• Nutrition Research and Practice
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• v.7 no.6
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• pp.481-487
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• 2013

High-fat diet up-regulates either insulin resistance or triglycerides, which is assumed to be related to the expression of peroxisome proliferator-activated receptor (PPAR)-${\alpha}$ and PPAR-${\gamma}$. The beneficial effects of vitamin E on insulin resistance are well known; however, it is not clear if vitamin E with a high-fat diet alters the expression of PPAR-${\alpha}$ and PPAR-${\gamma}$. We investigated the effects of d-${\alpha}$-tocopherol supplementation on insulin sensitivity, blood lipid profiles, lipid peroxidation, and the expression of PPAR-${\alpha}$ and PPAR-${\gamma}$ in a high-fat (HF) diet-fed male C57BL/6J model of insulin resistance. The animals were given a regular diet (CON; 10% fat), a HF diet containing 45% fat, or a HF diet plus d-${\alpha}$-tocopherol (HF-E) for a period of 20 weeks. The results showed that the HF diet induced insulin resistance and altered the lipid profile, specifically the triglyceride (TG) and total cholesterol (TC) levels (P < 0.05). In this animal model, supplementation with d-${\alpha}$-tocopherol improved insulin resistance as well as the serum levels of TG and very-low-density lipoprotein-cholesterol (VLDL-C) (P < 0.05). Moreover, the treatment decreased the levels of malondialdehyde (MDA) in the serum and liver while increasing hepatic PPAR-${\alpha}$ expression and decreasing PPAR-${\gamma}$ expression. In conclusion, the oral administration of d-${\alpha}$-tocopherol with a high-fat diet had positive effects on insulin resistance, lipid profiles, and oxidative stress through the expression of PPAR-${\alpha}$ and PPAR-${\gamma}$ in a high-fat diet-fed male mice.

• Journal of Pharmacopuncture
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• v.20 no.4
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• pp.235-242
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• 2017

Irisin is a novel hormone like polypeptide that is cleaved and secreted by an unknown protease from fibronectin type III domain-containing protein 5 (FNDC5), a membrane-spanning protein and which is highly expressed in skeletal muscle, heart, adipose tissue, and liver. Since its discovery in 2012, it has been the subject of many researches due to its potent physiological role. It is believed that understanding irisin's function may be the key to comprehend many diseases and their development. Irisin is a myokine that leads to increased energy expenditure by stimulating the 'browning' of white adipose tissue. In the first description of this hormone, increased levels of circulating irisin, which is cleaved from its precursor fibronectin type III domain-containing protein 5, were associated with improved glucose homeostasis by reducing insulin resistance. Irisin is a powerful messenger, sending the signal to determine the function of specific cells, like skeletal muscle, liver, pancreas, heart, fat and the brain. The action of irisin on different targeted tissues or organs in human being has revealed its physiological functions for promoting health or executing the regulation of variety of metabolic diseases. Numerous studies focus on the association of irisin with metabolic diseases which has gained great interest as a potential new target to combat type 2 diabetes mellitus and insulin resistance. Irisin is found to improve insulin resistance and type 2 diabetes by increasing sensitization of the insulin receptor in skeletal muscle and heart by improving hepatic glucose and lipid metabolism, promoting pancreatic ${\beta}$ cell functions, and transforming white adipose tissue to brown adipose tissue. This review is a thoughtful attempt to summarize the current knowledge of irisin and its effective role in mediating metabolic dysfunctions in insulin resistance and type 2 diabetes mellitus.

• The Journal of Pediatrics of Korean Medicine
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• v.32 no.4
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• pp.1-12
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• 2018

Objectives Bangpungtongsungsan is an herbal medicine that treats obesity and dampness-phlegm. The aim of this study was to investigate the efficacy of Bangpungtongsungsan on insulin resistance induced by non-alcoholic fatty liver disease. Methods Male 6-week-old C57BL/6 male mice were divided into four groups: control group (Ctrl), high fat diet group (HFF), high fat diet with Bangpungtongsungsan extract administration group (BT1), and high fat diet with double concentration of Bangpungtongsungsan extract administration group (BT2). Each 10 mice were allocated to each group (total of 40 mice). All mice were allowed to eat fat rich diet freely throughout the experiment. To examine the effect of Bangpungtongsungsan, we observed weight changes, lipid blot distributions, PGC-1, $p-I{\kappa}B$, 8-OHdG, p-JNK, total cholesterol and glucose levels. Results Comparing of body weight measurements between 4 groups, weight gain was significantly lower in BT1 and BT2 group than the HFF group. The distribution of lipid blots and positive reaction of PGC-1 were significantly lower in BT1 and BT2 group. The positive reaction of $p-I{\kappa}B$ and 8-OHdG in hepatic tissues was significantly lower in BT1 and BT2 group. The positive reaction of p-JNK in hepatic tissues was significantly lower in BT1 and BT2 group. Total cholesterol and glucose levels were significantly lower in BT1 and BT2 group. Conclusions Bangpungtongsungsan has the effect of improving non-alcoholic fatty liver induced insulin resistance through regulation of lipid metabolism.

• Development and Reproduction
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• v.24 no.3
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• pp.231-239
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• 2020

Many benefits of silk protein fibroin (SPF) have been suggested in biomedical applications; and notably, significant SPF effects have been observed for metabolic syndromes that are directly linked to insulin resistance, such as type 2 diabetes mellitus (T2DM). Based on our previous findings, we believe that SPF from spiders exhibits outstanding glucose-lowering effects in diabetic BKS.Cg-m+/+Lepr^db mice. In order to evaluate the dietary effects of SPF in diabetic animals, we generated several lines of transgenic rice (TR) that expresses SPF, and the feeding of TR-SPF to diabetic animals decreased blood glucose levels, but did not change insulin levels. Western blot analyses of hepatic proteins showed that AMP-activated protein kinase (AMPK) expression and phosphorylation both decreased in TR-SPF-fed groups, compared with controls. This finding suggests that the glucose-lowering effects in this diabetic animal model might be AMPK-independent. In contrast, six-transmembrane protein of prostate 2 (STAMP2) was upregulated after TR-SPF exposure. Together with STAMP2, the Akt protein phosphorylation increased after TR-SPF exposure, which indicates that STAMP2 leads to Akt phosphorylation and thus increases insulin sensitivity in hepatocytes. Importantly, the hepatic steatosis that was seen in the liver of diabetic mice was remarkably alleviated in TR-SPF-fed mice. Hepatocytes that were immunopositive for STAMP2 were overwhelmingly observed in hepatic tissues from TR-SPF-fed mice compared to the control. Taken together, these results suggest that feeding diabetic mice with TR-SPF upregulates STAMP2 expression and increases Akt phosphorylation in hepatic tissues and thus potentially alleviates insulin resistance and hepatic steatosis.

• The Korean Journal of Physiology and Pharmacology
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• v.19 no.5
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• pp.451-460
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• 2015

Sirtuin 1 (SIRT1) is a mammalian $NAD^+$-dependent protein deacetylase that regulates cellular metabolism and inflammatory response. The organ-specific deletion of SIRT1 induces local inflammation and insulin resistance in dietary and genetic obesity. Macrophage-mediated inflammation contributes to insulin resistance and metabolic syndrome, however, the macrophage-specific SIRT1 function in the context of obesity is largely unknown. C57/BL6 wild type (WT) or myeloid-specific SIRT1 knockout (KO) mice were fed a high-fat diet (HFD) or normal diet (ND) for 12 weeks. Metabolic parameters and markers of hepatic steatosis and inflammation in liver were compared in WT and KO mice. SIRT1 deletion enhanced HFD-induced changes on body and liver weight gain, and increased glucose and insulin resistance. In liver, SIRT1 deletion increased the acetylation, and enhanced HFD-induced nuclear translocation of nuclear factor kappa B (NF-${\kappa}B$), hepatic inflammation and macrophage infiltration. HFD-fed KO mice showed severe hepatic steatosis by activating lipogenic pathway through sterol regulatory element-binding protein 1 (SREBP-1), and hepatic fibrogenesis, as indicated by induction of connective tissue growth factor (CTGF), alpha-smooth muscle actin (${\alpha}$-SMA), and collagen secretion. Myeloid-specific deletion of SIRT1 stimulates obesity-induced inflammation and increases the risk of hepatic fibrosis. Targeted induction of macrophage SIRT1 may be a good therapy for alleviating inflammation-associated metabolic syndrome.

• Korean journal of food and cookery science
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• v.30 no.4
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• pp.369-377
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• 2014

Obesity increases oxidative stress, which could contribute to the development of insulin resistance and hyperglycemia. The purpose of this study was to investigate the hypoglycemic and antioxidant effect of sanchae-namul (SN) in mice with diet-induced obesity. Five-week-old male C57BL/6J mice were fed a basal or high-fat and high-sucrose (HFHS) diet with or without 3% freeze-dried SN powder composed of chamnamul, daraesoon, miyeokchwi, bangpung namul, and samnamul for 12 weeks after a 1-week adaptation. After sacrifice, serum glucose and insulin were measured and the homeostasis model assessment for insulin resistance (HOMA-IR) was determined as well. Hepatic lipid peroxidation, glutathione (GSH), and activities of the antioxidant enzymes were determined. SN given at 3% of the total diet did not significantly influence body weight and food intake in mice fed the HFHS diet. Serum glucose and insulin levels, as well as HOMA-IR values, were significantly lower in the SN group than those in the HFHS group. Thiobarbituric acid reactive substances (TBARS) levels in the liver were decreased significantly in the SN group compared with those in the HFHS group. SN significantly increased the GSH levels and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) in the liver compared with those in the HFHS group. Overall, these findings suggest that SN may be useful in alleviating insulin resistance and hyperglycemia in mice fed HFHS diet; further, the improvement of insulin resistance could partly occur by reducing the oxidative stress.

• Journal of Ginseng Research
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• v.39 no.3
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• pp.199-205
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• 2015

Background: Ginsenoside Rb1 (G-Rb1), the major active constituent of ginseng, improves insulin sensitivity and exerts antidiabetic effects. We tested whether the insulin-sensitizing and antidiabetic effects of G-Rb1 results from a reduction in ectopic fat accumulation, mediated by inhibition of lipolysis in adipocytes. Methods: Obese and diabetic db/db mice were treated with daily doses of 20 mg/kg G-Rb1 for 14 days. Hepatic fat accumulation was evaluated by measuring liver weight and triglyceride content. Levels of blood glucose and serum insulin were used to evaluate insulin sensitivity in db/db mice. Lipolysis in adipocytes was evaluated by measuring plasma-free fatty acids and glycerol release from 3T3-L1 adipocytes treated with G-Rb1. The expression of relevant genes was analyzed by western blotting, quantitative real-time polymerase chain reaction, and enzyme-linked immunosorbent assay kit. Results: G-Rb1 increased insulin sensitivity and alleviated hepatic fat accumulation in obese diabetic db/db mice, and these effects were accompanied by reduced liver weight and hepatic triglyceride content. Furthermore, G-Rb1 lowered the levels of free fatty acids in obese mice, which may contribute to a decline in hepatic lipid accumulation. Corresponding to these results, G-Rb1 significantly suppressed lipolysis in 3T3-L1 adipocytes and upregulated the perilipin expression in both 3T3-L1 adipocytes and mouse epididymal fat pads. Moreover, G-Rb1 increased the level of adiponectin and reduced that of tumor necrosis factor-${\alpha}$ in obese mice, and these effects were confirmed in 3T3-L1 adipocytes. Conclusion: G-Rb1 may improve insulin sensitivity in obese and diabetic db/db mice by reducing hepatic fat accumulation and suppressing adipocyte lipolysis; these effects may be mediated via the upregulation of perilipin expression in adipocytes.

• Korean Journal of Pharmacognosy
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• v.53 no.3
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• pp.145-152
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• 2022

Type II diabetes mellitus (T2DM) is a chronic metabolic disease caused by insulin resistance, and abnormally elevated hepatic gluconeogenesis is characterized. Phillyrin, one of the major active constituents of Forsythia suspense, is known to possess the anti-inflammatory and anti-oxidant effects. However, the anti-diabetes mellitus effect of phillyrin and its molecular mechanisms are unclear. The aim of the current study was to investigate the role of phillyrin on gluconeogenesis in insulin resistant HepG2 cells. Phillyrin suppressed high glucose (HG)-induced glucose production. In addition, phillyrin reduced HG-induced the expression of phosphoenolpyruvate carboxykinase (PEPCK) and glucose 6-phosphatase (G6Pase), major genes in hepatic gluconeogenesis. Phillyrin treatment attenuated HG-induced nucleus protein levels of FOXO1 and HDAC5 and increased the phosphorylation of Akt, AMPK, HDAC5, and FOXO1. The block of AMPK and Akt activity did not exert the inhibitory effect of phillyrin on gluconeogenesis in insulin resistant HepG2. Taken together, these results suggest that phillyrin inhibits gluconeogenesis of hepatocytes to improve glucose metabolism, through the regulation of LKB1/AMPK/HDAC5 and PI3K/AKT/FOXO1 pathway. These results indicate that phillyrin may be useful in improving hepatic gluconeogenesis associated with insulin resistant and T2DM.

• Food Science of Animal Resources
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• v.37 no.4
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• pp.529-534
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• 2017

Probiotics have been known to reduce high-fat diet (HFD)-induced metabolic diseases, such as obesity, insulin resistance, and type 2 diabetes. We recently observed that Lactobacillus acidophilus NS1 (LNS1), distinctly suppresses increase of blood glucose levels and insulin resistance in HFD-fed mice. In the present study, we demonstrated that oral administration of LNS1 with HFD feeding to mice significantly reduces hepatic expression of phosphoenolpyruvate carboxykinase (PEPCK), a key enzyme in gluconeogenesis which is highly increased by HFD feeding. This suppressive effect of LNS1 on hepatic expression of PEPCK was further confirmed in HepG2 cells by treatment of LNS1 conditioned media (LNS1-CM). LNS1-CM strongly and specifically inhibited $HNF4{\alpha}-induced$ PEPCK promoter activity in HepG2 cells without change of $HNF4{\alpha}$ mRNA levels. Together, these data demonstrate that LNS1 suppresses PEPCK expression in the liver by regulating $HNF4{\alpha}$ transcriptional activity, implicating its role as a preventive or therapeutic approach for metabolic diseases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.4
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• pp.501-509
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• 2012

The dietary intake of whole grains is known to reduce the incidence of chronic diseases such as obesity, diabetes, cardiovascular disease, and cancer. In our previous study, hog millet (HM, $Panicum$ $miliaceum$ L.) water extract showed the highest anti-lipogenic activity among nine cereal types in 3T3-L1 cells. In this study, the effect of hog millet water extract on hepatic steatosis and lipid metabolism in mice fed a high fat diet was investigated. Mice were fed a normal-fat diet (ND), high-fat diet (HFD) or HFD containing 1% or 2% (w/w) HM for 7 weeks. Body weight and food intake were monitored during the study period. Insulin resistance by homeostasis model assessment (HOMA-IR), fasting lipid profile, hepatic fatty acid metabolism-related gene expression determined, and intraperitoneal glucose tolerance test (IGTT) were performed at the study's end. The results indicated that 1% and 2% HM diets effectively decreased liver weights, blood TG and T-cholesterol levels (p<0.05), while the HDL-cholesterol level was increased (p<0.05) compared to HFD-induced steatotsis mice. Hepatic lipogenic-related gene ($PPAR{\alpha}$, L-FABP, and SCD1) expressions decreased, whereas lipolysis- related gene (CPT1) expression increased in animals fed the 2% PME diet (p<0.05). In addition, mice fed 1% or 2% HM diet had markedly decreased IGTT and HOMA-IR, compared to the those of the HFD-induced hepatic steatosis control group (p<0.05). These results indicated that HM inhibited hepatic lipid accumulation by regulating fatty acid metabolism, and suggested that HM is useful in the chemoprevention or treatment of high fat-induced hepatic steatosis and hepatic steatosis-related disorders including hyperlipidemia, glucose sensitivity, and insulin resistance.