Voluntary wheel running ameliorated the deleterious effects of high-fat diet on glucose metabolism,gut microbiota and microbial-associated metabolites

Exercise training is critical for the early prevention and treatment of obesity and diabetes mellitus.However,the mechanism with gut microbiota and fecal metabolites underlying the effects of voluntary wheel running on high-fat diet induced abnormal glucose metabolism has not been fully elaborated.C57BL/6 male mice were randomly assigned to 4 groups according to diets(fed with normal chow diet or high-fat diet)and running paradigm(housed in static cage or with voluntary running wheel).An integrative 16S rDNA sequencing and metabolites profiling was synchronously performed to characterize the effects of voluntary wheel running on gut microbiota and metabolites.It showed that voluntary wheel running prevented the detrimental effects of high-fat feeding on glucose metabolism 16S rDNA sequencing showed remarkable changes in Rikenella and Marvinbryantia genera.Metabolic profiling indicated multiple altered metabolites,which were enriched in secondary bile acid biosynthesis signaling.In conclusion,our study indicated that voluntary wheel running significantly improved glucose metabolism and counteracted the deleterious effects of high-fat feeding on body weight and glucose intolerance.We further found that voluntary wheel running could integratively program gut microbiota composition and fecal metabolites changes,and may regulate muricholic acid metabolism and secondary bile acid biosynthesis in high-fat fed mice.

Effects of forsythin extract in Forsythia leaves on intestinal microbiota and short-chain fatty acids in rats fed a high-fat diet

Forsythia suspensa,belonging to the deciduous shrubs of the Luteaceae family,a traditional Chinese medicine,has effects of alleviating swelling,clearing heat,detoxification and promoting blood circulation.The leaves of F.suspensa contain multiple chemical components and have a long history of use in folk medicines and health foods.The purpose of this study was to explore the effects of forsythin extract from F.suspensa leaves on intestinal microbiota and short-chain fatty acid(SCFA)content in rats with obesity induced by a high-fat diet.Forsythin extract in F.suspensa leaves increased the abundance of the intestinal microbiota,ameliorated intestinal microbiota disorders and inhibited the increase in total SCFA content in the intestinal tract in rats with obesity induced by a high-fat diet.These results suggested that forsythin extract in F.suspensa leaves may slow the development of obesity induced by a high-fat diet;thus,its active components and efficacy are worthy of further study.

Therapeutic effects of Lingguizhugan decoction in a rat model of high-fat diet-induced insulin resistance

BACKGROUND Lingguizhugan(LGZG)decoction is a widely used classic Chinese medicine formula that was recently shown to improve high-fat diet(HFD)-induced insulin resistance(IR)in animal studies.AIM To assess the therapeutic effect of LGZG decoction on HFD-induced IR and explore the potential underlying mechanism.METHODS To establish an IR rat model,a 12-wk HFD was administered,followed by a 4-wk treatment with LGZG.The determination of IR status was achieved through the use of biochemical tests and oral glucose tolerance tests.Using a targeted metabolomics platform to analyze changes in serum metabolites,quantitative real-time PCR(qRT-PCR)was used to assess the gene expression of the ribosomal protein S6 kinase beta 1(S6K1).RESULTS In IR rats,LGZG decreased body weight and indices of hepatic steatosis.It effectively controlled blood glucose and food intake while protecting islet cells.Metabolite analysis revealed significant differences between the HFD and HFDLGZG groups.LGZG intervention reduced branched-chain amino acid levels.Levels of IR-related metabolites such as tryptophan,alanine,taurine,and asparagine decreased significantly.IR may be linked to amino acids due to the contemporaneous increase in S6K1 expression,as shown by qRT-PCR.CONCLUSIONS Our study strongly suggests that LGZG decoction reduces HFD-induced IR.LGZG may activate S6K1 via metabolic pathways.These findings lay the groundwork for the potential of LGZG as an IR treatment.

Time-dependent impact of a high-fat diet on the intestinal barrier of male mice

BACKGROUND Excessive saturated fat intake compromises the integrity of the intestinal mucosa,leading to low-grade inflammation,impaired mucosal integrity,and increased intestinal permeability,resulting in the migration of lipopolysaccharide(LPS)to other tissues.AIM To evaluate the chronic effects(at 10 and 16 wk)of a high-fat diet(HFD)(with 50%energy as fat)on the phylogenetic gut microbiota distribution and intestinal barrier structure and protection in C57BL/6 mice.METHODS Forty adult male mice were divided into four nutritional groups,where the letters refer to the type of diet(control and HFD or HF)and the numbers refer to the period(in weeks)of diet administration:Control diet for 10 wk,HFD for 10 wk,control diet for 16 wk,and HFD for 16 wk.After sacrifice,biochemical,molecular,and stereological analyses were performed.RESULTS The HF groups were overweight,had gut dysbiosis,had a progressive decrease in occludin immunostaining,and had increased LPS concentrations.Dietary progression reduced the number of goblet cells per large intestine area and Mucin2 expression in the HF16 group,consistent with a completely disarranged intestinal ultrastructure after 16 wk of HFD intake.CONCLUSION Chronic HFD intake causes overweight,gut dysbiosis,and morphological and functional alterations of the intestinal barrier after 10 or 16 wk.Time-dependent reductions in goblet cell numerical density and mucus production have emerged as targets for countering obesity-driven intestinal damage.

Comparative transcriptomics analysis of Zygosaccharomyces mellis under high-glucose stress

The high-glucose tolerance of yeast is the main factor determining the efficiency of high-density alcohol fermentation.Zygosaccharomyces mellis LGL-1 isolated from honey could survive under 700 g/L high-glucose stress and its tolerant characteristics were identified in our previous study.This study was performed to explore and clarify the high-glucose tolerance mechanism of Z.mellis LGL-1.Comparative transcriptomic analysis was used to analyze the genes with differential expression in Z.mellis under high-glucose conditions of 300,500 and 700 g/L.With 300 g/L samples as reference,there were 937 and 2380 differentially expressed genes(DEGs)in the 500 and 700 g/L samples,respectively.Meanwhile,there was 825 significant DEGs in the 700 g/L samples compared with that of the 500 g/L samples.The result revealed that transcriptional changes in multiple metabolic pathways occur in response to high-glucose stress.q-RT PCR analysis further confirmed that several stress response pathways,such as the high osmolarity glycerol mitogen-activated protein kinase(HOG-MAPK)signal transduction pathway,trehalose synthesis pathway and oxidative stress response are closely related to high-glucose tolerance in Z.mellis.This study clarifies mechanisms of Z.mellis in response to high-glucose osmotic stress,providing theoretical basis for the process control of high-density alcohol fermentation.

High-fat diet and oral infection induced type 2 diabetes and obesity development under different genetic backgrounds

Background:Type 2 diabetes(T2D)is an adult-onset and obese form of diabetes caused by an interplay between genetic,epigenetic,and environmental components.Here,we have assessed a cohort of 11 genetically different collaborative cross(CC)mouse lines comprised of both sexes for T2D and obesity developments in response to oral infection and high-fat diet(HFD)challenges.Methods:Mice were fed with either the HFD or the standard chow diet(control group)for 12 weeks starting at the age of 8 weeks.At week 5 of the experiment,half of the mice of each diet group were infected with Porphyromonas gingivalis and Fusobacterium nucleatum bacteria strains.Throughout the 12-week experimental period,body weight(BW)was recorded biweekly,and intraperitoneal glucose tolerance tests were performed at weeks 6 and 12 of the experiment to evaluate the glucose tolerance status of mice.Results:Statistical analysis has shown the significance of phenotypic variations between the CC lines,which have different genetic backgrounds and sex effects in different experimental groups.The heritability of the studied phenotypes was estimated and ranged between 0.45 and 0.85.We applied machine learning methods to make an early call for T2D and its prognosis.The results showed that classification with random forest could reach the highest accuracy classification(ACC=0.91)when all the attributes were used.Conclusion:Using sex,diet,infection status,initial BW,and area under the curve(AUC)at week 6,we could classify the final phenotypes/outcomes at the end stage of the experiment(at 12 weeks).

Targeted microbiome metabolomics reveals flaxseed oil supplementation regulated the gut microbiota and farnesoid X receptor pathway in high-fat diet mice

Flaxseed oil(FSO)rich in n-3 polyunsaturated fatty acids(PUFAs)can protect against obesity and insulin resistance,but the underlying mechanism is unknown.An integrative multiomics of the microbiome and targeted metab olomics approach was performed to investigate the possible pathway for flaxseed oil supplementation on reducing serum total cholesterol,triglyceride and epididymal adipose in high-fat diet mice.FSO ameliorated the gut microbial dysbiosis by increasing the community diversity and the abundance of Clostridiales and Ruminococcaceae.These effects were associated with the regulation of bile acid(BAs)in the feces.FSO reduced the concentrations of conjugated BAs,such as cholic acid,tauro-α-murocholic acid,and tauro-ursodesoxycholic acid in feces,which in turn inhibit the intestinal farnesoid X receptor(FXR)-fibroblast growth factor(FGF)15 signaling pathway.Further analysis revealed that FSO activated FXR in the liver and regulated downstream gene expression(SHP,SREBP-1c,and CPT-1a),which promoted lipolysis and inhibited lipogenesis.The results of this study suggest that FSO modulates serum lipid concentrations by regulating the gut microbiota,FXR-FGF15 signaling and BA metabolism.

SESN2 ablation weakens exercise benefits on resilience of gut microbiota following high-fat diet consumption in mice

Gut dysbiosis is associated with several pathological processes.Previous study showed that regular exercise can protect against dysmetabolism in high-fat diet(HFD)fed mice through butyrate-SESN2 pathway,and SESN2 ablation weakened the protective effects of exercise.Here,we investigated whether SESN2-defi ciency suppresses the exercise response to microbiota composition and subsequently reduces the benefi ts of exercise on dysmetabolism induced by HFD.Wild type(WT)and SESN2^(-/-)mice were assigned to fi ve-groups,fed with either normal chow or HFD and with or without exercise training for 15-week.Fecal microbiota composition and function were assessed by 16S rRNA sequencing.The sequencing results showed that SESN2^(-/-)mice displayed differed microbiome profile from WT mice.Exercise enriched the microflora diversity and increased the benefi cial microbial species in WT mice,and SESN2 ablation weakened the benefi cial effects of exercise on microbial resilience following HFD consumption.Moreover,network analysis revealed that exercise increased correlation density and clustering of operational taxonomic units in WT mice only.KEGG demonstrated that some dominant metabolism-related enzymes and modules increased in SESN2^(-/-)mice.Our results indicated that the effects of exercise on metabolism are associated with the perturbations of gut microbiota composition and function,suggesting that SESN2 contributes to maintain metabolic homeostasis.

The prevention of high-fat diet-induced non-alcoholic fatty liver disease in mice by Fucoidan

Objective:To study the preventive effect of fucoidan on non-alcoholic fatty liver disease induced by high fat diet.Methods:The experimental mice were randomly divided into three groups:control group,high-fat diet group and fucoidan intervention group.The control group was fed a standard diet,and the other two groups were fed a high-fat diet.The control group and the high-fat diet group were given normal saline intragastric administration every day,and the intervention group was given intragastric administration of fucoidan polysaccharide solution at a dose of 100 mg∙kg^(-1)∙d^(-1) once a day for continuous intervention for 12 weeks.After the last intragastric administration for 12 h,the body weight and liver weight of each group of mice were measured,and the liver index was calculated.The contents of alanine aminotransferase(ALT),aspartate aminotransferase(AST),total cholesterol(TC)and triglyceride(TG)in liver tissues of mice in each group were detected by biochemical kit.Hematoxylin-eosin staining(HE)was used to compare the pathological morphological changes of liver tissue in each group.The contents of inflammatory factor interleukin-6(IL-6),tumor necrosis factor(TNF-α)and oxidative stress index malondialdehyde(MDA),and the activities of glutathione peroxidase(GSH-Px)and superoxide dismutase(SOD)in liver tissues of mice in each group were determined.Results:Compared with the control group,the body weight and liver index of mice receiving high fat diet increased significantly(P<0.01).In addition,the contents of TG,TC,AST and ALT in liver tissue of high-fat diet group were significantly increased compared with that of control group(P<0.01).The liver tissue of mice in the high-fat diet group also showed significant pathological changes,accompanied by increased expression of inflammatory factors and a significant increase in oxidative stress response.However,compared with the mice in the high-fat diet group,the above indexes were significantly improved in the liver tissue of the mice treated with fucoidan(P<0.01).Conclusion:Fucoidan can inhibit liver lipid deposition,liver inflammation and oxidative stress induced by high fat diet.

Endoplasmic Reticulum Stress-induced Endothelial Dysfunction Promotes Neointima Formation after Arteriovenous Grafts in Mice on High-fat Diet

Objective Endothelial dysfunction is one candidate for triggering neointima formation after arteriovenous grafts(AVGs),but the factors mediating this process are unclear.The purpose of this study was to investigate the role of endoplasmic reticulum stress(ERS)-induced endothelial dysfunction in neointima formation following AVGs in high-fat diet(HFD)mice.Methods CCAAT-enhancer-binding protein-homologous protein(CHOP)knockout(KO)mice were created.Mice were fed with HFD to produce HFD model.AVGs model were applied in the groups of WT ND,WT HFD,and CHOP KO HFD.Human umbilical vein endothelial cells(HUVECs)were cultured with oxidized low density lipoprotein(ox-LDL)(40 mg/L)for the indicated time lengths(0,6,12,24 h).ERS inhibitor tauroursodeoxycholic acid(TUDCA)was used to block ERS.Immunohistochemical staining was used to observe the changes of ICAM1.Changes of ERS were detected by real-time RT-PCR.Protein expression levels and ERS activation were detected by Western blotting.Endothellial cell function was determined by endothelial permeability assay and transendothelial migration assay.Results HFD increased neointima formation in AVGs associated with endothelial dysfunction.At the same time,ERS was increased in endothelial cells(ECs)after AVGs in mice consuming the HFD.In vitro,ox-LDL was found to stimulate ERS,increase the permeability of the EC monolayer,and cause endothelial dysfunction.Blocking ERS with TUDCA or CHOP siRNA reversed the EC dysfunction caused by ox-LDL.In vivo,knockout of CHOP(CHOP KO)protected the function of ECs and decreased neointima formation after AVGs in HFD mice.Conclusion Inhibiting ERS in ECs could improve the function of AVGs.

Effects of Polygonatum sibiricum Polysaccharide (PSP) on Inflammatory Factors in Rats Fed on High-fat Diet

[Objectives]This study was conducted to explore the effects of Polygonatum sibiricum polysaccharide(PSP)on chronic intestinal inflammation caused by high-fat diet.[Methods]Thirty five male healthy SD rats were randomly divided into a normal control group(NC,normal diet,n=10)and a high-fat diet group(HF,high-fat diet,n=25).After 8 weeks,an obesity model was established.The HF group was randomly divided into an HF group and a PSP treatment group[PSP,300 mg/(kg·d)].After 6 weeks of intervention with PSP,rat serum was collected,and the spleen and thymus were stripped,and weighed.Serum IgG,IgM,LPS and IL-1βand IL-6 contents were detected by ELISA,and HE staining was adopted to observe the pathological changes of the colon tissue.[Results]PSP reduced the level of LPS caused by high-fat diet and the levels of inflammatory factors IL-6 and TNF-α,increased the indexes of the thymus and spleen serving as immune organs,increased IgG and IgM contents,and alleviated pathological damage to the colon tissue caused by high-fat diet.[Conclusions]This study provides a theoretical basis and experimental basis for the development of drugs for treating metabolic diseases such as obesity and inflammation.

Effect of Mongolian Vinegar Soaked Licorice on Liver Fibrosis Induced by Carbon Tetrachloride Combined with High-fat Diet in Rats

[Objectives]To determine the improvement effect of vinegar soaked licorice on liver fibrosis induced by carbon tetrachloride(CCl_(4))combined with high-fat diet in rats.[Methods]Subcutaneous injection of 40%-60%CCl_(4)olive oil solution(0.3 mL/100 g)combined with a high-fat diet was used for 5 weeks to establish the rat model with liver fibrosis.After the modeling,the rats were divided into a low dose(0.8 g/kg),a medium dose(2.5 g/kg),a high dose(5 g/kg)group,a colchicine(1.5 mg/kg)positive group,and a vinegar group(2 mL/kg).The serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)levels in the rats were measured automatically.The serum hyaluronic acid(HA)was detected by radioimmunoassay,and the serum laminin(LN)and procollagen type III peptide(PIIIP)levels were measured by enzyme-linked immunoassay.Liver histopathological morphological changes were observed by HE and Masson staining,and expressions of cytochrome CYP2E1 and transcription factor Nrf2 were detected by immunohistochemistry.[Results]The rat liver fibrosis model was established successfully at the 6~(th)week.Compared with the model group,the levels of ALT,AST,HA,LA,PIIIP,CYP2E1 and Nrf2 of all the examined indexes in the dosing group were decreased(P<0.05).As shown in the pictures of liver pathological tissue sections,the liver fibrosis was significantly alleviated in the positive group and the 3 administration groups.[Conclusions]Vinegar soaked licorice can significantly improve the liver fibrosis induced by carbon tetrachloride combined with high-fat diet in rats,and the effect of the high-dose group was similar to that of the positive group.

Effects of Polygonatum sibiricum Polysaccharide on Antioxidant Capacity of the Liver in High-fat Diet Rats

[Objectives]This study was conducted to investigate the effects of Polygonatum sibiricum polysaccharide(PSP)on antioxidant function in high-fat diet obese rats.[Methods]Thirty five healthy male SD rats were selected to establish an obesity model after feeding a high-fat for 8 weeks.They were then randomly divided into a normal group(NC),a high-fat diet group(HF),and an HF+P.sibiricum polysaccharide group[HF+PSP,300 mg/(kg·d)].After 6 weeks of PSP intervention,the serum and liver of rats were collected,and the activity of aspartate transaminase(AST)and alanine aminotransferase(ALT)in serum,the enzyme activity of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GSH-Px)and malondialdehyde(MDA)in liver tissue were measured.The pathological changes of liver tissue were observed by HE staining.[Results]Compared with the HF group,PSP could effectively inhibit obesity caused by high-fat diet.It reduced body weight and serum AST and ALT levels,increased the contents of T-SOD,CAT and GSH-Px in the liver,and inhibited the accumulation of MDA content,thereby reducing damage to liver cells caused by a high-fat diet.It indicated that PSP could effectively inhibit obesity in high-fat diet rats and enhance their antioxidant capacity.[Conclusions]This study provides a reference for the study of the antioxidant capacity of PSP.

Effects of Polygonatum odoratum Polysaccharide on Reproductive Hormones in Male Rats Fed a High-fat Diet

[Objectives]This study was conducted to investigate the effects of Polygonatum odoratum polysaccharide(POP)on organ relative weights and reproductive hormone levels in male rats fed a high-fat diet.[Methods]Thirty healthy male Sprague-Dawley(SD)rats were randomly divided into two groups according to their body weight:10 in normal control group(Group NC,n=10)and 20 in experimental group(n=20).The rats in experimental group were fed a high-fat diet for eight weeks before they were further randomly divided into two groups:high fat group(Group HF)and high fat+400 mg/(kg·d)POP group(Group HF+POP).In Group HF+POP,the rats were administered with POP for another six weeks,before their blood plasma was collected,and the relative weights of their testis and epididymis were calculated.The plasma levels of testosterone(T),estrogen(E2),follicle-stimulating hormone(FSH),cortisol(C)and luteinizing hormone(LH)were measured by radioimmunoassay,and the plasma levels of sex hormone-binding globulin(SHBG)and insulin-like growth factor-1(IGF-1)were determined by enzyme-linked immunosorbent assay.[Results]Compared with Group HF,POP could effectively inhibit rat obesity caused by high-fat diets,increase the relative weights of their testis and epididymis,plasma levels of LH,E2,FSH,T,SHBG and IGF-1,and reduce the plasma level of E2.[Conclusions]Polygonatum odoratum polysaccharide(POP)is able to effectively regulate the level of reproductive hormones in high-fat diet fed rats,and helps to protect their reproductive function.

Potential of traditional Chinese medicine in the treatment of nonalcoholic fatty liver disease:A promising future

In this editorial,we provide insights into the publication by Niu et al featured in the latest edition of the World Journal of Gastroenterology.Specifically,our focus was on exploring the potential of traditional Chinese medicine(TCM)in treating nonalcoholic fatty liver disease(NAFLD)induced by a high-fat diet through various mechanisms.NAFLD is a common liver condition,affecting approximately 25%of the world's population.It is closely linked to metabolic syndrome,insulin resistance,excessive body weight,and irregular lipid processing,leading to fat accumulation in the liver,as well as oxidative stress and inflammation.While maintaining a healthy diet and active lifestyle are essential for managing NAFLD,treatment options are limited due to undefined pathogenesis and a lack of specific medications.TCM,rooted in traditional Chinese practices,presents a promising alternative through its"syndrome differentiation and treatment"principles,enhancing liver lipid metabolism,reducing inflammation,and addressing fibrosis.Certain herbs,such as Poria cocos,Puaria lobata,and Salvia miltiorrhiza,have shown significant efficacy in reducing fat deposition and improving liver function.Due to systematic research and analysis of mechanisms,TCM is anticipated to yield new approaches to prevent and treat NAFLD,increasing its clinical application.

Regulation role of miR-204 on SIRT1/VEGF in metabolic memory induced by high glucose in human retinal pigment epithelial cells

AIM:To examine the regulatory role of microRNA-204(miR-204)on silent information regulator 1(SIRT1)and vascular endothelial growth factor(VEGF)under highglucose-induced metabolic memory in human retinal pigment epithelial(hRPE)cells.METHODS:Cells were cultured with either normal(5 mmol/L)or high D-glucose(25 mmol/L)concentrations for 8d to establish control and high-glucose groups,respectively.To induce metabolic memory,cells were cultured with 25 mmol/L D-glucose for 4d followed by culture with 5 mmol/L D-glucose for 4d.In addition,exposed in 25 mmol/L D-glucose for 4d and then transfected with 100 nmol/L miR-204 control,miR-204 inhibitor or miR-204 mimic in 5 mmol/L D-glucose for 4d.Quantitative reverse transcription-polymerase chain reaction(RT-qPCR)was used to detect miR-204 mRNA levels.SIRT1 and VEGF protein levels were assessed by immunohistochemical and Western blot.Flow cytometry was used to investigate apoptosis rate.RESULTS:It was found that high glucose promoted miR-204 and VEGF expression,and inhibited SIRT1 activity,even after the return to normal glucose culture conditions.Upregulation of miR-204 promoted apoptosis inhibiting SIRT1 and increasing VEGF expression.However,downregulation of miR-204 produced the opposite effects.CONCLUSION:The study identifies that miR-204 is the upstream target of SIRT1and VEGF,and that miR-204 can protect hRPE cells from the damage caused by metabolic memory through increasing SIRT1 and inhibiting VEGF expression.

Etitiological Relationship between Hyperlipidemia and Acute Pancreatitis

Hyperlipidemia is a kind of pancreatitis caused by high triglyceride levels in the blood. The morbidity and mortality of this disease continue to increase worldwide, and it has become one of the most common gastrointestinal diseases in developed countries worldwide. Although many studies have been conducted, the pathogenesis still cannot be defined. Many studies have shown that this may be related to the triglyceride decomposition products free fatty acids are the main toxic substances, which can directly damage pancreatic acinar cells and vascular endothelial cells, causing tissue ischemia and acidic environment. Therefore, this paper focuses on the correlation of triglycerides and their decomposition products in plasma and provides evidence on the pathogenesis of AP and the disease progression of AP. Finally, the future potential to prevent and treat acute pancreatitis by some new drugs to reduce plasma triglycerides is summarized.

Partial Physiologic Differences between High-fat Diet Induced Obesity-prone and Obesity-resistant Rats

Objective: To observe the differences of partial physiologic indexes including weight, food intake, Lee's index, the wet weight of fat pad, plasma lipids and the genetic expression of LPL mRNA in adipose tissue between obesity-prone rats (OP) and obesity-resistant rats (OR) on a high-fat diet. Methods: After 1 week of free access to a high-fat diet (HFD), 48 rats were separated on the basis of 1 week body weight percentage gained in OP (OP≥P75) or OR (OR≤P25) groups. Rats were continuously fed on the HFD for another 4 weeks. The body weight and food intake were recorded in the course of model-making. And the Lee's index, the plasma lipid and lipoproteins, the wet weight of both epididymal and retroperitoneal fat pad were measured after the rat was killed. And the level of LPL mRNA expression in adipose tissue was detected by Northern Blot technique. Results: ① In OP rats, the speed of body weight gain, the cumulative energy intake, the Lee's index, and the wet weight of fat pad at both epididymal and retroperitoneal sites were significantly higher than those in OR rats, but there was no significant difference in the level of plasma lipid and lipoproteins between these two groups. ② After 1 week and 5 weeks on the high-fat diet, the gain of body weight in OP rats were about 6.45 and 4.25 times of those in OR rats. Meanwhile, the cumulative energy intake in OP rats was only about 1.13 and 1.15 times of those in OR rats. ③ Despite the depressive effect of the high-fat diet on the level of LPL mRNA expression in adipose tissue, there was a significant level of LPL mRNA in adipose tissue of OP rats compared with that in OR rats. Conclusion: The physiologic differences exist between OP and OR rats. Besides a higher level of energy intake, the higher energy efficiency associated with LPL mRNA expression in adipose tissue may also contribute to the enhancement of susceptibility to obesity in OP rats.

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.