Carbohydrate-responsive gene expression in the adipose tissue of rats

Association of daily carbohydrate intake with intermuscular adipose tissue in Korean individuals with obesity: a cross-sectional study

BACKGROUND/OBJECTIVES

The prevalence of obesity, a worldwide pandemic, has been increasing steadily in Korea. Reports have shown that increased intermuscular adipose tissue (IMAT) is associated with an increased risk of cardiovascular disease, independent of body mass index. However, the relationship between dietary intake and IMAT accumulation in the Korean population remains undetermined. The objective of this study was to evaluate regional fat compartments using advanced magnetic resonance imaging (MRI) techniques. We also aimed to investigate the association between IMAT amounts and dietary intake, including carbohydrate intake, among Korean individuals with obesity.

SUBJECTS/METHODS

This cross-sectional study, performed at a medical center in South Korea, recruited 35 individuals with obesity (15 men and 20 women) and classified them into 2 groups according to sex. Anthropometry was performed, and body fat distribution was measured using MRI. Blood parameters, including glucose and lipid profiles, were analyzed using commercial kits. Linear regression analysis was used to test whether the IMAT was associated with daily carbohydrate intake.

RESULTS

Carbohydrate intake was positively associated with IMAT in all individuals, with adjustments for age, sex, height, and weight. No significant differences in blood indicators were found between the sexes.

CONCLUSIONS

Regardless of sex and age, higher carbohydrate intake was strongly correlated with greater IMAT accumulation. This suggests the need to better understand sex differences and high carbohydrate diet patterns in relation to the association between obesity and metabolic risk, which may help reduce obesity prevalence.

Influence of Nutritional Intake of Carbohydrates on Mitochondrial Structure, Dynamics, and Functions during Adipogenesis

Obesity is an alarming yet increasing phenomenon worldwide, and more effective obesity management strategies have become essential. In addition to the numerous anti-adipogenic treatments promising a restauration of a healthy white adipose tissue (WAT) function, numerous studies reported on the critical role of nutritional parameters in obesity development. In a metabolic disorder context, a better control of nutrient intake is a key step in slowing down adipogenesis and therefore obesity. Of interest, the effect on WAT remodeling deserves deeper investigations. Among the different actors of WAT plasticity, the mitochondrial network plays a central role due to its dynamics and essential cellular functions. Hence, the present in vitro study, conducted on the 3T3-L1 cell line, aimed at evaluating the incidence of modulating the carbohydrates intake on adipogenesis through an integrated assessment of mitochondrial structure, dynamics, and functions-correlated changes. For this purpose, our experimental strategy was to compare the occurrence of adipogenesis in 3T3-L1 cells cultured either in a high-glucose (HG) medium (25 mM) or in a low-glucose (LG) medium (5 mM) supplemented with equivalent galactose (GAL) levels (20 mM). The present LG-GAL condition was associated, in differentiating adipocytes, to a reduced lipid droplet network, lower expressions of early and late adipogenic genes and proteins, an increased mitochondrial network with higher biogenesis marker expression, an equilibrium in the mitochondrial fusion/fission pattern, and a decreased expression of mitochondrial metabolic overload protein markers. Therefore, those main findings show a clear effect of modulating glucose accessibility on 3T3-L1 adipogenesis through a combined effect of adipogenesis modulation and overall improvement of the mitochondrial health status. This nutritional approach offers promising opportunities in the control and prevention of obesity.

The Good, the Bad, and the Ugly of Pregnancy Nutrients and Developmental Programming of Adult Disease

Maternal nutrition plays a decisive role in developmental programming of many non-communicable diseases (NCDs). A variety of nutritional insults during gestation can cause programming and contribute to the development of adult-onset diseases. Nutritional interventions during pregnancy may serve as reprogramming strategies to reverse programming processes and prevent NCDs. In this review, firstly we summarize epidemiological evidence for nutritional programming of human disease. It will also discuss evidence from animal models, for the common mechanisms underlying nutritional programming, and potential nutritional interventions used as reprogramming strategies.

Evaluation of the effects of extracts of Maytenus imbricata (Celastraceae) on the treatment of inflammatory and metabolic dysfunction induced by high-refined carbohydrate diet

The Maytenus genus is a member of the Celastraceae family. Numerous medicinal uses were assigned to species of this genus, with the use of roots, bark, and leaves for the treatment of gastric ulcers, as anti-inflammatory, analgesic, antiallergic, antitumor, among others. Several studies have demonstrated that natural products derived from plants have an important role in the prevention and treatment of obesity. Accordingly, we evaluated the effect of Maytenus imbricata extracts in the treatment of obesity induced by diet rich in refined carbohydrate (HC). BALB/c mice were fed chow or HC diet for 8 weeks. At the beginning of the 9th week, the HC group was subdivided into three groups: (i) group of animals that continued to consume only HC diet; (ii) the group of animals fed HC diet supplemented with ethyl acetate extract of M. imbricata roots (HC + EAE); (iii) the group of animals fed HC diet supplemented with extract in hexane/ethyl ether (HC + HEE). The period of extracts supplementation was 4 weeks. It was observed that EAE and EHE when added to the HC diet modulated the metabolic and inflammatory changes, such as: reduced the adipocytes area, improved glucose intolerance, reduced the levels of triglycerides and resistin in serum, and the number of total leukocytes in blood. In the epididymal adipose tissue, the extracts reduced proinflammatory mediators' concentration. According to the results, it was concluded that the species Maytenus imbricata has the potential to be used for the treatment of obesity.

Maternal Macronutrient Consumption and the Developmental Origins of Metabolic Disease in the Offspring

Recent research aimed at understanding the rise in obesity and cardiometabolic disease in children suggests that suboptimal maternal nutrition conditions organ systems and physiological responses in the offspring contributing to disease development. Understanding the mechanisms by which the macronutrient composition of the maternal diet during pregnancy or lactation affects health outcomes in the offspring may lead to new maternal nutrition recommendations, disease prevention strategies and therapies that reduce the increasing incidence of cardiometabolic disease in children. Recent mechanistic animal model research has identified how excess fats and sugars in the maternal diet alter offspring glucose tolerance, insulin signaling and metabolism. Maternal nutrition appears to influence epigenetic alterations in the offspring and the programming of gene expression in key metabolic pathways. This review is focused on experimental studies in animal models that have investigated mechanisms of how maternal consumption of macronutrients affects cardiometabolic disease development in the offspring. Future research using "-omic" technologies is essential to elucidate the mechanisms of how altered maternal macronutrient consumption influences the development of disease in the offspring.

Transcriptomic responses of the liver and adipose tissues to altered carbohydrate-fat ratio in diet: an isoenergetic study in young rats

Background

To elucidate the effects of altered dietary carbohydrate and fat balance on liver and adipose tissue transcriptomes, 3-week-old rats were fed three kinds of diets: low-, moderate-, and high-fat diets (L, M, and H) containing a different ratio of carbohydrate-fat (C-F) (65:15, 60:20, and 35:45 in energy percent, respectively).

Methods

The rats consumed the diets for 9 weeks and were subjected to biochemical and DNA microarray analyses.

Results

The rats in the H-group exhibited lower serum triacylglycerol (TG) levels but higher liver TG and cholesterol content than rats in the L-group. The analysis of differentially expressed genes (DEGs) between each group (L vs M, M vs H, and L vs H) in the liver revealed about 35% of L vs H DEGs that were regulated in the same way as M vs H DEGs, and most of the others were L- vs H-specific. Gene ontology analysis of these L vs H DEGs indicated that those related to fatty acid synthesis and circadian rhythm were enriched. Interestingly, about 30% of L vs M DEGs were regulated in a reverse way compared with L vs H and M vs H DEGs. These reversed liver DEGs included M-up/H-down genes (Sds for gluconeogenesis from amino acids) and M-down/H-up genes (Gpd2 for gluconeogenesis from glycerol, Agpat9 for TG synthesis, and Acot1 for beta-oxidation). We also analyzed L vs H DEGs in white (WAT) and brown (BAT) adipose tissues and found that both oxidation and synthesis of fatty acids were inhibited in these tissues.

Conclusions

These results indicate that the alteration of dietary C-F balance differentially affects the transcriptomes of metabolizing and energy-storing tissues.

Electronic supplementary material

The online version of this article (doi:10.1186/s12263-017-0558-2) contains supplementary material, which is available to authorized users.

In utero exposure to prepregnancy maternal obesity and postweaning high-fat diet impair regulators of mitochondrial dynamics in rat placenta and offspring

The proportion of pregnant women who are obese at conception continues to rise. Compelling evidence suggests the intrauterine environment is an important determinant of offspring health. Maternal obesity and unhealthy diets are shown to promote metabolic programming in the offspring. Mitochondria are maternally inherited, and we have previously shown impaired mitochondrial function in rat offspring exposed to maternal obesity in utero. Mitochondrial health is maintained by mitochondrial dynamics, or the processes of fusion and fission, which serve to repair damaged mitochondria, remove irreparable mitochondria, and maintain mitochondrial morphology. An imbalance between fusion and fission has been associated with obesity, insulin resistance, and reproduction complications. In the present study, we examined the influence of maternal obesity and postweaning high-fat diet (HFD) on key regulators of mitochondrial fusion and fission in rat offspring at important developmental milestones which included postnatal day (PND)35 (2 wk HFD) and PND130 (∼16 wk HFD). Our results indicate HFD-fed offspring had reduced mRNA expression of presenilin-associated rhomboid-like (PARL), optic atrophy (OPA)1, mitofusin (Mfn)1, Mfn2, fission (Fis)1, and nuclear respiratory factor (Nrf)1 at PND35, while OPA1 and Mfn2 remained decreased at PND130. Putative transcriptional regulators of mitochondrial dynamics were reduced in rat placenta and offspring liver and skeletal muscle [peroxisome proliferator-activated receptor gamma coactivator (PGC1)α, PGC1β, and estrogen-related receptor (ERR)α], consistent with indirect calorimetry findings revealing reduced energy expenditure and impaired fat utilization. Overall, maternal obesity detrimentally alters mitochondrial targets that may contribute to impaired mitochondrial health and increased obesity susceptibility in later life.

RNA-seq analysis of the rat placentation site reveals maternal obesity-associated changes in placental and offspring thyroid hormone signaling

INTRODUCTION

In animal models, maternal obesity (OB) leads to augmented risk of offspring OB. While placental function is influenced by maternal habitus, the effect of maternal obesity on the interacting zones of the placenta [the labyrinth (LZ), junctional (JZ) and metrial gland (MG)] remains unknown.

METHODS

Using a rat maternal obesity model, we conducted transcriptomic profiling of the utero-placental compartments and fetal liver (FL) at dpc 18.5, in conjunction with analyses of mRNA expression of key thyroid hormone (TH) signaling genes in the placenta, fetus and weanling offspring.

RESULTS AND DISCUSSION

Gene expression analysis of placenta and offspring revealed that each utero-placental compartment responds distinctly to maternal OB with changes in inflammatory signaling, lipid metabolism and hormone stimulus being the predominant effects. OB-induced alterations in 17 genes were confirmed by qPCR, including reductions in thyrotropin-releasing hormone (Trh) in JZ. We further characterized mRNA and protein expression of TH signaling regulators including deiodinases (Dio), TH receptors (Tr), and downstream targets (uncoupling proteins (Ucp)). A concerted down-regulation of multiple facets of thyroid hormone signaling in the JZ and FL was observed. JZ expression of thyroid hormone signaling components Trh, Dio2, Trα, and Ucp2 were negatively associated with maternal leptin. mRNA expression of TRH, TRβ and UCP1 were also decreased in term placenta from OB women. Finally, our studies identified persistent impairments in expression of TH related genes in tissues from offspring of obese dams.

CONCLUSIONS

The role of lower placental thyroid expression is worthy of further study as a possible pathway that leads to low energy metabolism and obesity in animals born to obese mothers.

Liver but not adipose tissue is responsive to the pattern of enteral feeding

Nutritional support is an important aspect of medical care, providing calories to patients with compromised nutrient intake. Metabolism has a diurnal pattern, responding to the light cycle and food intake, which in turn can drive changes in liver and adipose tissue metabolism. In this study, we assessed the response of liver and white adipose tissue (WAT) to different feeding patterns under nutritional support (total enteral nutrition or TEN). Mice received continuous isocaloric TEN for 10 days or equal calories of chow once a day (Ch). TEN was given either at a constant (CN, same infusion rate during 24 h) or variable rate (VN, 80% of calories fed at night, 20% at day). Hepatic lipogenesis and carbohydrate-responsive element-binding protein (ChREBP) expression increased in parallel with the diurnal feeding pattern. Relative to Ch, both patterns of enteral feeding increased adiposity. This increase was not associated with enhanced lipogenic gene expression in WAT; moreover, lipogenesis was unaffected by the feeding pattern. Surprisingly, leptin and adiponectin expression increased. Moreover, nutritional support markedly increased hepatic and adipose FGF21 expression in CN and VN, despite being considered a fasting hormone. In summary, liver but not WAT, respond to the pattern of feeding. While hepatic lipid metabolism adapts to the pattern of nutrient availability, WAT does not. Moreover, sustained delivery of nutrients in an isocaloric diet can cause adiposity without the proinflammatory state observed in hypercaloric feeding. Thus, the liver but not adipose tissue is responsive to the pattern of feeding behavior.

High fat diet and in utero exposure to maternal obesity disrupts circadian rhythm and leads to metabolic programming of liver in rat offspring

The risk of obesity in adulthood is subject to programming beginning at conception. In animal models, exposure to maternal obesity and high fat diets influences the risk of obesity in the offspring. Among other long-term changes, offspring from obese rats develop hyperinsulinemia, hepatic steatosis, and lipogenic gene expression in the liver at weaning. However, the precise underlying mechanisms leading to metabolic dysregulation in the offspring remains unclear. Using a rat model of overfeeding-induced obesity, we previously demonstrated that exposure to maternal obesity from pre-conception to birth, is sufficient to program increased obesity risk in the offspring. Offspring of obese rat dams gain greater body weight and fat mass when fed high fat diet (HFD) as compared to lean dam. Since, disruptions of diurnal circadian rhythm are known to detrimentally impact metabolically active tissues such as liver, we examined the hypothesis that maternal obesity leads to perturbations of core clock components and thus energy metabolism in offspring liver. Offspring from lean and obese dams were examined at post-natal day 35, following a short (2 wk) HFD challenge. Hepatic mRNA expression of circadian (CLOCK, BMAL1, REV-ERBα, CRY, PER) and metabolic (PPARα, SIRT1) genes were strongly suppressed in offspring exposed to both maternal obesity and HFD. Using a mathematical model, we identified two distinct biological mechanisms that modulate PPARα mRNA expression: i) decreased mRNA synthesis rates; and ii) increased non-specific mRNA degradation rate. Moreover, our findings demonstrate that changes in PPARα transcription were associated with epigenomic alterations in H3K4me3 and H3K27me3 histone marks near the PPARα transcription start site. Our findings indicated that offspring from obese rat dams have detrimental alternations to circadian machinery that may contribute to impaired liver metabolism in response to HFD, specifically via reduced PPARα expression prior to obesity development.

Metabolism and fatty acid profile in fat and lean rainbow trout lines fed with vegetable oil: effect of carbohydrates

The present study investigated the effect of dietary carbohydrates on metabolism, with special focus on fatty acid bioconversion and flesh lipid composition in two rainbow trout lines divergently selected for muscle lipid content and fed with vegetable oils. These lines were chosen based on previously demonstrated potential differences in LC-PUFA synthesis and carbohydrate utilization. Applying a factorial study design, juvenile trout from the lean (L) and the fat (F) line were fed vegetable oil based diets with or without gelatinised starch (17.1%) for 12 weeks. Blood, liver, muscle, intestine and adipose tissue were sampled after the last meal. Feed intake and growth was higher in the L line than the F line, irrespective of the diet. Moderate postprandial hyperglycemia, strong induction of hepatic glucokinase and repressed glucose-6-phosphatase transcripts confirmed the metabolic response of both lines to carbohydrate intake. Further at the transcriptional level, dietary carbohydrate in the presence of n-3 LC-PUFA deficient vegetable oils enhanced intestinal chylomicron assembly, disturbed hepatic lipid metabolism and importantly elicited a higher response of key desaturase and elongase enzymes in the liver and intestine that endorsed our hypothesis. PPARγ was identified as the factor mediating this dietary regulation of fatty acid bioconversion enzymes in the liver. However, these molecular changes were not sufficient to modify the fatty acid composition of muscle or liver. Concerning the genotype effect, there was no evidence of substantial genotypic difference in lipid metabolism, LC-PUFA synthesis and flesh fatty acid profile when fed with vegetable oils. The minor reduction in plasma glucose and triglyceride levels in the F line was linked to potentially higher glucose and lipid uptake in the muscle. Overall, these data emphasize the importance of dietary macro-nutrient interface in evolving fish nutrition strategies.

Acute and sustained inflammation and metabolic dysfunction induced by high refined carbohydrate-containing diet in mice

OBJECTIVE

The effects of high-refined carbohydrate-containing diet (HC) on inflammatory parameters and metabolic disarrangement of adipose tissue are poorly understood. The aim of this study was to evaluate the timing and progression of metabolic and inflammatory dysfunction induced by HC diet in mice.

DESIGN AND METHODS

BALB/c mice were fed chow or HC diet for 1 and 3 days, 1, 2, 4, 6, 8, 10, and 12 weeks.

RESULTS

Animals given HC diet exhibited acute and sustained increase in visceral adiposity, glucose intolerance, low insulin sensitivity, hyperlipemia, acute increase in mRNA expression of ACC, LPL, PPARγ, SREBP-1, and ChREBP and altered circulating levels of adiponectin, resistin, and leptin. There was leucocyte rolling and adhesion on adipose tissue microvessels already at 3 days and until 8 weeks of HC diet. Adipose tissue of mice had increased number of macrophages (M1 and M2), lymphocytes (CD8+ and CD4+ Foxp3+), and neutrophils (GR1+) already at 3 days after initiation of HC diet. Overall, concentration of cytokines and chemokines, TNF-α, IL-6, IL-10, TGF-β1, CCL2, and CXCL1, in adipose tissue was elevated throughout the experimental period. Levels of IL-10 and TGF-β1 tended to reach baseline levels at 12 weeks of HC diet.

CONCLUSIONS

We describe a novel murine model of fat pad expansion induced by HC diet that is characterized by early onset and sustained adipose tissue inflammation and metabolic disarrangement. The acute inflammatory response in adipose tissue occurs very early and is sustained, suggesting that adipose tissue inflammation is a homeostatic mechanism to regulate nutrient overload and adipose expansion.

Early growth response protein-1 mediates lipotoxicity-associated placental inflammation: role in maternal obesity

Obesity is associated with low-grade chronic inflammation, which contributes to cellular dysfunction promoting metabolic disease. Obesity during pregnancy leads to a proinflammatory milieu in the placenta; however, the underlying causes for obesity-induced placental inflammation remain unclear. Here, we examine the mechanisms by which saturated fatty acids and inflammatory cytokines induce inflammation in placental trophoblasts. We conducted global transcriptomic profiling in BeWo cells following palmitate and/or TNFα treatment and gene/protein expression analyses of MAPK pathways and characterized downstream transcription factors directly regulating inflammatory cytokines. Microarray analysis revealed increased expression of genes regulating inflammation, stress response, and immediate early response in cytotrophoblasts in response to palmitic acid (PA), TNFα, or a combination of both (PA + TNFα). Both gene ontology and gene set enrichment analysis revealed MAPK and EGR-1 signaling to be upregulated in BeWo cells, which was confirmed via immunoblotting. Importantly, activation of JNK signaling was necessary for increased proinflammatory cytokine (IL-6, TNFα, and IL-8) and EGR1 mRNA. Consistent with the requirement of JNK signaling, ChIP analysis confirmed the recruitment of c-Jun and other MAPK-responsive immediate early factors on the EGR1 promoter. Moreover, recruitment of EGR-1 on cytokine promoters (IL-6, TNFα, and IL-8) and an impaired proinflammatory response following knockdown of EGR-1 suggested it as a central component of the mechanism facilitating inflammatory gene expression. Finally, akin to in vitro findings, term placenta from obese women also had both increased JNK and p38 signaling and greater EGR-1 protein relative to lean women. Our results demonstrate that lipotoxic insults induce inflammation in placental cells via activation of JNK/EGR-1 signaling.

Dietary fat source alters hepatic gene expression profile and determines the type of liver pathology in rats overfed via total enteral nutrition

To determine if dietary fat composition affects the progression of nonalcoholic fatty liver disease (NAFLD), we overfed male Sprague-Dawley rats low (5%) or high (70%) fat diets with different fat sources: olive oil (OO), corn oil (CO), or echium oil (EO), with total enteral nutrition (TEN) for 21 days. Overfeeding of the 5% CO or 5% EO diets resulted in less steatosis than 5% OO (P < 0.05). Affymetrix array analysis revealed significant differences in hepatic gene expression signatures associated with greater fatty acid synthesis, ChREBP, and SREBP-1c signaling and increased fatty acid transport (P < 0.05) in the 5% OO compared with 5% CO group. The OO groups had macrosteatosis, but no evidence of oxidative stress or necrosis. The 70% CO and 70% EO groups had a mixture of micro- and macrosteatosis or only microsteatosis, respectively; increased oxidative stress; and increased necrotic injury relative to their respective 5% groups (P < 0.05). Oxidative stress and necrosis correlated with increasing peroxidizability of the accumulated triglycerides. Affymetrix array analysis comparing the 70% OO and 70% CO groups revealed increased antioxidant pathways and lower expression of genes linked to inflammation and fibrosis in the 70% OO group. A second study in which 70% OO diet was overfed for 50 days produced no evidence of progression of injury beyond simple steatosis. These data suggest that dietary fat type strongly influences the progression of NAFLD and that a Mediterranean diet high in olive oil may reduce the risk of NAFLD progressing to nonalcoholic steatohepatitis.

Serotonin availability in rat colon is reduced during a Western diet model of obesity

Constipation and slowed transit are associated with diet-induced obesity, although the mechanisms by which this occurs are unclear. Enterochromaffin (EC) cells within the intestinal epithelium respond to mechanical stimulation with the release of serotonin [5-hydroxytryptamine (5-HT)], which promotes transit. Thus our aim was to characterize 5-HT availability in the rat colon of a physiologically relevant model of diet-induced obesity. EC cell numbers were determined immunohistochemically in chow-fed (CF) and Western diet-fed (WD) rats, while electrochemical methods were used to measure mechanically evoked (peak) and steady-state (SS) 5-HT levels. Fluoxetine was used to block the 5-HT reuptake transporter (SERT), and the levels of mRNA for tryptophan hydroxylase 1 and SERT were determined by quantitative PCR, and SERT protein was determined by Western blot. In WD rats, there was a significant decrease in the total number of EC cells per crypt (0.86 ± 0.06 and 0.71 ± 0.05 in CF and WD, respectively), which was supported by a reduction in the levels of 5-HT in WD rats (2.9 ± 1.0 and 10.5 ± 2.6 μM at SS and peak, respectively) compared with CF rats (7.3 ± 0.4 and 18.4 ± 3.4 μM at SS and peak, respectively). SERT-dependent uptake of 5-HT was unchanged, which was supported by a lack of change in SERT protein levels. In WD rats, there was no change in tryptophan hydroxylase 1 mRNA but an increase in SERT mRNA. In conclusion, our data show that foods typical of a WD are associated with decreased 5-HT availability in rat colon. Decreased 5-HT availability is driven primarily by a reduction in the numbers and/or 5-HT content of EC cells, which are likely to be associated with decreased intestinal motility in vivo.

Differential effects of short term feeding of a soy protein isolate diet and estrogen treatment on bone in the pre-pubertal rat

Background

Previous reports suggest that beneficial effects of soy on bone quality are due to the estrogenic actions of isoflavone phytochemicals associated with the protein. However, mechanistic studies comparing the effects of soy diet and estrogens on bone, particularly in rapidly growing animals are lacking.

Methodology and Principal Findings

We studied the effects of short term feeding of soy protein isolate (SPI) on bone in comparison to the effects of 17β-estradiol (E2) in pre-pubertal rats. Female rats were weaned to one of 4 treatments: 1) a control casein-based diet (CAS); 2) CAS with subcutaneous E2 (10 µg/kg/d) (CAS+E2); 3) a SPI-containing diet (SPI); or 4) SPI with subcutaneous E2 (SPI) or SPI with 10 µg/kg/d E2 (SPI+E2) for 14 days beginning on postnatal day 20. SPI increased while E2 decreased bone turnover compared to CAS. In contrast, both treatments decreased serum sclerostin levels. Microarray analysis of RNA isolated from bone revealed 652 genes regulated by SPI, 491 genes regulated by E2, and 266 genes regulated by both SPI diet and E2 compared to CAS. The expression of caveolin-1, a protein localized in the cell membrane, was down-regulated (p<0.05) in rats fed SPI, but not by E2 compared to rats fed casein. Down-regulation of caveolin-1 by SPI was associated with increased BMP2, Smad and Runx2 expression in bone and osteoblasts (p<0.05).

Conclusions/Significance

These results suggest SPI and E2 have different effects on bone turnover prior to puberty. Approximately half of the genes are regulated in the same direction by E2 or SPI, but in combination, SPI blocks the estrogen effects and returns the profile towards control levels. In addition, there are E2 specific and SPI-specific gene changes related to regulation of bone formation.

Somatostatin is involved in anorexia in mice fed a valine-deficient diet

The ingestion of a valine (Val)-deficient diet results in a significant reduction of food intake and body weight within 24 h, and this phenomenon continues throughout the period over which such a diet is supplied. Both microarray and real-time PCR analyses revealed that the expression of somatostatin mRNA was increased in the hypothalamus in anorectic mice that received a Val-deficient diet. On the other hand, when somatostatin was administered intracerebroventricularly to intact animals that were fed a control diet, their 24-h food intake decreased significantly. In addition, Val-deficient but not pair-fed mice or those fasted for 24 h showed a less than 0.5-fold decrease in the hypothalamic mRNA expression levels of Crym, Foxg1, Itpka and two unknown EST clone genes and a more than twofold increase in those of Slc6a3, Bdh1, Ptgr2 and one unknown EST clone gene. These results suggest that hypothalamic somatostatin and genes responsive to Val deficiency may be involved in the central mechanism of anorexia induced by a Val-deficient diet.

RNA-seq analysis of the functional compartments within the rat placentation site

The rat placentation site is distinctly organized into interacting zones, the so-called labyrinth, junctional, and metrial gland compartments. These zones house unique cell populations equipped to undertake myriad prescribed functions including transport, hormonal responses, and immune interactions. Although much is known about the genesis of these cell types and specific markers that characterize each zone, a detailed global overview of gene expression in the three zones is absent. In this report, we used massively parallel sequencing (RNA-seq) to assess mRNA expression profiles and generated transcriptomic maps for each zone of the late-gestation rat placentation site (18.5 d postcoitum). Analysis of expression profiles revealed that each compartment expressed a unique signature, characterized by biological processes specific to the zone. Transport and vasculature-related processes predominated in the labyrinth, hormone secretion in the junctional, and immune interactions in the metrial gland. Furthermore, our analysis identified approximately 4000 differentially expressed genes within the zones. Using k-means clustering, we identified transcription factors with highest expression in either labyrinth, junctional, or metrial gland. Direct interaction (pathway) analysis revealed unique transcription factor networks operating in each compartment. The site-specific expression of 27 transcription factors in the three zones was ascertained via quantitative PCR and protein expression of six transcription factors was confirmed by immunohistochemistry. Finally, we elucidated the expression of key developmentally important families (Sox, GATA, Fox, Wnt, Tead, and IGF/IGFBP) in the placentation site to reveal novel expression of these several factors. The present dataset provides a novel resource to understand zonal gene expression and function in the placenta.

Inhibition of fetal bone development through epigenetic down-regulation of HoxA10 in obese rats fed high-fat diet

Epidemiological studies show that maternal obesity during intrauterine and early postnatal life increases the risk of low bone mass and fracture later in life. Here, we show that bone development is inhibited in gestational embryonic day 18.5 (E18.5) embryos from rat dams made obese by feeding a high-fat diet (HFD). Moreover, fetal rat osteogenic calvarial cells (FOCCs) from these obese dams have significantly less potential to develop into mature osteoblasts compared to cells from AIN-93G diet-fed controls. Profiling of transcriptional genes for osteogenesis revealed a profound decrease in the homeodomain-containing factor A10 (HoxA10) in FOCCs from fetuses of HFD-induced obese dams. Significant methylation of the HoxA10 promoter was found in those FOCCs, as well as in mouse ST2 cells treated with a mixture of free fatty acids similar to that found in serum from HFD-induced obese rats. This was accompanied by lower expression of osteogenic markers, but higher levels of PPARγ. Control FOCCs depleted of the HoxA10 gene (shRNA) ex vivo behave similarly to cells from fetuses of obese dams; conversely, overexpression of HoxA10 gene in FOCCs from HFD rats exhibit the same phenotype as controls. Treatment of FOCCs from control rats or of ST2 cells with an artificial mixture of free fatty acids significantly down-regulated HoxA10 protein expression, and cells exhibited adipocyte-like properties. These results suggest that maternal obesity impairs fetal skeletal development through down-regulation of the HoxA10 gene, which may lead to an increase in the prevalence of low bone mass in the offspring later in life.

Maternal obesity promotes a proinflammatory signature in rat uterus and blastocyst

Maternal obesity at conception increases the risk of offspring obesity, thus propagating an intergenerational vicious cycle. Male offspring born to obese dams are hyperresponsive to high fat-diets, gaining greater body weight, fat mass, and additional metabolic sequelae compared to lean controls. In this report, we identify the impact of maternal obesity before conception, on the embryo, and intrauterine milieu during the periimplantation period. We conducted global transcriptomic profiling in the uterus and periimplantation blastocyst, gene/protein expression analyses of inflammatory pathways in conjunction with endocrine and metabolic characterization in the dams at implantation. Uterine gene expression profiles of lean and obese dams revealed distinct signatures for genes regulating inflammation and lipid metabolism. Both pathway and gene-set enrichment analysis revealed uterine nuclear factor-κB and c-Jun N-terminal kinase signaling to be up-regulated in the uterus of obese dams, which was confirmed via immunoblotting. Obese uteri also evidenced an inflammatory secretome with higher chemokine mRNA abundance (CCL2, CCL5, CCL7, and CxCL10) and related regulators (TLR2, CD14, and Ccr1). Increased inflammation in the uterus was associated with ectopic lipid accumulation and expression of lipid metabolic genes. Gene expression in sex-identified male periimplantation blastocyst at day postcoitum 4.5 was clearly influenced by maternal obesity (359 transcripts, ±1.4-fold), including changes in developmental and epigenetic regulators. Akin to the uterus, nuclear factor-κB-regulated proinflammatory genes (CCL4 and CCL5) increased and expression of antioxidant (GPx3) and mitochondrial (TFAM and NRF1) genes decreased in the obese embryos. Our results suggest that ectopic lipid and inflammation may link maternal obesity to increased predisposition of offspring to obesity later in life.

Feeding blueberry diets in early life prevent senescence of osteoblasts and bone loss in ovariectomized adult female rats

BACKGROUND

Appropriate nutrition during early development is essential for maximal bone mass accretion; however, linkage between early nutrition, childhood bone mass, peak bone mass in adulthood, and prevention of bone loss later in life has not been studied.

METHODOLOGY AND PRINCIPAL FINDINGS

In this report, we show that feeding a high quality diet supplemented with blueberries (BB) to pre-pubertal rats throughout development or only between postnatal day 20 (PND20) and PND34 prevented ovariectomy (OVX)-induced bone loss in adult life. This protective effect of BB is due to suppression of osteoblastic cell senescence associated with acute loss of myosin expression after OVX. Early exposure of pre-osteoblasts to serum from BB-fed rats was found to consistently increase myosin expression. This led to maintenance osteoblastic cell development and differentiation and delay of cellular entrance into senescence through regulation of the Runx2 gene. High bone turnover after OVX results in insufficient collagenous matrix support for new osteoblasts and their precursors to express myosin and other cytoskeletal elements required for osteoblast activity and differentiation.

CONCLUSIONS/SIGNIFICANCE

These results indicate: 1) a significant prevention of OVX-induced bone loss from adult rats can occur with only 14 days consumption of a BB-containing diet immediately prior to puberty; and 2) the molecular mechanisms underlying these effects involves increased myosin production which stimulates osteoblast differentiation and reduces mesenchymal stromal cell senescence.

Maternal obesity during gestation impairs fatty acid oxidation and mitochondrial SIRT3 expression in rat offspring at weaning

In utero exposure to maternal obesity increases the offspring's risk of obesity in later life. We have also previously reported that offspring of obese rat dams develop hepatic steatosis, mild hyperinsulinemia, and a lipogenic gene signature in the liver at postnatal day (PND)21. In the current study, we examined systemic and hepatic adaptations in male Sprague-Dawley offspring from lean and obese dams at PND21. Indirect calorimetry revealed decreases in energy expenditure (p<0.001) and increases in RER values (p<0.001), which were further exacerbated by high fat diet (45% kcals from fat) consumption indicating an impaired ability to utilize fatty acids in offspring of obese dams as analyzed by PRCF. Mitochondrial function is known to be associated with fatty acid oxidation (FAO) in the liver. Several markers of hepatic mitochondrial function were reduced in offspring of obese dams. These included SIRT3 mRNA (p = 0.012) and mitochondrial protein content (p = 0.002), electron transport chain complexes (II, III, and ATPase), and fasting PGC-1α mRNA expression (p<0.001). Moreover, hepatic LCAD, a SIRT3 target, was not only reduced 2-fold (p<0.001) but was also hyperacetylated in offspring of obese dams (p<0.005) suggesting decreased hepatic FAO. In conclusion, exposure to maternal obesity contributes to early perturbations in whole body and liver energy metabolism. Mitochondrial dysfunction may be an underlying event that reduces hepatic fatty acid oxidation and precedes the development of detrimental obesity associated co-morbidities such as insulin resistance and NAFLD.

Isocaloric intake of a high-fat diet modifies adiposity and lipid handling in a sex dependent manner in rats

Background

High-fat (HF) diet feeding usually leads to hyperphagia and body weight gain, but macronutrient proportions in the diet can modulate energy intake and fat deposition. The mechanisms of fat accumulation and mobilization may differ significantly between depots, and gender can also influence these differences.

Aim

To investigate, in rats of both sexes, the effect of an isocaloric intake of a diet with an unbalanced proportion of macronutrients on fatty acid composition of visceral and subcutaneous adipose tissues and how this is influenced by both dietary fatty acids and levels of proteins involved in tissue lipid handling.

Methods

Eight-week-old Wistar rats of both sexes were fed a control diet (3% w/w fat) or high-fat diet (30% w/w fat) for 14 weeks. Fatty acid composition was analyzed by gas-chromatography and levels of LPL, HSL, α2-AR, β3-AR, PKA and CPT1 were determined by Western blot.

Results

The HF diet did not induce hyperphagia or body weight gain, but promoted an increase of adiposity index only in male rats. HF diet produced an increase of the proportion of MUFA and a decrease in that of PUFA in both adipose depots and in both sexes. The levels of proteins involved in the adrenergic control of the lipolytic pathway increased in the gonadal fat of HF females, whereas LPL levels increased in the inguinal fat of HF males and decreased in that of females.

Conclusion

Sexual dimorphism in adiposity index reflects a differential sex response to dietary fatty acid content and could be related to the levels of the proteins involved in tissue lipid management.

Differential effects of calorie restriction and exercise on the adipose transcriptome in diet-induced obese mice

We tested the hypothesis that obesity reversal by calorie restriction (CR) versus treadmill exercise (EX) differentially modulates adipose gene expression using 48 female C57BL/6 mice administered a diet-induced obesity (DIO) regimen for 8 weeks, then randomized to receive for 8 weeks either: (1) a control (AIN-76A) diet, fed ad libitum (DIO control); (2) a 30% CR regimen; (3) a treadmill EX regimen (with AIN-76A diet fed ad libitum); or (4) continuation of the DIO diet. Relative to the DIO controls, both CR and EX reduced adiposity by 35-40% and serum leptin levels by 80%, but only CR increased adiponectin and insulin sensitivity. Gene expression microarray analysis of visceral white adipose tissue revealed 209 genes responsive to both CR and EX, relative to the DIO group. However, CR uniquely altered expression of an additional 496 genes, whereas only 20 were uniquely affected by EX. Of the genes distinctly responsive to CR, 17 related to carbohydrate metabolism and glucose transport, including glucose transporter (GLUT) 4. Chromatin immunoprecipitation assays of the Glut4 promoter revealed that, relative to the DIO controls, CR significantly increased histone 4 acetylation, suggesting epigenetic regulation may underlie some of the differential effects of CR versus EX on the adipose transcriptome.

A Western diet increases serotonin availability in rat small intestine

Diet-induced obesity is associated with changes in gastrointestinal function and induction of a mild inflammatory state. Serotonin (5-HT) containing enterochromaffin (EC) cells within the intestine respond to nutrients and are altered by inflammation. Thus, our aim was to characterize the uptake and release of 5-HT from EC cells of the rat ileum in a physiologically relevant model of diet-induced obesity. In chow-fed (CF) and Western diet-fed (WD) rats electrochemical methods were used to measure compression evoked (peak) and steady state (SS) 5-HT levels with fluoxetine used to block the serotonin reuptake transporter (SERT). The levels of mRNA for tryptophan hydroxylase 1 (TPH1) and SERT were determined by quantitative PCR, while EC cell numbers were determined immunohistochemically. In WD rats, the levels of 5-HT were significantly increased (SS: 19.2 ± 3.7 μm; peak: 73.5 ± 14.1 μm) compared with CF rats (SS: 12.3 ± 1.8 μm; peak: 32.2 ± 7.2 μm), while SERT-dependent uptake of 5-HT was reduced (peak WD: 108% of control versus peak CF: 212% control). In WD rats, there was a significant increase in TPH1 mRNA, a decrease in SERT mRNA and protein, and an increase in EC cells. In conclusion, our data show that foods typical of a Western diet are associated with an increased 5-HT availability in the rat ileum. Increased 5-HT availability is driven by the up-regulation of 5-HT synthesis genes, decreased re-uptake of 5-HT, and increased numbers and/or 5-HT content of EC cells which are likely to cause altered intestinal motility and sensation in vivo.

Regulation of the promoter region of the human adiponutrin/PNPLA3 gene by glucose and insulin

The adiponutrin/PNPLA3 gene is highly expressed in adipose tissue and liver. Its expression is down-regulated by fasting and rapidly induced by refeeding a high carbohydrate diet. We aimed to determine whether the promoter region of adiponutrin is regulated by glucose and insulin. Endogenous adiponutrin mRNA was increased in mouse 3T3-L1 and human SGBS adipocytes and in human HepG2 cells cultured in 25 mM glucose compared to absence of glucose. A 3100 bp 5'-upstream region of the human adiponutrin gene was cloned into a luciferase reporter plasmid and used in transient transfection studies. Promoter activity was up-regulated by 25 mM glucose, 4.7-fold in HepG2 cells and 2-fold in CHO cells. The effect was shown in CHO cells to be concentration dependent and to depend on glucose metabolism as a non-metabolisable analogue was without effect. In CHO cells constitutively expressing human insulin receptor (CHO-IR), there was a concentration dependent increase of promoter activity by insulin in the presence of glucose. Cotransfection with an expression plasmid for upstream stimulatory factor 2 (USF2), increased promoter activity 1.6-fold in CHO-IR cells. The combined effect of insulin and USF2 (2.3-fold) was greater than the individual effects. Cotransfection of carbohydrate-response element binding protein did not elicit any induction of promoter activity. These results point to potential mechanisms for the observed in vivo nutritional regulation of adiponutrin expression and its up-regulation in fatty liver and by obesity.

Maternal overweight programs insulin and adiponectin signaling in the offspring

Gestational exposure to maternal overweight (OW) influences the risk of obesity in adult life. Male offspring from OW dams gain greater body weight and fat mass and develop insulin resistance when fed high-fat diets (45% fat). In this report, we identify molecular targets of maternal OW-induced programming at postnatal d 21 before challenge with the high-fat diet. We conducted global transcriptome profiling, gene/protein expression analyses, and characterization of downstream signaling of insulin and adiponectin pathways in conjunction with endocrine and biochemical characterization. Offspring born to OW dams displayed increased serum insulin, leptin, and resistin levels (P < 0.05) at postnatal d 21 preceding changes in body composition. A lipogenic transcriptome signature in the liver, before development of obesity, was evident in OW-dam offspring. A coordinated locus of 20 sterol regulatory element-binding protein-1-regulated target genes was induced by maternal OW. Increased nuclear levels of sterol regulatory element-binding protein-1 and recruitment to the fatty acid synthase promoter were confirmed via ELISA and chromatin immunoprecipitation analyses, respectively. Higher fatty acid synthase and acetyl coenzyme A carboxylase protein and pAKT (Thr(308)) and phospho-insulin receptor-beta were confirmed via immunoblotting. Maternal OW also attenuated AMP kinase/peroxisome proliferator-activated receptor-alpha signaling in the offspring liver, including transcriptional down-regulation of several peroxisome proliferator-activated receptor-alpha-regulated genes. Hepatic mRNA and circulating fibroblast growth factor-21 levels were significantly lower in OW-dam offspring. Furthermore, serum levels of high-molecular-weight adiponectin (P < 0.05) were decreased in OW-dam offspring. Phosphorylation of hepatic AMP-kinase (Thr(172)) was significantly decreased in OW-dam offspring, along with lower AdipoR1 mRNA. Our results strongly suggest that gestational exposure to maternal obesity programs multiple aspects of energy-balance regulation in the offspring.