High-fat diet feeding significantly attenuates anagliptin-induced regeneration of islets of Langerhans in streptozotocin-induced diabetic mice

Oligostilbenes extracts from Iris lactea Pall. var. chinensis (Fisch.) Koidz improve lipid metabolism in HFD/STZ-induced diabetic mice and inhibit adipogenesis in 3T3-L1 cells

The present study investigated the anti-diabetic effects of Oligostilbenes extracts (Olie) from Iris lactea Pall. var. chinensis (Fisch.) Koidz (I. lactea) and the potential mechanisms, in high-fat-diet (HFD)-induced diabetic mice and 3T3-L1 adipocytes. Olie are a group of major active extracts from I. lactea that have been used as nutraceutical because of their antioxidant activity. Six-week Olie treatment improved fasting blood glucose levels, as well as blood lipid profiles in HFD/streptozocin (STZ)-induced diabetic mice, compared with non-treated mice. Olie treatment upregulated the levels of phosphorylated of AMPK and lipolysis-related proteins, while the hepatic expression of ACC and FAS in diabetic mice was inhibited. In cultured 3T3-L1 cells, Olie (2-15 μg/mL) treatment dose-dependently suppressed the differentiation into mature adipocytes and lowered cellular lipid accumulation. Consistently, Olie reduced expression of adipogenic transcription factors including CCAAT/enhancer-binding protein β (C/EBPβ) and peroxisome proliferator-activated receptor γ (PPARγ). In addition, mitochondrial function in 3T3-L1 adipocytes was improved after Olie treatment. Taken together, our findings indicate that a lipid-lowering effect of Olie in HFD/STZ-induced diabetic mice and adipogenesis/ lipogenesis suppressing effect in 3T3-L1 cells, via regulating the expression of lipid metabolism-related proteins.

Anagliptin inhibits neointimal hyperplasia after balloon injury via endothelial cell-specific modulation of SOD-1/RhoA/JNK signaling in the arterial wall

Intimal hyperplasia is one of the major complications after stenting, but the underlying mechanisms remain unclear. Our previous study found that the dipeptidyl peptidase IV (DPP-4) inhibitor, Anagliptin, suppresses intimal hyperplasia after balloon injury. Here, we further investigated the effects of Anagliptin on endothelial cell (EC) migration after balloon injury. The results showed that Anagliptin administration significantly reduced intimal hyperplasia by stimulating the migration of endothelial cells, but had no effect on the medial area after balloon injury. Anagliptin elevated the total plasma activity of SOD by up-regulating the level of SOD-1, but not SOD-2, after balloon injury. Meanwhile, pre-incubation with Anagliptin suppressed the hydrogen peroxide-mediated formation of oxidant species and apoptosis in HUVECs. In vitro pre-incubation with Anagliptin promoted the migration of HUVECs via the SOD-1/RhoA/JNK signaling pathway mediating the formation of F-actin. Collectively, the DPP-4 inhibitor, Anagliptin, regulates SOD-1/RhoA/ JNK-mediated HUVECs migration. The results suggest that Anagliptin could serve as a potential drug to prevent intimal hyperplasia formation after balloon injury.

Anagliptin prevents apoptosis of human umbilical vein endothelial cells by modulating NOX-4 signaling pathways

Dipeptidyl peptidase IV (DPP-IV) inhibitors are novel oral anti-hyperglycemic agents. Here, the anti-apoptotic effect of Anagliptin in human umbilical vein endothelial cells (HUVECs) was evaluated. Cultured HUVECs were pre-incubated with Anagliptin, and then treated hydrongen peroxide (H₂O₂) to induce apoptosis. The apoptosis of HUVECs were detected by viability, LIVE/DEAD staining assay and flow cytometry assays. HUVECs were transfected with plasmid harboring human NADPH oxidases (NOX) 4 or an empty vector. The formation of reactive oxygen species (ROS) was measured by immunofluorescence. Apoptotic and anti-apoptotic factor were detected by Western Blot. Pre-incubation with Anagliptin protected HUVECs from H₂O₂ induced apoptosis. The transfection assay also indicated that pre-incubation with Anagliptin inhibited the apoptosis of HUVECs induced by NADPH oxidase 4 (NOX-4) overexpression. Immunofluorescence demonstrated that pre-incubation with Anagliptin suppressed the formation of ROS in apoptotic HUVECs. Pre-incubation with Anagliptin inhibited NOX-4 mediated the Bax, caspase-3, cleave caspase-3 and Cyto C overexpression, but up-regulated the protein level of Bcl-2 in HUVECs. The data help us to better understand the effect of Anagliptin on apoptosis, and will be valuable in identifying new targets to prevent the endothelial cell apoptosis after injury.

The effect of anagliptin on intimal hyperplasia of rat carotid artery after balloon injury

The present study evaluated the effect of anagliptin on intimal hyperplasia following carotid artery injury in Sprague-Dawley rats. Sprague-Dawley rats weighing 280–300 g were injured using a 2F Fogarty balloon embolectomy catheter. The rats were divided into injury-(saline) and anagliptin-(10 mg/kg/day) treated groups. vascular injuries were induced in the left carotid artery, followed by evaluation of neointima formation at 28 days. The right and left carotid arteries were harvested and evaluated with histological evaluation, and the plasma activity of glucagon-like peptide 1 receptor (GLP-1), stromal cell-derived factor (SDF)-1α, interleukin (IL)-6, IL-1β and tumor necrosis factor (TNF)-α were detected by ELISA analysis. Treatment with anagliptin decreased balloon injury-induced neointima formation, compared with the injury group (P<0.01). Body weight and food consumption did not alter following treatment with anagliptin. Anagliptin caused an increase in the serum active GLP-1 concentration, compared with the injury group. In addition, serum SDF-1α was significantly decreased by treatment with anagliptin (P<0.001). Anagliptin altered the serum activity of IL-6, IL-1β and TNF-α (P<0.01). The results of the present study demonstrated that anagliptin appeared to attenuate neointimal formation by inhibiting inflammatory cytokines and chemokines following balloon injury, and that treatment with a dipeptidyl peptidase 4 inhibitor may be useful for future preclinical studies and potentially for the inhibition of thrombosis formation following percutaneous coronary intervention.

Jiang Tang Xiao Ke Granule, a Classic Chinese Herbal Formula, Improves the Effect of Metformin on Lipid and Glucose Metabolism in Diabetic Mice

In the present study, the hypoglycemic, hypolipidemic, and antioxidative effects of metformin (MET) combined with Jiang Tang Xiao Ke (JTXK) granule derived from the “Di Huang Tang” were evaluated in mice with type 2 diabetes mellitus (DM) induced by high-fat diet/streptozotocin. DM mice were orally treated with MET (0.19 g/kg) either alone or combined with different doses (1.75, 3.5, or 7 g/kg) of JTXK for 4 weeks. Results showed that the serum and hepatic glucose, lipids, and oxidative stress levels were elevated in DM mice, when compared with the normal mice. MET treatment decreased FBG and serum glucagon levels of DM mice. Combination treatment with MET and JTXK 3.5 g/kg increased the hypoglycemia and insulin sensitivity at 4 weeks when compared with the DM mice treated with MET alone. However, neither MET nor MET/JTXK treatment could completely reverse the hyperglycemia in DM mice. JTXK enhanced the serum triglyceride (TG) and hepatic lipid-lowering effect of MET in a dose-dependent manner in DM mice. JTXK 1.75 and 3.5 g/kg improved the hepatoprotective effect of MET in DM mice. Synergistic effect of combination treatment with MET and JTXK on antioxidant stress was also found in DM mice compared with MET alone.

Pharmacological profiles of gemigliptin (LC15-0444), a novel dipeptidyl peptidase-4 inhibitor, in vitro and in vivo

Gemigliptin, a novel dipeptidyl peptidase (DPP)-4 inhibitor, is approved for use as a monotherapy or in combination therapy to treat hyperglycemia in patients with type 2 diabetes mellitus. In this study, we investigated the pharmacological profiles of gemigliptin in vitro and in vivo and compared them to those of the other DPP-4 inhibitors. Gemigliptin was a reversible and competitive inhibitor with a Ki value of 7.25±0.67nM. Similar potency was shown in plasma from humans, rats, dogs, and monkeys. The kinetics of DPP-4 inhibition by gemigliptin was characterized by a fast association and a slow dissociation rate compared to sitagliptin (fast on and fast off rate) or vildagliptin (slow on and slow off rate). In addition, gemigliptin showed at least >23,000-fold selectivity for DPP-4 over various proteases and peptidases, including DPP-8, DPP-9, and fibroblast activation protein (FAP)-α. In the rat, dog, and monkey, gemigliptin showed more potent DPP-4 inhibitory activity in vivo compared with sitagliptin. In mice and dogs, gemigliptin prevented the degradation of active glucagon-like peptide-1 by DPP-4 inhibition, which improved glucose tolerance by increasing insulin secretion and reducing glucagon secretion during an oral glucose tolerance test. The long-term anti-hyperglycemic effect of gemigliptin was evaluated in diet-induced obese mice and high-fat diet/streptozotocin-induced diabetic mice. Gemigliptin dose-dependently decreased hemoglobin A1c (HbA1c) levels and ameliorated β-cell damage. In conclusion, gemigliptin is a potent, long-acting, and highly selective DPP-4 inhibitor and can be a safe and effective drug for the long-term treatment of type 2 diabetes.