Developmental programming of hypothalamic neuronal circuits: impact on energy balance control

Control of tuberal hypothalamic development and its implications in metabolic disorders

The tuberal hypothalamus regulates a range of crucial physiological processes, including energy homeostasis and metabolism. In this Review, we explore the intricate molecular mechanisms and signalling pathways that control the development of the tuberal hypothalamus, focusing on aspects that shape metabolic outcomes. Major developmental events are discussed in the context of their effect on the establishment of both functional hypothalamic neuronal circuits and brain-body interfaces that are pivotal to the control of metabolism. Emerging evidence indicates that aberrations in molecular pathways during tuberal hypothalamic development contribute to metabolic dysregulation. Understanding the molecular underpinnings of tuberal hypothalamic development provides a comprehensive view of neurodevelopmental processes and offers a promising avenue for future targeted interventions to prevent and treat metabolic disorders.

DNA methylation and its potential roles in common oral diseases

Oral diseases are among the most common diseases worldwide and are associated with systemic illnesses, and the rising occurrence of oral diseases significantly impacts the quality of life for many individuals. It is crucial to detect and treat these conditions early to prevent them from advancing. DNA methylation is a fundamental epigenetic process that contributes to a variety of diseases including various oral diseases. Taking advantage of its reversibility, DNA methylation becomes a viable therapeutic target by regulating various cellular processes. Understanding the potential role of this DNA alteration in oral diseases can provide significant advances and more opportunities for diagnosis and therapy. This article will review the biology of DNA methylation, and then mainly discuss the key findings on DNA methylation in oral cancer, periodontitis, endodontic disease, oral mucosal disease, and clefts of the lip and/or palate in the background of studies on global DNA methylation and gene-specific DNA methylation.

Protein Tyrosine Phosphatase Receptors N and N2 Control Pituitary Melanotroph Development and POMC Expression

The neuroendocrine marker genes Ptprn and Ptprn2 encode protein tyrosine phosphatase receptors N and N2, 2 members of protein tyrosine phosphatase receptors void of enzymatic activity, and whose function and mechanism of action have not been elucidated. To explore the role(s) of Ptprn and Ptprn2 on the hypothalamic-pituitary-adrenal axis, we used mice in which both genes were knocked out (DKO). The focus in this study was on corticotrophs and melanotrophs from the anterior and intermediate lobes of the pituitary gland, respectively. In both sexes, DKO caused an increase in the expression of the corticotroph/melanotroph genes Pomc and Tbx19 and the melanotroph-specific gene Pax7. We also found in vivo and in vitro increased synthesis and release of beta-endorphin, alpha-melanocyte-stimulating hormone, and ACTH in DKO mice, which was associated with increased serum corticosterone levels and adrenal mass. DKO also increased the expression of other melanotroph-specific genes, but not corticotroph-specific genes. The dopaminergic pathway in the hypothalamus and dopaminergic receptors in melanotrophs were not affected in DKO mice. However, hyperplasia of the intermediate lobe was observed in DKO females and males, accompanied by increased proopiomelanocortin immunoreactivity per cell. These results indicate that protein tyrosine phosphatase receptor type N contributes to hypothalamic-pituitary-adrenal function by being involved in processes governing postnatal melanotroph development and Pomc expression.

A bird's-eye overview of molecular mechanisms regulating feed intake in chickens-with mammalian comparisons

In recent decades, a lot of research has been conducted to explore poultry feeding behavior. However, up to now, the processes behind poultry feeding behavior remain poorly understood. The review generalizes modern expertise about the hormonal regulation of feeding behavior in chickens, focusing on signaling pathways mediated by insulin, leptin, and ghrelin and regulatory pathways with a cross-reference to mammals. This overview also summarizes state-of-the-art research devoted to hypothalamic neuropeptides that control feed intake and are prime candidates for predictors of feeding efficiency. Comparative analysis of the signaling pathways that mediate the feed intake regulation allowed us to conclude that there are major differences in the processes by which hormones influence specific neuropeptides and their contrasting roles in feed intake control between two vertebrate clades.

Maternal macronutrient intake effects on offspring macronutrient targets and metabolism

OBJECTIVE

Exposure in utero to maternal diet can program offspring health and susceptibility to disease. Using C57BL6/JArc mice, we investigated how maternal dietary protein to carbohydrate balance influences male and female offspring appetite and metabolic health.

METHODS

Dams were placed on either a low-protein (LP) or high-protein (HP) diet. Male and female offspring were placed on a food choice experiment post weaning and were then constrained to either a standard diet or Western diet. Food intake, body weight, and composition were measured, and various metabolic tests were performed at different timepoints.

RESULTS

Offspring from mothers fed HP diets selected a higher protein intake and had increased body weight in early life relative to offspring from LP diet-fed dams. As predicted by protein leverage theory, higher protein intake targets led to increased food intake when offspring were placed on no-choice diets, resulting in greater body weight and fat mass. The combination of an HP maternal diet and a Western diet further exacerbated this obesity phenotype and led to long-term consequences for body composition and metabolism.

CONCLUSIONS

This work could help explain the association between elevated protein intake in humans during early life and increased risk of obesity in childhood and later life.

Maternal inulin alleviates high-fat diet-induced lipid disorder in offspring by epigenetically modulating hypothalamus feeding circuit-related genes

Increasing evidence supports the existence of fetal-originated adult diseases. Recent research indicates that the intrauterine environment affects the fetal hypothalamic energy intake center. Inulin is a probiotic that can moderate metabolic disorders, but whether maternal inulin intervention confers long-term metabolic benefits to lipid metabolism in offspring in their adult lives and the mechanism involved are unknown. Here, we used a maternal overnutrition model that was induced by excess energy intake before and during pregnancy and lactation and maternal inulin intervention was performed during pregnancy and lactation. The hypothalamic genome methylation in offspring was analyzed using a methylation array. The results showed that maternal inulin treatment modified the maternal high-fat diet (HFD)-induced increases in body weight, adipose tissue weight, and serum insulin and leptin levels and decreases in serum adiponectin levels. Maternal inulin intervention regulated the impairments in hypothalamic leptin resistance, induced the methylation of Socs3, Npy, and Il6, and inhibited the methylation of Lepr in the hypothalamus of offspring. In conclusion, maternal inulin intervention modifies offspring lipid metabolism, and the underlying mechanism involves the methylation of genes in the hypothalamus feeding circuit.

Sensitization of Hypertension: The Impact of Earlier Life Challenges: Excellence Award for Hypertension Research 2021

Hypertension affects over 1 billion individuals worldwide. Because the cause of hypertension is known only in a small fraction of patients, most individuals with high blood pressure are diagnosed as having essential hypertension. Elevated sympathetic nervous system activity has been identified in a large portion of hypertensive patients. However, the root cause for this sympathetic overdrive is unknown. A more complete understanding of the breadth of the functional capabilities of the sympathetic nervous system may lead to new insights into the cause of essential hypertension. By employing a unique experimental paradigm, we have recently discovered that the neural network controlling sympathetic drive is more reactive after rats are exposed to mild challenges (stressors) and that the hypertensive response can be sensitized (ie, hypertensive response sensitization [HTRS]). We have also found that the induction of HTRS involves plasticity in the neural network controlling sympathetic drive. The induction and maintenance of the latent HTRS state also require the functional integrity of the brain renin-angiotensin-aldosterone system and the presence of several central inflammatory factors. In this review, we will discuss the induction and expression of HTRS in adult animals and in the progeny of mothers with prenatal obesity/overnutrition or with maternal gestational hypertension. Also, interventions that reverse the effects of stressor-induced HTRS will be reviewed. Understanding the mechanisms underlying HTRS and identifying the beneficial effects of maternal or offspring early-life interventions that prevent or reverse the sensitized state can provide insights into therapeutic strategies for interrupting the vicious cycle of transgenerational hypertension.

Female and male C57BL/6J offspring exposed to maternal obesogenic diet develop altered hypothalamic energy metabolism in adulthood

Maternal obesity is exceedingly common and strongly linked to offspring obesity and metabolic disease. Hypothalamic function is critical to obesity development. Hypothalamic mechanisms causing obesity following exposure to maternal obesity have not been elucidated. Therefore, we studied a cohort of C57BL/6J dams, treated with a control or high-fat-high-sugar diet, and their adult offspring to explore potential hypothalamic mechanisms to explain the link between maternal and offspring obesity. Dams treated with obesogenic diet were heavier with mild insulin resistance, which is reflective of the most common metabolic disease in pregnancy. Adult offspring exposed to maternal obesogenic diet had no change in body weight but significant increase in fat mass, decreased glucose tolerance, decreased insulin sensitivity, elevated plasma leptin, and elevated plasma thyroid-stimulating hormone. In addition, offspring exposed to maternal obesity had decreased energy intake and activity without change in basal metabolic rate. Hypothalamic neurochemical profile and transcriptome demonstrated decreased neuronal activity and inhibition of oxidative phosphorylation. Collectively, these results indicate that maternal obesity without diabetes is associated with adiposity and decreased hypothalamic energy production in offspring. We hypothesize that altered hypothalamic function significantly contributes to obesity development. Future studies focused on neuroprotective strategies aimed to improve hypothalamic function may decrease obesity development.NEW & NOTEWORTHY Offspring exposed to maternal diet-induced obesity demonstrate a phenotype consistent with energy excess. Contrary to previous studies, the observed energy phenotype was not associated with hyperphagia or decreased basal metabolic rate but rather decreased hypothalamic neuronal activity and energy production. This was supported by neurochemical changes in the hypothalamus as well as inhibition of hypothalamic oxidative phosphorylation pathway. These results highlight the potential for neuroprotective interventions in the prevention of obesity with fetal origins.

Parental obesity-induced changes in developmental programming

Many studies support the link between parental obesity and the predisposition to develop adult-onset metabolic syndromes that include obesity, high blood pressure, dyslipidemia, insulin resistance, and diabetes in the offspring. As the prevalence of obesity increases in persons of childbearing age, so does metabolic syndrome in their descendants. Understanding how parental obesity alters metabolic programs in the progeny, predisposing them to adult-onset metabolic syndrome, is key to breaking this cycle. This review explores the basis for altered metabolism of offspring exposed to overnutrition by focusing on critical developmental processes influenced by parental obesity. We draw from human and animal model studies, highlighting the adaptations in metabolism that occur during normal pregnancy that become maladaptive with obesity. We describe essential phases of development impacted by parental obesity that contribute to long-term alterations in metabolism in the offspring. These encompass gamete formation, placentation, adipogenesis, pancreas development, and development of brain appetite control circuits. Parental obesity alters the developmental programming of these organs in part by inducing epigenetic changes with long-term consequences on metabolism. While exposure to parental obesity during any of these phases is sufficient to alter long-term metabolism, offspring often experience multiple exposures throughout their development. These insults accumulate to increase further the susceptibility of the offspring to the obesogenic environments of modern society.

Maternal free fatty acid concentration during pregnancy is associated with newborn hypothalamic microstructure in humans

OBJECTIVE

This study tested the hypothesis, in a prospective cohort study design, that maternal saturated free fatty acid (sFFA) concentration during pregnancy is prospectively associated with offspring (newborn) hypothalamic (HTH) microstructure and to explore the functional relevance of this association with respect to early-childhood body fat percentage (BF%).

METHODS

In N = 94 healthy newborns (born mean 39.3 [SD 1.5] weeks gestation), diffusion-weighted magnetic resonance imaging was performed shortly after birth (25.3 [12.5] postnatal days), and a subgroup (n = 37) underwent a dual-energy x-ray absorptiometry scan in early childhood (4.7 [SD 0.7] years). Maternal sFFA concentration during pregnancy was quantified in fasting blood samples via liquid chromatography-mass spectrometry. Infant HTH microstructural integrity was characterized using mean diffusivity (MD). Multiple linear regression was used to test the association between maternal sFFA and HTH MD, accounting for newborn sex, age at scan, mean white matter MD, and image quality. Multiple linear regression models also tested the association between HTH MD and early-childhood BF%, accounting for breastfeeding status.

RESULTS

Maternal sFFA during pregnancy accounted for 8.3% of the variation in newborn HTH MD (β-std = 0.25; p = 0.006). Furthermore, newborn HTH MD prospectively accounted for 15% of the variation in early-childhood BF% (β-std = 0.32; p = 0.019).

CONCLUSIONS

These findings suggest that maternal overnutrition during pregnancy may influence the development of the fetal hypothalamus, which, in turn, may have clinical relevance for childhood obesity risk.

Fetal programming of human energy homeostasis brain networks: Issues and considerations

In this paper, we present a transdisciplinary framework and testable hypotheses regarding the process of fetal programming of energy homeostasis brain circuitry. Our model proposes that key aspects of energy homeostasis brain circuitry already are functional by the time of birth (with substantial interindividual variation); that this phenotypic variation at birth is an important determinant of subsequent susceptibility for energy imbalance and childhood obesity risk; and that this brain circuitry exhibits developmental plasticity, in that it is influenced by conditions during intrauterine life, particularly maternal-placental-fetal endocrine, immune/inflammatory, and metabolic processes and their upstream determinants. We review evidence that supports the scientific premise for each element of this formulation, identify future research directions, particularly recent advances that may facilitate a better quantification of the ontogeny of energy homeostasis brain networks, highlight animal and in vitro-based approaches that may better address the determinants of interindividual variation in energy homeostasis brain networks, and discuss the implications of this formulation for the development of strategies targeted towards the primary prevention of childhood obesity.

Periconception and First Trimester Diet Modifies Appetite, Hypothalamic Gene Expression, and Carcass Traits in Bulls

Nulliparous yearling beef heifers (n=360) were used to evaluate the effects of maternal dietary protein during the periconception and first trimester periods of gestation on postnatal growth, feedlot performance, carcass characteristics, and the expression of genes associated with appetite in the arcuate nucleus of their male progeny. Heifers were individually fed a diet of 1.18g crude protein (CP)/day High protein (HPeri) or 0.62g CP/day Low protein (LPeri) beginning 60days before conception. From 24 to 98days post-conception (dpc), half of each treatment group changed to the alternative post-conception diet and were fed 1.49g CP/day (HPost) or 0.88g CP/day (LPost) yielding four treatment groups in a 2×2 factorial design. From day 98 of gestation, heifers received a common diet until parturition. Calves were weaned at 183days and developed on pasture before feedlot entry. Bulls underwent a 70-day Residual Feed Intake (RFI) feedlot test commencing at 528days of age. Feedlot entry and final body weight (BW), feedlot average daily gain (ADG) and RFI were not different (p>0.05). Progeny of dams that had a change in diet (LPeri/HPost and HPeri/LPost) had 9% higher daily dry matter intake (DMI) during the RFI test (p<0.05) than progeny of dams that received low diet throughout both the peri-conception period and first trimester (LPeri/LPost). Further, mRNA expression of the appetite-stimulating agouti-related protein (AGRP) was increased in the arcuate nucleus of High Peri/LPost bulls (p<0.05). Longissimus dorsi muscle cross sectional area, carcass dressing percentage, and estimated retail beef yield (RBY) were all higher (p<0.05), and rump (P8) fat tended to be lower (p=0.07), for bulls from HPost dams despite no difference in carcass weight (p<0.05). This study is of commercial importance to the livestock industry as specific periods of maternal dietary supplementation may increase feed intake, enhance progeny muscling, and alter fat deposition leading to improvement in efficiency of meat production in beef cattle.

Myo-Inositol Supplementation in Suckling Rats Protects against Adverse Programming Outcomes on Hypothalamic Structure Caused by Mild Gestational Calorie Restriction, Partially Comparable to Leptin Effects

We studied whether myo-inositol supplementation throughout lactation, alone and combined with leptin, may reverse detrimental effects on hypothalamic structure and function caused by gestational calorie gestation (CR) in rats. Candidate early transcript-based biomarkers of metabolic health in peripheral blood mononuclear cells (PBMC) were also studied. Offspring of dams exposed to 25% gestational CR and supplemented during lactation with physiological doses of leptin (CR-L), myo-inositol (CR-M), the combination (CR-LM), or the vehicle (CR-V) as well as control rats (CON-V) were followed and sacrificed at postnatal day 25. Myo-inositol and the combination increased the number of neurons in arcuate nucleus (ARC) (only in females) and paraventricular nucleus, and myo-inositol (alone) restored the number of αMSH⁺ neurons in ARC. Hypothalamic mRNA levels of Lepr in CR-M and Insr in CR-M and CR-LM males were higher than in CR-V and CON-V, respectively. In PBMC, increased expression levels of Lrp11 and Gls in CR-V were partially normalized in all supplemented groups (but only in males for Gls). Therefore, myo-inositol supplementation throughout lactation, alone and combined with leptin, reverts programmed alterations by fetal undernutrition on hypothalamic structure and gene expression of potential early biomarkers of metabolic health in PBMC, which might be attributed, in part, to increased leptin sensitivity.

Modulation of the Hypothalamic Nutrient Sensing Pathways by Sex and Early-Life Stress

There are sex differences in metabolic disease risk, and early-life stress (ES) increases the risk to develop such diseases, potentially in a sex-specific manner. It remains to be understood, however, how sex and ES affect such metabolic vulnerability. The hypothalamus regulates food intake and energy expenditure by sensing the organism's energy state via metabolic hormones (leptin, insulin, ghrelin) and nutrients (glucose, fatty acids). Here, we investigated if and how sex and ES alter hypothalamic nutrient sensing short and long-term. ES was induced in mice by limiting the bedding and nesting material from postnatal day (P)2-P9, and the expression of genes critical for hypothalamic nutrient sensing were studied in male and female offspring, both at P9 and in adulthood (P180). At P9, we observed a sex difference in both Ppargc1a and Lepr expression, while the latter was also increased in ES-exposed animals relative to controls. In adulthood, we found sex differences in Acacb, Agrp, and Npy expression, whereas ES did not affect the expression of genes involved in hypothalamic nutrient sensing. Thus, we observe a pervasive sex difference in nutrient sensing pathways and a targeted modulation of this pathway by ES early in life. Future research is needed to address if the modulation of these pathways by sex and ES is involved in the differential vulnerability to metabolic diseases.

Obesity cardiomyopathy: evidence, mechanisms, and therapeutic implications

The prevalence of heart failure is on the rise and imposes a major health threat, in part, due to the rapidly increased prevalence of overweight and obesity. To this point, epidemiological, clinical, and experimental evidence supports the existence of a unique disease entity termed “obesity cardiomyopathy,” which develops independent of hypertension, coronary heart disease, and other heart diseases. Our contemporary review evaluates the evidence for this pathological condition, examines putative responsible mechanisms, and discusses therapeutic options for this disorder. Clinical findings have consolidated the presence of left ventricular dysfunction in obesity. Experimental investigations have uncovered pathophysiological changes in myocardial structure and function in genetically predisposed and diet-induced obesity. Indeed, contemporary evidence consolidates a wide array of cellular and molecular mechanisms underlying the etiology of obesity cardiomyopathy including adipose tissue dysfunction, systemic inflammation, metabolic disturbances (insulin resistance, abnormal glucose transport, spillover of free fatty acids, lipotoxicity, and amino acid derangement), altered intracellular especially mitochondrial Ca²⁺ homeostasis, oxidative stress, autophagy/mitophagy defect, myocardial fibrosis, dampened coronary flow reserve, coronary microvascular disease (microangiopathy), and endothelial impairment. Given the important role of obesity in the increased risk of heart failure, especially that with preserved systolic function and the recent rises in COVID-19-associated cardiovascular mortality, this review should provide compelling evidence for the presence of obesity cardiomyopathy, independent of various comorbid conditions, underlying mechanisms, and offer new insights into potential therapeutic approaches (pharmacological and lifestyle modification) for the clinical management of obesity cardiomyopathy.

Epigenetics of the developing and aging brain: Mechanisms that regulate onset and outcomes of brain reorganization

Brain development is a life-long process that encompasses several critical periods of transition, during which significant cognitive changes occur. Embryonic development, puberty, and reproductive senescence are all periods of transition that are hypersensitive to environmental factors. Rather than isolated episodes, each transition builds upon the last and is influenced by consequential changes that occur in the transition before it. Epigenetic marks, such as DNA methylation and histone modifications, provide mechanisms by which early events can influence development, cognition, and health outcomes. For example, parental environment influences imprinting patterns in gamete cells, which ultimately impacts gene expression in the embryo which may result in hypersensitivity to poor maternal nutrition during pregnancy, raising the risks for cognitive impairment later in life. This review explores how epigenetics induce and regulate critical periods, and also discusses how early environmental interactions prime a system towards a particular health outcome and influence susceptibility to disease or cognitive impairment throughout life.

Ozone-induced fetal growth restriction in rats is associated with sexually dimorphic placental and fetal metabolic adaptation

Objective

The importance of the placenta in mediating the pre- and post-natal consequences of fetal growth restriction has been increasingly recognized. However, the influence of placental sexual dimorphism on driving these outcomes has received little attention. The purpose of this study was to characterize how sex contributes to the relationship between placental metabolism and fetal programming utilizing a novel rodent model of growth restriction.

Methods

Fetal growth restriction was induced by maternal inhalation of 0.8 ppm ozone (4 h/day) during implantation receptivity (gestation days [GDs] 5 and 6) in Long-Evans rats. Control rats were exposed to filtered air. At GD 21, placental and fetal tissues were obtained for metabolic and genomic assessments.

Results

Growth-restricted male placentae exhibited increased mitochondrial biogenesis, increased oxygen consumption, and reduced nutrient storage. Male growth-restricted fetuses also had evidence of reduced adiposity and downregulation of hepatic metabolic signaling. In contrast, placentae from growth-restricted females had elevated markers of autophagy accompanied by an observed protection against hepatic metabolic perturbations. Despite this, growth restriction in females induced a greater number of hypothalamic gene and pathway alterations compared to growth-restricted males.

Conclusions

Increases in mitochondrial metabolism in growth-restricted male placentae likely initiates a sequela of adaptations that promote poor nutrient availability and adiposity. Divergently, the female placenta expresses protective mechanisms that may serve to increase nutrient availability to support fetal metabolic development. Collectively, this work emphasizes the importance of sex in mediating alterations in placental metabolism and fetal programming.

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Peri-implantation exposure to the gaseous air pollutant ozone impairs fetal growth.

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Ozone-induced, growth-restricted male placentae have increased mitochondrial biogenesis and oxidative consumption.

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Female growth-restricted placentae show increased inflammatory and autophagy-like responses.

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Placental metabolic adaptations to growth restriction were associated with sexually dimorphic perturbations in fetal tissues.

Maternal High-Fat-High-Carbohydrate Diet-Induced Obesity Is Associated with Increased Appetite in Peripubertal Male but Not Female C57Bl/6J Mice

Diet-induced maternal obesity might play a critical role in altering hypothalamic development, predisposing the offspring to obesity and metabolic disease later in life. The objective of this study was to describe both phenotypic and molecular sex differences in peripubertal offspring energy homeostasis, using a mouse model of maternal obesity induced by a high-fat-high-carbohydrate (HFHC) diet. We report that males, not females, exposed to a maternal HFHC diet had increased energy intake. Males exposed to a maternal HFHC diet had a 15% increased meal size and a 46% increased frequency, compared to the control (CON) males, without a change in energy expenditure. CON and HFHC offspring did not differ in body weight, composition, or plasma metabolic profile. HFHC diet caused decreased hypothalamic glucocorticoid expression, which was further decreased in males compared to females. Maternal weight, maternal caloric intake, and male offspring meal frequency were inversely correlated with offspring hypothalamic insulin receptor (IR) expression. There was a significant interaction between maternal-diet exposure and sex in hypothalamic IR. Based on our preclinical data, we suggest that interventions focusing on normalizing maternal nutrition might be considered to attenuate nutritional influences on obesity programming and curb the continuing rise in obesity rates.

Postnatal Overnutrition Induces Changes in Synaptic Transmission to Leptin Receptor-Expressing Neurons in the Arcuate Nucleus of Female Mice

The adipocyte-derived hormone leptin is a potent neurotrophic factor that contributes to the neural plasticity and development of feeding circuitry, particularly in the arcuate nucleus of the hypothalamus (ARH). Postnatal overnutrition affects leptin secretion and sensitivity, but whether postnatal overnutrition produces changes in the development of the synaptic transmission to ARH neurons is currently unknown. We evaluated the excitatory and inhibitory currents to ARH leptin receptor (LepR)-expressing neurons in prepubertal, pubertal and adult female mice. The effects of postnatal overnutrition in the expression of genes that code ion channels subunits in the ARH were also evaluated. We observed that the transition from prepubertal to pubertal stage is characterized by a rise in both excitatory and inhibitory transmission to ARH LepR-expressing neurons in control mice. Postnatal overnutrition induces a further increase in the excitatory synaptic transmission in pubertal and adult animals, whereas the amplitude of inhibitory currents to ARH LepR-expressing cells was reduced. Postnatal overnutrition also contributes to the modulation of gene expression of N-methyl-D-aspartate, GABA_B and ATP-sensitive potassium channel subunits in ARH. In summary, the synaptic transmission to ARH cells is profoundly influenced by postnatal overnutrition. Thus, increased adiposity during early postnatal period induces long-lasting effects on ARH cellular excitability.

Long-term effects of pro-opiomelanocortin methylation induced in food-restricted dams on metabolic phenotypes in male rat offspring

Objective

Maternal malnutrition affects the growth and metabolic health of the offspring. Little is known about the long-term effect on metabolic indices of epigenetic changes in the brain caused by maternal diet. Thus, we explored the effect of maternal food restriction during pregnancy on metabolic profiles of the offspring, by evaluating the DNA methylation of hypothalamic appetite regulators at 3 weeks of age.

Methods

Sprague-Dawley rats were divided into 2 groups: a control group and a group with a 50% food-restricted (FR) diet during pregnancy. Methylation and expression of appetite regulator genes were measured in 3-week-old offspring using pyrosequencing, real-time polymerase chain reaction, and western blotting analyses. We analyzed the relationship between DNA methylation and metabolic profiles by Pearson's correlation analysis.

Results

The expression of pro-opiomelanocortin (POMC) decreased, whereas DNA methylation significantly increased in male offspring of the FR dams, compared to the male offspring of control dams. Hypermethylation of POMC was positively correlated with the levels of high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol in 3-week-old male offspring. In addition, there were significant positive correlations between hypermethylation of POMC and the levels of triglycerides, HDL-C, and leptin in 6-month-old male offspring.

Conclusion

Our findings suggest that maternal food restriction during pregnancy influences the expression of hypothalamic appetite regulators via epigenetic changes, leading to the development of metabolic disorders in the offspring.

Intermittent fasting, adipokines, insulin sensitivity, and hypothalamic neuropeptides in a dietary overload with high-fat or high-fructose diet in mice

The intermittent fasting (IF) might have benefits on metabolism and food intake. Twelve-week old C57BL/6 J mice were fed a control diet (C, 10% kcal fat), a high-fat diet (HF, 50% kcal fat) or a high-fructose diet (HFru, 50% kcal fructose) for 8 weeks, then half of the animals in each group underwent IF (24 h fed, 24 h fasting) for an additional 4 weeks. Although food intake on the fed day remained the same for all groups, all fasting groups showed a reduction in body mass compared to their counterparts. IF reduced total cholesterol, triacylglycerol, fasting glucose, fasting insulin resistance index, and plasma leptin, but increased plasma adiponectin. IF reduced Leptin gene expression in the HF-IF group, but increased proinflammatory markers in the hypothalamus, also in the C-IF group. Both groups HFru-IF and C-IF, showed alterations in the leptin signaling pathway (Leptin, OBRb, and SOCS3), mainly in the HFru-IF group, suggesting leptin resistance. NPY and POMC neuropeptides labeled the neurons of the hypothalamus by immunofluorescence, corroborating qualitatively other quantitative findings of the study. In conclusion, current results are convincing in demonstrating the IF effect on central regulation of food intake control, as shown by NPY and POMC neuropeptide expressions, resulting in a lower weight gain. Besides, IF improves glycemia, lipid metabolism, and consequently insulin and leptin resistance. However, there is increased expression of inflammatory markers in mouse hypothalamus challenged by the HF and HFru diets, which in the long term may induce adverse effects.

Aging is associated with loss of beneficial effects of estrogen on leptin responsiveness in mice fed high fat diet: Role of estrogen receptor α and cytokines

Aging causes changes in body composition and energy balance. Estrogen plays an important role in body's metabolism. The aim of this study was to determine whether estrogen has beneficial effects on leptin responsiveness in aged mice. Young 4 months and aged 19-21 female mice fed High Fat Diet (HFD) or Standard Diet (SD) for 12 weeks and following received estrogen for 4 weeks. Responsiveness to leptin was compared by measuring energy balance parameters. Results showed that HFD caused weight gain compared to SD in young, but had no effect on aged animals. Estrogen reduced body weight, energy intake and visceral fat in young, while none of these parameters was affected in aged animals. Although there was leptin sensitivity in aged compared to ovariectomized animals, estrogen only improved the sensitivity of young to leptin. Estrogen prevented increase in TNF-α and a decrease in IL-10 in HFD young and aged animals. Response to estrogen depended on age, and estrogen increased leptin sensitivity only in young animals. Determining the exact mechanism of this action is suggested in future studies.

Converging Relationships of Obesity and Hyperuricemia with Special Reference to Metabolic Disorders and Plausible Therapeutic Implications

BACKGROUND

Obesity and hyperuricemia mutually influence metabolic syndrome. This study discusses the metabolic relationships between obesity and hyperuricemia in terms of pathophysiology, complications, and treatments.

METHODS

We searched for preclinical or clinical studies on the pathophysiology, complications, and therapy of obesity and hyperuricemia on the PubMed database.

RESULTS

In this systemic review, we summarized our searching results on topics of pathophysiology, complications and therapeutic strategy. In pathophysiology, we firstly introduce genetic variations for obesity, hyperuricemia and their relationships by genetic studies. Secondly, we talk about the epigenetic influences on obesity and hyperuricemia. Thirdly, we describe the central metabolic regulation and the role of hyperuricemia. Then, we refer to the character of adipose tissue inflammation and oxidative stress in the obesity and hyperuricemia. In the last part of this topic, we reviewed the critical links of gut microbiota in the obesity and hyperuricemia. In the following part, we review the pathophysiology of major complications in obesity and hyperuricemia including insulin resistance and type 2 diabetes mellitus, chronic kidney disease, cardiovascular diseases, and cancers. Finally, we recapitulate the therapeutic strategies especially the novel pharmaceutic interventions for obesity and hyperuricemia, which concurrently show the mutual metabolic influences between two diseases.

CONCLUSION

The data reviewed here delineate the metabolic relationships between obesity and hyperuricemia, and provide a comprehensive overview of the therapeutic targets for the management of metabolic syndromes.

Gestational caloric restriction with micronutrients supplementation does not delay development and promotes feeding behavior benefits

Introduction: Caloric restriction (CR) has been proven to promote a series of health benefits from yeast to primates. Nowadays, increasing rates of obesity certainly encourage researchers to evaluate CR effects and establish it as a therapeutic approach. Maternal obesity is also a concern, and studies in the developmental origins of health and disease (DOHaD) have shown the importance of interventions during pregnancy, especially those involving maternal nutrition. On the other hand, undernutrition during pregnancy leads to increased weight gain, disturbed feeding behavior and dysfunctional metabolism in adulthood.Methods: In this way, we utilized moderate CR (20% compared to control consumption) in pregnant Wistar rats as intervention, with malnutrition control by micronutrients supplementation. We assessed CR effects on offspring's developmental milestones, feeding behavior, exploratory behavior, and memory on adolescence (PND21) and adulthood (PND60).Results: We did not find alterations on litter size or birth weight, although CR pups were leaner at adult ages. Importantly, no delay in development was observed. Besides, female pups showed earlier suction reflex and male pups showed earlier response to the negative geotaxis. CR pups also showed less preference for palatable food (Froot Loops®) at adult age, which could be decisive on obesity tendency. Locomotor activity was increased by CR on PND60 and there was no effect on memory at all.Discussion: Our results on development and behavior demonstrate that gestational CR may be a helpful health strategy if malnutrition is well controlled, with potential clinical impact.

Methyl Donor Deficiency during Gestation and Lactation in the Rat Affects the Expression of Neuropeptides and Related Receptors in the Hypothalamus

The micronutrients vitamins B9 and B12 act as methyl donors in the one-carbon metabolism involved in transmethylation reactions which critically influence epigenetic mechanisms and gene expression. Both vitamins are essential for proper development, and their deficiency during pregnancy has been associated with a wide range of disorders, including persisting growth retardation. Energy homeostasis and feeding are centrally regulated by the hypothalamus which integrates peripheral signals and acts through several orexigenic and anorexigenic mediators. We studied this regulating system in a rat model of methyl donor deficiency during gestation and lactation. At weaning, a predominance of the anorexigenic pathway was observed in deficient pups, with increased plasma peptide YY and increased hypothalamic pro-opiomelanocortin (POMC) mRNA, in line with abnormal leptin, ghrelin, and insulin secretion and/or signaling during critical periods of fetal and/or postnatal development of the hypothalamus. These results suggest that early methyl donor deficiency can affect the development and function of energy balance circuits, resulting in growth and weight deficits. Maternal administration of folic acid (3 mg/kg/day) during the perinatal period tended to rectify peripheral metabolic signaling and central neuropeptide and receptor expression, leading to reduced growth retardation.

Insulin receptor localization in the embryonic avian hypothalamus

The hypothalamus is a brain region critical for the homeostatic regulation of appetite and energy expenditure. Hypothalamic neuronal activity that is altered during development can produce permanent physiological changes later in life. For example, circulating hormones such as insulin have been shown to influence hypothalamic neuronal projections, leading to altered metabolism in adult rodents. While insulin signaling in the post-hatch chicken has been shown to mirror that of mammals, the developmental role of insulin in the avian embryonic hypothalamus remains largely unexplored. Here we present the earliest known evidence for insulin receptor (InsR) expression in embryonic avian hypothalamic nuclei governing energy homeostasis. RT-PCR analysis reveals InsR mRNA in E8, E10, and E12 neurons while western blot data demonstrate protein expression in E12 avian whole brain and hypothalamic lysates. Immunohistochemical analysis of avian hypothalamic brain slices demonstrates a shift in InsR localization from paraventricular expression in E8 to a more defined concentration of InsR in developmental regions resembling the ventromedial hypothalamus (VMH) and arcuate nucleus (ARC) in E12 time points. In addition, InsR expression appears in a heterogeneous pattern, suggesting receptor localization to subpopulations of avian hypothalamic neurons as early as E8. With increasing evidence suggesting energy homeostasis pathways may be altered via the gestational environment, it is important to understand how insulin signaling may affect embryogenesis. Our research provides evidence for the earliest known embryonic expression of InsR protein in the avian hypothalamus and may suggest a developmental role for insulin signaling in the early patterning of metabolic pathways in the central nervous system.

Evidence for liver energy metabolism programming in offspring subjected to intrauterine undernutrition during midgestation

Background

Maternal undernutrition programs fetal energy homeostasis and increases the risk of metabolic disorders later in life. This study aimed to identify the signs of hepatic metabolic programming in utero and during the juvenile phase after intrauterine undernutrition during midgestation.

Methods

Fifty-three pregnant goats were assigned to the control (100% of the maintenance requirement) or restricted (60% of the maintenance requirement from day 45 to day 100 of midgestation and realimentation thereafter) group to compare hepatic energy metabolism in the fetuses (day 100 of gestation) and kids (postnatal day 90).

Results

Undernutrition increased the glucagon concentration and hepatic hexokinase activity, decreased the body weight, liver weight and hepatic expression of G6PC, G6PD, and PGC1α mRNAs, and tended to decrease the hepatic glycogen content and ACOX1 mRNA level in the dams. Maternal undernutrition decreased the growth hormone (GH) and triglyceride concentrations, tended to decrease the body weight and hepatic hexokinase activity, increased the hepatic PCK1, PCK2 and PRKAA2 mRNAs levels and glucose-6-phosphatase activity, and tended to increase the hepatic PRKAB1 and CPT1α mRNAs levels in the male fetuses. In the restricted female fetuses, the hepatic hexokinase activity and G6PC mRNA level tended to be increased, but PKB1 mRNA expression was decreased and the ACACA, CPT1α, NR1H3 and STK11 mRNA levels tended to be decreased. Maternal undernutrition changed the hepatic metabolic profile and affected the metabolic pathway involved in amino acid, glycerophospholipid, bile acid, purine, and saccharide metabolism in the fetuses, but not the kids. Additionally, maternal undernutrition increased the concentrations of GH and cortisol, elevated the hepatic glucose-6-phosphate dehydrogenase activity, and tended to decrease the hepatic glycogen content in the male kids. No alterations in these variables were observed in the female kids.

Conclusions

Maternal undernutrition affects the metabolic status in a sex- and stage-specific manner by changing the metabolic profile, expression of genes involved in glucose homeostasis and enzyme activities in the liver of the fetuses. The changes in the hormone levels in the male fetuses and kids, but not the female offspring, represent a potential sign of metabolic programming.

The forgotten effects of thyrotropin-releasing hormone: Metabolic functions and medical applications

Thyrotropin-releasing hormone (TRH) causes a variety of thyroidal and non-thyroidal effects, the best known being the feedback regulation of thyroid hormone levels. This was employed in the TRH stimulation test, which is currently little used. The role of TRH as a cancer biomarker is minor, but exaggerated responses to TSH and prolactin levels in breast cancer led to the hypothesis of a potential role for TRH in the pathogenesis of this disease. TRH is a rapidly degraded peptide with multiple targets, limiting its suitability as a biomarker and drug candidate. Although some studies reported efficacy in neural diseases (depression, spinal cord injury, amyotrophic lateral sclerosis, etc.), therapeutic use of TRH is presently restricted to spinocerebellar degenerative disease. Regulation of TRH production in the hypothalamus, patterns of expression of TRH and its receptor in the body, its role in energy metabolism and in prolactin secretion are addressed in this review.

Early Life Origins of Obesity and Related Complications

The idea that nutrition in early life (such as before conception, during pregnancy and in infancy) can influence, or programme, long-term health, known as the 'Developmental Origins of Health and Disease Hypothesis', has generated great scientific interest. This concept is particularly relevant for the development of obesity and its complications, arguably the most important public health issue of the twenty-first century worldwide. The concept is strongly supported by evidence from animal studies, both observational and experimental (randomised) studies in humans, and is highly relevant for population health in both low-income and high-incomes countries. For instance, optimising nutrition in pregnancy (both in terms of under-nutrition and over-nutrition) and preventing too fast infant weight gain have been shown to reduce the risk of future obesity. Proposed mechanisms have included effects of early nutrition on the epigenome, hormones such as insulin, and regulation of appetite, that effect long-term risk of obesity. Although further data from experimental studies is required to support a causal link between early nutrition and future adiposity, the developmental origins hypothesis is already changing health policy and practice globally. The present review considers the evidence for the developmental origins of obesity, the mechanisms involved, and the implications for public health.

Maternal overnutrition programs epigenetic changes in the regulatory regions of hypothalamic Pomc in the offspring of rats

Background and objective

Maternal overnutrition has been implicated in affecting the offspring by programming metabolic disorders such as obesity and diabetes, by mechanisms that are not clearly understood. This study aimed to determine the long-term impact of maternal high-fat (HF) diet feeding on epigenetic changes in the offspring’s hypothalamic Pomc gene, coding a key factor in the control of energy balance. Further, it aimed to study the additional effects of postnatal overnutrition on epigenetic programming by maternal nutrition.

Methods

Eight-week-old female Sprague–Dawley rats were fed HF diet or low-fat (LF) diet for 6 weeks before mating, and throughout gestation and lactation. At postnatal day 21, samples were collected from a third offspring and the remainder were weaned onto LF diet for 5 weeks, after which they were either fed LF or HF diet for 12 weeks, resulting in four groups of offspring differing by their maternal and postweaning diet.

Results

With maternal HF diet, offspring at weaning had rapid early weight gain, increased adiposity, and hyperleptinemia. The programmed adult offspring, subsequently fed LF diet, retained the increased body weight. Maternal HF diet combined with offspring HF diet caused more pronounced hyperphagia, fat mass, and insulin resistance. The ARC Pomc gene from programmed offspring at weaning showed hypermethylation in the enhancer (nPE1 and nPE2) regions and in the promoter sequence mediating leptin effects. Interestingly, hypermethylation at the Pomc promoter but not at the enhancer region persisted long term into adulthood in the programmed offspring. However, there were no additive effects on methylation levels in the regulatory regions of Pomc in programmed offspring fed a HF diet.

Conclusion

Maternal overnutrition programs long-term epigenetic alterations in the offspring’s hypothalamic Pomc promoter. This predisposes the offspring to metabolic disorders later in life.

Complementary food - important components of the child’s ration: effects on health and ways of optimization

Relevance of the research. Timing, order and sequence of complementary feeding remain the subject of discussion until now. The aim of the study. Estimate influence of different outlines of introduction of complementary foods on nutritional status and food behavior in children of first year of life. Materials and methods. Examined 96 children in age of 4-6 months during introduction of complementary foods. Main group – 50 children (27 breast-feed (BF) children and 23 on milk formulas (MF)), in whose diet were introduced only complementary foods, which were made in special factories. Comparison group – 46 children (33 – BF and 13 – MF) received complementary foods made at home and in special factories. Duration of follow-up was 3 months. Physical examination, mother’s diary analysis, evaluation of tolerance of complementary foods, bacteriological examination of feces. Results. On the background of introduction of complementary foods in the main group, increased the number of children with normal fatness (BF from 66.8% to 74.2%, MF from 82.7 to 88.4%), in comparison group, their number decreased (BF from 84.8% to 78.8%, MF from 69.3 to 62.3%). In the main group when a child refuses a product, mother continues offer it insistently. 61.5% of children began to eat unloved product at the end of first year of life. In comparison group, where mother changed unloved product at once, only 25% of children began to relate to it positively. In the main group dyspeptic disorders were mild in 4% of children. In in comparison group prevailed diarrheal syndrome, related to contamination with pathogenic strains of E. coli in 13% of children. Conclusions. Using of industrial made complimentary foods according to the optimal order, with determined mothers perseverance provides equalization of fatness, allows to form a correct food behavior and decreases risk of intestinal colonization by pathogenic microorganisms.

Effects of postnatal overfeeding and fish oil diet on energy expenditure in rats

BackgroudEarly life nutrition may have a role in the regulation of metabolism in adulthood. The present study aimed to evaluate the effects of postnatal overfeeding and a postweaning fish oil diet on energy expenditure.MethodsOn postnatal day 3, rat litters were adjusted to a litter size of three (small litters, SLs) or ten (normal litters, NLs). After weaning, SLs were fed the standard diet or a fish oil diet enriched with polyunsaturated fatty acids (SL-FOs) for 10 weeks. The metabolic parameters of rats were monitored using the TSE LabMaster at postnatal week 3 (W₃) and postnatal week 13 (W₁₃).ResultsAt W₃, the O₂ consumption and heat production in SLs were lower than those in NLs, while the respiratory exchange ratio (RER) was higher than NLs. SLs showed obesity, dyslipidemia, and impaired glucose tolerance at W₁₃. The postweaning fish oil diet in SLs not only increased O₂ consumption, CO₂ production, heat production, and reduced the RER but it also reduced weight gain, serum triglycerides, and improved glucose tolerance at W₁₃.ConclusionPostnatal overfeeding can decrease the level of body energy expenditure and induce obesity, but a fish oil diet can increase the energy expenditure and prevent the development of metabolic dysregulation in adults.

Impact of maternal high fat diet on hypothalamic transcriptome in neonatal Sprague Dawley rats

Maternal consumption of a high fat diet during early development has been shown to impact the formation of hypothalamic neurocircuitry, thereby contributing to imbalances in appetite and energy homeostasis and increasing the risk of obesity in subsequent generations. Early in postnatal life, the neuronal projections responsible for energy homeostasis develop in response to appetite-related peptides such as leptin. To date, no study characterises the genome-wide transcriptional changes that occur in response to exposure to high fat diet during this critical window. We explored the effects of maternal high fat diet consumption on hypothalamic gene expression in Sprague Dawley rat offspring at postnatal day 10. RNA-sequencing enabled discovery of differentially expressed genes between offspring of dams fed a high fat diet and offspring of control diet fed dams. Female high fat diet offspring displayed altered expression of 86 genes (adjusted P-value<0.05), including genes coding for proteins of the extra cellular matrix, particularly Collagen 1a1 (Col1a1), Col1a2, Col3a1, and the imprinted Insulin-like growth factor 2 (Igf2) gene. Male high fat diet offspring showed significant changes in collagen genes (Col1a1 and Col3a1) and significant upregulation of two genes involved in regulation of dopamine availability in the brain, tyrosine hydroxylase (Th) and dopamine reuptake transporter Slc6a3 (also known as Dat1). Transcriptional changes were accompanied by increased body weight, body fat and body length in the high fat diet offspring, as well as altered blood glucose and plasma leptin. Transcriptional changes identified in the hypothalamus of offspring of high fat diet mothers could alter neuronal projection formation during early development leading to abnormalities in the neuronal circuitry controlling appetite in later life, hence priming offspring to the development of obesity.

Exposure of C57BL/6J mice to long photoperiod during early life stages increases body weight and alters plasma metabolomic profiles in adulthood

Perinatal photoperiod is an important regulator of physiological phenotype in adulthood. In this study, we demonstrated that postnatal (0–4 weeks old) exposure of C57BL/6J mice to long photoperiod induced persistent increase in body weight until adulthood, compared with the mice maintained under short photoperiod. The expression of peroxisome proliferator‐activated receptor δ, a gene involved in fatty acid metabolism, was decreased in 10‐week‐old mice exposed to long photoperiod during 0–4 or 4–8 weeks of age. Plasma metabolomic profiles of adult mice exposed to a long photoperiod during the postnatal period (0–4 LD) were compared to those in the mice exposed to short photoperiod during the same period. Cluster analysis revealed that both carbon metabolic pathway and nucleic acid pathway were altered by the postnatal photoperiod. Levels of metabolites involved in glycolysis were significantly upregulated in 0–4 LD, suggesting that the mice in 0–4 LD use the glycolytic pathway for energy expenditure rather than the fatty acid oxidation pathway. In addition, the mice in 0–4 LD exhibited high levels of purine metabolites, which have a role in neuroprotection. In conclusion, postnatal exposure of C57BL/6J mice to long photoperiod induces increase in body weight and various changes in plasma metabolic profiles during adulthood.

Hippocampal mechanisms in impaired spatial learning and memory in male offspring of rats fed a low-protein isocaloric diet in pregnancy and/or lactation

Maternal nutritional challenges during fetal and neonatal development result in developmental programming of multiple offspring organ systems including brain maturation and function. A maternal low-protein diet during pregnancy and lactation impairs associative learning and motivation. We evaluated effects of a maternal low-protein diet during gestation and/or lactation on male offspring spatial learning and hippocampal neural structure. Control mothers (C) ate 20% casein and restricted mothers (R) 10% casein, providing four groups: CC, RR, CR, and RC (first letter pregnancy, second lactation diet). We evaluated the behavior of young adult male offspring around postnatal day 110. Corticosterone and ACTH were measured. Males were tested for 2 days in the Morris water maze (MWM). Stratum lucidum mossy fiber (MF) area, total and spine type in basal dendrites of stratum oriens in the hippocampal CA3 field were measured. Corticosterone and ACTH were higher in RR vs. CC. In the MWM acquisition test CC offspring required two, RC three, and CR seven sessions to learn the maze. RR did not learn in eight trials. In a retention test 24 h later, RR, CR, and RC spent more time locating the platform and performed fewer target zone entries than CC. RR and RC offspring spent less time in the target zone than CC. MF area, total, and thin spines were lower in RR, CR, and RC than CC. Mushroom spines were lower in RR and RC than CC. Stubby spines were higher in RR, CR, and RC than CC. We conclude that maternal low-protein diet impairs spatial acquisition and memory retention in male offspring, and that alterations in hippocampal presynaptic (MF), postsynaptic (spines) elements and higher glucocorticoid levels are potential mechanisms to explain these learning and memory deficits.

Epigenetic programming, early life nutrition and the risk of metabolic disease

Time separates the past from the present, during this period memory are formed - written in code and decoded to be read while other memories are erased - but when it comes to the epigenome some memories are harder to forget than others. Recent studies show chemical information is written in the context of the epigenome and codified on histone and non-histone proteins to regulate nuclear processes such as gene transcription. The genome is also subject to modification in the form of 5-methylcytosine, which has been implicated in metabolic memory. In this review, we examine some of the chemical modifications that signal early life events and explore epigenetic changes that underlie the diabetic vasculature. The fine balance between past and present is discussed, as it pertains to gestational diabetes and obesity in context to the Barker hypothesis. We also examine emerging experimental evidence suggesting the hypothalamus as a central regulator of obesity risk and explore current genomic medicine. As for how cells recall specific chemical information, we examine the experimental evidence implicating chemical cues on the epigenome, providing examples of diet during pregnancy and the increased risk of disease in offspring.

Early-Life Nutritional Programming of Cognition-The Fundamental Role of Epigenetic Mechanisms in Mediating the Relation between Early-Life Environment and Learning and Memory Process

The perinatal period is a window of heightened plasticity that lays the groundwork for future anatomic, physiologic, and behavioral outcomes. During this time, maternal diet plays a pivotal role in the maturation of vital organs and the establishment of neuronal connections. However, when perinatal nutrition is either lacking in specific micro- and macronutrients or overloaded with excess calories, the consequences can be devastating and long lasting. The brain is particularly sensitive to perinatal insults, with several neurologic and psychiatric disorders having been linked to a poor in utero environment. Diseases characterized by learning and memory impairments, such as autism, schizophrenia, and Alzheimer disease, are hypothesized to be attributed in part to environmental factors, and evidence suggests that the etiology of these conditions may date back to very early life. In this review, we discuss the role of the early-life diet in shaping cognitive outcomes in offspring. We explore the endocrine and immune mechanisms responsible for these phenotypes and discuss how these systemic factors converge to change the brain's epigenetic landscape and regulate learning and memory across the lifespan. Through understanding the maternal programming of cognition, critical steps may be taken toward preventing and treating diseases that compromise learning and memory.

A seasonal switch in histone deacetylase gene expression in the hypothalamus and their capacity to modulate nuclear signaling pathways

Seasonal animals undergo changes in physiology and behavior between summer and winter conditions. These changes are in part driven by a switch in a series of hypothalamic genes under transcriptional control by hormones and, of recent interest, inflammatory factors. Crucial to the control of transcription are histone deacetylases (HDACs), generally acting to repress transcription by local histone modification. Seasonal changes in hypothalamic HDAC transcripts were investigated in photoperiod-sensitive F344 rats by altering the day-length (photoperiod). HDAC4, 6 and 9 were found to change in expression. The potential influence of HDACs on two hypothalamic signaling pathways that regulate transcription, inflammatory and nuclear receptor signaling, was investigated. For inflammatory signaling the focus was on NF-κB because of the novel finding made that its expression is seasonally regulated in the rat hypothalamus. For nuclear receptor signaling it was discovered that expression of retinoic acid receptor beta was regulated seasonally. HDAC modulation of NF-κB-induced pathways was examined in a hypothalamic neuronal cell line and primary hypothalamic tanycytes. HDAC4/5/6 inhibition altered the control of gene expression (Fos, Prkca, Prkcd and Ptp1b) by inducers of NF-κB that activate inflammation. These inhibitors also modified the action of nuclear receptor ligands thyroid hormone and retinoic acid. Thus seasonal changes in HDAC4 and 6 have the potential to epigenetically modify multiple gene regulatory pathways in the hypothalamus that could act to limit inflammatory pathways in the hypothalamus during long-day summer-like conditions.

Chronic Maternal Low-Protein Diet in Mice Affects Anxiety, Night-Time Energy Expenditure and Sleep Patterns, but Not Circadian Rhythm in Male Offspring

Offspring of murine dams chronically fed a protein-restricted diet have an increased risk for metabolic and neurobehavioral disorders. Previously we showed that adult offspring, developmentally exposed to a chronic maternal low-protein (MLP) diet, had lower body and hind-leg muscle weights and decreased liver enzyme serum levels. We conducted energy expenditure, neurobehavioral and circadian rhythm assays in male offspring to examine mechanisms for the body-weight phenotype and assess neurodevelopmental implications of MLP exposure. C57BL/6J dams were fed a protein restricted (8%protein, MLP) or a control protein (20% protein, C) diet from four weeks before mating until weaning of offspring. Male offspring were weaned to standard rodent diet (20% protein) and single-housed until 8–12 weeks of age. We examined body composition, food intake, energy expenditure, spontaneous rearing activity and sleep patterns and performed behavioral assays for anxiety (open field activity, elevated plus maze [EPM], light/dark exploration), depression (tail suspension and forced swim test), sociability (three-chamber), repetitive (marble burying), learning and memory (fear conditioning), and circadian behavior (wheel-running activity during light-dark and constant dark cycles). We also measured circadian gene expression in hypothalamus and liver at different Zeitgeber times (ZT). Male offspring from separate MLP exposed dams had significantly greater body fat (P = 0.03), less energy expenditure (P = 0.004), less rearing activity (P = 0.04) and a greater number of night-time rest/sleep bouts (P = 0.03) compared to control. MLP offspring displayed greater anxiety-like behavior in the EPM (P<0.01) but had no learning and memory deficit in fear-conditioning assay (P = 0.02). There was an effect of time on Per1, Per 2 and Clock circadian gene expression in the hypothalamus but not on circadian behavior. Thus, transplacental and early developmental exposure of dams to chronic MLP reduces food intake and energy expenditure, increases anxiety like behavior and disturbs sleep patterns but not circadian rhythm in adult male offspring.

Effect of Maternal Obesity on Foetal Growth and Metabolic Health of the Offspring

Maternal and placental conditions that are unfavourable for the embryo/foetus have long-lasting effects on different tissues and functions of the body, which may persist for life and, potentially, also be transmitted to the offspring. This review resumes current evidence on principle maternal and gestational conditions associated with unfavourable metabolic programming of the offspring, along with their mechanisms of action, either supposed or already proved.

Advances in TRH signaling

The activity of the hypothalamus-pituitary-thyroid axis (HPT) is coordinated by hypophysiotropic thyrotropin releasing hormone (TRH) neurons present in the paraventricular nucleus of the hypothalamus. Hypophysiotropic TRH neurons act as energy sensors. TRH controls the synthesis and release of thyrotropin, which activates the synthesis and secretion of thyroid hormones; in target tissues, transporters and deiodinases control their local availability. Thyroid hormones regulate many functions, including energy homeostasis. This review discusses recent evidence that covers several aspects of TRH role in HPT axis regulation. Knowledge about the mechanisms of TRH signaling has steadily increased. New transcription factors engaged in TRH gene expression have been identified, and advances made on how they interact with signaling pathways and define the dynamics of TRH neurons response to acute and/or long-term influences. Albeit yet incomplete, the relationship of TRH neurons activity with positive energy balance has emerged. The importance of tanycytes as a central relay for the feedback control of the axis, as well as for HPT responses to alterations in energy balance, and other stimuli has been reinforced. Finally, some studies have started to shed light on the interference of prenatal and postnatal stress and nutrition on HPT axis programing, which have confirmed the axis susceptibility to early insults.

60 YEARS OF POMC: Transcriptional and epigenetic regulation of POMC gene expression

Expression of the pro-opiomelanocortin (POMC) gene integrates numerous inputs that reflect the developmental history of POMC-expressing cells of the pituitary and hypothalamus, as well as their critical role in the endocrine system. These inputs are integrated at specific regulatory sequences within the promoter and pituitary or hypothalamic enhancers of the POMC locus. Investigations of developmental mechanisms and transcription factors (TFs) responsible for pituitary activation of POMC transcription led to the discovery of the Pitx factors that have critical roles in pituitary development and striking patterning functions in embryonic development. Terminal differentiation of the two pituitary POMC lineages, the corticotrophs and melanotrophs, is controlled by Tpit; mutations of the human TPIT gene cause isolated adrenocorticotrophic hormone deficiency. Intermediate lobe and melanotroph identity is provided by the pioneer TF Pax7 that remodels chromatin to reveal a new repertoire of enhancers for Tpit action. Many signaling pathways regulate POMC transcription including activation by hypothalamic corticotrophin-releasing hormone acting through the orphan nuclear receptors of the Nur family and feedback repression by glucocorticoids and their glucocorticoid receptor. TFs of the basic helix-loop-helix, Smad, Stat, Etv, and nuclear factor-B families also mediate signals for control of POMC transcription. Whereas most of these regulatory processes are conserved in different species, there are also notable differences between specific targets for regulation of the human compared with mouse POMC genes.

DNA methylation regulates hypothalamic gene expression linking parental diet during pregnancy to the offspring's risk of obesity in Psammomys obesus

BACKGROUND/OBJECTIVE

The rising incidence of obesity is a major public health issue worldwide. Recent human and animal studies suggest that parental diet can influence fetal development and is implicated with risk of obesity and type 2 diabetes in offspring. The hypothalamus is central to body energy homoeostasis and appetite by controlling endocrine signals. We hypothesise that offspring susceptibility to obesity is programmed in the hypothalamus in utero and mediated by changes to DNA methylation, which persist to adulthood. We investigated hypothalamic genome-wide DNA methylation in Psammomys obesus diet during pregnancy to the offspring's risk of obesity.

METHODS

Using methyl-CpG binding domain capture and deep sequencing (MBD-seq), we examined the hypothalamus of offspring exposed to a low-fat diet and standard chow diet during the gestation and lactation period.

RESULTS

Offspring exposed to a low-fat parental diet were more obese and had increased circulating insulin and glucose levels. Methylome profiling identified 1447 genomic regions of differential methylation between offspring of parents fed a low-fat diet compared with parents on standard chow diet. Pathway analysis shows novel DNA methylation changes of hypothalamic genes associated with neurological function, nutrient sensing, appetite and energy balance. Differential DNA methylation corresponded to changes in hypothalamic gene expression of Tas1r1 and Abcc8 in the offspring exposed to low-fat parental diet.

CONCLUSION

Subject to parental low-fat diet, we observe DNA methylation changes of genes associated with obesity in offspring.

Epigenetics and obesity cardiomyopathy: From pathophysiology to prevention and management

Uncorrected obesity has been associated with cardiac hypertrophy and contractile dysfunction. Several mechanisms for this cardiomyopathy have been identified, including oxidative stress, autophagy, adrenergic and renin-angiotensin aldosterone overflow. Another process that may regulate effects of obesity is epigenetics, which refers to the heritable alterations in gene expression or cellular phenotype that are not encoded on the DNA sequence. Advances in epigenome profiling have greatly improved the understanding of the epigenome in obesity, where environmental exposures during early life result in an increased health risk later on in life. Several mechanisms, including histone modification, DNA methylation and non-coding RNAs, have been reported in obesity and can cause transcriptional suppression or activation, depending on the location within the gene, contributing to obesity-induced complications. Through epigenetic modifications, the fetus may be prone to detrimental insults, leading to cardiac sequelae later in life. Important links between epigenetics and obesity include nutrition, exercise, adiposity, inflammation, insulin sensitivity and hepatic steatosis. Genome-wide studies have identified altered DNA methylation patterns in pancreatic islets, skeletal muscle and adipose tissues from obese subjects compared with non-obese controls. In addition, aging and intrauterine environment are associated with differential DNA methylation. Given the intense research on the molecular mechanisms of the etiology of obesity and its complications, this review will provide insights into the current understanding of epigenetics and pharmacological and non-pharmacological (such as exercise) interventions targeting epigenetics as they relate to treatment of obesity and its complications. Particular focus will be on DNA methylation, histone modification and non-coding RNAs.

Connecting the Dots in Childhood Obesity Disparities: A Review of Growth Patterns from Birth to Pre-Adolescence

In this review, we considered how disparities in obesity emerge between birth, when socially disadvantaged infants tend to be small, and later in childhood, when socially disadvantaged groups have high risk of obesity. We reviewed epidemiologic evidence of socioeconomic and racial/ethnic differences in growth from infancy to pre-adolescence. Minority race/ethnicity and lower socioeconomic status was associated with rapid weight gain in infancy but not in older age groups, and social differences in linear growth and relative weight were unclear. Infant feeding practices was the most consistent mediator of social disparities in growth, but mediation analysis was uncommon and other factors have only begun to be explored. Complex life course processes challenge the field of social epidemiology to develop innovative study designs and analytic techniques with which to pose and test challenging yet impactful research questions about how obesity disparities evolve throughout childhood.

Developmental expression of Kv1 voltage-gated potassium channels in the avian hypothalamus

Specialized hypothalamic neurons integrate the homeostatic balance between food intake and energy expenditure, processes that may become dysregulated during the development of diabetes, obesity, and other metabolic disorders. Shaker family voltage-gated potassium channels (Kv1) contribute to the maintenance of resting membrane potential, action potential characteristics, and neurotransmitter release in many populations of neurons, although hypothalamic Kv1 channel expression has been largely unexplored. Whole-cell patch clamp recordings from avian hypothalamic brain slices demonstrate a developmental shift in the electrophysiological properties of avian arcuate nucleus neurons, identifying an increase in outward ionic current that corresponds with action potential maturation. Additionally, RT-PCR experiments identified the early expression of Kv1.2, Kv1.3, and Kv1.5 mRNA in the embryonic avian hypothalamus, suggesting that these channels may underlie the electrophysiological changes observed in these neurons. Real-time quantitative PCR analysis on intact microdissections of embryonic hypothalamic tissue revealed a concomitant increase in Kv1.2 and Kv1.5 gene expression at key electrophysiological time points during development. This study is the first to demonstrate hypothalamic mRNA expression of Kv1 channels in developing avian embryos and may suggest a role for voltage-gated ion channel regulation in the physiological patterning of embryonic hypothalamic circuits governing energy homeostasis.

[Pregnancy-associated hormones and fetal-maternal relations]

Pregnancy is an immunological paradox that implies that a semi-allogeneic fetus is not rejected by the maternal immune system, from implantation of the embryo to delivery. Progesterone (P4), estradiol (E2) and human chorionic gonadotropin (hCG), contribute to the transformation of immune cells in a transient tolerance state, necessary to the maintenance of pregnancy. The effects of pregnancy hormones depend probably of their maternal plasma level. hCG is dangerous at high concentrations because it can stimulate autoantibodies production, whereas in physiological concentrations, hCG, P4 and E2 upregulate immune response expanding regulatory T and B cells, allowing the fetus to grow within the maternal uterus in a protective environment. A second example of fetal-maternal relation found recently is the role of maternal nutrition on development of the fetal hypothalamic neurons. Experiments in mice fed on a high fat diet reveal a critical timing when altered maternal metabolism affect formation of hypothalamic neurocircuits of the offspring and predispose him to long-term metabolic disorders.

Intrauterine Programming of Diabetes and Adiposity

The prevalence of diabetes and adiposity has increased at an alarming rate and together they contribute to the rise in morbidity and mortality worldwide. Genetic studies till date have succeeded in explaining only a proportion of heritability, while a major component remains unexplained. Early life determinants of future risk of these diseases are likely contributors to the missing heritability and thus have a significant potential in disease prevention. Epidemiological and animal studies show the importance of intrauterine and early postnatal environment in programming of the fetus to adverse metabolic outcomes and support the notion of Developmental Origins of Health and Disease (DOHaD). Emerging evidence highlights the role of epigenetic mechanisms in mediating effects of environmental exposures, which in certain instances may exhibit intergenerational transmission even in the absence of exposure. In this article, we will discuss the complexity of diabetes and increased adiposity and mechanisms of programming of these adverse metabolic conditions.