Phenylalanine derivatives as GPR142 agonists for the treatment of Type II diabetes

GPR142 is a novel GPCR that is predominantly expressed in pancreatic β-cells. GPR142 agonists potentiate glucose-dependent insulin secretion, and therefore can reduce the risk of hypoglycemia. Optimization of our lead pyridinone-phenylalanine series led to a proof-of-concept compound 22, which showed in vivo efficacy in mice with dose-dependent increase in insulin secretion and a decrease in glucose levels.     

5-Hydroxy-eicosapentaenoic acid is an endogenous GPR119 agonist and enhances glucose-dependent insulin secretion

GPR119 is one of the G-protein-coupled receptors expressed in pancreatic β-cells and intestinal endocrine cells. Since agonists to GPR119 stimulate glucose-dependent insulin secretion, GPR119 agonists are anticipated to promote anti-diabetic effects and control of glucose homeostasis. Here, we reported that an omega-3 unsaturated fatty acid metabolite, 5-hydroxy-eicosapentaenoic acid (5-HEPE), was a potent agonist for GPR119 and enhanced glucose-dependent insulin secretion. 5-HEPE stimulated cAMP accumulation in mouse MIN6 insulinoma cells and human HuTu80 intestinal adenocarcinoma cells. These effects were blunted by GPR119-specific siRNA. Recombinant GPR119 also responded to 5-HEPE as well as authentic agonists. Several previous reports have indicated the beneficial biological effects of omega-3 unsaturated fatty acids, and epidemiological studies have suggested that these fatty acids plays a protective role against diabetes. However, the molecular pharmacology and receptor identifications of omega-3 unsaturated fatty acids and their metabolites have not yet been well investigated. It is hoped that our findings will encourage novel investigations into the molecular relationships between omega-3 fatty acids and diabetes.     

Discovery and pharmacological effects of a novel GPR142 antagonist

GPR142 is a G-protein-coupled receptor (GPCR), whose most potent and efficacious ligand has been reported as being the natural amino acid l-tryptophan. GPR142 is highly expressed in pancreatic β-cells and immune cells, suggesting the receptor may play a role in the pathogenesis and development of diabetes or inflammatory diseases. In a previous report, we developed GPR142 agonists as insulin secretagogues. In this report, we show the discovery of a selective, potent small-molecule GPR142 antagonist, CLP-3094, and its pharmacological characteristics. These data support targeting this receptor for the treatment of chronic inflammatory diseases.     

G蛋白偶联受体119——治疗糖尿病的新靶点

G蛋白偶联受体119(GPR119)与激动剂结合后,通过cAMP信号转导途径,促进葡萄糖依赖性胰岛素和肠肽激素的分泌,是新一代的治疗2型糖尿病药物靶点。本文对GPR119的组织学分布、生理学作用、内源性配体以及小分子激动剂作一简要的介绍。     

Phytonutrient genistein is a survival factor for pancreatic β-cells via GPR30-mediated mechanism

We previously discovered that phytonutrient genistein rapidly activates cAMP signaling in β-cells and improves islet mass in diabetic mice. However, the mechanism underlying these actions of genistein is still unclear. Here, we show that pharmacological or molecular inhibition of Gαs blocked genistein-stimulated adenylate cyclase activity in plasma membrane and intracellular cAMP production in INS1 cells and islets. Further, genistein stimulation of cAMP generation was abolished in islets exposed to a specific GPR30 inhibitor G15 or islets from GPR30 deficient (GPR30−/−) mice. In vivo, dietary provision of genistein (0.5 g/kg diet) significantly mitigated streptozotocin-induced hyperglycemia in male WT mice, which was associated with improved blood insulin levels and pancreatic islet mass and survival, whereas these effects were absent in Gpr30−/− mice. Genistein treatment promoted survival of INS1 cells and human islets chronically exposed to palmitate and high glucose. At molecular level, genistein activated CREB phosphorylation and subsequently induced Bcl-2 expression, and knockdown of CREB diminished the protective effect of genistein on β-cells induced by lipoglucotoxicity. Finally, deletion of GPR30 in β-cells or islets ablated genistein-induced CREB phosphorylation and its cytoprotective effect. These findings demonstrate that genistein is a survival factor for β-cells via GPR30-initiated, Gαs-mediated activation of CREB.     

Free fatty acids regulate gut incretin glucagon-like peptide-1 secretion through GPR120

Diabetes, a disease in which the body does not produce or use insulin properly, is a serious global health problem. Gut polypeptides secreted in response to food intake, such as glucagon-like peptide-1 (GLP-1), are potent incretin hormones that enhance the glucose-dependent secretion of insulin from pancreatic beta cells. Free fatty acids (FFAs) provide an important energy source and also act as signaling molecules in various cellular processes, including the secretion of gut incretin peptides. Here we show that a G-protein-coupled receptor, GPR120, which is abundantly expressed in intestine, functions as a receptor for unsaturated long-chain FFAs. Furthermore, we show that the stimulation of GPR120 by FFAs promotes the secretion of GLP-1 in vitro and in vivo, and increases circulating insulin. Because GLP-1 is the most potent insulinotropic incretin, our results indicate that GPR120-mediated GLP-1 secretion induced by dietary FFAs is important in the treatment of diabetes.     

Diphenyl Ether Derivatives as Novel GPR120 Agonists for the Treatment of Type 2 Diabetes Mellitus

Diabetes mellitus (DM) is a serious disease affecting human health. Numerous attempts have been made to develop safe and effective new antidiabetic drugs. Recently, a series of G protein-coupled receptors for free fatty acids (FFAs) have been described and characterized, and small molecule agonists and antagonists of these receptors show considerable promise for managing diabetes and related complications. FFA-activated GPR120 could stimulate the release of glucagon-like peptide-1(GLP-1), which can enhance the glucose-dependent secretion of insulin from pancreatic β cells. GPR120 is a promising target for treating type 2 DM (T2DM). Herein we designed and synthesized a series of novel GPR120 agonists based on the structure of TUG-891, which was the first potent and selective GPR120 agonist. Among the designed compounds, 18 f showed excellent GPR120 activation activity and high selectivity for GPR40 in vitro. Compound 18 f dose-dependently improved glucose tolerance in normal mice, and no hypoglycemic side effects were observed at high dose. In addition, compound 18 f increased insulin release and displayed good antidiabetic effect in diet-induced obese mice. Molecular simulations illustrated that compound 18 f could enter the active site of GPR120 and interact with Arg99. Based on these observations, compound 18 f may be a promising lead compound for the design of novel GPR120 agonists to treat T2DM.     

A Novel Antidiabetic Drug,Fasiglifam/TAK-875, Acts as an Ago-Allosteric Modulator of FFAR1

Selective free fatty acid receptor 1 (FFAR1)/GPR40 agonist fasiglifam (TAK-875), an antidiabetic drug under phase 3 development, potentiates insulin secretion in a glucose-dependent manner by activating FFAR1 expressed in pancreatic β cells. Although fasiglifam significantly improved glycemic control in type 2 diabetes patients with a minimum risk of hypoglycemia in a phase 2 study, the precise mechanisms of its potent pharmacological effects are not fully understood. Here we demonstrate that fasiglifam acts as an ago-allosteric modulator with a partial agonistic activity for FFAR1. In both Ca²⁺ influx and insulin secretion assays using cell lines and mouse islets, fasiglifam showed positive cooperativity with the FFAR1 ligand γ-linolenic acid (γ-LA). Augmentation of glucose-induced insulin secretion by fasiglifam, γ-LA, or their combination was completely abolished in pancreatic islets of FFAR1-knockout mice. In diabetic rats, the insulinotropic effect of fasiglifam was suppressed by pharmacological reduction of plasma free fatty acid (FFA) levels using a lipolysis inhibitor, suggesting that fasiglifam potentiates insulin release in conjunction with plasma FFAs in vivo. Point mutations of FFAR1 differentially affected Ca²⁺ influx activities of fasiglifam and γ-LA, further indicating that these agonists may bind to distinct binding sites. Our results strongly suggest that fasiglifam is an ago-allosteric modulator of FFAR1 that exerts its effects by acting cooperatively with endogenous plasma FFAs in human patients as well as diabetic animals. These findings contribute to our understanding of fasiglifam as an attractive antidiabetic drug with a novel mechanism of action.     

β-Arrestin Recruitment and Biased Agonism at Free Fatty Acid Receptor 1

FFAR1/GPR40 is a seven-transmembrane domain receptor (7TMR) expressed in pancreatic β cells and activated by FFAs. Pharmacological activation of GPR40 is a strategy under consideration to increase insulin secretion in type 2 diabetes. GPR40 is known to signal predominantly via the heterotrimeric G proteins G_q/11. However, 7TMRs can also activate functionally distinct G protein-independent signaling via β-arrestins. Further, G protein- and β-arrestin-based signaling can be differentially modulated by different ligands, thus eliciting ligand-specific responses (“biased agonism”). Whether GPR40 engages β-arrestin-dependent mechanisms and is subject to biased agonism is unknown. Using bioluminescence resonance energy transfer-based biosensors for real-time monitoring of cell signaling in living cells, we detected a ligand-induced GPR40-β-arrestin interaction, with the synthetic GPR40 agonist TAK-875 being more effective than palmitate or oleate in recruiting β-arrestins 1 and 2. Conversely, TAK-875 acted as a partial agonist of G_q/11-dependent GPR40 signaling relative to both FFAs. Pharmacological blockade of G_q activity decreased FFA-induced insulin secretion. In contrast, knockdown or genetic ablation of β-arrestin 2 in an insulin-secreting cell line and mouse pancreatic islets, respectively, uniquely attenuated the insulinotropic activity of TAK-875, thus providing functional validation of the biosensor data. Collectively, these data reveal that in addition to coupling to G_q/11, GPR40 is functionally linked to a β-arrestin 2-mediated insulinotropic signaling axis. These observations expose previously unrecognized complexity for GPR40 signal transduction and may guide the development of biased agonists showing improved clinical profile in type 2 diabetes.     

Does glyceraldehyde enter pancreatic islet metabolism via both the triokinase and the glyceraldehyde phosphate dehydrogenase reactions? A study of these enzymes in islets

Glyceraldehyde has been known to be an insulin secretagogue for more than 15 years. It has been (reasonably) assumed that glyceraldehyde enters the glycolytic pathway via its phosphorylation by ATP to form glyceraldehyde phosphate, a reaction catalyzed by the enzyme triokinase, and that subsequent metabolism is identical to that of glucose. glucose. However, up to now there have been no studies verifying the presence of triokinase in the pancreatic beta cell. We report here that (1) the activity of triokinase in pancreatic islets is very low, indicating that the activity is intrinsically low and/or the enzyme was rapidly inactivated during the preparation of tissue for assay; (2) the activity is much lower than glucose phosphorylating activity (hexokinase plus glucokinase) in islets, even though glyceraldehyde is a more efficient insulin secretagogue than glucose; (3) glyceraldehyde phosphate dehydrogenase from pancreatic islets can use glyceraldehyde as a substrate in place of glyceraldehyde phosphate (the Vmax of glyceraldehyde phosphate dehydrogenase from islets when glyceraldehyde is the substrate is 20-fold that of triokinase when glyceraldehyde is the substrate); and (4) the Km of glyceraldehyde phosphate dehydrogenase with respect to glyceraldehyde (4.8 mM) is similar to the concentration of glyceraldehyde that gives one-half maximal rates of insulin release from pancreatic islets, whereas the Km of triokinase with respect to glyceraldehyde is much lower (less than 50 microM). These data suggest that besides stimulating insulin release in islets via its entering metabolism by phosphorylation to glyceraldehyde phosphate in the triokinase reaction, glyceraldehyde could be phosphorylated by Pi in the glyceraldehyde phosphate dehydrogenase reaction to form glycerate 1-phosphate which is probably unmetabolizable in islets. The second reaction could drastically increase the NADH/NAD ratio in islets without providing substrates for hydrogen shuttles that reoxidize cytosolic NADH. Since an increased NAD(P)H/NAD(P) ratio is believed to be a key part of the signal for insulin release, such a mechanism would explain the potent insulinotropism of glyceraldehyde in short-term experiments. In addition, the formation of unmetabolizable acids may explain the toxic effects of long-term exposure of islets to glyceraldehyde and why glyceraldehyde causes the beta cell to become acidic, whereas glucose does not.     

GPR40 is expressed in glucagon producing cells and affects glucagon secretion

The free fatty acid receptor, GPR40, has been coupled with insulin secretion via its expression in pancreatic beta-cells. However, the role of GPR40 in the release of glucagon has not been studied and previous attempts to identify the receptor in alpha-cells have been unfruitful. Using double-staining for glucagon and GPR40 expression, we demonstrate that the two are expressed in the same cells in the periphery of mouse islets. In-R1-G9 hamster glucagonoma cells respond dose-dependently to linoleic acid stimulation by elevated phosphatidyl inositol hydrolysis and glucagon release and the cells become increasingly responsive to fatty acid stimulation when overexpressing GPR40. Isolated mouse islets also secrete glucagon in response to linoleic acid, a response that was abolished by antisense treatment against GPR40. This study demonstrates that GPR40 is present and active in pancreatic alpha-cells and puts further emphasis on the importance of this nutrient sensing receptor in islet function.     

AMG 837: a potent, orally bioavailable GPR40 agonist

The discovery that certain long chain fatty acids potentiate glucose stimulated insulin secretion through the previously orphan receptor GPR40 sparked interest in GPR40 agonists as potential antidiabetic agents. Optimization of a series of β-substituted phenylpropanoic acids led to the identification of (S)-3-(4-((4'-(trifluoromethyl)biphenyl-3-yl)methoxy)phenyl)hex-4-ynoic acid (AMG 837) as a potent GPR40 agonist with a superior pharmacokinetic profile and robust glucose-dependent stimulation of insulin secretion in rodents.     

Critical role of cAMP-GEFII--Rim2 complex in incretin-potentiated insulin secretion

Incretins such as glucagon-like peptide-1 and gastric inhibitory polypeptide/glucose-dependent insulinotropic peptide are known to potentiate insulin secretion mainly through a cAMP/protein kinase A (PKA) signaling pathway in pancreatic beta-cells, but the mechanism is not clear. We recently found that the cAMP-binding protein cAMP-GEFII (or Epac 2), interacting with Rim2, a target of the small G protein Rab3, mediates cAMP-dependent, PKA-independent exocytosis in a reconstituted system. In the present study, we investigated the role of the cAMP-GEFII--Rim2 pathway in incretin-potentiated insulin secretion in native pancreatic beta-cells. Treatment of pancreatic islets with antisense oligodeoxynucleotides (ODNs) against cAMP-GEFII alone or with the PKA inhibitor H-89 alone inhibited incretin-potentiated insulin secretion approximately 50%, while a combination of antisense ODNs and H-89 inhibited the secretion approximately 80-90%. The effect of cAMP-GEFII on insulin secretion is mediated by Rim2 and depends on intracellular calcium as well as on cAMP. Treatment of the islets with antisense ODNs attenuated both the first and second phases of insulin secretion potentiated by the cAMP analog 8-bromo-cAMP. These results indicate that the PKA-independent mechanism involving the cAMP-GEFII--Rim2 pathway is critical in the potentiation of insulin secretion by incretins.     

Discovery and biological evaluation of novel 4-amino-2-phenylpyrimidine derivatives as potent and orally active GPR119 agonists

Novel 4-amino-2-phenylpyrimidine derivatives were synthesized and evaluated as GPR119 agonists. Optimization of the substituents on the phenyl ring at the 2-position and the amino group at the 4-position led to the identification of 3,4-dihalogenated and 2,4,5-trihalogenated phenyl derivatives showing potent GPR119 agonistic activity. The advanced analog (2R)-3-{[2-(4-chloro-2,5-difluorophenyl)-6-ethylpyrimidin-4-yl]amino}propane-1,2-diol (24g) was found to improve glucose tolerance at 1mg/kg po in mice and to show excellent pharmacokinetic profiles in mice and monkeys. Compound 24g also showed an excellent antidiabetic effect in diabetic kk/Ay mice after one week of single daily treatment. These results demonstrate that novel GPR119 agonist 24g improves glucose tolerance not only by enhancing glucose-dependent insulin secretion but also by preserving pancreatic β-cell function.     

Insulin-secretagogue activity and cytoprotective role of the traditional antidiabetic plant Scoparia dulcis (Sweet Broomweed)

Scoparia dulcis (Sweet Broomweed) has been documented as a traditional treatment of diabetes. The administration of an aqueous extract of Scoparia dulcis at a dose of 200 mg/kg body weight significantly decreased the blood glucose with significant increase in plasma insulin level in streptozotocin diabetic rats at the end of 15 days treatment. The insulin secretagogue action of Scoparia dulcis plant extract (SPEt) was further investigated using isolated pancreatic islets from mice. SPEt at a dose of 10 microg/ml evoked 6.0 fold stimulation of insulin secretion from isolated islets indicating its insulin secretagogue activity. In addition the effect of SPEt on streptozotocin induced cell death and nitric oxide (NO) in terms of nitrite production were also examined. SPEt protected against streptozotocin- mediated cytotoxicity (88%) and NO production in rat insulinoma cell line (RINm5F). Above results suggest the glucose lowering effect of SPEt to be associated with potentiation of insulin release from pancreatic islets. Our results revealed the possible therapeutic value of Scoparia dulcis for the better control, management and prevention of diabetes mellitus progression.     

A Potent Class of GPR40 Full Agonists Engages the EnteroInsular Axis to Promote Glucose Control in Rodents

Type 2 diabetes is characterized by impaired glucose homeostasis due to defects in insulin secretion, insulin resistance and the incretin response. GPR40 (FFAR1 or FFA1) is a G-protein-coupled receptor (GPCR), primarily expressed in insulin-producing pancreatic β-cells and incretin-producing enteroendocrine cells of the small intestine. Several GPR40 agonists, including AMG 837 and TAK-875, have been disclosed, but no GPR40 synthetic agonists have been reported that engage both the insulinogenic and incretinogenic axes. In this report we provide a molecular explanation and describe the discovery of a unique and potent class of GPR40 full agonists that engages the enteroinsular axis to promote dramatic improvement in glucose control in rodents. GPR40 full agonists AM-1638 and AM-6226 stimulate GLP-1 and GIP secretion from intestinal enteroendocrine cells and increase GSIS from pancreatic islets, leading to enhanced glucose control in the high fat fed, streptozotocin treated and NONcNZO10/LtJ mouse models of type 2 diabetes. The improvement in hyperglycemia by AM-1638 was reduced in the presence of the GLP-1 receptor antagonist Ex(9–39)NH₂.     

Glyceraldehyde phosphate: an insulin secretagogue with possible effects on inositol phosphate formation in pancreatic islets

The insulinotropic action of glucose, the most potent physiologic insulin secretagogue, involves its metabolism. However, no glucose metabolite has ever been identified as a key intermediate. We tested the abilities of a number of glucose metabolites to stimulate insulin release from pancreatic islets. Of all of these metabolites, glyceraldehyde 3-phosphate was the most potent insulin secretagogue. In numerous experiments over 3 years, insulin release by 4 mM glyceraldehyde phosphate ranged from 50 to 200% of that initiated by 16.7 mM glucose--a near-maximal insulin stimulus. At concentrations of 1 and 4 mM, glyceraldehyde phosphate was even more potent than the known secretagogues glucose and glyceraldehyde. Glucose metabolites were also tested for their ability to stimulate inositol tris-, bis-, and monophosphate formation by permeabilized islets. Only glyceraldehyde phosphate stimulated inositol phosphate formation and this stimulation occurred at concentrations of glyceraldehyde phosphate which could be present in the beta cell under physiologic conditions (K0.5 = 25 microM). The current results are consistent with the idea that glyceraldehyde phosphate is a key insulinotropic glucose metabolite that might act directly (or rather directly via a receptor) on the phospholipase C that forms inositol trisphosphate in the plasma membrane.     

Glucose-regulated glucagon secretion requires insulin receptor expression in pancreatic alpha-cells

The insulin receptor (IR) and its signaling appear to be essential for insulin secretion from pancreatic beta-cells. However, much less is known about the role of the IR in alpha-cells. To assess the role of the IR in glucagon and insulin secretion, we engineered adeno-viruses for high efficiency small interference RNA (siRNA)-IR expression in isolated mouse pancreatic islets and lentiviruses for siRNA-IR expression in pancreatic alpha- and beta-cell lines (alpha-TC6 and MIN6) with specific, long term stable IR knockdown. Western blot analysis showed that these strategies resulted in 60-80% reduction of IR protein in islets and alpha- and beta-cell lines. Cell growth was reduced by 35-50% in alpha-TC and MIN6 cells stably expressing siRNA-IR, respectively. Importantly, glucagon secretion, in response to glucose (25 to 2.8 mm), was completely abolished in islets expressing siRNA-IR, whereas secretion increased 1.7-fold in islets expressing control siRNA. In contrast, there was no difference in glucose-stimulated insulin secretion when comparing siRNA-IR and siRNA control, with both groups showing a 1.7-fold increase. Islet glucagon and insulin content were also unaffected by IR knockdown. To further explore the role of the IR, siRNA-IR was stably expressed in pancreatic cell lines, which dramatically suppressed glucose-regulated glucagon secretion in alpha-TC6 cells (3.4-fold) but did not affect GSIS in MIN6 cells. Defects in siRNA-IR-expressing alpha-cells were associated with an alteration in the activity of Akt and p70S6K where insulin-induced phosphorylation of protein kinase B/AKt was greatly reduced while p70S6K activation was enhanced, suggesting that the related pathways play important roles in alpha cell function. This study provides direct evidence that appropriate expression of the IR in alpha-cells is required for glucose-dependent glucagon secretion.     

Free fatty acid accumulation in secretagogue-stimulated pancreatic islets and effects of arachidonate on depolarization-induced insulin secretion

Free fatty acids in isolated pancreatic islets have been quantified by gas chromatography-mass spectrometry after stimulation with insulin secretagogues. The fuel secretagogue D-glucose has been found to induce little change in islet palmitate levels but does induce the accumulation of sufficient unesterified arachidonate by mass to achieve an increment in cellular levels of 38-75 microM. Little of this free arachidonate is released into the perifusion medium, and most remains associated with the islets. Glucose-induced hydrolysis of arachidonate from islet cell phospholipids is reflected by release of the arachidonate metabolite prostaglandin E2 (PGE2) from perifused islets. Both the depolarizing insulin secretagogue tolbutamide (which is thought to act by inducing closure of beta-cell ATP-sensitive K+ channels and the influx of extracellular Ca2+ through voltage-dependent channels) and the calcium ionophore A23187 have also been found to induce free arachidonate accumulation within and PGE2 release from islets. Surprisingly, a major fraction of glucose-induced eicosanoid release was found not to require Ca2+ influx and occurred even in Ca(2+)-free medium, in the presence of the Ca(2+)-chelating agent EGTA, and in the presence of the Ca2+ channel blockers verapamil and nifedipine. Exogenous arachidonic acid was found to amplify the insulin secretory response of perifused islets to submaximally depolarizing concentrations of KCl, and the maximally effective concentration of arachidonate was 30-40 microM. These observations suggest that glucose-induced phospholipid hydrolysis and free arachidonate accumulation in pancreatic islets are not simply epiphenomena associated with Ca2+ influx and that arachidonate accumulation may play a role in the signaling process which leads to insulin secretion.     

Novel GPR40 agonist AS2575959 exhibits glucose metabolism improvement and synergistic effect with sitagliptin on insulin and incretin secretion

Aims

GPR40 is a free fatty acid receptor that regulates glucose-dependent insulin secretion at pancreatic β-cells and glucagon-like peptide-1 (GLP-1), one of the major incretins, secretion at the endocrine cells of the gastrointestinal tract. We investigated the synergistic effect of AS2575959, a novel GPR40 agonist, in combination with sitagliptin, a major dipeptidyl peptidase-IV (DPP-IV) inhibitor, on glucose-dependent insulin secretion and GLP-1 secretion. In addition, we investigated the chronic effects of AS2575959 on whole-body glucose metabolism.

Main methods

We evaluated acute glucose metabolism on insulin and GLP-1 secretion using an oral glucose tolerance test (OGTT) as well as assessed the chronic glucose metabolism in diabetic ob/ob mice following the repeated administration of AS2575959.

Key findings

We discovered the novel GPR40 agonist sodium [(3S)-6-({4′-[(3S)-3,4-dihydroxybutoxy]-2,2′,6′-trimethyl[1,1′-biphenyl]-3-yl}methoxy)-3H-spiro[1-benzofuran-2,1′-cyclopropan]-3-yl]acetate (AS2575959) and found that the compound influenced glucose-dependent insulin secretion both in vitro pancreas β-cell-derived cells and in vivo mice OGTT. Further, we observed a synergistic effect of AS2575959 and DPP-IV inhibitor on insulin secretion and plasma GLP-1 level. In addition, we discovered the improvement in glucose metabolism on repeated administration of AS2575959.

Significance

To our knowledge, this study is the first to demonstrate the synergistic effect of a GPR40 agonist and DPP-IV inhibitor on the glucose-dependent insulin secretion and GLP-1 concentration increase. These findings suggest that GPR40 agonists may represent a promising therapeutic strategy for the treatment of type 2 diabetes mellitus, particularly when used in combination with DPP-IV inhibitors.