Early growth restriction leads to down regulation of protein kinase C zeta and insulin resistance in skeletal muscle

Neurodevelopmental Programming of Adiposity: Contributions to Obesity Risk

This review analyzes the published evidence regarding maternal factors that influence the developmental programming of long-term adiposity in humans and animals via the central nervous system (CNS). We describe the physiological outcomes of perinatal underfeeding and overfeeding and explore potential mechanisms that may mediate the impact of such exposures on the development of feeding circuits within the CNS-including the influences of metabolic hormones and epigenetic changes. The perinatal environment, reflective of maternal nutritional status, contributes to the programming of offspring adiposity. The in utero and early postnatal periods represent critically sensitive developmental windows during which the hormonal and metabolic milieu affects the maturation of the hypothalamus. Maternal hyperglycemia is associated with increased transfer of glucose to the fetus driving fetal hyperinsulinemia. Elevated fetal insulin causes increased adiposity and consequently higher fetal circulating leptin concentration. Mechanistic studies in animal models indicate important roles of leptin and insulin in central and peripheral programming of adiposity, and suggest that optimal concentrations of these hormones are critical during early life. Additionally, the environmental milieu during development may be conveyed to progeny through epigenetic marks and these can potentially be vertically transmitted to subsequent generations. Thus, nutritional and metabolic/endocrine signals during perinatal development can have lifelong (and possibly multigenerational) impacts on offspring body weight regulation.

Maternal low-protein diet reduces skeletal muscle protein synthesis and mass via Akt-mTOR pathway in adult rats

Several studies have demonstrated that a maternal low-protein diet induces long-term metabolic disorders, but the involved mechanisms are unclear. This study investigated the molecular effects of a low-protein diet during pregnancy and lactation on glucose and protein metabolism in soleus muscle isolated from adult male rats. Female rats were fed either a normal protein diet or low-protein diet during gestation and lactation. After weaning, all pups were fed a normal protein diet until the 210th day postpartum. In the 7th month of life, mass, contractile function, protein and glucose metabolism, and the Akt-mTOR pathway were measured in the soleus muscles of male pups. Dry weight and contractile function of soleus muscle in the low-protein diet group rats were found to be lower compared to the control group. Lipid synthesis was evaluated by measuring palmitate incorporation in white adipose tissue. Palmitate incorporation was higher in the white adipose tissue of the low-protein diet group. When incubated soleus muscles were stimulated with insulin, protein synthesis, total amino acid incorporation and free amino acid content, glucose incorporation and uptake, and glycogen synthesis were found to be reduced in low-protein diet group rats. Fasting glycemia was higher in the low-protein diet group. These metabolic changes were associated with a decrease in Akt and GSK-3β signaling responses to insulin and a reduction in RPS6 in the absence of the hormone. There was also notably lower expression of Akt in the isolated soleus muscle of low-protein diet group rats. This study is the first to demonstrate how maternal diet restriction can reduce skeletal muscle protein and mass by downregulating the Akt-mTOR pathway in adulthood.

Regulation of Pancreatic β-Cell Mass by Gene-Environment Interaction

The main pathogenic mechanism of diabetes consists of an increase in insulin resistance and a decrease in insulin secretion from pancreatic β-cells. The number of diabetic patients has been increasing dramatically worldwide, especially in Asian people whose capacity for insulin secretion is inherently lower than that of other ethnic populations. Causally, changes of environmental factors in addition to intrinsic genetic factors have been considered to have an influence on the increased prevalence of diabetes. Particular focus has been placed on "gene-environment interactions" in the development of a reduced pancreatic β-cell mass, as well as type 1 and type 2 diabetes mellitus. Changes in the intrauterine environment, such as intrauterine growth restriction, contribute to alterations of gene expression in pancreatic β-cells, ultimately resulting in the development of pancreatic β-cell failure and diabetes. As a molecular mechanism underlying the effect of the intrauterine environment, epigenetic modifications have been widely investigated. The association of diabetes susceptibility genes or dietary habits with gene-environment interactions has been reported. In this review, we provide an overview of the role of gene-environment interactions in pancreatic β-cell failure as revealed by previous reports and data from experiments.

Chronic Effects of Maternal Low-Protein and Low-Quality Protein Diets on Body Composition, Glucose-Homeostasis and Metabolic Factors, Followed by Reversible Changes upon Rehabilitation in Adult Rat Offspring

Several studies suggest that the maternal protein content and source can affect the offspring's health. However, the chronic impact of maternal quality and quantity protein restriction, and reversible changes upon rehabilitation, if any, in the offspring, remains elusive. This study examined the effects of maternal low-quality protein (LQP) and low-protein (LP) intake from preconception to post-weaning, followed by rehabilitation from weaning, on body composition, glucose-homeostasis, and metabolic factors in rat offspring. Wistar rats were exposed to normal protein (NP; 20% casein), LQP (20% wheat gluten) or LP (8% casein) isocaloric diets for 7 weeks before pregnancy until lactation. After weaning, the offspring were exposed to five diets: NP, LQP, LQPR (LQP rehabilitated with NP), LP, and LPR (LP rehabilitated with NP) for 16 weeks. Body composition, glucose-homeostasis, lipids, and plasma hormones were investigated. The LQP and LP offspring had lower bodyweight, fat and lean mass, insulin and HOMA-IR than the NP. The LQP offspring had higher cholesterol, T3 and T4, and lower triacylglycerides and glucose, while these were unaltered in LP compared to NP. The majority of the above outcomes were reversed upon rehabilitation. These results suggest that the chronic exposure of rats to maternal LQP and LP diets induced differential adverse effects by influencing body composition and metabolism, which were reversed upon rehabilitation.

Small-RNA Sequencing Reveals Altered Skeletal Muscle microRNAs and snoRNAs Signatures in Weanling Male Offspring from Mouse Dams Fed a Low Protein Diet during Lactation

Maternal diet during gestation and lactation affects the development of skeletal muscles in offspring and determines muscle health in later life. In this paper, we describe the association between maternal low protein diet-induced changes in offspring skeletal muscle and the differential expression (DE) of small non-coding RNAs (sncRNAs). We used a mouse model of maternal protein restriction, where dams were fed either a normal (N, 20%) or a low protein (L, 8%) diet during gestation and newborns were cross-fostered to N or L lactating dams, resulting in the generation of NN, NL and LN offspring groups. Total body and tibialis anterior (TA) weights were decreased in weanling NL male offspring but were not different in the LN group, as compared to NN. However, histological evaluation of TA muscle revealed reduced muscle fibre size in both groups at weaning. Small RNA-sequencing demonstrated DE of multiple miRs, snoRNAs and snRNAs. Bioinformatic analyses of miRs-15a, -34a, -122 and -199a, in combination with known myomiRs, confirmed their implication in key muscle-specific biological processes. This is the first comprehensive report for the DE of sncRNAs in nutrition-associated programming of skeletal muscle development, highlighting the need for further research to unravel the detailed molecular mechanisms.

In utero low-protein-diet-programmed type 2 diabetes in adult offspring is mediated by sex hormones in rats†

Sex steroids regulate insulin sensitivity and glucose metabolism. We had characterized a lean type 2 diabetes (T2D) rat model using gestational low-protein (LP) diet programming. Our objective was to identify if endocrine dysfunction leading to decreased sex hormone levels will precede the development of T2D and if steroid replacement will prevent the onset of the disease. Pregnant rats were fed control or isocaloric LP diet from gestational day 4 until delivery. Normal diet was given to all mothers after delivery and to pups after weaning. LP offspring developed glucose intolerance and insulin resistance at 4 months. We measured sex steroid hormone profiles and expression of key genes involved in steroidogenesis in testis and ovary. Furthermore, one-month old rats were implanted with 90-day slow release T and E2 pellets for males and females, respectively. Glucose tolerance test (GTT) and euglycemic hyperinsulinemic clamp was performed at 4 months. LP-programmed T2D males had low T levels and females had low E2 levels due to dysregulated gene expression during steroidogenesis in gonads. GTT and euglycemic hyperinsulinemic clamp showed that LP males and females were glucose intolerant and insulin resistant; however, steroid supplementation prevented the onset of glucose intolerance and insulin resistance. Rats that developed T2D by LP programming have compromised gonadal steroidogenesis leading to low T and E2 in males and females, respectively. Sex steroid supplementation prevented the onset of glucose intolerance and insulin resistance indicating low sex steroid levels could cause compromised glucose metabolism ultimately leading to T2D.

Perinatal programming of metabolic diseases: The role of glucocorticoids

The worldwide increase in metabolic diseases has urged the scientific community to improve our understanding about the mechanisms underlying its cause and effects. A well supported area of studies had related maternal stress with early programming to the later metabolic diseases. Mechanisms upon origins of metabolic disturbances are not yet fully understood, even though stressful factors rising glucocorticoids have been put out as pivotal trigger by programming metabolic diseases as long-term consequence. Considering energy balance and glucose homeostasis, by producing and/or sensing regulator signals, hypothalamus-pituitary-adrenal axis and endocrine pancreas are directly affected by glucocorticoids excess. We focus on the evidences reporting the role of increased glucocorticoids due to perinatal insults on the physiological systems involved in the metabolic homeostasis and in the target organs such as endocrine pancreas, white adipose tissue and blood vessels. Besides, we review some mechanisms underlining the malprogramming of type 2 diabetes, obesity and hypertension. Studies on this field are currently ongoing and even there is a good understanding regarding the effects of glucocorticoids addressing metabolic diseases, few is known about the relationship between maternal insults rising glucocorticoids to pups' metabolic disturbances, a thorough understanding about that may provide pivotal clinical clues regarding those disorders.

Nutritional Models of Type 2 Diabetes Mellitus

In order to better understand the events that precede and precipitate the onset of type 2 diabetes (T2DM), several nutritional animal models have been developed. These models are generated by manipulating the diet of either the animal itself, or its mother during her pregnancy, and in comparison to traditional genetic and knock out models, have the advantage that they more accurately reflect the etiology of human T2DM. This chapter will discuss some of the most widely used nutritional models of T2DM: Diet-induced obesity (DIO) in adult rodents, and studies of offspring of mothers fed a low-protein, high-fat and/or high-sugar diet during pregnancy and/or lactation. Several common mechanisms have been identified through which these nutritional manipulations can lead to metabolic disease, including pancreatic beta-cell dysfunction, impaired insulin signaling in skeletal muscle, and the excess accumulation of visceral adipose tissue and consequent deposition of nonesterified fatty acids in peripheral tissues. In addition, there is an emerging concept that obesity/poor quality diets result in increased production and release of pro-inflammatory cytokines from adipose tissue leading to a state of chronic low-grade inflammation, and that this is likely to represent an important link between obesity/diet and metabolic dysfunction. The following chapter will discuss the most common nutritional models of T2DM in experimental animals, their application, and relationship to human etiology, and will highlight the important insights these models have provided into the pathogenesis of T2DM.

Maternal low protein exposure alters glucose tolerance and intestinal nutrient-responsive receptors and transporters expression of rat offspring

AIMS

Maternal protein malnutrition during perinatal period has long-term consequences on the offspring's metabolic phenotype. Here we determined the effects of maternal protein-restricted (PR) diet on offspring's metabolism in 3- and 12-week-old.

MAIN METHODS

Sprague-Dawley rats were fed with standard chow diet or PR diet during pregnancy and lactation. Food intake and body weight of offspring were measured weekly. The oral glucose tolerance tests were underwent, the pancreases were collected for histochemical staining, and the duodenum, jejunum and ileum were collected for gene and protein expression analysis in 3- and 12-week-old offspring.

KEY FINDINGS

PR offspring had significant lower body weight and persisted till 12-week-old. From 3- to 12-week-old, PR offspring presented considerably impaired glucose tolerance, while no marked change was shown in control rats. Additionally, the average islet size of PR offspring decreased significantly in 12-week-old. The mRNA and protein expression of nutrient-responsive receptors and transporters T1R3, SGLT1 and GLUT2 increased significantly in the intestine of 3-week-old PR offspring. And from 3- and 12-week-old, the increase tendency of expression subdued.

SIGNIFICANCE

These results suggest that maternal PR diet during critical developmental windows influences offspring metabolism, which may be subdued partially, but not be reversed completely by chow diet after weaning.

Metabolic analysis of adipose tissues in a rodent model of pre-pregnancy maternal obesity combined with offsprings on high-carbohydrate diet

Maternal obesity is associated with adverse effects on the health of offsprings. Consumption of a high-carbohydrate (HC) diet has been found to promote abnormal fatty acid metabolism in adipose tissue. Therefore, we hypothesised that maternal obesity combined with an offspring HC diet would alter the fatty acid metabolism of adipose tissue and subsequently contribute to offspring obesity. Lepr^db/+ mice were used to model pre-pregnancy maternal obesity and the C57BL/6 wildtype were used as a control group. Offspring were fed either HC diet or a normal-carbohydrate (NC) diet after weaning. Brown adipose tissue (BAT) and white adipose tissue (WAT) were collected from offspring at 20 weeks of age and their fatty acid metabolome was characterized using gas chromatography-mass spectrometry. We found that HC diet increased the body weight of offspring (males increased by 14.70% and females increased by 1.05%) compared to control mothers. However, maternal obesity alone caused a 7.9% body weight increase in female offspring. Maternal obesity combined with an offspring HC diet resulted in dynamic alterations of the fatty acid profiles of adipose tissue in male offspring. Under the impact of a HC diet, the fatty acid metabolome was solely elevated in female WAT, whereas, the fatty acid metabolites in BAT showed a similar trend in the male and female offsprings. 6,9-octadecadienoic acid and 12,15-cis-octadecatrienoic acid were significantly affected in female WAT, in response to offspring consumption of a HC diet. Our study demonstrated that maternal obesity and offspring HC diet have different metabolic effects on adipose tissue in male and female offsprings.

Sex-specific programming of adult insulin resistance in guinea pigs by variable perinatal growth induced by spontaneous variation in litter size

Intrauterine growth restriction (IUGR) and subsequent neonatal catch-up growth are implicated in programming of insulin resistance later in life. Spontaneous IUGR in the guinea pig, due to natural variation in litter size, produces offspring with asymmetric IUGR and neonatal catch-up growth. We hypothesized that spontaneous IUGR and/or accelerated neonatal growth would impair insulin sensitivity in adult guinea pigs. Insulin sensitivity of glucose metabolism was determined by hyperinsulinemic-euglycemic clamp (HEC) in 38 (21 male, 17 female) young adult guinea pigs from litters of two-to-four pups. A subset (10 male, 8 female) were infused with d-[3-³H]glucose before and during the HEC to determine rates of basal and insulin-stimulated glucose utilization, storage, glycolysis, and endogenous glucose production. n males, the insulin sensitivity of whole body glucose uptake ( r = 0.657, P = 0.002) and glucose utilization ( r = 0.884, P = 0.004) correlated positively and independently with birth weight, but not with neonatal fractional growth rate (FGR_10-28). In females, the insulin sensitivity of whole body and partitioned glucose metabolism was not related to birth weight, but that of endogenous glucose production correlated negatively and independently with FGR_10-28 ( r = -0.815, P = 0.025). Thus, perinatal growth programs insulin sensitivity of glucose metabolism in the young adult guinea pig and in a sex-specific manner; impaired insulin sensitivity, including glucose utilization, occurs after IUGR in males and impaired hepatic insulin sensitivity after rapid neonatal growth in females.

Protein malnutrition mitigates the effects of a high-fat diet on glucose homeostasis in mice

Nutrient malnutrition, during the early stages of development, may facilitate the onset of metabolic diseases later in life. However, the consequences of nutritional insults, such as a high-fat diet (HFD) after protein restriction, are still controversial. We assessed overall glucose homeostasis and molecular markers of mitochondrial function in the gastrocnemius muscle of protein-restricted mice fed an HFD until early adulthood. Male C57BL/6 mice were fed a control (14% protein-control diet) or a protein-restricted (6% protein-restricted diet) diet for 6 weeks. Afterward, mice received an HFD or not for 8 weeks (mice fed a control diet and HFD [CH] and mice fed a protein-restricted diet and HFD [RH]). RH mice showed lower weight gain and fat accumulation and did not show an increase in fasting plasma glucose and insulin levels compared with CH mice. RH mice showed higher energy expenditure, increased citrate synthase, peroxisome-proliferator-activated receptor gamma coactivator 1-alpha protein content, and higher levels of malate and α-ketoglutarate compared with CH mice. Moreover, RH mice showed increased AMPc-dependent kinase and acetyl coenzyme-A (CoA) carboxylase phosphorylation, lower intramuscular triacylglycerol content, and similar malonyl-CoA levels. In conclusion, protein undernourishment after weaning does not potentiate fat accumulation and insulin resistance in adult young mice fed an HFD. This outcome seems to be associated with increased skeletal muscle mitochondrial oxidative capacity and reduced lipids accumulation.

Maternal Exercise Improves the Metabolic Health of Adult Offspring

The intrauterine environment can modulate the course of development and confer an enduring effect on offspring health. The effects of maternal diet to impair offspring metabolic health are well established, but the effects of maternal exercise on offspring metabolic health have been less defined. Because physical exercise is a treatment for obesity and type 2 diabetes (T2D), maternal exercise is an appealing intervention to positively influence the intrauterine environment and improve the metabolic health of offspring. Recent research has provided insights into the effects of maternal exercise on the metabolic health of adult offspring, which is the focus of this review.

Generation of the Maternal Low-Protein Rat Model for Studies of Metabolic Disorders

Poor nutrition during pregnancy leads to an increased risk of metabolic disorders and other diseases in the offspring. This can be modelled in animals through manipulation of the maternal diet. One such model is the maternal low-protein rat which gives rise to offspring characterized by insulin resistance. This chapter gives a detailed protocol for generation of the maternal low-protein rat, which has been used in the study of several disorders including diabetes and psychiatric disorders.

Birthweight and cardiometabolic risk patterns in multiracial children

BACKGROUND/OBJECTIVES

Prenatal growth, which is widely marked by birthweight, may have a pivotal role in affecting the lifelong risk of cardiometabolic disorders; however, comprehensive evaluation of its relations with childhood cardiometabolic risk patterns and the ethnic and gender disparities in national representative populations is still lacking. The aim of this study was to evaluate the associations between birthweight and comprehensive patterns of cardiometabolic risk in a nationally representative sample of children and adolescents.

SUBJECTS/METHODS

Prospective analyses were performed using data from 28 153 children 0 to 15 years in the National Health and Nutrition Examination Survey from 1999 through 2014. We defined childhood cardiometabolic disorders using standard definitions for obesity, high blood pressure, hyperglycemia and dyslipidemia.

RESULTS

Five birthweight categories <2.5, 2.5-3.0, 3.0-3.5, 3.5-4.2 and ⩾4.2 kg accounted for 8.2%, 17.9%, 35.7%, 27.9% and 10.4% of the population, respectively. In all children, with increasing birthweight, we observed significantly increasing trends of the risk of general and central obesity (P for trend <0.01) and significantly decreasing trends of the risk of high systolic blood pressure (SBP), high HbA1c and low high-density lipoprotein cholesterol (HDL-C) (P for trend <0.05). The associations were independent of current body mass index (BMI). In addition, we found that the relations of birthweight with high waist circumference in Black children showed U-shape, as well as high SBP in Mexican and Hispanic children. Moreover, we found that the associations of low birthweight with high SBP and low HDL-C appeared to more prominent significant in boys, whereas the inverse association with high HbA1c was more evident in girls.

CONCLUSIONS

Our data indicate that birthweight is significantly related to childhood cardiometabolic risk, independent of current BMI, and the associations exhibit race and gender-specific patterns.

Maternal Exercise Improves Glucose Tolerance in Female Offspring

Poor maternal diet can lead to metabolic disease in offspring, whereas maternal exercise may have beneficial effects on offspring health. In this study, we determined ifmaternal exercise could reverse the detrimental effects of maternal high-fat feeding on offspring metabolism of female mice. C57BL/6 female mice were fed a chow (21%) or high-fat (60%) diet and further divided by housing in static cages or cages with running wheels for 2 weeks prior to breeding and throughout gestation. Females were bred with chow-fed sedentary C57BL/6 males. High fat-fed sedentary dams produced female offspring with impaired glucose tolerance compared with offspring of chow-fed dams throughout their first year of life, an effect not present in the offspring from high fat-fed dams that had trained. Offspring from high fat-fed trained dams had normalized glucose tolerance, decreased fasting insulin, and decreased adiposity. Liver metabolic function, measured by hepatic glucose production in isolated hepatocytes, hyperinsulinemic-euglycemic clamps, liver triglyceride content, and liver enzyme expression, was enhanced in offspring from trained dams. In conclusion, maternal exercise negates the detrimental effects of a maternal high-fat diet on glucose tolerance and hepatocyte glucose metabolism in female offspring. The ability of maternal exercise to improve the metabolic health of female offspring is important, as this intervention could combat the transmission of obesity and diabetes to subsequent generations.

Neuromuscular junctions (NMJs): ultrastructural analysis and nicotinic acetylcholine receptor (nAChR) subunit mRNA expression in offspring subjected to protein restriction throughout pregnancy

Protein restriction during gestation can alter the skeletal muscle phenotype of offspring; however, little is known with regard to whether this also affects the neuromuscular junction (NMJ), as muscle phenotype maintenance depends upon NMJ functional integrity. This study aimed to evaluate the effects of a low protein (6%) intake by dams throughout gestation on male offspring NMJ morphology and nicotinic acetylcholine receptor (nAChR) α1, γ and ε subunit expression in the soleus (SOL) and extensor digitorum longus (EDL) muscles. Four groups of male Wistar offspring rats were studied. The offspring of dams fed low-protein (6% protein, LP) and normal protein (17% protein, NP) diets were evaluated at 30 and 120 days of age, and the SOL and EDL muscles were collected for analysis. Morphological studies using transmission electron microscopy revealed that only SOL NMJs were affected in 30-day-old offspring in the LP group compared with the NP group. SOL NMJs exhibited fewer synaptic folds, the postsynaptic membranes were smooth and myelin figures were also frequently observed in the terminal axons. With regard to the expression of mRNAs encoding nAChR subunits, only 30-day-old LP offspring EDL muscles exhibited reduced α, γ and ε subunit expression compared with the NP group. In conclusion, our results demonstrate that a low-protein diet (6%) imposed throughout pregnancy impairs the expression of mRNAs encoding the nAChR α, γ and ε subunits in EDL NMJs and promotes morphological changes in SOL NMJs of 30-day-old offspring, indicating specific differences among muscle types following long-term maternal protein restriction.

Gestational Protein Restriction Impairs Glucose Disposal in the Gastrocnemius Muscles of Female Rats

Gestational low-protein (LP) diet causes hyperglycemia and insulin resistance in adult offspring, but the mechanism is not clearly understood. In this study, we explored the role of insulin signaling in gastrocnemius muscles of gestational LP-exposed female offspring. Pregnant rats were fed a control (20% protein) or an isocaloric LP (6%) diet from gestational day 4 until delivery. Normal diet was given to mothers after delivery and to pups after weaning until necropsy. Offspring were euthanized at 4 months, and gastrocnemius muscles were treated with insulin ex vivo for 30 minutes. Messenger RNA and protein levels of molecules involved in insulin signaling were assessed at 4 months. LP females were smaller at birth but showed rapid catchup growth by 4 weeks. Glucose tolerance test in LP offspring at 3 months showed elevated serum glucose levels (P < 0.01; glycemia Δ area under the curve 342 ± 28 in LP vs 155 ± 23 in controls, mmol/L * 120 minutes) without any change in insulin levels. In gastrocnemius muscles, LP rats showed reduced tyrosine phosphorylation of insulin receptor substrate 1 upon insulin stimulation due to the overexpression of tyrosine phosphatase SHP-2, but serine phosphorylation was unaffected. Furthermore, insulin-induced phosphorylation of Akt, glycogen synthase kinase (GSK)-3α, and GSK-3β was diminished in LP rats, and they displayed an increased basal phosphorylation (inactive form) of glycogen synthase. Our study shows that gestational protein restriction causes peripheral insulin resistance by a series of phosphorylation defects in skeletal muscle in a mechanism involving insulin receptor substrate 1, SHP-2, Akt, GSK-3, and glycogen synthase causing dysfunctional GSK-3 signaling and increased stored glycogen, leading to distorted glucose homeostasis.

Age-Dependent Control of Energy Homeostasis by Brown Adipose Tissue in Progeny Subjected to Maternal Diet-Induced Fetal Programming

Epidemiological and animal studies show that deleterious maternal environments predispose aging offspring to metabolic disorders and type 2 diabetes. Young progenies in a rat model of maternal low-protein (LP) diet are normoglycemic despite collapsed insulin secretion. However, without further worsening of the insulin secretion defect, glucose homeostasis deteriorates in aging LP descendants. Here we report that normoglycemic and insulinopenic 3-month-old LP progeny shows increased body temperature and energy dissipation in association with enhanced brown adipose tissue (BAT) activity. In addition, it is protected against a cold challenge and high-fat diet (HFD)-induced obesity with associated insulin resistance and hyperglycemia. Surgical BAT ablation in 3-month-old LP offspring normalizes body temperature and causes postprandial hyperglycemia. At 10 months, BAT activity declines in LP progeny with the appearance of reduced protection to HFD-induced obesity; at 18 months, LP progeny displays a BAT activity comparable to control offspring and insulin resistance and hyperglycemia occur. Together our findings identify BAT as a decisive physiological determinant of the onset of metabolic dysregulation in offspring predisposed to altered β-cell function and hyperglycemia and place it as a critical regulator of fetal programming of adult metabolic disease.

Gene-environment interaction in type 2 diabetes

Type 2 diabetes is a typical multifactorial disease, but the causes can largely be divided into genetic and environmental factors. In recent years, focus has shifted to the interaction between these factors (i.e., gene-environment interactions). It has become widely known that changes in the intrauterine environment such as intrauterine growth restriction result in gene expression changes in various tissues, which ultimately lead to the onset of diabetes. Epigenetic modification is considered to be a particularly important mechanism in these effects, as it is easily affected by environmental changes that occur during the fetal and neonatal periods. Moreover, recent reports have revealed that epigenetic modifications are passed down through generations. Although genome-wide association studies have identified many type 2 diabetes susceptibility genes, these genes do not pose a significantly high risk when isolated as single factors. In particular, it has been suggested that the interaction of the FTO or KCNQ1 genes with environmental factors increases the incidence of diabetes. These findings suggest that detailed analyses of individual gene-environment interactions hold promise for gaining new insight into the mechanisms and risk factors contributing to type 2 diabetes, with application to personalized diagnoses and treatments. We look forward to future developments in this regard.

Maternal protein restriction during pregnancy and lactation alters central leptin signalling, increases food intake, and decreases bone mass in 1 year old rat offspring

The effects of perinatal nutrition on offspring physiology have mostly been examined in young adult animals. Aging constitutes a risk factor for the progressive loss of metabolic flexibility and development of disease. Few studies have examined whether the phenotype programmed by perinatal nutrition persists in aging offspring. Persistence of detrimental phenotypes and their accumulative metabolic effects are important for disease causality. This study determined the effects of maternal protein restriction during pregnancy and lactation on food consumption, central leptin sensitivity, bone health, and susceptibility to high fat diet-induced adiposity in 1-year-old male offspring. Sprague-Dawley rats received either a control or a protein restricted diet throughout pregnancy and lactation and pups were weaned onto laboratory chow. One-year-old low protein (LP) offspring exhibited hyperphagia. The inability of an intraperitoneal (i.p.) leptin injection to reduce food intake indicated that the hyperphagia was mediated by decreased central leptin sensitivity. Hyperphagia was accompanied by lower body weight suggesting increased energy expenditure in LP offspring. Bone density and bone mineral content that are negatively regulated by leptin acting via the sympathetic nervous system (SNS), were decreased in LP offspring. LP offspring did not exhibit increased susceptibility to high fat diet induced metabolic effects or adiposity. The results presented here indicate that the programming effects of perinatal protein restriction are mediated by specific decreases in central leptin signalling to pathways involved in the regulation of food intake along with possible enhancement of different CNS leptin signalling pathways acting via the SNS to regulate bone mass and energy expenditure.

Day-restricted feeding during pregnancy and lactation programs glucose intolerance and impaired insulin secretion in male rat offspring

AIM

The maternal environment during pregnancy and lactation plays a determining role in programming energy metabolism in offspring. Among a myriad of maternal factors, disruptions in the light/dark cycle during pregnancy can program glucose intolerance in offspring. Out-of-phase feeding has recently been reported to influence metabolism in adult humans and rodents; however, it is not known whether this environmental factor impacts offspring metabolism when applied during pregnancy and lactation. This study aims to determine whether maternal day-restricted feeding (DF) influences energy metabolism in offspring.

METHODS

Pregnant and lactating Wistar rats were subjected to ad libitum (AL) or DF during pregnancy and lactation. The offspring born to the AL and DF dams were intra- and interfostered, which resulted in 4 group types.

RESULTS

The male offspring born to and breastfed by the DF dams (DF/DF off) were glucose intolerant, but without parallel insulin resistance as adults. Experiments with isolated pancreatic islets demonstrated that the male DF/DF off rats had reduced insulin secretion with no parallel disruption in calcium handling. However, this reduction in insulin secretion was accompanied by increased miRNA-29a and miRNA34a expression and decreased syntaxin 1a protein levels.

CONCLUSION

We conclude that out-of-phase feeding during pregnancy and lactation can lead to glucose intolerance in male offspring, which is caused by a disruption in insulin secretion capacity. This metabolic programming is possibly caused by mechanisms dependent on miRNA modulation of syntaxin 1a.

Maternal high fructose and low protein consumption during pregnancy and lactation share some but not all effects on early-life growth and metabolic programming of rat offspring

Maternal nutritional stress during pregnancy acts to program offspring metabolism. We hypothesized that the nutritional stress caused by maternal fructose or low protein intake during pregnancy would program the offspring to develop metabolic aberrations that would be exacerbated by a diet rich in fructose or fat during adult life. The objective of this study was to characterize and compare the fetal programming effects of maternal fructose with the established programming model of a low-protein diet on offspring. Male offspring from Sprague-Dawley dams fed a 60% starch control diet, a 60% fructose diet, or a low-protein diet throughout pregnancy and lactation were weaned onto either a 60% starch control diet, 60% fructose diet, or a 30% fat diet for 15 weeks. Offspring from low-protein and fructose-fed dam showed retarded growth (P<.05) at weaning (50.3, 29.6 vs 59.1±0.8 g) and at 18 weeks of age (420, 369 vs 464±10.9 g). At 18 weeks of age, offspring from fructose dams expressed greater quantities (P<.05) of intestinal Pgc1a messenger RNA compared with offspring from control or low-protein dams (1.31 vs 0.89, 0.85; confidence interval, 0.78-1.04). Similarly, maternal fructose (P=.09) and low-protein (P<.05) consumption increased expression of Pgc1a in offspring liver (7.24, 2.22 vs 1.22; confidence interval, 2.11-3.45). These data indicate that maternal fructose feeding is a programming model that shares some features of maternal protein restriction such as retarded growth, but is unique in programming of selected hepatic and intestinal transcripts.

Cell-autonomous programming of rat adipose tissue insulin signalling proteins by maternal nutrition

AIMS/HYPOTHESIS

Individuals with a low birthweight have an increased risk of developing type 2 diabetes mellitus in adulthood. This is associated with peripheral insulin resistance. Here, we aimed to determine whether changes in insulin signalling proteins in white adipose tissue (WAT) can be detected prior to the onset of impaired glucose tolerance, determine whether these changes are cell-autonomous and identify the underlying mechanisms involved.

METHODS

Fourteen-month-old male rat offspring born to dams fed a standard protein (20%) diet or a low (8%) protein diet throughout gestation and lactation were studied. Fat distribution and adipocyte size were determined. Protein content and mRNA expression of key insulin signalling molecules were analysed in epididymal WAT and in pre-adipocytes that had undergone in vitro differentiation.

RESULTS

The offspring of low protein fed dams (LP offspring) had reduced visceral WAT mass, altered fat distribution and a higher percentage of small adipocytes in epididymal WAT. This was associated with reduced levels of IRS1, PI3K p110β, Akt1 and PKCζ proteins and of phospho-Akt Ser473. Corresponding mRNA transcript levels were unchanged. Similarly, in vitro differentiated adipocytes from LP offspring showed reduced protein levels of IRβ, IRS1, PI3K p85α and p110β subunits, and Akt1. Levels of Akt Ser473 and IRS1 Tyr612 phosphorylation were reduced, while IRS1 Ser307 phosphorylation was increased.

CONCLUSIONS/INTERPRETATION

Maternal protein restriction during gestation and lactation changes the distribution and morphology of WAT and reduces the levels of key insulin signalling proteins in the male offspring. This phenotype is retained in in vitro differentiated adipocytes, suggesting that programming occurs via cell-autonomous mechanism(s).

Nutritional limitation in early postnatal life and its effect on aging and longevity in rodents

Nutrient limitation in the form of chronic dietary restriction (DR), or more specifically a life-long reduction of total daily nutritional intake, was first shown to extend longevity in rats more than eight decades ago and is one of the most robust anti-aging interventions known. More recently, it has become apparent that dietary restriction limited to only the first few weeks of life in rodents is also capable of significantly impacting aging and longevity. The imposition of nutrient limitation is often achieved via the manipulation of litter size or the modulation of maternal nutrient intake during the lactational period. Not surprisingly, nutrient limited pups are smaller at weaning, and remain so throughout their life, while exhibiting signs of slowed aging. In this review, we discuss potential mechanisms that account for the anti-aging effects of postnatal undernutrition with an emphasis on those pathways that parallel changes seen with chronic DR.

Increased IGFBP-1 phosphorylation in response to leucine deprivation is mediated by CK2 and PKC

Insulin-like growth factor binding protein-1 (IGFBP-1), secreted by fetal liver, is a key regulator of IGF-I bioavailability and fetal growth. IGFBP-1 phosphorylation decreases IGF-I bioavailability and diminishes its growth-promoting effects. Growth-restricted fetuses have decreased levels of circulating essential amino acids. We recently showed that IGFBP-1 hyperphosphorylation (pSer101/119/169) in response to leucine deprivation is regulated via activation of the amino acid response (AAR) in HepG2 cells. Here we investigated nutrient-sensitive protein kinases CK2/PKC/PKA in mediating IGFBP-1 phosphorylation in leucine deprivation. We demonstrated that leucine deprivation stimulated CK2 activity (enzymatic assay) and induced IGFBP-1 phosphorylation (immunoblotting/MRM-MS). Inhibition (pharmacological/siRNA) of CK2/PKC, but not PKA, prevented IGFBP-1 hyperphosphorylation in leucine deprivation. PKC inhibition also prevented leucine deprivation-stimulated CK2 activity. Functionally, leucine deprivation decreased IGF-I-induced-IGF-1R autophosphorylation when CK2/PKC were not inhibited. Our data strongly support that PKC promotes leucine deprivation-induced IGFBP-1 hyperphosphorylation via CK2 activation, mechanistically linking decreased amino acid availability and reduced fetal growth.

SIRT1 Disruption in Human Fetal Hepatocytes Leads to Increased Accumulation of Glucose and Lipids

There are unprecedented epidemics of obesity, such as type II diabetes and non-alcoholic fatty liver diseases (NAFLD) in developed countries. A concerning percentage of American children are being affected by obesity and NAFLD. Studies have suggested that the maternal environment in utero might play a role in the development of these diseases later in life. In this study, we documented that inhibiting SIRT1 signaling in human fetal hepatocytes rapidly led to an increase in intracellular glucose and lipids levels. More importantly, both de novo lipogenesis and gluconeogenesis related genes were upregulated upon SIRT1 inhibition. The AKT/FOXO1 pathway, a major negative regulator of gluconeogenesis, was decreased in the human fetal hepatocytes inhibited for SIRT1, consistent with the higher level of gluconeogenesis. These results indicate that SIRT1 is an important regulator of lipid and carbohydrate metabolisms within human fetal hepatocytes, acting as an adaptive transcriptional response to environmental changes.

The early origins of obesity and insulin resistance: timing, programming and mechanisms

Maternal obesity is associated with an increased risk of developing gestational diabetes mellitus and it also results in an increased risk of giving birth to a large baby with increased fat mass. Furthermore, it is also contributes to an increased risk of obesity and insulin resistance in the offspring in childhood, adolescence and adult life. It has been proposed that exposure to maternal obesity may therefore result in an 'intergenerational cycle' of obesity and insulin resistance. There is significant interest in whether exposure to maternal obesity around the time of conception alone contributes directly to poor metabolic outcomes in the offspring and whether dieting in the obese mother before pregnancy or around the time of conception has metabolic benefits for the offspring. This review focusses on experimental and clinical studies that have investigated the specific impact of exposure to maternal obesity during the periconceptional period alone or extending beyond conception on adipogenesis, lipogenesis and on insulin signalling pathways in the fat, liver and muscle of the offspring. Findings from these studies highlight the need for a better evidence base for the development of dietary interventions in obese women before pregnancy and around the time of conception to maximize the metabolic benefits and minimize the metabolic costs for the next generation.

The Role of Maternal Dietary Proteins in Development of Metabolic Syndrome in Offspring

The prevalence of metabolic syndrome and obesity has been increasing. Pre-natal environment has been suggested as a factor influencing the risk of metabolic syndrome in adulthood. Both observational and experimental studies showed that maternal diet is a major modifier of the development of regulatory systems in the offspring in utero and post-natally. Both protein content and source in maternal diet influence pre- and early post-natal development. High and low protein dams’ diets have detrimental effect on body weight, blood pressure191 and metabolic and intake regulatory systems in the offspring. Moreover, the role of the source of protein in a nutritionally adequate maternal diet in programming of food intake regulatory system, body weight, glucose metabolism and blood pressure in offspring is studied. However, underlying mechanisms are still elusive. The purpose of this review is to examine the current literature related to the role of proteins in maternal diets in development of characteristics of the metabolic syndrome in offspring.

The impact of in utero heat stress and nutrient restriction on progeny body composition

We recently demonstrated that in utero heat stress (IUHS) alters future tissue accretion in pigs, but whether this is a conserved response among species, is due to the direct effects of heat stress (HS) or mediated by reduced maternal feed intake (FI) is not clear. Study objectives were to compare the quantity and rate of tissue accretion in rats exposed to differing in utero thermal environments while eliminating the confounding effect of dissimilar maternal FI. On d3 of gestation, pregnant Sprague-Dawley rats (189.0±5.9g BW) were exposed to thermoneutral (TN; 22.2±0.1°C; n=8), or HS conditions (cyclical 30 to 34°C; n=8) until d18 of gestation. A third group was pair-fed to HS dams in TN conditions (PFTN; 22.2±0.1°C; n=8) from d4 to d19 of gestation. HS increased dam rectal temperature (p=0.01; 1.3°C) compared to TN and PFTN mothers, and reduced FI (p=0.01; 33%) compared to TN ad libitum fed controls. Although litter size was similar (p=0.97; 10.9 pups/litter), pup birth weight was reduced (p=0.03; 15.4%) in HS compared to PFTN and TN dams. Two male pups per dam [n=8 in utero TN (IUTN); n=8 IUHS; n=8 in utero PFTN (IUPFTN)] were selected from four dams per treatment based on similar gestation length, and body composition was determined using dual-energy x-ray absorptiometry (DXA) on d26, d46, and d66 of postnatal life. Whole-body fat content increased (p=0.01; 11.2%), and whole-body lean tissue decreased (p=0.01; 2.6%) in IUPFTN versus IUTN and IUHS offspring. Whole-body composition was similar between IUHS and IUTN offspring. Epididymal fat pad weight increased (p=0.03; 21.6%) in IUPFTN versus IUHS offspring. In summary and in contrast to pigs, IUHS did not impact rodent body composition during this stage of growth; however, IUPFTN altered the future hierarchy of tissue accretion.

Coenzyme Q10 Prevents Insulin Signaling Dysregulation and Inflammation Prior to Development of Insulin Resistance in Male Offspring of a Rat Model of Poor Maternal Nutrition and Accelerated Postnatal Growth

Low birth weight and rapid postnatal growth increases the risk of developing insulin resistance and type 2 diabetes in later life. However, underlying mechanisms and potential intervention strategies are poorly defined. Here we demonstrate that male Wistar rats exposed to a low-protein diet in utero that had a low birth weight but then underwent postnatal catch-up growth (recuperated offspring) had reductions in the insulin signaling proteins p110-β (13% ± 6% of controls [P < .001]) and insulin receptor substrate-1 (39% ± 10% of controls [P < .05]) in adipose tissue. These changes were not accompanied by any change in expression of the corresponding mRNAs, suggesting posttranscriptional regulation. Recuperated animals displayed evidence of a proinflammatory phenotype of their adipose tissue with increased IL-6 (139% ± 8% [P < .05]) and IL1-β (154% ± 16% [P < .05]) that may contribute to the insulin signaling protein dysregulation. Postweaning dietary supplementation of recuperated animals with coenzyme Q (CoQ10) (1 mg/kg of body weight per day) prevented the programmed reduction in insulin receptor substrate-1 and p110-β and the programmed increased in IL-6. These findings suggest that postweaning CoQ10 supplementation has antiinflammatory properties and can prevent programmed changes in insulin-signaling protein expression. We conclude that CoQ10 supplementation represents an attractive intervention strategy to prevent the development of insulin resistance that results from suboptimal in utero nutrition.

Early life origins of metabolic disease: Developmental programming of hypothalamic pathways controlling energy homeostasis

A wealth of animal and human studies demonstrate that perinatal exposure to adverse metabolic conditions - be it maternal obesity, diabetes or under-nutrition - results in predisposition of offspring to develop obesity later in life. This mechanism is a contributing factor to the exponential rise in obesity rates. Increased weight gain in offspring exposed to maternal obesity is usually associated with hyperphagia, implicating altered central regulation of energy homeostasis as an underlying cause. Perinatal development of the hypothalamus (a brain region key to metabolic regulation) is plastic and sensitive to metabolic signals during this critical time window. Recent research in non-human primate and rodent models has demonstrated that exposure to adverse maternal environments impairs the development of hypothalamic structure and consequently function, potentially underpinning metabolic phenotypes in later life. This review summarizes our current knowledge of how adverse perinatal environments program hypothalamic development and explores the mechanisms that could mediate these effects.

Elevated galanin may predict the risk of type 2 diabetes mellitus for development of Alzheimer's disease

Alzheimer's disease is the most common form of dementia among the elderly and is characterized by progressive loss of memory and cognition. Epidemiological and clinical studies demonstrated that type 2 diabetes mellitus is an important risk factor for the development of Alzheimer's disease, i.e., the patients with type 2 diabetes mellitus are frequently companied with Alzheimer's disease symptoms. Despite many studies recently probed into the comorbid state of both diseases, so far the precise mechanism for this association is poorly understood. Emerging evidences suggest that defects in galanin play a central role on type 2 diabetes mellitus and is considered to be a risk factor for Alzheimer's disease development. This review provides a new insight into the multivariate relationship among galanin, type 2 diabetes mellitus and Alzheimer's disease, highlighting the effect of galanin system on the cross-talk between both diseases in human and rodent models. The current data support that activating central GalR2 attenuates insulin resistance and Alzheimer's disease feature in animal models. These may help us better understanding the pathogenesis of both diseases and provide useful hints for the development of novel therapeutic approaches to treat type 2 diabetes mellitus and Alzheimer's disease.

I'm eating for two: parental dietary effects on offspring metabolism

It has long been understood that the pathogenesis of complex diseases such as diabetes includes both genetic and environmental components. More recently, it has become clear that not only does an individual's environment influence their own metabolism, but in some cases, the environment experienced by their parents may also contribute to their risk of metabolic disease. Here, we review the evidence that parental diet influences metabolic phenotype in offspring in mammals and provide a current survey of our mechanistic understanding of these effects.

Effects of aging and maternal protein restriction on the muscle fibers morphology and neuromuscular junctions of rats after nutritional recovery

Changes in the nutritional status of mothers may predispose their offspring to neuromuscular disorders in the long term. This study evaluated the effects of maternal protein restriction during pregnancy and lactation on the muscle fibers and neuromuscular junctions (NMJs) of the soleus muscle in the offspring of rats at 365 days of age that had undergone nutritional recovery. Wistar rats were divided into two groups: control (CG)--the offspring of mothers fed a normal protein diet (17%) and restricted (RG)--offspring of mothers fed a low protein diet (6%). After lactation, the male pups received standard chow ad libitum. At 365 days, samples of soleus muscle were collected for muscle fiber analysis (HE staining, NADH-TR reaction and ultrastructure), intramuscular collagen quantification (picrosirius red staining) and NMJs analysis (non-specific esterase technique). The cross-sectional area of type I fibers was reduced by 20% and type IIa fibers by 5% while type IIb fibers increased by 5% in the RG compared to the CG. The percentage of intramuscular collagen was 19% lower in the RG. Disorganization of the myofibrils and Z line was observed, with the presence of clusters of mitochondria in both groups. Regarding the NMJs, in the RG there was a reduction of 10% in the area and 17% in the small diameter and an increase of 7% in the large diameter. The results indicate that the effects of maternal protein restriction on muscle fibers and NMJs seem to be long-lasting and irreversible.

Gene-environment interactions controlling energy and glucose homeostasis and the developmental origins of obesity

Obesity and type 2 diabetes mellitus (T2DM) often occur together and affect a growing number of individuals in both the developed and developing worlds. Both are associated with a number of other serious illnesses that lead to increased rates of mortality. There is likely a polygenic mode of inheritance underlying both disorders, but it has become increasingly clear that the pre- and postnatal environments play critical roles in pushing predisposed individuals over the edge into a disease state. This review focuses on the many genetic and environmental variables that interact to cause predisposed individuals to become obese and diabetic. The brain and its interactions with the external and internal environment are a major focus given the prominent role these interactions play in the regulation of energy and glucose homeostasis in health and disease.

Genetic, nongenetic and epigenetic risk determinants in developmental programming of type 2 diabetes

Low birthweight (LBW) individuals and offspring of women with gestational diabetes mellitus (GDM) exhibit increased risk of developing type 2 diabetes (T2D) and associated cardiometabolic traits in adulthood, which for both groups may be mediated by adverse events and developmental changes in fetal life. T2D is a multifactorial disease occurring as a result of complicated interplay between genetic and both prenatal and postnatal nongenetic factors, and it remains unknown to what extent the increased risk of T2D associated with LBW or GDM in the mother may be due to, or confounded by, genetic factors. Indeed, it has been shown that genetic changes influencing risk of diabetes may also be associated with reduced fetal growth as a result of reduced insulin secretion and/or action. Similarly, increased risk of T2D among offspring could be explained by T2D susceptibility genes shared between the mother and her offspring. Epigenetic mechanisms may explain the link between factors operating in fetal life and later risk of developing T2D, but so far convincing evidence is lacking for epigenetic changes as a prime and direct cause of T2D. This review addresses recent literature on the early origins of adult disease hypothesis, with a special emphasis on the role of genetic compared with nongenetic and epigenetic risk determinants and disease mechanisms.

The developmental origins of sarcopenia: from epidemiological evidence to underlying mechanisms

Sarcopenia is defined as the loss of skeletal muscle mass and strength with age. There is increasing recognition of the serious health consequences in terms of disability, morbidity and mortality as well as major healthcare costs. Adult determinants of sarcopenia including age, gender, size, levels of physical activity and heritability have been well described. Nevertheless, there remains considerable unexplained variation in muscle mass and strength between older adults that may reflect not only the current rate of loss but the peak attained earlier in life. To date most epidemiological studies of sarcopenia have focused on factors modifying decline in later life; however, a life course approach to understanding sarcopenia, additionally, focuses on factors operating earlier in life including developmental influences. The epidemiological evidence linking low birth weight with lower muscle mass and strength is strong and consistent with replication in a number of different groups including children, young and older adults. However, most of the evidence for the cellular, hormonal, metabolic and molecular mechanisms underlying these associations comes from animal models. The next stage is to translate the understanding of mechanisms from animal muscle to human muscle enabling progress to be made not only in earlier identification of individuals at risk of sarcopenia but also in the development of beneficial interventions across the life course.

Gestational protein restriction impairs insulin-regulated glucose transport mechanisms in gastrocnemius muscles of adult male offspring

Type II diabetes originates from various genetic and environmental factors. Recent studies showed that an adverse uterine environment such as that caused by a gestational low-protein (LP) diet can cause insulin resistance in adult offspring. The mechanism of insulin resistance induced by gestational protein restriction is not clearly understood. Our aim was to investigate the role of insulin signaling molecules in gastrocnemius muscles of gestational LP diet-exposed male offspring to understand their role in LP-induced insulin resistance. Pregnant Wistar rats were fed a control (20% protein) or isocaloric LP (6%) diet from gestational day 4 until delivery and a normal diet after weaning. Only male offspring were used in this study. Glucose and insulin responses were assessed after a glucose tolerance test. mRNA and protein levels of molecules involved in insulin signaling were assessed at 4 months in gastrocnemius muscles. Muscles were incubated ex vivo with insulin to evaluate insulin-induced phosphorylation of insulin receptor (IR), Insulin receptor substrate-1, Akt, and AS160. LP diet-fed rats gained less weight than controls during pregnancy. Male pups from LP diet-fed mothers were smaller but exhibited catch-up growth. Plasma glucose and insulin levels were elevated in LP offspring when subjected to a glucose tolerance test; however, fasting levels were comparable. LP offspring showed increased expression of IR and AS160 in gastrocnemius muscles. Ex vivo treatment of muscles with insulin showed increased phosphorylation of IR (Tyr972) in controls, but LP rats showed higher basal phosphorylation. Phosphorylation of Insulin receptor substrate-1 (Tyr608, Tyr895, Ser307, and Ser318) and AS160 (Thr642) were defective in LP offspring. Further, glucose transporter type 4 translocation in LP offspring was also impaired. A gestational LP diet leads to insulin resistance in adult offspring by a mechanism involving inefficient insulin-induced IR, Insulin receptor substrate-1, and AS160 phosphorylation and impaired glucose transporter type 4 translocation.

Early-life nutritional programming of longevity

Available data from both experimental and epidemiological studies suggest that inadequate diet in early life can permanently change the structure and function of specific organs or homoeostatic pathways, thereby ‘programming’ the individual’s health status and longevity. Sufficient evidence has accumulated showing significant impact of epigenetic regulation mechanisms in nutritional programming phenomenon. The essential role of early-life diet in the development of aging-related chronic diseases is well established and described in many scientific publications. However, the programming effects on lifespan have not been extensively reviewed systematically. The aim of the review is to provide a summary of research findings and theoretical explanations that indicate that longevity can be influenced by early nutrition.

Maternal protein restriction impairs the transcriptional metabolic flexibility of skeletal muscle in adult rat offspring

Skeletal muscle exhibits a remarkable flexibility in the usage of fuel in response to the nutrient intake and energy demands of the organism. In fact, increased physical activity and fasting trigger a transcriptional programme in skeletal muscle cells leading to a switch from carbohydrate to lipid oxidation. Impaired metabolic flexibility has been reported to be associated with obesity and type 2 diabetes, but it is not known whether the disability to adapt to metabolic demands is a cause or a consequence of these pathological conditions. Inasmuch as a poor nutritional environment during early life is a predisposing factor for the development of metabolic diseases in adulthood, in the present study, we aimed to determine the long-term effects of maternal malnutrition on the metabolic flexibility of offspring skeletal muscle. To this end, the transcriptional responses of the soleus and extensor digitorum longus muscles to fasting were evaluated in adult rats born to dams fed a control (17 % protein) or a low-protein (8 % protein, protein restricted (PR)) diet throughout pregnancy and lactation. With the exception of reduced body weight and reduced plasma concentrations of TAG, PR rats exhibited a metabolic profile that was the same as that of the control rats. In the fed state, PR rats exhibited an enhanced expression of key regulatory genes of fatty acid oxidation including CPT1a, PGC-1α, UCP3 and PPARα and an impaired expression of genes that increase the capacity for fat oxidation in response to fasting. These results suggest that impaired metabolic inflexibility precedes and may contribute to the development of metabolic disorders associated with early malnutrition.

Modeling combined schizophrenia-related behavioral and metabolic phenotypes in rodents

Schizophrenia is a chronic, debilitating disorder with a complex behavioral and cognitive phenotype underlined by a similarly complex etiology involving an interaction between susceptibility genes and environmental factors during early development. Limited progress has been made in developing novel pharmacotherapy, partly due to a lack of valid animal models. The recent recognition of the potentially causal role of central and peripheral energy metabolism in the pathophysiology of schizophrenia raises the need of research on animal models that combine both behavioral and metabolic phenotypic domains, similar to what have been identified in humans. In this review we focus on selected genetic (DBA/2J mice, leptin receptor mutants, and PSD-93 knockout mice), early neurodevelopmental (maternal protein deprivation) and pharmacological (acute phencyclidine) animal models that capture the combined behavioral and metabolic abnormalities shown by schizophrenic patients. In reviewing behavioral phenotypes relevant to schizophrenia we apply the principles established by the Research Domain Criteria (RDoC) for better translation. We demonstrate that etiologically diverse manipulations such as specific breeding, deletion of genes that are primarily involved in metabolic regulation and in synaptic plasticity, as well as early metabolic deprivation and adult pharmacological challenge of the glutamate system can lead to schizophrenia-related behavioral and metabolic phenotypes, which suggest that these pathways might be interlinked. We propose that using animal models that combine different domains of schizophrenia can be used as a translationally valid approach to capture the system-level complex interplay between peripheral and central processes in the development of psychopathology.

The impact of early nutrition on the ageing trajectory

Epidemiological studies, including those in identical twins, and in individuals in utero during periods of famine have provided robust evidence of strong correlations between low birth-weight and subsequent risk of disease in later life, including type 2 diabetes (T2D), CVD, and metabolic syndrome. These and studies in animal models have suggested that the early environment, especially early nutrition, plays an important role in mediating these associations. The concept of early life programming is therefore widely accepted; however the molecular mechanisms by which early environmental insults can have long-term effects on a cell and consequently the metabolism of an organism in later life, are relatively unclear. So far, these mechanisms include permanent structural changes to the organ caused by suboptimal levels of an important factor during a critical developmental period, changes in gene expression caused by epigenetic modifications (including DNA methylation, histone modification and microRNA) and permanent changes in cellular ageing. Many of the conditions associated with early-life nutrition are also those which have an age-associated aetiology. Recently, a common molecular mechanism in animal models of developmental programming and epidemiological studies has been development of oxidative stress and macromolecule damage, specifically DNA damage and telomere shortening. These are phenotypes common to accelerated cellular ageing. Thus, this review will encompass epidemiological and animal models of developmental programming with specific emphasis on cellular ageing and how these could lead to potential therapeutic interventions and strategies which could combat the burden of common age-associated disease, such as T2D and CVD.