechanisms. In a murine model we studied the offspring of three groups of dams (non-diabetic, diabetic, and diabetic treated with insulin). Mean systolic blood pressure in the offspring was monitored from 8 to 20 weeks. Body and kidney weights in the offspring of diabetic mothers were significantly lower than in offspring of non-diabetic mothers. Offspring of diabetic mothers developed hypertension, microalbuminuria, and glucose intolerance. Increased accumulation of extracellular matrix proteins in the glomeruli and marked upregulation of angiotensinogen, angiotensin II type 1 receptor, angiotensin-converting enzyme, transforming growth factor beta-1 (TGF-beta1), and plasminogen activator inhibitor-1 (PAI-1) gene expression were evident in the renal cortex of hypertensive offspring of diabetic mothers. By contrast, angiotensin-converting enzyme-2 (ACE2) gene expression was lower in the hypertensive offspring of diabetic mothers than in that of non-diabetic mothers. These changes were prevented in the offspring of insulin-treated diabetic mothers. These data indicate that maternal diabetes induces perinatal programming of hypertension, renal injury, and glucose intolerance in the offspring and suggest a central role for the activation of the intrarenal renin-angiotensin system and TGF-beta1 gene expression in this process.

Metabolic programming: Role of nutrition in the immediate postnatal life

Although genes and dietary habits are generally implicated in the aetiology of the prevailing obesity epidemic, the steep increase in the incidence of obesity within a relatively short span of time suggests that other contributing factors may be at play. The role of nutritional experience during the very early periods of life is increasingly being recognized as contributing to growth and metabolic changes in later life. Epidemiological data and studies from animal models have established a strong correlation between an aberrant intrauterine environment and adult-onset disorders in offspring. The nutritional experience in the immediate postnatal life is another independent factor contributing to the development of metabolic diseases in adulthood. Although studies on the small-litter rat model have shown that overnourishment during the suckling period results in adult-onset metabolic disorders, our studies have shown that a change in the quality of calories-specifically, increased carbohydrate intake by newborn rat pups in the immediate postnatal period-results in chronic hyperinsulinaemia and adult-onset obesity. Several functional alterations in islets and in the hypothalamic energy homeostatic mechanism appear to support this phenotype. Remarkably, female rats that underwent the high-carbohydrate dietary modification as neonates spontaneously transmitted the obesity phenotype to their offspring, thus establishing a vicious generational effect. The high-carbohydrate diet-fed rat model has particular relevance in the context of the current human infant feeding practices: reduction in breast feeding and increase in formula feeding for infants, accompanied by early introduction of carbohydrate-enriched baby foods.

Dietary fructose during the suckling period increases body weight and fatty acid uptake into skeletal muscle in adult rats

OBJECTIVE

The suckling period is one potentially "critical" period during which nutritional intake may permanently "program" metabolism to promote increased adult body weight and insulin resistance in later life. This study determined whether fructose introduced during the suckling period altered body weight and induced changes in fatty acid transport leading to insulin resistance in adulthood in rats.

METHODS AND PROCEDURES

Pups were randomly assigned to one of four diets: suckle controls (SCs), rat milk substitute formula (Rat Milk Substitute), fructose-containing formula (Fructose), or galactose-containing formula (Galactose). Starting at weaning, all pups received the same diet; at 8 weeks of age, half of the SC rats began ingesting a diet containing 65% kcal fructose (SC-Fructose). This continued until animals were 12 weeks old and the study ended.

RESULTS

At weeks 8, 10, and 11, the Fructose group weighed more than SC and SC-Fructose groups (P < 0.05). At weeks 8 and 10 of age, the Fructose group had significantly higher insulin concentrations vs. rats in the SC-Fructose group. (3)H-Palmitate transport into vesicles from hind limb skeletal muscle was higher in Fructose vs. SC rats (P < 0.05). CD36 expression was increased in the sarcolemma but not in whole tissue homogenates from skeletal muscle from Fructose rats (P < 0.05) suggesting a redistribution of this protein associated with fatty acid uptake across the plasma membrane. This change in subcellular localization of CD36 is associated with insulin resistance in muscle.

DISCUSSION

Consuming fructose during suckling may result in lifelong changes in body weight, insulin secretion, and fatty acid transport involving CD36 in muscle and ultimately promote insulin resistance.

Acute administration of cefepime lowers L-carnitine concentrations in early lactation stage rat milk

Our study investigated the potential for important in vivo drug-nutrient transport interactions at the lactating mammary gland using the L-carnitine transporter substrates, cefepime and L-carnitine, as proof-of-concept. On d 4 (n = 6/treatment) and d 10 (n = 6/treatment) of lactation, rats were administered cefepime (250 mg/h) or saline by continuous i.v. infusion (4 h). Serum and milk L-carnitine and cefepime concentrations were quantified by HPLC-UV. In whole mammary gland, organic cation/carnitine transporter (OCTN)1, OCTN2, OCTN3, amino acid transporter B(0,+) (ATB(0,+)), and L-carnitine transporter 2 expression were determined by quantitative RT-PCR and by western blot and immunohistochemistry when possible. Cefepime caused a 56% decrease in milk L-carnitine concentrations on lactation d 4 (P = 0.0048) but did not affect milk L-carnitine at lactation d 10 or serum L-carnitine concentrations at either time. The mean L-carnitine and cefepime milk:serum ratios (M/S) decreased from 9.1 +/- 0.4 to 4.9 +/- 0.6 (P < 0.0001) and 0.89 +/- 0.3 to 0.12 +/- 0.02 (P = 0.0473), respectively, between d 4 and d 10 of lactation. In both groups, OCTN2 (P < 0.0001), OCTN3 (P = 0.0039), and ATB(0,+) (P = 0.004) mRNA expression and OCTN2 protein (P < 0.0001) were higher in mammary glands at d 4 of lactation compared with d 10. Immunohistochemistry revealed OCTN1 and OCTN2 localization in the mammary alveolar epithelium and OCTN3 expression in the interstitial space and blood vessel endothelium. In conclusion, cefepime significantly decreased milk L-carnitine concentrations only at d 4 of lactation. Relative to d 10, enhanced expression of OCTN2 and ATB(0,+) in mammary glands at d 4 of lactation and higher M/S (L-carnitine and cefepime) suggests cefepime competes with L-carnitine for L-carnitine transporters expressed in the lactating mammary gland to adversely affect L-carnitine milk concentrations and these effects depend upon lactation stage.

Effects of high-fat diet exposure during fetal life on type 2 diabetes development in the progeny

Nutrition during fetal life is a critical factor contributing to diabetes development in adulthood. The aim of our study was to verify: 1) whether a high-fat (HF) diet in young adult mice induces alterations in beta-cell mass, proliferation, neogenesis, and apoptosis, as well as insulin sensitivity and secretion; 2) whether these alterations may be reversible after HF diet suspension; 3) the effects in a first (F1) and second generation (F2) of mice without direct exposure to a HF diet after birth. Type 2 diabetes developed in adult mice on a HF diet, in F1 mice that were HF diet-exposed during fetal or neonatal life, and in F2 mice whose mothers were HF diet-exposed during their fetal life. beta-cell mass, replication, and neogenesis were high in HF diet-exposed mice and decreased after diet suspension. beta-cell mass and replication remained high in F1 mice and decreased in F2 mice whose mothers were exposed to a HF diet. beta-cell neogenesis was present in adult mice on a HF diet and in F1 mice that were HF diet-exposed during fetal and/or neonatal life. We conclude that a HF diet during fetal life, particularly if combined with the same insult during the suckling period, can induce the type 2 diabetes phenotype, which can be directly transmitted to the progeny even in the absence of additional dietary insults.

Metabolic programming in the immediate postnatal period

In recent decades, there has been a dramatic increase in the incidence of obesity in all age groups of the population in the USA. In addition to genetics and life style changes, the important role of metabolic programming effects in the etiology of the obesity epidemic is being increasingly recognized. Although the role of a compromised intrauterine environment in fetal metabolic programming is well documented to contribute to the development of adult-onset diseases, vulnerability in the immediate postnatal period to similar conditions has also been shown. Metabolic programming effects induced by altered nutritional experiences in the immediate postnatal period can give rise to long-term consequences in the context of the current obesity epidemic.

The blind men ‘see’ the elephant-the many faces of fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is a group of diseases with excess fat in liver in the absence of a poorly defined limit of alcohol consumption. Most common variety, a universal public health problem, is associated with insulin resistance caused by a host of genetic and epigenetic defects modulated by life style and environmental factors. In fact the term NAFLD is loose to incorporate so many etiologies except alcoholism and few other etiologies, presenting as fat in liver. However as a sign fatty liver is very important in predicting the risk of diabetes, cardiovascular disease, stroke, cirrhosis and cancer. Abnormal fat accumulation can result from several defects in nuclear receptors associated with lipid sensing, synthesis and oxidation like LXR, FXR, SREBP, ChREBP and PPAR; defects in the lipid influx-efflux channels, insulin signaling, proteins involved in fatty acid catabolism, defects in adipose tissue development and function, inappropriate nutrition and finally defects in neural regulatory mechanisms. The progress of the disease is determined by the basic defects which results in fat accumulation, an individual’s immunological response to the accumulated fat and its derivatives and the oxidant stress response. Congregation of unrelated genetic defects under same diagnosis ‘NAFLD’ can result in inefficient patient management. Further studies are required to understand the molecular basis of fatty liver to enable a personalized management of diseases presenting as fatty liver in the absence of alcohol abuse.

Impact of early postnatal weight gain and feeding patterns on body mass index in adolescence

Postnatal weight gain may predispose to the development of obesity during childhood. The aims of this study were to study the impact of weight gain during specific periods of the first year of life and of feeding patterns on the body mass index (BMI) of adolescents. Growth records during the first 24 months of life of 88 obese and 214 non-obese 12 year-old Arab children were evaluated. Birth weight and length were similar for obese and non-obese adolescents, while the rate of breastfeeding was significantly lower in the obese group (p < 0.01). Obese adolescents demonstrated a small yet significant accelerated weight gain at 4 (p = 0.002) and 12 (p = 0.01) months of age. Weight gain during the first 2 months of life and feeding pattern were independent predictors of BMI at the age of 12 years. Thus, early postnatal weight gain is associated with obesity in adolescence, while breastfeeding seems to have a protective effect.

Report on the IASO Stock Conference 2006: early and lifelong environmental epigenomic programming of metabolic syndrome, obesity and type II diabetes

Now that analysis of the organization of the human genome sequence is reaching completion, studies of the finely tuned chromatin epigenetic networks, DNA methylation and histone modifications, are required to determine how the same DNA sequence generates different cells, lineages and organs, i.e. the phenotype. Maternal nutrition, behaviour and metabolic disturbances as well as other environmental factors have been shown to have major effects on these epigenetic processes, potentially affecting the predisposition of offspring to obesity and related adult disorders. The March 2006 Stock Conference considered the latest evidence from studies in the field of obesity and other related areas that elucidate mechanisms by which the environment can modify gene expression and the resulting individual phenotype. Presentations included evaluation of the molecular basis of epigenetic memory and the nature of relevant sequence targets, windows of susceptibility, and maternal dietary and behavioural factors that determine epigenetic changes. Imprinted genes, age and tissue-related exposures, transgenerational and potential interventions were also discussed. In summary, it is clear that epigenetic alterations can no longer be ignored in evaluations of the causes of obesity and its associated disorders. There is a need for systematic large-scale epigenetic studies of obesity, employing appropriate strategies and techniques and appropriately chosen environmental factors in critical spatio-temporal windows.

The influence of L-arginine on blood pressure, vascular nitric oxide and renal morphometry in the offspring from diabetic mothers

The present study was designed to evaluate the effects of L-arginine (L-arg) supplementation on blood pressure, vascular nitric oxide content, and renal morphometry in the adult offspring from diabetic mothers. Diabetes mellitus was induced in female rats with a single dose of streptozotocin (50 mg/kg), before mating. The offspring was divided into four groups: group C (controls); group DO (diabetic offspring); group CA (controls receiving 2% L-arg solution dissolved in 2% sucrose in the drinking water) and group DA (DO receiving the L-arg solution). Oral supplementation began after weaning and continued until the end of the experiments. In DO, hypertension was observed, from 3 mo on. In DA, pressure levels were not different from C and CA. In 6-mo-old animals, basal NO production (assessed by DAF-2) was significantly depressed in DO in comparison to controls. The NO production was significantly increased after stimulation with Ach or BK in all groups, the increase being greater in control than in DO rats. L-arg was able to improve the NO production and to prevent the glomerular hypertrophy in the DO. Our data suggest that the bioavailability of NO is reduced in the DO, because L-arg corrected both the hypertension and glomerular hypertrophy.

Nutri-epigenomics: lifelong remodelling of our epigenomes by nutritional and metabolic factors and beyond

The phenotype of an individual is the result of complex interactions between genotype, epigenome and current, past and ancestral environment, leading to lifelong remodelling of our epigenomes. Various replication-dependent and -independent epigenetic mechanisms are involved in developmental programming, lifelong stochastic and environmental deteriorations, circadian deteriorations, and transgenerational effects. Several types of sequences can be targets of a host of environmental factors and can be associated with specific epigenetic signatures and patterns of gene expression. Depending on the nature and intensity of the insult, the critical spatiotemporal windows and developmental or lifelong processes involved, these epigenetic alterations can lead to permanent changes in tissue and organ structure and function, or to reversible changes using appropriate epigenetic tools. Given several encouraging trials, prevention and therapy of age- and lifestyle-related diseases by individualised tailoring of optimal epigenetic diets or drugs are conceivable. However, these interventions will require intense efforts to unravel the complexity of these epigenetic, genetic and environment interactions and to evaluate their potential reversibility with minimal side effects.

Maternal diabetes mellitus--early consequences for the offspring

Although several studies have focused on the effects of nutritional status during intrauterine development, few have addressed the impact of maternal diabetes mellitus on renal function and morphology in the young offspring. In the present study, renal morpho-functional aspects were studied in the offspring of diabetic rats. Diabetes was induced in female rats with a single dose of streptozotocyn (STZ), 10 days before mating. After weaning, the offspring (DO) had free access to food and water. Arterial blood pressure was measured, by tail plethysmography, from 2 months on. Renal function was evaluated in 2- and 3-month-old rats in the DO group and in controls (C). Analysis of renal morphology was carried out in newborn and in 1-, 2- and 3-month-old rats in both groups. Although the nephron number was not changed in the DO group, glomerular hypertrophy was observed from 2 months on. At the same age, the glomerular filtration rate was significantly reduced in DO, and blood pressure was significantly increased, when compared to C. Glucose tolerance test (GTT) from DO showed a different profile when compared to C. The number of PCNA positive cells in renal tissue was similar in both groups. Our data suggests that exposure to intrauterine diabetes may be an important cause of both impaired renal function and hypertension in offspring, without changes in the nephron number.

The impact of early nutrition in premature infants on later childhood insulin sensitivity and growth

OBJECTIVES

Children born prematurely have decreased insulin sensitivity. The etiology of this insulin resistance is unknown. The aim of this study was to evaluate infant nutrition and its influence on insulin sensitivity and postnatal growth in children born < or = 32 weeks' gestation.

METHODS

A total of 56 healthy, developmentally normal, prepubertal children, aged 4 to 10 years were recruited. Thirty-seven were born < or = 32 weeks' gestation, and 19 were control subjects born at term with a birth weight > 10th percentile. Insulin sensitivity (10(-4) min(-1) microU/mL) was calculated from a 90-minute frequently sampled intravenous glucose tolerance test. Perinatal, nutritional, and growth data were obtained retrospectively from both neonatal and early infancy records in the premature cohort.

RESULTS

Children born prematurely had decreased insulin sensitivity when compared with those born at term (13.8 vs 30.6). Neonatal nutrition was not correlated with insulin sensitivity; however, all of the infants had inadequate protein in the first month followed by excessive fat intake thereafter. Premature children with greater weight gain had lower insulin sensitivity. Higher carbohydrate intake in the first month of life was associated with greater weight gain from birth. No relationship was seen between weight gain and either protein or lipid intake.

CONCLUSIONS

Prematurely born children are insulin resistant and have suboptimal neonatal nutrition. Greater childhood weight gain magnifies this reduction in insulin sensitivity and seems to be associated with early nutrition. We speculate that a high carbohydrate neonatal diet may lead to greater weight gain and a greater reduction in insulin sensitivity in this group.

Metabolic programming: fetal origins of obesity and metabolic syndrome in the adult

Exposure of the fetus to the intrauterine milieu can have profound effects on the health of the offspring in adulthood. Results of a series of studies demonstrate the powerful influence of the mother's metabolic state on whether the emerging adult develops obesity and hyperinsulinemia. Importantly, these attributes can be passed on to the next generation nongenetically and can be reversed and prevented.

Impact of diets and nutrients/drugs on early epigenetic programming

Specific, often unbalanced diets are used to circumvent the metabolic defects of patients with monogenic inborn errors of metabolism. Human epidemiological studies and appropriately designed dietary interventions in animal models have provided considerable evidence to suggest that nutritional imbalance and metabolic disturbances, during critical time windows of developmental programming, may have a persistent effect on the health of the child and later in adulthood. Thus patients with monogenic inborn errors of metabolism may also suffer additional types of alterations due to the lack or excess of key nutrients. Interactions of nutrients with the epigenetic machinery lead to epigenetic changes associated with chromatin remodelling and regulation of gene expression that underlie the developmental programming of pathological consequences in adulthood. Today, with the explosion of new technologies, we can explore on a large scale the effects of nutrients on the level of expression of thousands of expressed genes (nutritional genomics and epigenomics), the corresponding protein products and their posttranslationally modified derivatives (proteomics), and the host of metabolites (metabolomics) generated from endogenous metabolic processes or exogenous dietary nutrients and can establish the relationship between these biological entities and diet, health or disease. The combination of these various lines of research on epigenetic programming processes should highlight new strategies for the prevention and treatment of inborn errors of metabolism.

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.

Can we slow the rising incidence of childhood-onset autoimmune diabetes? The overload hypothesis

Overload of the beta cell, mediated by a variety of mechanisms, may sensitise it to immune damage and apoptosis, and thus accelerate ongoing autoimmune processes leading to its destruction. Environmental risk determinants that may exert such overload effects include insulin resistance due to excess fat cell accumulation, and increased insulin requirement due to a high growth rate, physical stress (infection, inflammation) or psychological stress. The increasing incidence of childhood diabetes, and the shift to younger age at onset, is unlikely to be driven by environmental risk factors that have been associated with initiation of autoimmunity, e.g. virus infections or early infant feeding. Risk factors that may accelerate beta cell destruction have shown a steady increase in the population, and are more plausible causes of such a pattern of change. Child growth, weight and birthweight are well-established estimates of community wealth and increase in most countries of Europe. Overfeeding of children early in life leads to both accelerated growth and weight, and even a moderate excess of child growth, not necessarily associated with obesity, is associated with risk of type 1 diabetes. New, safe and effective immune-modulating drugs for possible arrest of the autoimmune process may become available in time, but in the interim these accelerating factors may be targeted. Public health programmes for pregnant mothers and young families, aiming at changing overfeeding and the sedentary lifestyle of the children would be preferable to other alternatives. Interventions such as these would be safe and could potentially influence future risks of type 1 and type 2 diabetes and other major threats to adult health.

Long-term effects of maternal diabetes on vascular reactivity and renal function in rat male offspring

Fetal growth impairment can occur in pregnancy complicated by diabetes. Although several studies have focused the effects of nutritional status on intrauterine development, the long-term impact of maternal diabetes on vascular and renal function in the offspring is poorly investigated. In the present study, blood pressure profiles and renal function parameters were investigated in the offspring of diabetic rats (DO). Female rats were made diabetic throughout gestation with a single dose of streptozotocyn (STZ) 10 d before mating. After weaning, the offspring had free access to food and water. Arterial pressure was evaluated every 15 d. Functional and morphometric kidney studies were performed in newborn, 3, 6 and 12-mo-old male rats in DO and in controls, C. Although maternal diabetes did not affect nephron number in the young adult rat, glomerular hypertrophy developed from 3 mo on. Glomerular Filtration Rate and Renal Plasma Flow were observed to be significantly decreased in DO when compared with C, from 3 mo on. In DO, hypertension was observed from 8 wk on and persisted elevated throughout the experimental period (12 mo). Vascular reactivity, evaluated in mesenteric arterial bed showed a decreased endothelium-dependent vasodilatation in 12-mo-old DO animals, while preserved response to sodium nitroprusside was demonstrated. Our data show that exposure to intrauterine diabetes induced by STZ does not affect nephron number in the young offspring but can cause permanent changes in Nitric Oxide (NO)-related vascular response, which, in turn may accelerate the natural age-related nephron loss.

Nutritional epigenomics of metabolic syndrome: new perspective against the epidemic

Human epidemiological studies and appropriately designed dietary interventions in animal models have provided considerable evidence to suggest that maternal nutritional imbalance and metabolic disturbances, during critical time windows of development, may have a persistent effect on the health of the offspring and may even be transmitted to the next generation. We now need to explain the mechanisms involved in generating such responses. The idea that epigenetic changes associated with chromatin remodeling and regulation of gene expression underlie the developmental programming of metabolic syndrome is gaining acceptance. Epigenetic alterations have been known to be of importance in cancer for approximately 2 decades. This has made it possible to decipher epigenetic codes and machinery and has led to the development of a new generation of drugs now in clinical trials. Although less conspicuous, epigenetic alterations have also been progressively shown to be relevant to common diseases such as atherosclerosis and type 2 diabetes. Imprinted genes, with their key roles in controlling feto-placental nutrient supply and demand and their epigenetic lability in response to nutrients, may play an important role in adaptation/evolution. The combination of these various lines of research on epigenetic programming processes has highlighted new possibilities for the prevention and treatment of metabolic syndrome.

Épigénomique nutritionnelle du syndrome métabolique

The importance of epigenetic alterations has been acknowledged in cancer for about two decades by an increasing number of molecular oncologists who contributed to deciphering the epigenetic codes and machinery and opened the road for a new generation of drugs now in clinical trials. However, the relevance of epigenetics to common diseases such as metabolic syndrome and cardiovascular disease was less conspicuous. This review focuses on converging data supporting the hypothesis that, in addition to "thrifty genotype" inheritance, individuals with metabolic syndrome (MetS)--combining disturbances in glucose and insulin metabolism, excess of predominantly abdominally distributed weight, mild dyslipidemia and hypertension, with the subsequent development of obesity, type 2 diabetes mellitus (T2D) and cardiovascular disease (CVD)--have suffered improper "epigenetic programming" during their fetal/postnatal development due to maternal inadequate nutrition and metabolic disturbances and also during their lifetime. Moreover, as seen for obesity and T2D, MetS tends to appear earlier in childhood, to be more severe from generation to generation and to affect more pregnant women. Thus, in addition to maternal effects, MetS patients may display "transgenerational effects" via the incomplete erasure of epigenetic marks endured by their parents and grandparents. We highlight the susceptibility of epigenetic mechanisms controlling gene expression to environmental influences due to their inherent malleability, emphasizing the participation of transposable elements and the potential role of imprinted genes during critical time windows in epigenetic programming, from the very beginning of development throughout life. Increasing our understanding on epigenetic patterns significance and small molecules (nutrients, drugs) that reverse epigenetic (in)activation should provide us with the means to "unlock" silenced (enhanced) genes, and to "convert" the obsolete human thrifty genotype into a "squandering" phenotype.

Unraveling the Pathogenesis of Type 1 Diabetes with Proteomics: Present And Future Directions

Type 1 diabetes (T1D) is the result of selective destruction of the insulin-producing beta-cells in the pancreatic islets of Langerhans. T1D is due to a complex interplay between the beta-cell, the immune system, and the environment in genetically susceptible individuals. The initiating mechanism(s) behind the development of T1D are largely unknown, and no genes or proteins are specific for most T1D cases. Different pro-apoptotic cytokines, IL-1 beta in particular, are present in the islets during beta-cell destruction and are able to modulate beta-cell function and induce beta-cell death. In beta-cells exposed to IL-1 beta, a race between destructive and protective events are initiated and in susceptible individuals the deleterious events prevail. Proteins are involved in most cellular processes, and it is thus expected that their cumulative expression profile reflects the specific activity of cells. Proteomics may be useful in describing the protein expression profile and thus the diabetic phenotype. Relatively few studies using proteomics technologies to investigate the T1D pathogenesis have been published to date despite the defined target organ, the beta-cell. Proteomics has been applied in studies of differentiating beta-cells, cytokine exposed islets, dietary manipulated islets, and in transplanted islets. Although that the studies have revealed a complex and detailed picture of the protein expression profiles many functional implications remain to be answered. In conclusion, a rather detailed picture of protein expression in beta-cell lines, islets, and transplanted islets both in vitro and in vivo have been described. The data indicate that the beta-cell is an active participant in its own destruction during diabetes development. No single protein alone seems to be responsible for the development of diabetes. Rather the cumulative pattern of changes seems to be what favors a transition from dynamic stability in the unperturbed beta-cell to dynamic instability and eventually to beta-cell destruction.

Intergenerational consequences of fetal programming by in utero exposure to glucocorticoids in rats

Epidemiological studies linking low birth weight and subsequent cardiometabolic disease have given rise to the hypothesis that events in fetal life permanently program subsequent cardiovascular risk. The effects of fetal programming may not be limited to the first-generation offspring. We have explored intergenerational effects in the dexamethasone-programmed rat, a model in which fetal exposure to excess glucocorticoid results in low birth weight with subsequent adult hyperinsulinemia and hyperglycemia underpinned by increased activity of the key hepatic gluconeogenic enzyme, phosphoenolpyruvate carboxykinase (PEPCK). We found that the male offspring of female rats that had been exposed prenatally to dexamethasone, but were not manipulated in their own pregnancy, also had reduced birth weight (5.66 +/- 0.06 vs. 6.12 +/- 0.06 g, P < 0.001), glucose intolerance, and elevated hepatic PEPCK activity (5.7 +/- 0.6 vs. 3.3 +/- 0.2 nmol.min(-1).mg protein(-1), P < 0.001). These effects resolved in a third generation. Similar intergenerational programming was observed in offspring of male rats exposed prenatally to dexamethasone mated with control females. The persistence of such programming effects through several generations, transmitted by either maternal or paternal lines, indicates the potential importance of epigenetic factors in the intergenerational inheritance of the "programming phenotype" and provides a basis for the inherited association between low birth weight and cardiovascular risk factors.