BACKGROUNDThe change of glucose transporter 4 (GLUT4) expression could influence glucose uptake in the myocardial cells and then effect myocardial metabolism, which maybe one of the factor for the diabetes cardiovascular disease. This study aimed to explore the influence of glucose and insulin at different concentrations on H9c2 (2-1) cell proliferation and its GLUT4 expression in vitro, and evaluate the correlation between myocardial cells proliferation and GLUT4 expression. This might be helpful for understanding the relationship between glucose metabolism and cardiovascular disease.

METHODSAccording to glucose concentrations in culture medium, cultured H9c2 rat myocardial cells were divided into five groups: control group (NC, glucose concentration 5.0 mmol/L), low glucose group (LG, glucose concentration 0.1 mmol/L), high glucose group 1 (HG1, glucose concentration 10 mmol/L), high glucose group 2 (HG2, glucose concentration 15 mmol/L), high glucose group 3 (HG3, glucose concentration 20 mmol/L). Then according to different insulin concentrations in culture medium, each group was further divided into two subgroups: normal insulin subgroup (INSc, insulin concentration 3.8 mU/L), high insulin subgroup (INSh, insulin concentration 7.6 mU/L). H9c2 (2-1) cells were cultured for 1, 2, 3 days, the proliferation of cells were assayed by cell counting Kit-8 assay, the expressions of GLUT4 mRNA and protein were detected with RT-PCR and Western Blotting technique, and the relation between myocardial cells proliferation and GLUT4 expression was evaluated.

RESULTSCompared with NC group, cell proliferation (OD value) was lower in LG, HG2, HG3 group but higher in HG1 group on the second and the third day (P < 0.05). There was a negative correlation between OD value and the glucose level in HG1, HG2, HG3 groups (P < 0.05). OD value in INSc subgroups was lower than that in INSh subgroups (P < 0.05). GLUT4 mRNA was lower in LG, HG2, HG3 groups than that in NC group (P < 0.05). Compared with NC group, GLUT4 mRNA level in HG1 group was higher on the first day but lower on the second and third day (P < 0.05). In HG1, HG2 and HG3 groups, GLUT4 mRNA level had a negative correlation with the level of glucose (P < 0.05). GLUT4 mRNA in INSc subgroups was lower than that in INSh subgroups (P < 0.05). The expression of GLUT4 protein was similar to that of GLUT4 mRNA. There was a positive correlation between H9c2 cell proliferation and GLUT4 expression (P < 0.02).

CONCLUSIONSGlucose levels could regulate glucose uptake in myocardial cells through influencing GLUT4 expression, and thus affected the cell proliferation and cell function. Insulin levels could affect the myocardial cell function by regulating GLUT4 expression. Effects of glucose and insulin on the myocardial cells proliferation might be mediated through regulating GLUT4 expression. There may be a mechanism of hyperglycemia pre-accommodation (HGPA) in myocardial cells mediated through regulation of GLUT4 expression.

Animals ; Blotting, Western ; Cell Line ; Cell Proliferation ; drug effects ; Glucose ; pharmacology ; Glucose Transporter Type 4 ; genetics ; metabolism ; Insulin ; pharmacology ; Myocardium ; cytology ; Rats ; Reverse Transcriptase Polymerase Chain Reaction

PURPOSE: Effect of recombinant human growth hormone (rhGH) administration on lipid storage, and its subsequent effect on insulin sensitivity have not yet been adequately examined. Thus, we investigated the effects of rhGH treatment on muscle triglyceride (TG) and ceramide content, and insulin sensitivity after 4 weeks of rhGH administration in rats. MATERIALS AND METHODS: Fourteen rats were randomly assigned to two groups: rhGH injection group (GH, n = 7) and saline injection group (CON, n = 7). GH received rhGH by subcutaneous injections (130microgram/kg(-1)/day(-1), 6 days/week(-1)) for 4 weeks, while CON received saline injections that were equivalent in volume to GH group. Intramuscular TG and ceramide content and hepatic TG content were measured. To determine insulin sesitivity, oral glucose tolerance test (OGTT) and muscle incubation for glucose transport rate were performed in rats, and used as indicators of insulin sensitivity. We also examined plasm lipid profiles. RESULTS: After 4 weeks of rhGH treatment, the GH group had higher muscle and liver TG contents than the CON (p < 0.05). Ceramide content in GH was significantly greater than that in CON (p < 0.05). GH also had higher plasma levels of FFA (p < 0.05), glucose and insulin responses during OGTT (p < 0.05), and lower glucose transport rates in submaximal insulin concentration (p < 0.05) as compared with CON. Results indicate that rhGH treatment is associated with insulin resistance in rats. CONCLUSION: rhGH treatment elevated muscle TG and ceramide content, and hepatic TG content. Thus, elevation of these compounde by rhGH treatment could contribute to the development of insulin resistance in rats.
Animals ; Ceramides/metabolism ; Glucose/metabolism ; Glucose Transporter Type 4/metabolism ; Human Growth Hormone/*administration & dosage ; Humans ; *Insulin Resistance ; Male ; Muscle, Skeletal/*drug effects/*metabolism ; Rats ; Rats, Sprague-Dawley ; Recombinant Proteins/administration & dosage ; Triglycerides/metabolism

By repeated column chromatography, including silica gel, macroporous resin, and preparative HPLC, a new compound (1) was isolated and purified. On the basis of spectroscopic methods, the structure of 1 was elucidated as ( - ) -epiafzelechin-3, 5-di-O-beta-D-apiofuranoside (1). In the bioassay screening experiments, glucose consumption assays in IR HepG2 cells and colorimetric assay of surface GLUT4myc translocation were used to assess the effects on glucose metabolism of compound 1. Both compound 1 and its derivatives--naringin could improve glucose consumption in IR HepG2 cells and enhance GLUT4 translocation in skeletal muscle cell L6myc in a dose-dependent manner, indicating that these two compouds showed potential anti-diabetic activities in vitro.
Catechin ; analogs & derivatives ; pharmacology ; Dose-Response Relationship, Drug ; Glucose ; metabolism ; Glucose Transporter Type 4 ; metabolism ; Glycosides ; pharmacology ; Hep G2 Cells ; Humans ; Hypoglycemic Agents ; pharmacology ; Polypodiaceae ; chemistry ; Protein Transport ; drug effects

BACKGROUND: Recent research has reported that high sugar diets increase insulin resistance, without abdominal obesity, in male, but not female Wister rats. Whether a high sucrose (SU) diet increased insulin resistance in ovariectomized (OVX) rats was determined. METHODS: Female Sprague Dawley rats, weighing 273 +/- 20 g, had either an ovariectomy or a sham operation (sham). OVX and sham rats were divided into two groups: one group had a 68 En% SU diet and the other a 68 En% starch (ST) diet for 8 weeks. RESULTS: The body weight was higher in the OVX than the sham rats, regardless of dietary carbohydrate subtype. The fasting serum glucose levels did not differ according to diet and ovariectomy. However, the fasting serum insulin levels were higher in the OVX than the sham rats, and in the OVX rats, a high SU diet increased the serum insulin levels more than a high ST diet. The whole body glucose disposal rates, which referred to the state of insulin sensitivity, were lower in the OVX rats fed both the high SU and ST diets, compared to sham rats. Glycogen deposits in the soleus and quadriceps muscles were lower in the OVX rats fed high SU and ST diets than in sham rats. The glucose transporter 4 content and fraction velocity of glycogen synthase in muscles showed similar glucose disposal rates. However, the triacylglycerol content in the muscles were higher in the OVX rats with a high SU diet than those with a high ST diet. CONCLUSION: These results suggested that an OVX increased the weight gain due to higher food intakes, regardless of dietary carbohydrate subtypes. OVX-induced obesity may be involved in the induction of insulin resistance from an increased triacylglycerol content, decreased glucose uptake and glycogen synthesis in skeletal muscles, regardless of dietary carbohydrate subtypes.
Animals ; Blood Glucose/*drug effects/*metabolism ; Body Weight/drug effects ; Dietary Carbohydrates/*administration & dosage ; Energy Intake/drug effects ; Estradiol/blood ; Female ; Glucose Clamp Technique ; Glucose Transporter Type 4/drug effects/metabolism ; Glycogen/metabolism ; Glycogen Synthase/drug effects/metabolism ; Insulin/blood ; *Insulin Resistance ; Leptin/blood ; Models, Animal ; Muscle, Skeletal/metabolism ; *Ovariectomy ; Rats ; Rats, Sprague-Dawley ; Time Factors ; Triglycerides/metabolism

Xiao Ke Qing (XKQ) granule has been clinically used to treat type 2 diabetes mellitus (T2DM) for 10 years in Chinese traditional medication. However, its mechanisms against hyperglycemia remain poorly understood. This study aims to investigate XKQ mechanisms on diabetes and diabetic liver disease by using the KKAy mice model. Our results indicate that XKQ can significantly reduce food and water intake. XKQ treatment also remarkably decreases both the fasting blood glucose and blood glucose in the oral glucose tolerance test. Additionally, XKQ can significantly decrease the serum alanine aminotransferase level and liver index and can alleviate the fat degeneration in liver tissues. Moreover, XKQ can ameliorate insulin resistance and upregulate the expression of IRS-1, PI3K (p85), p-Akt, and GLUT4 in the skeletal muscle of KKAy mice. XKQ is an effective drug for T2DM by ameliorating insulin resistance and regulating the PI3K/Akt signaling pathway in the skeletal muscle.
Animals ; Blood Glucose ; drug effects ; metabolism ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Female ; Glucose Tolerance Test ; Glucose Transporter Type 4 ; metabolism ; Hypoglycemic Agents ; pharmacology ; Insulin ; blood ; Insulin Resistance ; Liver ; drug effects ; pathology ; Mice ; Mice, Inbred C57BL ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction ; drug effects

OBJECTIVETo study the effect of a new obesity-related gene NYGGF4 on the insulin sensitivity and secretory function of adipocytes.

METHODS3T3-L1 preadipocytes transfected with either an empty expression vector (pcDNA3.1; control group) or an NYGGF4 expression vector (NYGGF4-pcDNA3.1) were cultured in vitro and differentiated into the matured adipocytes with the standard insulin plus dexamethasone plus 3-isobutyl-methylxanthine (MDI) induction cocktail. 2-deoxy-D-[3H] glucose uptake was determined by liquid scintillation counting. Western blot was performed to detect the protein content and translocation of glucose transporter 4 (GLUT4). The supernatant concentrations of TNF-alpha, IL-6, adiponectin and resistin were measured using ELISA.

RESULTSNYGGF4 over-expression in 3T3-L1 adipocytes reduced insulin-stimulated glucose uptake. NYGGF4 over-expression impaired insulin-stimulated GLUT4 translocation without affecting the total protein content of GLUT4. The concentrations of TNF-alpha, IL-6, adiponectin and resistin in the culture medium of 3T3-L1 transfected with NYGGF4 were not significantly different from those in the control group.

CONCLUSIONSNYGGF4 over-expression impairs the insulin sensitivity of 3T3-L1 adipocytes through decreasing GLUT4 translocation and had no effects on the secretory function of adipocytes.

3T3-L1 Cells ; Adipocytes ; drug effects ; secretion ; Adiponectin ; secretion ; Animals ; Carrier Proteins ; genetics ; physiology ; Glucose ; metabolism ; Glucose Transporter Type 4 ; analysis ; metabolism ; Insulin ; pharmacology ; Interleukin-6 ; secretion ; Mice ; Resistin ; analysis ; Transfection ; Tumor Necrosis Factor-alpha ; secretion

OBJECTIVETo investigate the effects of Huanglian Jiedu Decoction (HLJDD) on glucose transporter 4 (GLUT4) protein expressions in insulin-resistant murine target tissues.

METHODSThe experimental male Wistar rats were established into insulin resistant models by injecting streptozotocin (STZ 30 mg/kg) via caudal vein and feeding them with high fat high caloric diet, and randomly divided into the model group, the aspirin group and the HLJDD group. Besides, a normal group was set up for control. Changes of body weight (BW), levels of serum fasting blood glucose (FBG), serum fasting insulin (FINS) and oral glucose tolerance test (OGTT) were routinely determined. The expression of GLUT4 protein in adipose and skeletal muscle tissues before and after insulin stimulation was determined with Western blot.

RESULTSIn the HLJDD group after treatment, BW and FBG got decreased, OGTT improved, and the expression and translocation of GLUT4 protein elevated obviously, either before or after insulin stimulation, as compared with those in the model group, showing significant differences respectively.

CONCLUSIONThe mechanism of improving insulin resistance by HLJDD is probably associated with its effect in elevating GLUT4 protein expression and translocation in adipose and skeletal muscle tissues of insulin resistant rats.

Adipose Tissue ; drug effects ; metabolism ; Animals ; Blood Glucose ; metabolism ; Body Weight ; drug effects ; Drugs, Chinese Herbal ; pharmacology ; Fasting ; blood ; Glucose Tolerance Test ; Glucose Transporter Type 4 ; drug effects ; metabolism ; Insulin ; blood ; Insulin Resistance ; physiology ; Male ; Muscle, Skeletal ; drug effects ; metabolism ; Rats ; Rats, Wistar

OBJECTIVETo explore the molecular mechanism of puerarin (Pue) in improving insulin resistance through observing its effect on the insulin resistance of 3T3-Li lipocyte induced by free fatty acid (FFA).

METHODS3T3-L1 preadipocyte was induced by a culture solution containing insulin, isobutyo-menthyl-xanthine, and dexamethasone to mature lipocyte, and it was divided into six groups: the control group (normal cells), the model group (untreated model cells), and the four drug treatment group exposed to dimethyl biguanide (Met group), highdose puerarin (PueH group), low-dose puerarin (PueL group), and propylene glycol (PG group), respectively. Mature lipocytes in various groups, except those in the normal group, were established into insulin resistance model by FFA induction and treated respectively with corresponding drugs. Peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA expressions at the fourth, sixth, and eighth day were observed using reverse transcription polymerase chain reaction (RT-PCR); glucose transportation in various groups were observed by 2-deoxy-[(3)H]-D-glucose intake method; mRNA expression of Cb1 binding protein (CAP) was determined by RT-PCR; and glucose transporter-4 (Glut-4) transposition was detected by immune-fluorescence method.

RESULTSPPAR-γmRNA expression increased gradually, and it showed lower levels at the fourth, sixth, and eighth day in all treatment groups than that in the model group. Glucose transportation determination showed that the transportation in the model group was 2.23±0.63, significantly lower than that in the normal group 5.05 ± 0.66 (P<0.01); as compared with the model group, they were significantly higher in the PueH and the PueL groups. In addition, the CAP mRNA expression and membranous distribution of Glut-4 were higher in the two Pue treated groups than those in the model group, respectively.

CONCLUSIONPue could markedly improve the insulin resistance of 3T3-L1 lipocyte, which is realized possibly by way of inactivating CAP path, promoting Glut-4 transposition to cell membrane to increase the transportation of glucose.

3T3-L1 Cells ; Adipocytes ; drug effects ; metabolism ; Animals ; Biological Transport ; drug effects ; Carrier Proteins ; metabolism ; Gene Expression Regulation ; drug effects ; Glucose ; metabolism ; Glucose Transporter Type 4 ; metabolism ; Insulin Resistance ; Isoflavones ; pharmacology ; Mice ; PPAR gamma ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Signal Transduction ; drug effects

It has been recognized that ginseng has anti-diabetic effects in skeletal muscle, but the mechanism has not been intensively investigated. The aim of this study was to investigate the effects of Korean red ginseng (Panax ginseng) supplementation on muscle glucose uptake in high-fat fed rats. Sixteen rats were randomly divided into two groups: a control group (CON, n = 8) and a Korean red ginseng group (KRG, n = 8). The KRG group ingested RG extract (1 g·kg(-1), 6 days/week) mixed in water for two weeks. After the two-week treatment, plasma lipid profiles, and glucose and insulin concentrations were measured. The triglyceride (TG) and glucose transporter 4 (GLUT-4) contents were measured in the skeletal muscle and liver. The rate of glucose transport was determined under a submaximal insulin concentration during muscle incubation. Plasma FFA concentrations were significantly decreased in KRG (P < 0.05). Liver and muscle triglyceride concentrations were also decreased in the KRG treatment group (P < 0.05) compared to the CON group. In addition, resting plasma insulin and glucose levels were significantly lower after Korean red ginseng treatment (P < 0.05). However, muscle glucose uptake was not affected by Korean red ginseng treatment, as evidenced by the rate of glucose transport in the epitorchealis muscle under submaximal insulin concentrations. These results suggest that while KRG supplementation could improve whole body insulin resistance and plasma lipid profiles, it is unlikely to have an effect on the insulin resistance of skeletal muscle, which is the major tissue responsible for plasma glucose handling.
Animals ; Diabetes Mellitus, Type 2 ; drug therapy ; metabolism ; Diet, High-Fat ; adverse effects ; Dietary Fats ; adverse effects ; Dietary Supplements ; analysis ; Glucose ; metabolism ; Glucose Transporter Type 4 ; metabolism ; Humans ; Hypoglycemic Agents ; administration & dosage ; Male ; Muscle, Skeletal ; drug effects ; metabolism ; Panax ; chemistry ; Phytotherapy ; Plant Extracts ; administration & dosage ; Rats ; Triglycerides ; metabolism

OBJECTIVETo explore the effects of arecoline on hepatic insulin resistance in type 2 diabetes rats and to elucidate its possible mechanism.

METHODSForty five Wistar rats were fed with high fructose diet for 12 weeks to induce type 2 diabetic rat model. rats were randomly divided into 5 groups (n = 8): control group, model group and model group were treated with different dose (0, 0.5, 1, 5 mg/kg) of arecoline. After 4 weeks, the fasting blood glucose, blood lipid and insulin level measured , mRNA expression of liver constitutive androstane receptor (CAR), pregnane X receptor (PXR), glucose-6-phosphatase (G6Pase), phosphoenolpyruvate carboxykinase (PEPCK), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were detected by reverse transcription polymerase chain reaction (RT-PCR), the protein expression of p-AKT and glucose transporter4 (GLUT4) were detected by Western blot.

RESULTS1.5 mg/kg arecoline could significantly decrease the level of fasting blood glucose, blood lipid, blood insulin level and liver G6Pase, PEPCK, IL-6, TNF-alpha mRNA level in type 2 diabetes rats. 1.5 mg/kg arecoline also could significantly increase CAR, PXR mRNA level and p-AKT and GLUT4 protein expression.

CONCLUSIONArecoline improved hepatic insulin resistance in type 2 diabetes rats by increasing the mRNA levels of CAR and PXR leading to the creased glucose metabolism and inflammation related genes expression.

Animals ; Arecoline ; pharmacology ; Diabetes Mellitus, Experimental ; metabolism ; Diabetes Mellitus, Type 2 ; metabolism ; Glucose Transporter Type 4 ; metabolism ; Glucose-6-Phosphatase ; metabolism ; Insulin Resistance ; Interleukin-6 ; metabolism ; Intracellular Signaling Peptides and Proteins ; metabolism ; Liver ; drug effects ; metabolism ; Male ; Phosphoenolpyruvate Carboxykinase (GTP) ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Wistar ; Receptors, Cytoplasmic and Nuclear ; metabolism ; Receptors, Steroid ; metabolism ; Tumor Necrosis Factor-alpha ; metabolism