OBJECTIVE: To elucidate the effect of Huanglian-Renshen-Decoction (HRD) on ameliorating type 2 diabetes mellitus by maintaining islet β -cell identity through regulating paracrine and endocrine glucagon-like peptide-1 (GLP-1)/GLP-1 receptor (GLP-1R) in both islet and intestine. METHODS: The db/db mice were divided into the model (distilled water), low-dose HRD (LHRD, 3 g/kg), high-dose HRD (HHRD, 6 g/kg), and liraglutide (400 µ g/kg) groups using a random number table, 8 mice in each group. The db/m mice were used as the control group (n=8, distilled water). The entire treatment of mice lasted for 6 weeks. Blood insulin, glucose, and GLP-1 levels were quantified using enzyme-linked immunosorbent assay kits. The proliferation and apoptosis factors of islet cells were determined by immunohistochemistry (IHC) and immunofluorescence (IF) staining. Then, GLP-1, GLP-1R, prohormone convertase 1/3 (PC1/3), PC2, v-maf musculoaponeurotic fibrosarcoma oncogene homologue A (MafA), and pancreatic and duodenal homeobox 1 (PDX1) were detected by Western blot, IHC, IF, and real-time quantitative polymerase chain reaction, respectively. RESULTS: HRD reduced the weight and blood glucose of the db/db mice, and improved insulin sensitivity at the same time (P<0.05 or P<0.01). HRD also promoted mice to secrete more insulin and less glucagon (P<0.05 or P<0.01). Moreover, it also increased the number of islet β cell and decreased islet α cell mass (P<0.01). After HRD treatment, the levels of GLP-1, GLP-1R, PC1/3, PC2, MafA, and PDX1 in the pancreas and intestine significantly increased (P<0.05 or P<0.01). CONCLUSION HRD can maintain the normal function and identity of islet β cell, and the underlying mechanism is related to promoting the paracrine and endocrine activation of GLP-1 in pancreas and intestine.
Animals ; Glucagon-Like Peptide 1/metabolism* ; Diabetes Mellitus, Type 2/metabolism* ; Glucagon-Like Peptide-1 Receptor/metabolism* ; Insulin-Secreting Cells/pathology* ; Drugs, Chinese Herbal/pharmacology* ; Male ; Blood Glucose/metabolism* ; Insulin/blood* ; Mice ; Intestinal Mucosa/pathology* ; Apoptosis/drug effects* ; Cell Proliferation/drug effects* ; Islets of Langerhans/pathology*

To explore the possible new mechanism of acupuncture in the treatment of diabetes mellitus type 2 (T2DM) based on the islet inflammatory response. Islet macrophages, pancreatic adipose cells and islet β cells all participate in the pathogenesis of T2DM, and the three could form a network interaction. Acupuncture could regulate the functional phenotype of islet macrophages, improve the ectopic deposition of pancreatic adipose and repair the function of islet β cells, and play a unique advantage of overall regulation. It is suggested that acupuncture can be a potential treatment strategy for T2DM.
Acupuncture Therapy ; Diabetes Mellitus, Type 2/therapy* ; Humans ; Insulin-Secreting Cells/pathology* ; Islets of Langerhans/pathology* ; Macrophages

β-cell failure coupled with insulin resistance plays a key role in the development of type 2 diabetes mellitus (T2DM). Changed adipokines in circulating level form a remarkable link between obesity and both β-cell failure and insulin resistance. Some adipokines have beneficial effects,whereas others have detrimental properties. The overall contribution of adipokines to β-cell failure mainly depends on the interactions among adipokines. This article reviews the role of individual adipokines such as leptin,adiponectin,and resistin in the function,proliferation,death,and failure of β-cells. Future studies focusing on the combined effects of adipokines on β-cells failure may provide new insights in the treatment of T2DM.
Adipokines ; metabolism ; Adiponectin ; metabolism ; Diabetes Mellitus, Type 2 ; physiopathology ; Humans ; Insulin Resistance ; Insulin-Secreting Cells ; pathology ; Leptin ; metabolism ; Obesity ; Resistin ; metabolism

Thioredoxin-interacting protein (TXNIP), also known as vitamin D3-up-regulated protein (VDUP1), is an endogenous inhibitor of thioredoxin (Trx), which regulates the cellular reduction-oxidation (redox) state. TXNIP regulates cellular survival, apoptosis and inflammation induced by glucotoxicity, heat shock and mechanical pressure. The above functions of TXNIP are regulated by carbohydrate response element binding protein (ChREBP) and AMP-dependent protein kinase (AMPK). In recent years, numerous studies showed that TXNIP is involved in diabetes and diabetic complications. On the one hand, TXNIP functions in diabetes by increasing insulin resistance and hepatic gluconeogenesis. TXNIP expression is induced by high glucose, which is implicated in pancreatic beta cell glucotoxicity and endothelial cells dysfunction. TXNIP may contribute to the development and progression of diabetes and its vascular complications. TXNIP may be a new target for diabetes and its vascular complications therapy.
Apoptosis ; Carrier Proteins ; metabolism ; Diabetes Complications ; drug therapy ; metabolism ; Diabetes Mellitus ; drug therapy ; metabolism ; Endothelial Cells ; pathology ; Humans ; Inflammation ; Insulin Resistance ; Insulin-Secreting Cells ; pathology ; Vascular Diseases ; drug therapy ; metabolism

The loss of or decreased functional pancreatic β-cell is a major cause of type 1 and type 2 diabetes. Previous studies have shown that adult β-cells can maintain their ability for a low level of turnover through replication and neogenesis. Thus, a strategy to prevent and treat diabetes would be to enhance the ability of β-cells to increase the mass of functional β-cells. Consequently, much effort has been devoted to identify factors that can effectively induce β-cell expansion. This review focuses on recent reports on small molecules and protein factors that have been shown to promote β-cell expansion.
Cell Communication ; genetics ; Cell Differentiation ; genetics ; Cell Proliferation ; Diabetes Mellitus, Type 1 ; genetics ; pathology ; Diabetes Mellitus, Type 2 ; genetics ; pathology ; Humans ; Insulin-Secreting Cells ; chemistry ; metabolism ; pathology

OBJECTIVETo study the effects of Meilian Xiaoke capsule (a traditional Chinese medicinal preparation) combined with metformin for protecting islet cells and lowering blood glucose in diabetic rats.

METHODSRat models with type 2 diabetes, established by high-fat and high-glucose diet combined with streptozotocin (STZ) injection, were treated with a low dose of metformin, Meilian Xiaoke capsule, or both for 4 weeks by gavage. Blood glucose level was tested in the rats, and islet pathologies and changes in islet β cell number after the treatment were observed with HE staining and aldehyde fuchsin staining, respectively.

RESULTSTreatment with metformin or Meilian Xiaoke capsule alone for 2 or 4 weeks did not produce significant improvement of blood glucose in the diabetic rats. Their combined treatment for 4 weeks resulted in significantly lowered blood glucose level and improved glucose tolerance with also obviously increased islet β cell number and lessened islet pathologies.

CONCLUSIONSMeilian Xiaoke capsule and metformin show a synergistic effect to significantly enhance the therapeutic effect in rats with type 2 diabetes.

Animals ; Blood Glucose ; drug effects ; Diabetes Mellitus, Experimental ; drug therapy ; Diabetes Mellitus, Type 2 ; drug therapy ; Drug Synergism ; Drugs, Chinese Herbal ; pharmacology ; Hypoglycemic Agents ; pharmacology ; Insulin-Secreting Cells ; pathology ; Metformin ; pharmacology ; Rats ; Streptozocin

PURPOSE: Although the presence of cannabinoid type 1 (CB1) receptor in islets has been reported, the major contributor to the protective effect of rimonabant on islet morphology is unknown. We determined whether the protective effect of rimonabant on pancreatic islet morphology is valid in established diabetes and also whether any effect was independent of decreased food intake. MATERIALS AND METHODS: After diabetes was confirmed, Otsuka Long-Evans Tokushima Fatty rats, aged 32 weeks, were treated with rimonabant (30 mg/kg/d, rimonabant group) for 6 weeks. Metabolic profiles and islet morphology of rats treated with rimonabant were compared with those of controls without treatment (control group), a pair-fed control group, and rats treated with rosiglitazone (4 mg/kg/d, rosiglitazone group). RESULTS: Compared to the control group, rats treated with rimonabant exhibited reduced glycated albumin levels (p<0.001), islet fibrosis (p<0.01), and improved glucose tolerance (p<0.05), with no differences from the pair-fed control group. The retroperitoneal adipose tissue mass was lower in the rimonabant group than those of the pair-fed control and rosiglitazone groups (p<0.05). Rimonabant, pair-fed control, and rosiglitazone groups showed decreased insulin resistance and increased adiponectin, with no differences between the rimonabant and pair-fed control groups. CONCLUSION: Rimonabant had a protective effect on islet morphology in vivo even in established diabetes. However, the protective effect was also reproduced by pair-feeding. Thus, the results of this study did not support the significance of islet CB1 receptors in islet protection with rimonabant in established obesity-associated type 2 diabetes.
Adiponectin/metabolism ; Adiposity/drug effects ; Animals ; Cell Proliferation/drug effects ; Diabetes Mellitus, Type 2/diet therapy/*drug therapy ; Eating/*drug effects ; Glucose Intolerance/diet therapy/*drug therapy ; Insulin Resistance ; Insulin-Secreting Cells/*drug effects/pathology ; Male ; Piperidines/adverse effects/*therapeutic use ; Pyrazoles/adverse effects/*therapeutic use ; Rats ; Rats, Inbred OLETF ; Receptor, Cannabinoid, CB1/physiology ; Thiazolidinediones/*therapeutic use

BACKGROUNDThe effects of triterpenic acid from Prunella vulgaris L. (TAP) on diabetes and its mechanism are uncertain. The aim of this study was to investigate the effects of TAP on antihyperglycemic, antioxidant, and pancreas-protective in streptozotozin (STZ)-diabetic rats.

METHODSThe diabetic model was produced by injection of 60 mg/kg STZ. Blood was drawn from the tail vein of rats after 72 hours. Rats with blood glucose ≥ 16.7 mmol/L were considered diabetic. Diabetic rats were randomly divided into four groups: (1) Diabetes rat (STZ), (2) Diabetic rats treated with 50 mg/kg of triterpenic acid from Prunella vulgaris L (STZ + TAP50), (3) Diabetic rats treated with 100 mg/kg TAP (STZ + TAP100), and (4) Diabetic rats treated with 200 mg/kg TAP (STZ + TAP200). Normal rats (n = 10) acted as the control group (NC). TAP was administered by the intragastric route once each day for six weeks. Body weight and the concentration of blood glucose (BG) were measured after three and six weeks. Fructosamine (FMN), malondialdehyde (MDA), and nitric oxide (NO), and the activities of nitric oxide synthase (NOS) and superoxide dismutase (SOD) in serum were determined after six weeks using commercially available kits following the manufacturer's instructions. Pathologic changes in pancreatic β-cells were also investigated by microscopic examination after hematoxylin-eosin (HE) staining. The level of SOD mRNA in pancreatic β-cells was measured by polymerase chain reaction (PCR).

RESULTSThe levels of BG, FMN, NO, and MDA and the activities of NOS in serum in the four diabetes groups were significantly increased compared with the control group (P < 0.01). The activity of SOD in serum and the body weight was significantly decreased compared with the control group (P < 0.01). After administration of TAP to diabetic rats for six weeks, the body weight and the levels of BG, FMN, MDA, NO and the activity of NOS in serum decreased significantly compared with the STZ group in a dose-dependent manner. The activity of SOD in serum and body weight increased significantly compared with the STZ group in a dose-dependent manner. In addition, diabetic rats showed a significant decrease in SOD mRNA expression in pancreatic β cells. However, these changes were reversed by TAP. Histopathological examination also showed the protective effect of TAP on pancreatic β cells.

CONCLUSIONSTriterpenic acid from Prunella vulgaris L. has an anti-diabetic effect, by controlling blood glucose and antioxidants, and has a protective effect on the pancreas.

Animals ; Blood Glucose ; analysis ; Diabetes Mellitus, Experimental ; drug therapy ; metabolism ; Insulin-Secreting Cells ; drug effects ; pathology ; Male ; Prunella ; chemistry ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Streptozocin ; Superoxide Dismutase ; genetics ; Triterpenes ; therapeutic use

BACKGROUNDGrowing evidence from population and clinic based studies showed that obstructive sleep apnea (OSA) and its characterizing chronic intermittent hypoxia (IH) were independently associated with the development of type 2 diabetes mellitus. However, the pathogenesis by which OSA induces glucose metabolic disorders is not clear. We determined changes in pancreatic β cell mass and the mammalian target of rapamycin (mTOR)/hypoxia inducible factor 1 (HIF-1)/vascular endothelial growth factor A (VEGF-A) pathway following IH exposure.

METHODSA controlled gas delivery system regulated the flow of nitrogen and oxygen into a customized cage housing mice during the experiment. Twenty-four male wild C57BL/6J mice were either exposed to IH (n = 12) or intermittent air as a control (n = 12) for 56 days. Mice were anaesthetized and sacrificed after exposure, pancreas samples were dissected for immunofluorescent staining. Insulin and DAPI staining labelled islet β cells. Insulin positive area and β cell number per islet were measured. P-S6, HIF-1α and VEGF-A staining were performed to detect the activation of mTOR/HIF-1/VEGF-A pathway.

RESULTSAfter eight weeks of IH exposure, insulin positive area increased by an average of 18.5% (P < 0.05). The β cell number per islet increased (92 vs. 55, respectively for IH and the control groups, P < 0.05) with no change in the size of individual β cells. Islet expression of HIF-1α and VEGF-A were higher in IH group than control group, and percentage of p-S6 positive β cell also increased after IH exposure (16.8% vs. 4.6% respectively for IH and the control groups, P < 0.05).

CONCLUSIONThe number of pancreatic β cells increased as did the activity of the mTOR/HIF-1/VEGF-A pathway after exposure to IH.

Animals ; Hypoxia ; pathology ; Hypoxia-Inducible Factor 1 ; physiology ; Insulin-Secreting Cells ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL ; Signal Transduction ; TOR Serine-Threonine Kinases ; physiology ; Vascular Endothelial Growth Factor A ; physiology

Metformin has been reported to increase the expression of the glucagon-like peptide-1 (GLP-1) receptor in pancreatic beta cells in a peroxisome proliferator-activated receptor (PPAR)-alpha-dependent manner. We investigated whether a PPARalpha agonist, fenofibrate, exhibits an additive or synergistic effect on glucose metabolism, independent of its lipid-lowering effect, when added to metformin. Non-obese diabetic Goto-Kakizaki (GK) rats were divided into four groups and treated for 28 days with metformin, fenofibrate, metformin plus fenofibrate or vehicle. The random blood glucose levels, body weights, food intake and serum lipid profiles were not significantly different among the groups. After 4 weeks, metformin, but not fenofibrate, markedly reduced the blood glucose levels during oral glucose tolerance tests, and this effect was attenuated by adding fenofibrate. Metformin increased the expression of the GLP-1 receptor in pancreatic islets, whereas fenofibrate did not. During the intraperitoneal glucose tolerance tests with the injection of a GLP-1 analog, metformin and/or fenofibrate did not alter the insulin secretory responses. In conclusion, fenofibrate did not confer any beneficial effect on glucose homeostasis but reduced metformin's glucose-lowering activity in GK rats, thus discouraging the addition of fenofibrate to metformin to improve glycemic control.
Animals ; Blood Glucose/metabolism ; Body Weight/drug effects ; Diabetes Mellitus, Experimental/*drug therapy/*metabolism ; Drug Therapy, Combination ; Feeding Behavior/drug effects ; Fenofibrate/*pharmacology/therapeutic use ; Glucagon-Like Peptide 1/agonists/metabolism ; Glucose/*metabolism ; Glucose Tolerance Test ; Homeostasis/*drug effects ; Immunohistochemistry ; Injections, Intraperitoneal ; Insulin-Secreting Cells/drug effects/metabolism/pathology ; Lipid Metabolism/drug effects ; Male ; Metformin/*pharmacology/therapeutic use ; Peptides/administration & dosage/pharmacology ; Rats ; Receptors, Glucagon/metabolism ; Venoms/administration & dosage/pharmacology