The 1975 Japanese diet has a stress reduction effect in mice: search for physiological effects using metabolome analysis

Abstract

We aimed to find new physiological effects of the Japanese diet. First, to determine the key components in serum from mice fed the 1975 diet, serum from mice fed the 1960, 1975, 1990 or 2005 Japanese diet was analyzed using CE-TOFMS and LC-TOFMS. Based on these results, the key components were determined by principal component analysis. Among the identified compounds, GABA was included. Therefore, a stress reduction effect was inferred as a novel physiological effect of this diet. Next, we tested whether the 1975 diet had an actual stress reduction effect in mice. Mice were given the 1975 diet or a control diet for 4 weeks, after which they were divided into restraint stress and non-stress groups. Mice fed the 1975 diet had significantly decreased stress parameters compared with those fed the control diet. These results provide the first evidence that the 1975 Japanese diet has a stress reduction effect.     

Altered adipocyte progenitor population and adipose-related gene profile in adipose tissue by long-term high-fat diet in mice

AimsHigh-fat diet (HFD) is associated with adipose inflammation, which contributes to key components of metabolic abnormalities. The expanded adipose tissue mass associated with obesity is the result of hyperplasia and hypertrophy of adipocytes. In this study, we investigated the effects of long-term HFD on adipocyte progenitor cell (APC) population and adipose-specific gene profiles in both white and brown adipose, and the role of perivascular adipose in the alteration of vascular function in response to HFD.Main methodsMale C57BL/6 mice were fed a standard normal diet (ND) or HFD for about 8 months. Glucose metabolism was assessed by an intraperitoneal glucose tolerance test. APC population and adipose-related gene profile were evaluated, and vascular function was measured in the presence or absence of perivascular adipose. Adiponectin and AMPK activity were also investigated.Key findingsHFD induced insulin resistance and glucose intolerance, and resulted in a decrease in APC population in brown, but not in white adipose tissue, when compared with animals fed a ND, with differential alterations of white and brown adipocyte-specific gene expression in brown and white adipose. Additionally, HFD led to altered vascular function in arteries in the presence of perivascular adipose tissue, which is associated with increased superoxide production. Adiponectin and AMPK activity were significantly decreased in response to long-term HFD.SignificanceThese findings suggest that long-term high-fat intake differentially alters adipocyte progenitor population and adipose-related gene expression in adipose tissue, and adiponectin-AMPK signaling might be involved. In addition, HFD induces changes in perivascular adipose-mediated vascular function.     

Regulation of adipose tissue inflammation and systemic metabolism in murine obesity by polymer implants loaded with lentiviral vectors encoding human interleukin-4

Dysfunctional adipose tissue plays a central role in the pathogenesis of the obesity-related metabolic disease, including type 2 diabetes. Targeting adipose tissue using biopolymer implants is a novel therapeutic approach for metabolic disease. We transplanted porous poly(lactide-co-glycolide) (PLG) implants coated with human interleukin-4 (hIL-4)-expressing lentivirus into epididymal white adipose tissue (eWAT) of mice fed a high-fat diet. Tissue and systemic inflammation and metabolism were studied with flow cytometry, immunohistochemistry, quantitative real-time polymerase chain reaction, adipose tissue histology, and in vivo glucose tolerance testing at 2 and 10 weeks of a high-fat diet. PLG implants carrying hIL-4-expressing lentivirus implanted into epididymal white adipose tissue of mice-regulated adipose tissue inflammation, including increased CD3⁺CD4⁺ T-cell frequency, increased eWAT adipocyte hypertrophy, and decreased FASN and ATGL expression, along with reduced fasting blood glucose levels. These effects were observed in early obesity but were not maintained in established obesity. Local delivery of bioimplants loaded with cytokine-expressing lentivirus vectors to adipose tissue influences tissue inflammation and systemic metabolism in early obesity. Further study will be required to show more durable metabolic effects. These data demonstrate that polymer biomaterials implanted into adipose tissue have the potential to modulate local tissue and systemic inflammation and metabolism.     

Reduced lipogenesis in cafeteria-fed rats exhibiting diet-induced thermogenesis

Fatty-acid synthesis has been measured in vivo with³H₂O in cafeteria-fed rats exhibiting diet-induced thermogenesis. Synthesis was decreased in brown adipose tissue, the liver, white adipose tissue, and the carcass of the cafeteria-fed animals compared to rats fed the normal stock diet. Whole-body synthesis was also decreased in the cafeteria-fed group. Diet-induced thermogenesis, in contrast to cold-induced non-shivering thermogenesis does not lead to increased fatty-acid synthesis and this is presumably due to the inhibitory effects on lipogenesis of the high dietary fat intake characteristic of cafeteria diets. The results also indicate that the energy cost of body fat deposition in cafeteria-fed rats is lower than in animals fed a low-fat/high-carbohydrate stock diet.     

SOCS2 modulates adipose tissue inflammation and expansion in mice

IntroductionObesity is usually triggered by a nutrient overload that favors adipocyte hypertrophy and increases the number of pro-inflammatory cells and mediators into adipose tissue. These mediators may be regulated by suppressors of cytokine signaling (SOCS), such as SOCS2, which is involved in the regulation of the inflammatory response of many diseases, but its role in obesity is not yet known. We aimed to investigate the role of SOCS2 in metabolic and inflammatory dysfunction induced by a high-refined carbohydrate-containing diet (HC).Material and methodsMale C57BL/6 wild type (WT) and SOCS2 deficient (SOCS2^−/−) mice were fed chow or an HC diet for 8 weeks.ResultsIn general, SOCS2 deficient mice, independent of the diet, showed higher adipose tissue mass compared with their WT counterparts that were associated with decreased lipogenesis rate in adipose tissue, lipolysis in adipocyte culture and energy expenditure. An anti-inflammatory profile was observed in adipose tissue of SOCS2^−/− by reduced secretion of cytokines, such as TNF and IL-6, and increased M2-like macrophages and regulatory T cells compared with WT mice. Also, SOCS2 deficiency reduced the differentiation/expansion of pro-inflammatory cells in the spleen but increased Th2 and Treg cells compared with their WT counterparts.ConclusionThe SOCS2 protein is an important modulator of obesity that regulates the metabolic pathways related to adipocyte size. Additionally, SOCS2 is an inflammatory regulator that appears to be essential for controlling the release of cytokines and the differentiation/recruitment of cells into adipose tissue during the development of obesity.     

Mesenteric adipose tissue B lymphocytes promote local and hepatic inflammation in non‐alcoholic fatty liver disease mice

Mesenteric adipose tissue (MAT) inflammation is associated with non‐alcoholic fatty liver disease (NAFLD), and immune cells play pivotal roles in the inflammation of adipose tissue. Here, we investigated the roles of MAT B lymphocytes in NAFLD. Mice fed with high‐fat diet (HFD) and normal diet (ND) were killed in time gradients (4, 8 and 12 weeks). Compared with ND‐fed mice, intra‐hepatic CD45⁺CD19⁺ B lymphocytes increased after 4 weeks (P < 0.01) of HFD feeding, and lasted until the 12th week, infiltrated earlier than CD45⁺CD3⁺ T lymphocytes and CD45⁺F4/80⁺ macrophages. The mRNA expression of tumour necrosis factor (TNF)‐α, interleukin (IL)‐6 and monocyte chemotactic protein (MCP)‐1 decreased in MAT of B^null HFD‐fed mice compared to that in wild‐type HFD‐fed mice, along with lesser macrophages. Mesenteric adipose tissue B cells from HFD‐fed mice promoted macrophage differentiation to type‐Ι macrophages and expression of pro‐inflammatory cytokines in vitro. Macrophages pre‐treated with MAT B cells from HFD‐fed mice showed elevated mRNA expression of IL‐6 and TNF‐α and declined IL‐10 levels in adipocytes compared to ND MAT B cell pre‐treated macrophages. Besides, internal near‐infrared scanning and external transwell assay showed that HFD MAT B cells migrated to the liver more than ND MAT B cells. High‐fat diet MAT B cells induced higher MCP‐1 and lower IL‐10 expression in primary hepatocytes compared to ND MAT B cells in co‐culture experiment. These data indicate that B lymphocytes infiltrate early in MAT during the development of NAFLD, which may not only promote MAT inflammation by regulating macrophages but also migrate to the liver and induce hepatocytes inflammation.     

Helminth infection modulates number and function of adipose tissue Tregs in high fat diet-induced obesity

BackgroundEpidemiological and experimental studies have shown a protective effect of helminth infections in weight gain and against the development of metabolic dysfunctions in the host. However, the mechanisms Treg cells exert in the helminth-obesity interface has been poorly investigated. The present study aimed to verify the influence of Heligmosomoides polygyrus infection in early stages of high fat diet-induced obesity.Principal findingsThe presence of infection was able to prevent exacerbated weight gain in mice fed with high fat diet when compared to non-infected controls. In addition, infected animals displayed improved insulin sensitivity and decreased fat accumulation in the liver. Obesity-associated inflammation was reduced in the presence of infection, demonstrated by lower levels of leptin and resistin, lower infiltration of Th1 and Th17 cells in adipose tissue, higher expression of IL10 and adiponectin, increased infiltration of Th2 and eosinophils in adipose tissue of infected animals. Of note, the parasite infection was associated with increased Treg frequency in adipose tissue which showed higher expression of cell surface markers of function and activation, like LAP and CD134. The infection could also increase adipose Treg suppressor function in animals on high fat diet.ConclusionThese data suggest that H. polygyrus modulates adipose tissue Treg cells with implication for weight gain and metabolic syndrome.     

Acute reduction of serum leptin level by dietary conjugated linoleic acid in Sprague-Dawley rats

The purpose of this study was to clarify the effect of conjugated linoleic acid on lipid accumulation in adipose tissue. Sprague-Dawley rats were fed a diet containing 2% conjugated linoleic acid for 1, 3, 6, and 12 weeks. In rats fed 2% conjugated linoleic acid, the weight of perirenal white adipose tissue was comparable with that of rats fed a conjugated linoleic acid-free diet. For fatty acid composition of perirenal white adipose tissue, both 16:1/16:0 and 18:1/18:0 ratios were significantly lower in the conjugated linoleic acid-fed group than the control group. Although there was no remarkable difference in serum triglyceride, total cholesterol, and phospholipid levels between dietary groups, serum leptin level was significantly lower than the control group, and lipid content in the perirenal white adipose tissue exerted a tendency toward low compared to the control value at 1-week feeding. On the other hand, leptin level in perirenal white adipose tissue was significantly lower in the conjugated linoleic acid-fed group than the control group at 12-week feeding. In conclusion, these observations suggest dietary conjugated linoleic acid is an acute reducer of serum leptin level. This may afford an explanation of the mechanism of anti-obesity effect in conjugated linoleic acid.     

Self‐Selected Macronutrient Diet Affects Energy and Glucose Metabolism in Brown Fat‐Ablated Mice

Objective: Obese transgenic UCP‐DTA mice have largely ablated brown adipose tissue and develop obesity and diabetes, which are highly susceptible to a high‐fat diet. We investigated macronutrient self‐selection and its effect on development of obesity, diabetes, and energy homeostasis in UCP‐DTA mice. Research Methods and Procedures: UCP‐DTA and wild‐type littermates were fed a semisynthetic macronutrient choice diet (CD) ad libitum from weaning until 17 weeks. Energy homeostasis was assessed by measurement of food intake, food digestibility, body composition, and energy expenditure. Diabetes was assessed by blood glucose measurements and insulin tolerance test. Results: Wild‐type and UCP‐DTA mice showed a high fat preference and increased energy digestion on CD compared with a low‐fat standard diet. On CD, wild‐type mice accumulated less body fat (16.9%) than UCP‐DTA (32.6%) mice, although they had a higher overall energy intake. Compared with wild‐type mice, resting metabolic rate was reduced in UCP‐DTA mice irrespective of diet. UCP‐DTA mice progressively decreased their carbohydrate intake, resulting in an almost complete avoidance of carbohydrate. UCP‐DTA mice developed severe insulin resistance but showed decreased fed and fasted blood glucose on CD. Discussion: In contrast to wild‐type mice, UCP‐DTA mice were not able to reduce their weight gain efficiency on CD. This suggests that, because of the high fat preference of the background strain and the increased metabolic efficiency, brown adipose tissue‐deficient mice still develop obesity and insulin resistance on a macronutrient CD even when decreasing overall energy intake. Through the avoidance of carbohydrates, however, they are able to maintain normoglycemia.     

Deletion of natriuretic peptide receptor C alleviates adipose tissue inflammation in hypercholesterolemic Apolipoprotein E knockout mice

The inflammation of adipose tissue is one of the most common secondary pathological changes in atherosclerosis, which in turn influences the process of atherosclerosis. Natriuretic peptides have been revealed important effect in regulating adipose metabolism. However, the relationship between natriuretic peptide receptor C and inflammation of adipose tissue in atherosclerosis remains unknown. This study aims to explore the effect natriuretic peptide receptor C exerts on the regulation of the adipose inflammation in atherosclerotic mice induced by western-type diet and its overlying mechanisms. To clarify the importance of NPRC of adipose inflammation in atherosclerotic mice, NPRC expression was measured in mice fed with chow diet and western-type diet for 12 weeks and we found a considerable increase in adipose tissue of atherosclerotic mice. Global NPRC knockout in mice was bred onto ApoE^−/− mice to generate NPRC^−/−ApoE^−/− mice, which displayed remarked increase in browning of white adipose tissue and lipolysis of adipose tissue and decrease in adipose inflammation manifested by decreased macrophage invasion to form less CLS (crown-like structure), reduced oxidative stress and alleviated expression of TNFα, IL-6, IL-1β and MCP1, but increased expression of adiponectin in adipose tissue. Moreover, our study showed that white adipose tissue browning in NPRC^−/−ApoE^−/− atherosclerotic mice was associated with decreased inflammatory response through cAMP/PKA signalling activation. These results identify NPRC as a novel regulator for adipose inflammation in atherosclerotic mice by modulating white adipose tissue browning.     

A dairy‐based high calcium diet improves glucose homeostasis and reduces steatosis in the context of preexisting obesity

Objective:

High dietary calcium (Ca) in the context of a dairy food matrix has been shown to reduce obesity development and associated inflammation in diet‐induced obese (DIO) rodents. The influence of Ca and dairy on these phenotypes in the context of preexisting obesity is not known. Furthermore, interpretations have been confounded historically by differences in body weight gain among DIO animals fed dairy‐based protein or high Ca.

Design and Methods:

Adiposity along with associated metabolic and inflammatory outcomes were measured in DIO mice previously fattened for 12 week on a soy protein‐based obesogenic high fat diet (45% energy, 0.5% adequate Ca), then fed one of three high fat diets (n = 29‐30/group) for an additional 8 week: control (same as lead‐in diet), high‐Ca (1.5% Ca), or high‐Ca + nonfat dry milk (NFDM).

Results and Conclusion:

Mice fed high‐Ca + NFDM had modestly, but significantly, attenuated weight gain compared to mice fed high‐Ca or versus controls (P < 0.001), whereas mice fed high‐Ca alone had increased weight gain compared to controls (P < 0.001). Total measured adipose depot weights between groups were similar, as were white adipose tissue inflammation and macrophage infiltration markers (e.g. TNFα, IL‐6, CD68 mRNAs). Mice fed high‐Ca + NFDM had significantly improved glucose tolerance following a glucose tolerance test, and markedly lower liver triglycerides compared to high‐Ca and control groups. Improved metabolic phenotypes in prefattened DIO mice following provision of a diet enriched with dairy‐based protein and carbohydrates appeared to be driven by non‐Ca components of dairy and were observed despite minimal differences in body weight or adiposity.     

The flavan-3-ol fraction of cocoa powder suppressed changes associated with early-stage metabolic syndrome in high-fat diet-fed rats

Aims

Previous epidemiological studies have suggested that ingestion of chocolate reduces the risk of cardiovascular disease. In the present study, we examined the effects of flavan-3-ols derived from cocoa on blood pressure, lipolysis, and thermogenesis in rats fed a high-fat diet and that showed early signs of metabolic syndrome.

Main methods

The rats were divided into three groups, and fed either normal diet (normal), 60% fat high-fat diet (HFD), or HFD containing 0.2% flavan-3-ols (HFD-flavan) for 4 weeks. At the end of the feeding period, blood pressure was measured and animals were sacrificed under anesthesia. Lipolysis and thermogenesis-related protein levels were measured in several tissues by Western blotting, and mitochondrial DNA copy number was measured by RT-PCR.

Key findings

Mean blood pressure and epididymal adipose tissue weight of HFD-flavan were significantly lower compared with those of HFD. Uncoupling protein (UCP)1 in brown adipose tissue and UCP3 in gastrocnemius of HFD-flavan were significantly increased compared with those of HFD group. Carnitine palmitoyltransferase (CPT) 2 levels in liver and medium-chain acyl-CoA dehydrogenase (MCAD) levels in gastrocnemius and liver were significantly increased by the supplementation of flavan-3-ols.

Significance

In addition to having hypotensive effects, flavan-3-ols enhance thermogenesis and lipolysis and consequently reduce white adipose tissue weight gain in response to high-fat diet feeding.     

White adipose tissue genome wide-expression profiling and adipocyte metabolic functions after soy protein consumption in rats

Obesity is associated with an increase in adipose tissue mass due to an imbalance between high dietary energy intake and low physical activity; however, the type of dietary protein may contribute to its development. The aim of the present work was to study the effect of soy protein versus casein on white adipose tissue genome profiling, and the metabolic functions of adipocytes in rats with diet-induced obesity. The results showed that rats fed a Soy Protein High-Fat (Soy HF) diet gained less weight and had lower serum leptin concentration than rats fed a Casein High-Fat (Cas HF) diet, despite similar energy intake. Histological studies indicated that rats fed the Soy HF diet had significantly smaller adipocytes than those fed the Cas HF diet, and this was associated with a lower triglyceride/DNA content. Fatty acid synthesis in isolated adipocytes was reduced by the amount of fat consumed but not by the type of protein ingested. Expression of genes of fatty acid oxidation increased in adipose tissue of rats fed Soy diets; microarray analysis revealed that Soy protein consumption modified the expression of 90 genes involved in metabolic functions and inflammatory response in adipose tissue. Network analysis showed that the expression of leptin was regulated by the type of dietary protein and it was identified as a central regulator of the expression of lipid metabolism genes in adipose tissue. Thus, soy maintains the size and metabolic functions of adipose tissue through biochemical adaptations, adipokine secretion, and global changes in gene expression.     

Dietary conjugated linoleic acid reduces body fat mass and affects gene expression of proteins regulating energy metabolism in mice

ICR and C57BL/6J mice were fed experimental diets containing either a 2% fatty acid preparation rich in conjugated linoleic acid (CLA) or a preparation rich in linoleic acid and free of CLA for 21 days. CLA greatly decreased weights of white adipose tissue and interscapular brown adipose tissue in the two strains. CLA reduced mRNA levels of glucose transporter 4 (Glut 4) in white and brown adipose tissue of both strains. A CLA-dependent decrease in mRNA levels of peroxisome proliferator activated receptor (PPAR) gamma was seen in interscapular brown adipose tissue of both strains and in white adipose tissue of C57BL/6J but not ICR mice. Dietary CLA was found to cause a decrease in the mRNA levels of uncoupling protein (UCP) 1 in brown adipose tissue when the value was corrected for the expression of a house-keeping gene (beta-actin) in the two strains. Uncorrected values were, however, indistinguishable between the animals fed the CLA diet and CLA-free diet. UCP 3 expression in brown adipose tissue was much lower in mice fed the CLA diet than in those fed the control diet in both strains. In contrast, CLA greatly up-regulated the gene expression of UCP 2 in brown adipose tissue. Dietary CLA also increased UCP 2 mRNA level in skeletal muscle. It is apparent that dietary CLA decreases white and brown adipose tissue mass, accompanying changes in the gene expression of proteins regulating energy metabolism in white and brown adipose tissues, and skeletal muscle of mice.     

Role of maternal tissue in the synthesis of polyunsaturated fatty acids in response to a lipid-deficient diet during pregnancy and lactation in rats

During pregnancy and lactation, metabolic adaptations involve changes in expression of desaturases and elongases (Elovl2 and Elovl5) in the mammary gland and liver for the synthesis of long-chain polyunsaturated fatty acids (LC-PUFAs) such as arachidonic acid (AA) required for fetal and postnatal growth. Adipose tissue is a pool of LC-PUFAs. The response of adipose tissue for the synthesis of these fatty acids in a lipid-deficient diet of dams is unknown. The aim of this study was to explore the role of maternal tissue in the synthesis of LC-PUFAs in rats fed a low-lipid diet during pregnancy and lactation. Fatty acid composition (indicative of enzymatic activity) and gene expression of encoding enzymes for fatty acid synthesis were measured in liver, mammary gland and adipose tissue in rats fed a low-lipid diet. Gene expression of desaturases, elongases, fatty acid synthase (Fasn) and their regulator Srebf-1c was increased in the mammary gland, liver and adipose tissue of rats fed a low-lipid diet compared with rats from the adequate-lipid diet group throughout pregnancy and lactation. Genes with the highest (P < 0.05) expression in the mammary gland, liver and adipose tissue were Elovl5 (1333%), Fads2 (490%) and Fasn (6608%), respectively, in a low-lipid diet than in adequate-lipid diet. The percentage of AA in the mammary gland was similar between the low-lipid diet and adequate-lipid diet groups during the second stage of pregnancy and during lactation. The percentage of monounsaturated and saturated fatty acids was significantly (P < 0.05) increased throughout pregnancy and lactation in all tissues in rats fed a low-lipid diet than in rats fed an adequate-lipid diet. Results suggest that maternal metabolic adaptations used to compensate for lipid-deficient diet during pregnancy and lactation include increased expression of genes involved in LC-PUFAs synthesis in a stage- and tissue-specific manner and elevated lipogenic activity (saturated and monounsaturated fatty acid synthesis) of maternal tissues including adipose tissue.     

Fgf21 Impairs Adipocyte Insulin Sensitivity in Mice Fed a Low-Carbohydrate,High-Fat Ketogenic Diet

Background

A low-carbohydrate, high-fat ketogenic diet (KD) induces hepatic ketogenesis and is believed to affect energy metabolism in mice. As hepatic Fgf21 expression was markedly induced in mice fed KD, we examined the effects of KD feeding on metabolism and the roles of Fgf21 in metabolism in mice fed KD using Fgf21 knockout mice.

Methodology/Principal Findings

We examined C57BL/6 mice fed KD for 6 or 14 days. Blood β-hydroxybutyrate levels were greatly increased at 6 days, indicating that hepatic ketogenesis was induced effectively by KD feeding for 6 days. KD feeding for 6 and 14 days impaired glucose tolerance and insulin sensitivity, although it did not affect body weight, blood NEFA, and triglyceride levels. Hepatic Fgf21 expression and blood Fgf21 levels were markedly increased in mice fed KD for 6 days. Blood β-hydroxybutyrate levels in the knockout mice fed KD for 6 days were comparable to those in wild-type mice fed KD, indicating that Fgf21 is not required for ketogenesis. However, the impaired glucose tolerance and insulin sensitivity caused by KD feeding were improved in the knockout mice. Insulin-stimulated Akt phosphorylation was significantly decreased in the white adipose tissue in wild-type mice fed KD compared with those fed normal chow, but not in the muscle and liver. Its phosphorylation in the white adipose tissue was significantly increased in the knockout mice fed KD compared with wild-type mice fed KD. In contrast, hepatic gluconeogenic gene expression in Fgf21 knockout mice fed KD was comparable to those in the wild-type mice fed KD.

Conclusions/Significance

The present findings indicate that KD feeding impairs insulin sensitivity in mice due to insulin resistance in white adipose tissue. In addition, our findings indicate that Fgf21 induced to express by KD is a negative regulator of adipocyte insulin sensitivity in adaptation to a low-carbohydrate malnutritional state.