High Sugar-Fat Diet Induces Metabolic-Inflammatory Disorders Independent of Obesity Development

Background: The modern dietary habit, which is rich in refined carbohydrates and saturated fats, increases the risk of chronic diseases due to the proinflammatory effect of these nutrients. Aim: To evaluate the impact of high sugar-fat diet in the development of metabolic-inflammatory disorders in non-obese animals. Methods: Male Wistar rats were distributed into two groups according to the diet: control and high sugar-fat for 30 weeks. It was analyzed: dietary efficiency;chow, water and caloric intake;metabolic and hormonal profile in plasma and inflammatory cytokines in epididymal adipose tissue. Data were compared by Student’s t test or by Mann-Whitney U test with p Results: HSF presented lower chow intake, higher water consumption and dietary efficiency with no difference in the caloric intake. The final body weight (FBW) and weight gain (WG) were lower in the HSF group and there was no difference in the adiposity index (AI). HSF diet-induced hyperglycemia and hyperinsulinemia with no difference for Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). Triglycerides, uric acid, adiponectin and leptin levels were higher in the HSF group. The HSF group showed increased interleukin-6 (IL-6) and tumoral necrosis factor-alpha (TNF-α) levels in epidydimal adipose tissue. The urinary protein-creatinine ratio and albuminuria were higher in the HSF group. Conclusion: HSF diet intake is directly involved in the development of metabolic-inflammatory disorders independent of obesity, dissociating the view that increased adiposity is the major risk factor for complications commonly found in obese individuals.

Dietary sodium acetate and sodium butyrate improve high-carbohydrate diet utilization by regulating gut microbiota, liver lipid metabolism, oxidative stress, and inflammation in largemouth bass(Micropterus salmoides)

Background Adequate level of carbohydrates in aquafeeds help to conserve protein and reduce cost. However, studies have indicated that high-carbohydrate(HC) diet disrupt the homeostasis of the gut–liver axis in largemouth bass, resulting in decreased intestinal acetate and butyrate level.Method Herein, we had concepted a set of feeding experiment to assess the effects of dietary sodium acetate(SA) and sodium butyrate(SB) on liver health and the intestinal microbiota in largemouth bass fed an HC diet. The experimental design comprised 5 isonitrogenous and isolipidic diets, including LC(9% starch), HC(18% starch), HCSA(18% starch;2 g/kg SA), HCSB(18% starch;2 g/kg SB), and HCSASB(18% starch;1 g/kg SA + 1 g/kg SB). Juvenile largemouth bass with an initial body weight of 7.00 ± 0.20 g were fed on these diets for 56 d.Results We found that dietary SA and SB reduced hepatic triglyceride accumulation by activating autophagy(ATG101, LC3B and TFEB), promoting lipolysis(CPT1α, HSL and AMPKα), and inhibiting adipogenesis(FAS, ACCA, SCD1 and PPARγ). In addition, SA and SB decreased oxidative stress in the liver(CAT, GPX1α and SOD1) by activating the Keap1-Nrf2 pathway. Meanwhile, SA and SB alleviated HC-induced inflammation by downregulating the expression of pro-inflammatory factors(IL-1β, COX2 and Hepcidin1) through the NF-κB pathway. Importantly, SA and SB increased the abundance of bacteria that produced acetic acid and butyrate(Clostridium_sensu_stricto_1). Combined with the KEGG analysis, the results showed that SA and SB enriched carbohydrate metabolism and amino acid metabolism pathways, thereby improving the utilization of carbohydrates. Pearson correlation analysis indicated that growth performance was closely related to hepatic lipid deposition, autophagy, antioxidant capacity, inflammation, and intestinal microbial composition.Conclusions In conclusion, dietary SA and SB can reduce hepatic lipid deposition;and alleviate oxidative stress and inflammation in largemouth bass fed on HC diet. These beneficial effects may be due to the altered composition of the gut microbiota caused by SA and SB. The improvement effects of SB were stronger than those associated with SA.

Modulating Effects of Chlorogenic Acid on Lipids and Glucose Metabolism and Expression of Hepatic Peroxisome Proliferator-activated Receptor-α in Golden Hamsters Fed on High Fat Diet

Objective To examine the effects of chlorogenic acid （CGA） on lipid and glucose metabolism under a high dietary fat burden and to explore the possible role of peroxisome proliferator-activated receptor-α （PPAR-α） in these effects. Methods Twenty male golden hamsters were randomly divided into CGA treatment group （n=10, given peritoneal injection of CGA solution prepared with PBS, 80 mg CGA/kg body weight daily）, and control group （n=10, given PBS i.p. at the average volume of the treatment group）. Animals in both groups were given 15% high fat diet. Eight weeks after treatment with CGA, the level of biochemical parameters in fasting serum and tissues and the expression of hepatic mRNA and protein PPAR-α were determined. Results Eight weeks after treatment with CGA, the levels of fasting serum triglyceride （TG）, free fatty acid （FFA）, total cholesterol （TC）, low density lipoprotein cholesterol （LDL-C）, high density lipoprotein cholesterol （HDL-C）, glucose （FSG）, and insulin （FSI） were significantly lower in the GGA treatment group than in the control group. CGA also led to higher activity of hepatic lipase （HL） lower contents of TG and FFA in liver, and lower activity of lipoprotein lipase （LPL） in skeletal muscle. Furthermore, CGA significantly elevated significantly elevated the expression level of mRNA and protein expression in hepatic PPAR-α. Conclusion CGA can modify lipids and glucose metabolism, which may be attributed to PPAR-α facilitated lipid clearance in liver and improved insulin sensitivity.

Freeze-dried Si-Ni-San powder can ameliorate high fat diet-induced non-alcoholic fatty liver disease

BACKGROUND Non-alcoholic fatty liver disease(NAFLD)is a common chronic liver disease worldwide.However,to date,there is no ideal therapy for this disease.AIM To study the effects of Si-Ni-San freeze-dried powder on high fat diet-induced NAFLD in mice.METHODS Twenty-four male C57BL/6 mice were randomized into three groups of eight.The control group(CON)was allowed ad libitum access to a normal chow diet.The high fat diet group(FAT)and Si-Ni-San group(SNS)were allowed ad libitum access to a high fat diet.The SNS group was intragastrically administered Si-Ni-San freeze-dried powder(5.0 g/kg)once daily,and the CON and FAT groups were intragastrically administered distilled water.After 12 wk,body weight,liver index,visceral fat index,serum alanine aminotransferase(ALT),portal lipopoly-saccharide(LPS),liver tumor necrosis factor(TNF)-αand liver triglycerides were measured.Intestinal microbiota were analyzed using a 16S r DNA sequencing technique.RESULTS Compared with the FAT group,the SNS group exhibited decreased body weight,liver index,visceral fat index,serum ALT,portal LPS,liver TNF-αand liver triglycerides(P<0.05).Intestinal microbiota analysis showed that the SNS group had different bacterial composition and function compared with the FAT group.In particular,Oscillospira genus was a bacterial biomarker of SNS group samples.CONCLUSION The beneficial effects of Si-Ni-San freeze-dried powder on high fat diet-induced NAFLD in mice may be associated with its anti-inflammatory and changing intestinal microbiota effects.

Effects of a high fat diet on intestinal microbiota and gastrointestinal diseases

Along with the rapid development of society, lifestyles and diets have gradually changed. Due to overwhelming material abundance, high fat, high sugar and high protein diets are common. Numerous studies have determined that diet and its impact on gut microbiota are closely related to obesity and metabolic diseases. Different dietary components affect gut microbiota, thus impacting gastrointestinal disease occurrence and development. A large number of related studies are progressing rapidly. Gut microbiota may be an important intermediate link, causing gastrointestinal diseases under the influence of changes in diet and genetic predisposition. To promote healthy gut microbiota and to prevent and cure gastrointestinal diseases, diets should be improved and supplemented with probiotics.

High fat diet feeding results in gender specific steatohepatitis and inflammasome activation

AIM: To develop an animal model that encompasses the different facets of non-alcoholic steatohepatitis (NASH), which has been a challenge.

High fat diet dysregulates microRNA-17-5p and triggers retinal inflammation:Role of endoplasmic-reticulum-stress

AIM To elucidate how high diet-induced endoplasmic reticulum-stress upregulates thioredoxin interacting protein expression in Müller cells leading to retinal inflammation. METHODS Male C57Bl/J mice were fed either normal diet or 60% high fat diet for 4-8 wk. During the 4 wk study, mice received phenyl-butyric acid(PBA); endoplasmic reticulum-stress inhibitor; for 2 wk. Insulin resistance was assessed by oral glucose tolerance. Effects of palmitate-bovine serum albumin(BSA)(400 μmol/L) were examined in retinal Müller glial cell line and primary Müller cells isolated from wild type and thioredoxin interacting protein knock-out mice. Expression of thioredoxin interacting protein, endoplasmic reticulum-stress markers, mi R-17-5p m RNA, as well as nucleotide-binding oligomerization domain-like receptor protein(NLRP3) and IL1β protein was determined.RESULTS High fat diet for 8 wk induced obesity and insulin resistance evident by increases in body weight and impaired glucose tolerance. By performing quantitative real-time polymerase chain reaction, we found that high fat diet triggered the expression of retinal endoplasmic reticulum-stress markers(P < 0.05). These effects were associated with increased thioredoxin interacting protein and decreased mi R-17-5p expression, whichwere restored by inhibiting endoplasmic reticulumstress with PBA(P < 0.05). In vitro, palmitate-BSA triggered endoplasmic reticulum-stress markers, which was accompanied with reduced mi R-17-5p and induced thioredoxin interacting protein m RNA in retinal Müller glial cell line(P < 0.05). Palmitate upregulated NLRP3 and IL1β expression in primary Müller cells isolated from wild type. However, using primary Müller cells isolated from thioredoxin interacting protein knock-out mice abolished palmitate-mediated increase in NLRP3 and IL1β.CONCLUSION Our work suggests that targeting endoplasmic reticulumstress or thioredoxin interacting protein are potential therapeutic strategies for early intervention of obesityinduced retinal inflammation.

Characterization of inflammation and insulin resistance in high-fat diet-induced male C57BL/6J mouse model of obesity

Background: Animal models of diet-induced obesity(DIO) are commonly used in medical research for mimicking human diseases. There is no universal animal model, and careful evaluation of variety of factors needs to be considered when designing new experiments. Here, we investigated the effect of 9 weeks high-fat diet(HFD) intervention, providing 60% energy from fat, on parameters of inflammation and insulin resistance in male C57 BL/6 J mice.Methods: Six weeks old mice were initiated on regular diet(RD) or HFD providing 60 kcal energy from fat for 9 weeks. Fasting blood glucose levels were measured by glucometer, and fasting plasma levels of insulin and proinflammatory cytokines by Luminex assay. Insulin sensitivity was evaluated by using QUICKI and HOMA2 indexes.Results: HFD mice showed ~ 40% higher body weight and ~ 20% larger abdominal circumference, due to an increase in the white adipose tissue mass. Liver examination revealed increased size and higher hepatic lipid accumulation in livers from HFD mice compared to their RD counterparts. Animals from the HFD group were characterized with significantly higher presence of crown-like structures(CLS) in WAT and higher plasma levels of proinflammatory cytokines(TNF-α, IL-6, leptin, MCP-1, PAI-1, and resistin). HFD-fed mice also demonstrated impaired insulin sensitivity(lower QUICKI, higher HOMA-insulin resistance(HOMA-IR), and lower HOMA-percent sensitivity(HOMA-%S)) index values.Conclusion: Male C57 BL/6 J mice on 9 weeks HFD providing 60 kcal energy from fat display impaired insulin sensitivity and chronic inflammation, thus making this DIO mouse model appropriate for studies of early stages of obesity-related pathology.

The effects of the extract of oolong tea and its metabolites from Andraca theae in high fat diet induced obese Wistar rat

Obesity is a critical health issue worldwide.For a long time,the concept of drinking tea for health and pleasure is widely accepted.The strain of Andraca theae lives on the tea leaf and the bioactivity of its metabolites in the feces is unknown yet.Thus,the objective of this study was to investigate whether the extract of tea(Taiwan Tea Experiment Station No.12(TE))and its metabolites from Andraca theae(TME)could prevent obesity in the high fat diet-induced obese rats.Our results showed that TE had higher concentrations of epigallocatechin gallate(EGCG)and caffeine than that from TME.TE significantly decreased abdominal adipose tissue,especially epididymal fat via increasing preadipocyte factor 1(Pref-1),SRY(sex determining region Y)-box 9(SOX-9)and decreasing peroxisome proliferator-activated receptorγ(PPARγ),CCAAT/enhancer binding protein(C/EBP)β,C/EBPαand C/EBPβprotein expression.Taken together,these results suggest that the content of tea polyphenols in TE play an important role for alleviating abdominal fat.

Salvia miltiorrhiza extract may exert an anti-obesity effect in rats with high-fat diet-induced obesity by modulating gut microbiome and lipid metabolism

BACKGROUND Studies have shown that a high-fat diet(HFD) can alter gut microbiota(GM)homeostasis and participate in lipid metabolism disorders associated with obesity.Therefore, regulating the construction of GM with the balance of lipid metabolism has become essential for treating obesity. Salvia miltiorrhiza extract(Sal), a common traditional Chinese medicine, has been proven effective against atherosclerosis, hyperlipidemia, obesity, and other dyslipidemia-related diseases.AIM To investigate the anti-obesity effects of Sal in rats with HFD-induced obesity, and explore the underlying mechanism by focusing on GM and lipid metabolism.METHODS Obesity was induced in rats with an HFD for 7 wk, and Sal(0.675 g/1.35 g/2.70g/kg/d) was administered to treat obese rats for 8 wk. The therapeutic effect was evaluated by body weight, body fat index, waistline, and serum lipid level. Lipid factors(cAMP, PKA, and HSL) in liver and fat homogenates were analyzed by ELISA. The effect of Sal on GM and lipid metabolism was assessed by 16S rRNAbased microbiota analysis and untargeted lipidomic analysis(LC-MS/MS),respectively.RESULTS Sal treatment markedly reduced weight, body fat index, serum triglycerides(TG), total cholesterol(TC), low-density lipoprotein, glucose, free fatty acid, hepatic lipid accumulation, and adipocyte vacuolation, and increased serum high-density lipoprotein(HDL-C) in rats with HFD-induced obesity. These effects were associated with increased concentrations of lipid factors such as c AMP, PKA, and HSL in the liver and adipose tissues, enhanced gut integrity, and improved lipid metabolism. GM analysis revealed that Sal could reverse HFD-induced dysbacteriosis by promoting the abundance of Actinobacteriota and Proteobacteria, and decreasing the growth of Firmicutes and Desulfobacterita. Furthermore, LC-MS/MS analysis indicated that Sal decreased TGs(TG18:2/18:2/20:4, TG16:0/18:2/22:6), DGs(DG14:0/22:6, DG22:6/22:6), CL(18:2/18:1/18:1/20:0), and increased ceramides(Cers;Cer d16:0/21:0, Cer d16:1/24:1),(O-acyl)-ω-hydroxy fatty acids(OAHFAs;OAHFA18:0/14:0) in the feces of rats. Spearman’s correlation analysis further indicated that TGs, DGs, and CL were negatively related to the abundance of Facklamia and Dubosiella, and positively correlated with Blautia and Quinella, while OAHFAs and Cers were the opposite.CONCLUSION Sal has an anti-obesity effect by regulating the GM and lipid metabolism.

Effects of Siraitia grosvenorii extracts on high fat diet-induced obese mice:a comparison with artificial sweetener aspartame

Long-term artificial sweetener intake is linked to increased risk of obesity. In the present study, supplement of natural sweetener from Siraitia grosvenorii(SG)(or Momordica grosvenorii) fruit, compared with the artificial sweetener aspartame(ASM), was evaluated for anti-obesity effects on mice fed with high fat diet(HFD). We found that, in contrary to ASM, SG extracts prevented body weight gain, the insulin resistance and fat mass accumulation in HFD mice. SG extracts treatment inhibited the infiltration of inflammatory macrophages and lowered the levels of the fat inflammatory cytokines(leptin, macrophage chemoattractant protein 1(MCP-1) and tumor necrosis factor-α(TNF-α)) in adipose tissues. In addition, SG extracts supplement counteracted the remodeling of gut microbiota resulted from HFD. However, ASM supplement aggravated the HFD-induced obese performances, fat inflammation and dysregulation of gut microbiota. Taken together, our results indicate that supplement of SG extracts may represent a promising alternation of artificial sweeteners in preventing metabolic diseases.

Comparative proteomic analysis of the effects of high-concentrate diet on the hepatic metabolism and inflammatory response in lactating dairy goats

Background： To understand the impact of feeding a high-concentrate diet to mid-lactating goats for a long time on liver metabolism and inflammatory response, two dimensional polyacrylamide gel electrophoresis（2-DE） and real-time PCR method were employed to detect proteins differentially expressed in liver and their m RNAs expression in goats fed high concentrate diet（HC） or low concentrate diet（LC）. Twelve lactating dairy goats were randomly assigned to either a HC diet group（65 % concentrate of dry matter; n = 6） or a LC diet group（35 % concentrate of dry matter; n = 6） for 10 wk.Results： Twenty differentially expressed spots（≥2.0-fold changes） in the hepatic tissues were excised and successfully identified using MALDI TOF/TOF. Of these, 8 proteins were up-regulated, while the rest 12 proteins were down-regulated in HC goats compared to LC. Differential expressed proteins including alpha enolase 1（ENO1）, glutamate dehydrogenase 1（GLUD1）, glutathione S-transferase A1（GSTA1）, ATP synthase subunit 5β（ATP5β）, superoxide dismutase [Cu-Zn]（SOD1）, cytochrom c oxidase subunit Via（COX6A1） and heat shock protein 60（HSP60） were further verified by real-time PCR and/or western blot at m RNA or protein expression level. Consistent with the 2-DE results, a significant decrease of β-actin protein expression and SOD enzyme activity was observed in liver of HC goats（P 〈 0.05）, while ENO1 protein expression was significantly up-regulated in HC compared to LC goats（P 〈 0.05）. However, western blot analysis did not show a significant difference of hepatic HSP60 protein between HC and LC group, which did not match the decrease of HSP60 content detected by 2-DE analysis. Real-time PCR showed that glutathione S-transferase P1（GSTP1） and SOD1 m RNA expression was significantly decreased in liver of HC goats, while cytochrom c oxidase（COX3） and ATPase 8（ATP8） m RNAs expression were markedly increased compared to LC（P 〈 0.05）. Gene Ontology（GO） analysis revealed that HC diet resulted in altered expression of proteins related to catalytic and mitochondrial metabolism in the liver, and may increase the stress response with up-regulating the expression of differentiation 14（CD14） cluster and serum amyloid A（SAA） as well as C-reactive protein（CRP） in the liver.Conclusions： These results suggest that feeding high concentrate diet to lactating goats for 10 wk leads to the activation of the inflammatory response, and decreases the anti-oxidant capacity, and subsequently impairs the mitochondrial function in the liver.

Hypolipidemic Activity of Olive Oil (Olea europaea) against High Fat Diet-Induced Nonalcoholic Fatty Liver Disease (NAFLD) in Mice

Aim: The aim of the present study is to access the effect of olive oil supplementation against high fat diet induced fatty liver disease in mice. Methods: Mice were divided into five groups: Group I (normal diet), Group II (high fat diet), Group III (olive oil), Group IV and V (High Fat Diet along with olive oil). All mice were fed for 16 weeks with weight measurements every 2 weeks and then sacrificed. Biochemical analysis of blood samples was done and mice livers were histologically examined. Results: Group II mice showed significant increase in body weight as compared with Group I (p < 0.05). Group IV and V mice were significantly (p < 0.05) reduced in body weight as compared with Group II. Olive oil groups had significantly decreased triglyceride and low density lipoprotein levels as compared with Group II whereas high density lipoprotein levels were significantly increased (p < 0.05). The liver enzymes were significantly increased in Group II as compared with other groups (p < 0.05). Liver histopathology revealed drastically increased lipid droplets in Group II mice as compared with Group IV & V. Conclusion: Olive oil causes weight reduction, decreases the serum triglycerides, normalizes the liver enzymes and significantly reduces the accumulation of fat in liver. Therefore, olive oil may represent a potential therapeutic alternative for NAFLD and other fatty diseases.

High Protein Diet that Cause Weight Loss and Lower Blood Glucose Level Have a Serious Impact on the Kidney Functions of Male Diabetic Obese Albino Rats

Background: High protein (HP) diets are increasingly being recommended as one of the management strategies for weight control in overweight and obese individuals. The health benefits of high protein diets are well-established, but the mechanisms of action on body systems responsible for the changes in body weight and glycaemic control are not well-clear. Objective: The present study aimed to examine the effect of HP diets on the kidney functions of diabetic obese albino rats. Material and Methods: Eighty male adult male albino rats were used in this study. The animals were divided into eight equal groups (10 rats for each). Type 2 DM and obesity were induced. At the end of the 12 weeks, samples were collected for biochemical analysis. Results: The high protein diet led to significant decrease in BW, FI, BG, TC, LDL, TG, Lactate dehydrogenase, albumin, urine pH and urine citrate;while serum insulin, HDL, urea, creatinine, total protein, urine volume and urinary excretion of Ca were significantly higher in high protein diet groups. Conclusion: A high protein intake in diabetic obese albino rats for 12 weeks led to changes in the serum and urine levels of markers of renal function which indicated abnormalities in the functions of the kidney.

Negative effects of long-term feeding of high-grain diets to lactating goats on milk fat production and composition by regulating gene expression and DNA methylation in the mammary gland

Background： It is well known that feeding a high concentrate（HC） diet to lactating ruminants likely induces subacute ruminal acidosis（SARA） and leads to a decrease in milk fat production. However, the effects of feeding a HC diet for long periods on milk fatty acids composition and the mechanism behind the decline of milk fat still remains poorly understood. The aim of this study was to investigate the impact of feeding a HC diet to lactating dairy goats on milk fat yield and fatty acids composition with an emphasis on the mechanisms underlying the milk fat depression. Seventeen mid-lactating dairy goats were randomly allocated to three groups. The control treatment was fed a low-concentrate diet（35% concentrate, n = 5, LC） and there were two high-concentrate treatments（65% concentrate, HC）, one fed a high concentrate diet for a long period（19 wks, n = 7, HL）; one fed a high concentrate diet for a short period of time（4 wk, n = 5, HS）. Milk fat production and fatty acids profiles were measured. In order to investigate the mechanisms underlying the changes in milk fat production and composition,the gene expression involved in lipid metabolism and DNA methylation in the mammary gland were also analyzed.Results： Milk production was increased by feeding the HC diet in the HS and HL groups compared with the LC diet（P 〈 0.01）, while the percentage of milk fat was lower in the HL（P 〈 0.05） but not in the HS group. The total amount of saturated fatty acids（SFA） in the milk was not changed by feeding the HC diet, whereas the levels of unsaturated fatty acids（UFA） and monounsaturated fatty acids（MUFA） were markedly decreased in the HL group compared with the LC group（P 〈 0.05）. Among these fatty acids, the concentrations of C15：0（P 〈 0.01）, C17：0（P 〈 0.01）, C17：1（P 〈 0.01）, C18：1 n-9 c（P 〈 0.05）, C18：3 n-3 r（P 〈 0.01） and C20：0（P 〈 0.01） were markedly lower in the HL group, and the concentrations of C20：0（P 〈 0.05） and C18：3 n-3 r（P 〈 0.01） were lower in the HS group compared with the LC group. However, the concentrations of C18：2 n-6 c（P 〈 0.05） and C20：4 n-6（P 〈 0.05） in the milk fat were higher in the HS group. Real-time PCR results showed that the m RNA expression of the genes involved in milk fat production in the mammary gland was generally decreased in the HL and HS groups compared with the LC group. Among these genes, ACSL1, ACSS1 ＆ 2, ACACA, FAS, SCD, FADS2, and SREBP1 were downregulated in the mammary gland of the HL group（P 〈 0.05）, and the expressions of ACSS2, ACACA, and FADS2 m RNA were markedly decreased in the HS goats compared with the LC group（P 〈 0.05）. In contrast to the gene expression, the level of DNA methylation in the promoter regions of the ACACA and SCD genes was increased in the HL group compared with the LC group（P 〈 0.05）. The levels of ACSL1 protein expression and FAS enzyme activity were also decreased in the mammary gland of the HL compared with the LC group（P 〈 0.05）.Conclusions： Long-term feeding of a HC diet to lactating goats induced milk fat depression and FAs profile shift with lower MUFAs but higher SFAs. A general down-regulation of the gene expression involved in the milk fat production and a higher DNA methylation in the mammary gland may contribute to the decrease in milk fat production in goats fed a HC diet for long time periods.

Immunohistochemical expression of intrarenal renin angiotensin system components in response to tempol in rats fed a high salt diet

AIM To determine the effect of tempol in normal rats fed high salt on arterial pressure and the balance between antagonist components of the renal renin-angiotensin system.METHODS Sprague-Dawley rats were fed with 8% NaCl high-salt （HS） or 0.4% NaCl （normal-salt, NS） diet for 3 wk, with or without tempol （T） （1 mmol/L, administered in drinking water）. Mean arterial pressure （MAP）, glomerular fltration rate （GFR）, and urinary sodium excretion （UVNa） were measured. We evaluated angiotensin Ⅱ （Ang Ⅱ）, angiotensin 1-7 （Ang 1-7）, angiotensin converting enzyme 2 （ACE2）, mas receptor （MasR）, angiotensin type 1 receptor （AT1R） and angiotensin type 2 receptor （AT2R） in renal tissues by immunohistochemistry.RESULTSThe intake of high sodium produced a slight but signifcant increase in MAP and differentially regulated components of the renal renin-angiotensin system （RAS）. This included an increase in Ang Ⅱ and AT1R, and decrease in ACE-2 staining intensity using immunohistochemistry. Antioxidant supplementation with tempol increased natriuresis and GFR, prevented changes in blood pressure and reversed the imbalance of renal RAS components. This includes a decrease in Ang Ⅱ and AT1R, as increase in AT2, ACE2, Ang （1-7） and MasR staining intensity using immunohistochemistry. In addition, the natriuretic effects of tempol were observed in NS-T group, which showed an increased staining intensity of AT2, ACE2, Ang （1-7） and MasR.CONCLUSION These findings suggest that a high salt diet leads to changes in the homeostasis and balance between opposing components of the renal RAS in hypertension to favour an increase in Ang Ⅱ. Chronic antioxidant supplementation can modulate the balance between the natriuretic and antinatriuretic components of the renal RAS.

Comparison of gene expression in cynomolgus monkeys with preclinical type Ⅱ diabetes induced by different high energy diets

Background : Cynomolgus disease models that are similar to the preclinical stage of human type 2 diabetes mellitus(T2 DM) were established by feeding middle-aged cynomolgus monkeys different high energy diets to study the differential expression of diabetes-related genes. Methods : A total of 36 male monkeys were randomly divided into four groups and fed human diets with high sugar, high fat, double high sugar and fat, and a normal diet. The preclinical diabetes phase was determined by monitoring the metabolic characteristic indices and the results of oral glucose tolerance tests( OGTT). The mRNA expression of 45 diabetes-related genes in peripheral blood leukocytes was analyzed using real-time PCR. Results : A total of 22, 25, and 21 genes were significantly up-regulated( P < 0.05) and 5, 7, and 5 genes were significantly down-regulated( P < 0.05) in the above three induced groups, respectively, compared with the control group. Of the 45 tested genes, the expression profiles of 21 genes were consistent. Most of the expression levels in the double high sugar-and-fat individuals were slightly lower than those in the high glucose and high fat groups, although the expression patterns of the three groups were essentially similar. Conclusion : The different high energy diets all induced diabetes and shared some phenotypic properties with human T2 DM. Most of the expression patterns of the related genes were identical. The gene expression profiles could be used as references for the study of early diagnostic indicators and T2 DM pathogenesis.

Long-Term Treatment with an Herbal Formula MCC Ameliorates Obesity-Associated Metabolic Dysfunction in High Fat Diet-Induced Obese Mice: A Comparative Study among MCC and Various Combinations of Its Constituents

Obesity has been found to be associated with increased incidence of various metabolic disorders. Anti-obesity interventions are therefore urgently needed. An earlier study has demonstrated that treatment with an herbal formula MCC, which comprises the fruit of Momordica charantia (MC), the pericarpium of Citri reticulate (CR) and L-carnitine (CA), reduced the weight gain in high fat diet (HFD)-fed mice. In the present study, we investigated the effect of long-term treatment with MCC (6 g/kg/day × 40 doses) and various combinations of its constituents in HFD-fed female ICR mice. Body weight change was monitored during the course of the experiment. Total and differential adiposity, plasma lipid contents, metabolic enzyme activities and mitochondrial coupling efficiency in skeletal muscle were measured. Glucose homeostasis was also assessed. Results showed that HFD increased the body weight, total and differential adiposity, and plasma lipid contents as well as impaired metabolic status in skeletal muscle and glucose homeostasis. MCC and all combinations of its constituents reduced the weight gain in HFD-fed mice, which was accompanied with an improvement on glucose homeostasis. While MC, CA and CR independently suppressed the HFD-induced weight gain in mice, MC seems to be the most effective in weight reduction, all of which correlated with the induction of mitochondrial uncoupling in skeletal muscle. Only CA and CR, but not MC, significantly reduced the total adiposity and visceral adiposity as well as plasma cholesterol level. However, the two component combinations, MC + CR and MC + CA, decreased the degree of visceral adiposity and plasma cholesterol level, respectively. MCC treatment at 1.5 g/kg (but not a higher dose of 6 g/kg) suppressed visceral adiposity and induced mitochondrial uncoupling in skeletal muscle in HFD-fed mice. The finding suggests that MCC may offer a promising prospect for ameliorating the diet-induced obesity and metabolic disorders in humans.

Mitofusin-2 ameliorates high-fat diet-induced insulin resistance in liver of rats

AIM:To investigate the effects of mitofusin-2(MFN2) on insulin sensitivity and its potential targets in the liver of rats fed with a high-fat diet(HFD).METHODS:Rats were fed with a control or HFD for 4 or 8 wk,and were then infected with a control or an MFN2 expressing adenovirus once a week for 3wk starting from the 9th wk.Blood glucose(BG),plasma insulin and insulin sensitivity of rats were determined at end of the 4th and 8th wk,and after treatment with different amounts of MFN2 expressing adenovirus(108,109 or 1010 vp/kg body weight).BG levels were measured by Accu-chek Active Meter.Plasma insulin levels were analyzed by using a Rat insulin enzymelinked immunosorbent assay kit.Insulin resistance was evaluated by measuring the glucose infusion rate(GIR) using a hyperinsulinemic euglycemic clamp technique.The expression or phosphorylation levels of MFN2 and essential molecules in the insulin signaling pathway,such as insulin receptor(INSR),insulin receptor substrate 2(IRS2),phosphoinositide-3-kinase(PI3K),protein kinase beta(AKT2) and glucose transporter type 2(GLUT2) was assayed by quantitative real-time polymerase chain reaction and Western-blotting.RESULTS:After the end of 8wk,the body weight of rats receiving the normal control diet(ND) and the HFD was not significantly different(P>0.05).Compared with the ND group,GIR in the HFD group was significantly decreased(P<0.01),while the levels of BG,triglycerides(TG),total cholesterol(TC) and insulin in the HFD group were significantly higher than those in the ND group(P<0.05).Expression of MFN2 mRNA and protein in liver of rats was significantly downregulated in the HFD group(P<0.01) after 8 wk of HFD feeding.The expression of INSR,IRS2 and GLUT2 were down-regulated markedly(P<0.01).Although there were no changes in PI3K-P85 and AKT2 expression,their phosphorylation levels were decreased significantly(P<0.01).After intervention with MFN2 expressing adenovirus for 3wk,the expression of MFN2 mRNA and protein levels were up-regulated(P<0.01).There was no difference in body weight of rats between the groups.The levels of BG,TG,TC and insulin in rats were lower than those in the Ad group(P<0.05),but GIR in rats infected with Ad-MFN2 was significantly increased(P<0.01),compared with the Ad group.The expression of INSR,IRS2 and GLUT2 was increased,while phosphorylation levels of PI3K-P85 and AKT2 were increased(P<0.01),compared with the Ad group.CONCLUSION:HFDs induce insulin resistance,and this can be reversed by MFN2 over-expression targeting the insulin signaling pathway.

Effect of a high-fat diet in development of colonic adenoma in an animal model

AIM: To investigate the effect of a high-fat diet in the formation of the precursors of colorectal cancer using an animal model.