This study is to evaluate the effects of the metformin (Met) on β cell function of diabetic KKAy mice. Female diabetic KKAy mice selected by insulin tolerance test (ITT) were divided randomly into two groups. Con group was orally administered by gavage with water, Met group with metformin hydrochloride at a dose of 0.2 g x kg(-1) for about 12 weeks. ITT and glucose tolerance tests (OGTT) were determined. Beta cell function was assessed by hyperglycemic clamp. Pancreatic biochemical indicators were tested. The changes of gene and protein expression in the pancreas and islets were also analyzed by Real-Time-PCR and immunostaining. Met significantly improved glucose intolerance and insulin resistance in KKAy mice. Fasting plasma glucose and insulin levels were also decreased. In addition, Met markedly increased glucose infusion rate (GIR) and elevated the Ist phase and maximum insulin secretion during clamp. It showed that Met decreased TG content and iNOS activities and increased Ca(2+) -Mg(2+)-ATPase activity in pancreas. Islets periphery was improved, and down-regulation of glucagon and up-regulated insulin protein expressions were found after Met treatment. Pancreatic mRNA expressions of inflammation factors including TLR4, NF-κB, JNK, IL-6 and TNF-α were down-regulated, p-NF-κB p65 protein levels also down-regulated by Met. And mRNA expressions of ion homeostasis involved in insulin secretion including SERCA2 and Kir6.2 were up-regulated by Met. Met increased SIRT5 expression level in pancreas of KKAy mice under the hyperglycemic clamp. These results indicated that chronic administration of Met regulated pancreatic inflammation generation, ion and hormone homeostasis and improved β cell function of diabetic KKAy mice.
Animals ; Blood Glucose ; Diabetes Mellitus, Experimental ; drug therapy ; Down-Regulation ; Female ; Glucose Tolerance Test ; Homeostasis ; Inflammation ; drug therapy ; Insulin ; secretion ; Insulin Resistance ; Insulin-Secreting Cells ; drug effects ; Interleukin-6 ; metabolism ; Metformin ; pharmacology ; Mice ; NF-kappa B ; metabolism ; Pancreas ; drug effects ; Tumor Necrosis Factor-alpha ; metabolism

OBJECTIVETo study the effect of Mudan Granule (MD) on the glucose metabolism and beta cell function in monosodium glutamate (MSG) induced obese mice with insulin resistance (IR).

METHODSMSG obese mice were induced by subcutaneous injecting MSG (4 g/kg for 7 successive days in neonatal ICR mice). Forty MSG mice with IR features were recruited and divided into four groups according to body weight, fasting blood glucose, triglyceride (TG), total cholesterol (TC), and the percentage of blood glucose decreased within 40 min in the IR test, i.e., the model group (Con), the low dose MD group, the high dose MD group, and the Metformin group (Met). Besides, another 10 ICR mice were recruited as the normal control group (Nor). The water solvent of 2.5 g/kg MD or 5 g/kg MD was respectively administered to mice in the low dose MD group and the high dose MD group. Metformin hydrochloride was given to mice in the Met group at 0.2 g/kg body weight. Equal dose solvent distilled water was administered to mice in the Nor group and the Con group by gastrogavage, once per day. All medication was lasted for 15 weeks. Insulin tolerance test (ITT) and oral glucose tolerance test (OGTT) were performed after 6 weeks of treatment. Beta cell function was assessed by hyperglycemic clamp technique. The morphological changes in the pancreas were evaluated by hematoxylin-eosin (HE) staining. Changes of iNOS, NF-kappaB p65, and p-NF-kappaB p65 in the pancreas were tested.

RESULTSCompared with the Nor group, the blood glucose level, AUC, and fasting blood insulin, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, pNF-kappaB p65 subunit obviously increased; decreased percentage of blood glucose within 40 min in ITT, glucose infusion rate (GIR), Clamp 1 min insulin, and Max-Insulin obviously decreased in the Con group (P < 0.05, P < 0.01). Compared with the Con group, the aforesaid indices could be improved in the Met group (P < 0.05, P < 0.01). In the low dose MD group, AUC, iNOS activities, and the expression of iNOS and p-NF-kappaB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT and GIR obviously increased (P < 0.05, P < 0.01). In the high dose MD group, AUC, ONOO-contents, iNOS activities, and the expression of iNOS, NF-kappaB p65 subunit, and p-NF-KB p65 subunit obviously decreased; percentage of blood glucose within 40 min in ITT, Max-Insulin, and GIR obviously increased (P < 0.05, P < 0.01).

CONCLUSIONMD could significantly improve IR and functional disorder of 3 cells in MSG obese mice, which might be associated with lowering inflammatory reaction in the pancreas.

Animals ; Disease Models, Animal ; Drugs, Chinese Herbal ; pharmacology ; Female ; Insulin Resistance ; Insulin-Secreting Cells ; drug effects ; metabolism ; Male ; Metformin ; pharmacology ; Mice ; Mice, Inbred ICR ; Mice, Obese ; Obesity ; chemically induced ; metabolism ; Pancreas ; cytology ; drug effects ; Sodium Glutamate

ObjectiveTo study the effect of Jinlida granules on visceral fat accumulation and its induced inflammatory response in prediabetic rats. MethodMale SD rats were randomly divided into normal group， model group， Jinlida low-dose group （1.5 g·kg^-1）， Jinlida high-dose group （3.0 g·kg^-1） and atorvastatin group （10 mg·kg^-1）. Prediabetic rat model was established using high-carbohydrate， high-fat diet combined with low-dose streptozotocin （STZ） by multiple small-dose intraperitoneal injections. After 8 weeks of modeling and drug intervention for 13 consecutive weeks， body weight， oral glucose tolerance test（OGTT）， fasting blood glucose （FBG）， fasting insulin （FINS）， insulin resistance index （HOMA-IR）， total cholesterol （TC）， low-density lipoprotein cholesterol （LDL-C） and high-density lipoprotein cholesterol （HDL-C） were measured in each group of rats. The content of visceral fat was quantified by micro-computed tomography （Micro-CT）. Hematoxylin-eosin staining （HE） was used to observe the pathological changes of fat cells. The levels of tumor necrosis factor-α （TNF-α） and interleukin- 6 （IL-6） in rat visceral fat and serum were determined by enzyme linked immunosorbent assay （ELISA）. The expression of macrophage marker CD68 in visceral fat was detected by immunofluorescence and Western blot. ResultCompared with normal group， model group had increased oral glucose tolerance， FBG， FINS， HOMA-IR， TC， LDL-C （P<0.01）， elevated body weight and visceral fat accumulation （P<0.05， P<0.01）， enhanced CD68 protein expression and TNF-α and IL-6 levels （P<0.01）， decreased HDL-C （P<0.01）， and abnormal hypertrophy of adipocytes. Compared with model group， Jinlida high- and low-dose groups lowered oral glucose tolerance， HOMA-IR， TC and LDL-C （P<0.05， P<0.01）， body weight and visceral fat accumulation （P<0.05）， and CD68 protein expression and TNF-α and IL-6 levels （P<0.05， P<0.01） and lessened hypertrophy of fat cells. ConclusionJinlida can improve the insulin resistance in prediabetic rats by reducing visceral fat accumulation and its induced inflammatory response， which provides a new pharmacological basis for clinical treatment of prediabetes by Jinlida granules.

Bile acids (BAs) are increasingly being appreciated as signaling molecules. Studies have shown that BAs regulate glucose and lipid metabolism mainly through the intracellular nuclear receptor farnesoid X receptor (FXR) and the transmembrane G protein-coupled receptor 5 (TGR5). FXR and TGR5 are highly expressed in the intestine. This article summarizes the synthesis, circulation, and regulation of BAs, as well as the effects of BAs on glycolipid metabolism through activation of liver FXR and inhibition or activation of intestinal FXR and TGR5. Furthermore, we illustrate the molecular mechanism of BAs on glycolipid metabolism by the relevant signaling pathways, including small heterodimer partner (SHP), fibroblast growth factor 15/19 (FGF15/19), ceramide and glucagon like peptide-1 (GLP-1). This review may serve as a reference for basic and clinical studies.

The GPCR family component leukotriene B4 receptor 1 (LTB4R1) is the receptor of leukotriene B4 (LTB4), the metabolic product of ω6 fatty acid. LTB4R1 is a potential therapeutic target for the treatment of insulin resistance, chronic inflammation and type 2 diabetes. Here we established a LTB4R1 inhibitor screen model based on the GPCR family protein property that its activation causes the cytosolic escalation of calcium. The cytosolic calcium probe Fluo-8 represents the change of calcium ion. After adding LTB4, the fluorescent signal of Fluo-8 in the CHO cells which are co-transfected with LTB4R1 and Gα16 will change with the increase of cytosolic calcium, and LTB4R1 inhibitor blocked the effect of LTB4 on fluorescent signal of Fluo-8 in the CHO cells. Here, we used 0.2% DMSO as a negative control, and cp-105696 as a positive control in the screen model. After stimulation with LTB4, the Fluo-8 signal in 0.2% DMSO treated CHO cells increased 2 fold and fell back slowly, while the signal in inhibitor (cp-105696) treated cells was not induced by LTB4. The results showed that LTB4 increased the cytosolic calcium detected by Fluo-8 in a dose dependent manner. Similarly, cp-105696 inhibited the Fluo-8 signal dose dependently, indicating that this method can quantify the inhibitory activity of the compounds. The Z'-factor, reflecting the robustness of the screen model, was 0.777 with a series of experiments. In sum, we over-expressed LTB4R1α and Gα16 in CHO cell, used Fluo-8 to detect the calcium signal activated by LTB4, and established the in vitro screen model for LTB4 receptor 1.

Galectin-3 (Gal-3) belongs to the galectin family and is specific in binding β-galactoside. Through its C-terminal domain, Gal-3 binds to the galactoside group of the glycosylated insulin receptor (IR) and inhibits IR signaling pathway, which leads to the insulin resistance. Thus, Gal-3 is a potential therapeutic target for the treatment of insulin resistance and type 2 diabetes. Here we report a simple Gal-3 screening model based on the property that Gal-3 binds to the galactoside. We expressed and purified human Gal-3 in Escherichia coli (E.coli), and labeled it with fluorescein isothiocyanate (FITC) in vitro. After incubating FITC labeled Gal-3 (Gal-3-FITC) with PANC-1 cells, which express glycosylated membrane protein, PANC-1 cells started to show green fluorescent signal due to the Gal-3-FITC binding to the glycosylated membrane protein. Gal-3 inhibitor disrupts the binding of Gal-3-FITC and PANC1 cells, subsequently leads to the decrease of the fluorescent signal in PANC-1 cells. We can evaluate the inhibitory efficiency of Gal-3 inhibitors through measurement of the fluorescent signal. Further studies show this model is simple, stable, and repeatable with a Z' factor between 0.7 and 0.85. In sum, we have successfully established an in vitro high-throughput screening model for Gal-3 inhibitors.

Nonalcoholic steatohepatitis (NASH) is the leading chronic liver disease worldwide. NASH is commonly associated with metabolic risk factors, including obesity, hypertension, and diabetes. Hepatic glucose and lipid metabolism disorder, bile acid toxicity, oxidative stress, inflammation, fibrosis, intestinal dysbacteriosis, and susceptibility gene variation are involved in the pathogenesis of NASH. Drug development for NASH has been slow, this article focuses on the clinical research and development of several promising NASH drugs and their mechanisms, such as drugs targeting gut-liver axis, improving metabolism, inhibiting inflammation and fibrosis.

Jin-tang-ning (JTN), a Chinese patent medicine, mainly comprised of Bombyx moriL., has been proved to show α-glucosidase inhibitory efficacy and clinically effective for the treatment of type 2 diabetes (T2DM). Recently, we have reported that JTN could ameliorate postprandial hyperglycemia and improved β cell function in monosodium glutamate (MSG)-induced obese mice, suggesting that JTN might play a potential role in preventing the conversion of impaired glucose tolerance (IGT) to T2DM. In this study, we evaluated the effect of JTN on the progression of T2DM in the pre-diabetic KKAy mice. During the 10 weeks of treatment, blood biochemical analysis and oral glucose tolerance tests were performed to evaluate glucose and lipid profiles. The β cell function was quantified using hyperglycemic clamp at the end of the study. JTN-treated groups exhibited slowly raised fasting and postprandial blood glucose levels, and also ameliorated lipid profile. JTN improved glucose intolerance after 8 weeks of treatment. Meanwhile, JTN restored glucose-stimulated first-phase of insulin secretion and induced higher maximum insulin levels in the hyperglycemic clamp. Thus, to investigate the underlying mechanisms of JTN in protecting β cell function, the morphologic changes of the pancreatic islets were observed by optical microscope and immunofluorescence of hormones (insulin and glucagon). Pancreatic protein expression levels of key factors involving in insulin secretion-related pathway and ER stress were also detected by Western blot. Pre-diabetic KKAy mice exhibited a compensatory augment in β cell mass and abnormal α cell distribution. Long-term treatment of JTN recovered islet morphology accompanied by reducing α cell area in KKAy mice. JTN upregulated expression levels of glucokinase (GCK), pyruvate carboxylase (PCB) and pancreas duodenum homeobox-1 (PDX-1), while down-regulating C/EBP homologous protein (Chop) expression in pancreas of the hyperglycemic clamp, which indicated the improvement of mitochondrial metabolism and relief of endoplasmic reticulum (ER) stress of β cells after JTN treatment. These results will provide a new insight into exploring a novel strategy of JTN for protecting β cell function and preventing the onset of pre-diabetes to T2DM.