GPR40 partial agonist MK-2305 lower fasting glucose in the Goto Kakizaki rat via suppression of endogenous glucose production

<div><p>GPR40 (FFA1) is a fatty acid receptor whose activation results in potent glucose lowering and insulinotropic effects <i>in vivo</i>. Several reports illustrate that GPR40 agonists exert glucose lowering in diabetic humans. To assess the mechanisms by which GPR40 partial agonists improve glucose homeostasis, we evaluated the effects of MK-2305, a potent and selective partial GPR40 agonist, in diabetic Goto Kakizaki rats. MK-2305 decreased fasting glucose after acute and chronic treatment. MK-2305-mediated changes in glucose were coupled with increases in plasma insulin during hyperglycemia and glucose challenges but not during fasting, when glucose was normalized. To determine the mechanism(s) mediating these changes in glucose metabolism, we measured the absolute contribution of precursors to glucose production in the presence or absence of MK-2305. MK-2305 treatment resulted in decreased endogenous glucose production (EGP) driven primarily through changes in gluconeogenesis from substrates entering at the TCA cycle. The decrease in EGP was not likely due to a direct effect on the liver, as isolated perfused liver studies showed no effect of MK-2305 <i>ex vivo</i> and GPR40 is not expressed in the liver. Taken together, our results suggest MK-2305 treatment increases glucose stimulated insulin secretion (GSIS), resulting in changes to hepatic substrate handling that improve glucose homeostasis in the diabetic state. Importantly, these data extend our understanding of the underlying mechanisms by which GPR40 partial agonists reduce hyperglycemia.</p></div

Effects of chronic treatment with MK-2305 in the GK rat.

<p>(A) Morning blood glucose levels in GK rats treated with vehicle, 10, or 30 mg/kg of MK-2305, or 10 mg/kg rosiglitazone for 20 days in feed. (B) Fasted blood glucose levels on days 7 and 14 of the study were significantly reduced with MK-2305 and rosiglitazone treatment compared to vehicle controls. (C) Fasted plasma insulin levels on days 7 and 14. (D) Effects on food intake and (E) body weight during the chronic study. (F) Plasma insulin levels during a OGTT in chronically treated rats on day 13. Changes in blood glucose, food intake or body weight over time with MK-2305 or rosiglitazone vs. vehicle were analyzed by two-way ANOVA with repeated measures followed by Tukeys post hoc analysis. Changes in fasted glucose or insulin of glucose AUC were analyzed by one way ANOVA comparing MK-2305 or rosiglitazone treatments with vehicle followed by Dunnetts post hoc analysis. *p<0.05, **p<0.01.</p

In vitro and ex-vivo pharmacology of MK-2305.

<p>(A) Structure of the synthetic GPR40 partial agonist MK-2305. (B) Dose-response curves for MK-2305 were generated monitoring IP accumulation in CHO cells expressing rat GPR40. Data are expressed as a percentage of the control response of an in-house partial agonist, and fitted to a standard 4-parameter non-linear regression model. EC₅₀’s were determined for each test compound using a custom in-house developed software package. Each experiment was multiple times with a representative graph shown. The mean parameters of these and other individual experiments are shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0176182#pone.0176182.t001" target="_blank">Table 1</a>. (C) Effect of MK-2305 on GSIS in isolated GPR40 WT and KO islets under high (15 mM) and not basal (2 mM) glucose. Data provided are means +/- SEM. Data were analyzed via ANOVA followed by Bonferroni multiple comparisons test. **p<0.01compared to DMSO treated islets under 15 mM glucose.</p

Effects of MK-2305 on glucose metabolism in perfused mouse livers.

<p>Effect of 10 μM MK-2305 or DMSO on the conversion of [2-¹³C] pyruvate to ¹³C-glucose, ¹³C-glycogen, and ¹³C-lactate in perfused db/db mouse livers. MK-2305 treatments were compared to vehicle for each endpoint via students ttest.</p

Uptake and metabolic conversion of [1-¹³C] glucose in liver (A) and muscle (B) following acute treatment with MK-2305 or vehicle.

<p>Data were analyzed via students ttest comparing MK-2305 treatment vs. vehicle for each metabolite in each tissue measured.</p

Effect of (A) acute treatment and (B) chronic treatment with 10 mg/kg MK-2305 or vehicle on endogenous glucose production (EGP) from various substrates in the GK or WKY rats.

<p>Data were analyzed via ANOVA followed by Tukey’s multiple comparisons test comparing MK-2305 treatment to vehicle within GK or WKY rats or comparing WKY rats treated with vehicle to GK rats treated with vehicle. *p< 0.05, **p<0.01, ***p<0.005, ****p<0.001.</p

<i>In vitro</i> pharmacology of MK-2305.

<p><i>In vitro</i> pharmacology of MK-2305.</p

Structure–Activity Relationship of Novel and Selective Biaryl-Chroman GPR40 AgoPAMs

A series of biaryl chromans exhibiting potent and selective agonism for the GPR40 receptor with positive allosteric modulation of endogenous ligands (AgoPAM) were discovered as potential therapeutics for the treatment of type II diabetes. Optimization of physicochemical properties through modification of the pendant aryl rings resulted in the identification of compound <i>AP5</i>, which possesses an improved metabolic profile while demonstrating sustained glucose lowering

Design, Synthesis, and Evaluation of Novel and Selective G‑protein Coupled Receptor 120 (GPR120) Spirocyclic Agonists

Type 2 diabetes mellitus (T2DM) is an ever increasing worldwide epidemic, and the identification of safe and effective insulin sensitizers, absent of weight gain, has been a long-standing goal of diabetes research. G-protein coupled receptor 120 (GPR120) has recently emerged as a potential therapeutic target for treating T2DM. Natural occurring, and more recently, synthetic agonists have been associated with insulin sensitizing, anti-inflammatory, and fat metabolism effects. Herein we describe the design, synthesis, and evaluation of a novel spirocyclic GPR120 agonist series, which culminated in the discovery of potent and selective agonist <b>14</b>. Furthermore, compound <b>14</b> was evaluated <i>in vivo</i> and demonstrated acute glucose lowering in an oral glucose tolerance test (oGTT), as well as improvements in homeostatic measurement assessment of insulin resistance (HOMA-IR; a surrogate marker for insulin sensitization) and an increase in glucose infusion rate (GIR) during a hyperinsulinemic euglycemic clamp in diet-induced obese (DIO) mice

Discovery of a Potent and Selective ROMK Inhibitor with Pharmacokinetic Properties Suitable for Preclinical Evaluation

A new subseries of ROMK inhibitors exemplified by <b>28</b> has been developed from the initial screening hit <b>1</b>. The excellent selectivity for ROMK inhibition over related ion channels and pharmacokinetic properties across preclinical species support further preclinical evaluation of <b>28</b> as a new mechanism diuretic. Robust pharmacodynamic effects in both SD rats and dogs have been demonstrated