A pyruvate dehydrogenase kinase inhibitor prevents retinal cell death and improves energy metabolism in rat retinas after ischemia/reperfusion injury.

We aimed to assess the neuroprotective effect of a pyruvate dehydrogenase kinase (PDK) inhibitor, Nov3r after ischemia/reperfusion (IR) injury in rats. IR injury was induced by applying 150 mmHg of intraocular pressure for 50 min. Nov3r was orally administered (100 mg/kg) 3 h before and 24 h after IR injury. TUNEL-positive cells increased and immunoreactive RBPMS-positive cells decreased in the rat retinas after IR injury. Administration of Nov3r significantly ameliorated the increase in TUNEL-positive cells and prevented the RBPMS-positive cell decrease. Similarly, the number of IR-induced Iba1-positive microglial cells was significantly reduced with Nov3r treatment. Among metabolic parameters, IR damage induced the elevation of lactate and pyruvate, and the reduction of ATP. Oral administration of Nov3r ameliorated these changes. Our data suggest that the Nov3r had a retinal neuroprotective effect in IR injury in rats. This finding suggests that the regulation of pyruvate dehydrogenase (PDH) activity has potential therapeutic value by enabling metabolic reprograming in diseases associated with ischemic retinal damage, such as diabetic retinopathy, retinopathy of prematurity, retinal vein occlusion, ischemic optic neuropathy and glaucoma.

A Novel TNF-α Converting Enzyme (TACE) Selective Inhibitor JTP-96193 Prevents Insulin Resistance in KK-Ay Type 2 Diabetic Mice and Diabetic Peripheral Neuropathy in Type 1 Diabetic Mice.

Tumor necrosis factor-α (TNF-α) converting enzyme/a disintegrin and metalloproteinase domain-containing protein 17 (TACE/ADAM17) is a key sheddase that releases TNF-α from its inactive precursor and is thought as a new drug target to inhibit TNF-α production. In the present study, pharmacological effects of a novel TACE selective inhibitor, JTP-96193, on type 2 diabetes and diabetic peripheral neuropathy (DPN) as its major complication was examined. Enzyme inhibitory activity of JTP-96193 on TACE and other ADAMs was measured in in vitro. High fat-induced obese mice and type 2 diabetic KK-Ay mice were used to evaluate the effect of JTP-96193 on insulin resistance. Finally, streptozotocin (STZ)-induced diabetic mice were treated with JTP-96193 to evaluate the sciatic motor nerve conduction velocities (MNCV). JTP-96193 selectively inhibited human TACE activity with IC50 value of 5.4 nM and showed more than 1800-fold selectivity against other matrix metalloproteinases. In mouse models of obesity and diabetes, JTP-96193 reduced the TNF-α release from the fat tissue and prevented development of diabetes and improved insulin resistance, respectively. Furthermore, JTP-96193 prevented delay of sciatic MNCV without any effects on blood glucose or insulin levels in STZ-induced diabetic mice. TACE inhibitor is effective on insulin resistance and DPN independent from glucose-lowering effect. These pharmacological properties of JTP-96193 may be helpful to treat type 2 diabetes accompanied by its microvascular complications.

JTT-553, a novel Acyl CoA:diacylglycerol acyltransferase (DGAT) 1 inhibitor, improves glucose metabolism in diet-induced obesity and genetic T2DM mice.

Type 2 diabetes mellitus (T2DM) arises primarily due to lifestyle factors and genetics. A number of lifestyle factors are known to be important in the development of T2DM, including obesity. JTT-553, a novel Acyl CoA:diacylglycerol acyltransferase 1 inhibitor, reduced body weight depending on dietary fat in diet-induced obesity (DIO) rats in our previous study. Here, the effect of JTT-553 on glucose metabolism was evaluated using body weight reduction in T2DM mice. JTT-553 was repeatedly administered to DIO and KK-A(y) mice. JTT-553 reduced body weight gain and fat weight in both mouse models. In DIO mice, JTT-553 decreased insulin, non-esterified fatty acid (NEFA), total cholesterol (TC), and liver triglyceride (TG) plasma concentrations in non-fasting conditions. JTT-553 also improved insulin-dependent glucose uptake in adipose tissues and glucose intolerance in DIO mice. In KK-A(y) mice, JTT-553 decreased glucose, NEFA, TC and liver TG plasma concentrations in non-fasting conditions. JTT-553 also decreased glucose, insulin, and TC plasma concentrations in fasting conditions. In addition, JTT-553 decreased TNF-α mRNA levels and increased GLUT4 mRNA levels in adipose tissues in KK-A(y) mice. These results suggest that JTT-553 improves insulin resistance in adipose tissues and systemic glucose metabolism through reductions in body weight.

Pharmacological characterization of [trans-5'-(4-amino-7,7-dimethyl-2-trifluoromethyl-7H-pyrimido[4,5-b][1,4]oxazin-6-yl)-2',3'-dihydrospiro(cyclohexane-1,1'-inden)-4-yl]acetic acid monobenzenesulfonate (JTT-553), a novel acyl CoA:diacylglycerol transferase (DGAT) 1 inhibitor.

Acyl CoA:diacylglycerol acyltransferase (DGAT) 1 is an enzyme that catalyzes the final step in triglyceride (TG) synthesis. This enzyme is considered to be a potential therapeutic target for obesity and diabetes. Here, results of an investigation of the pharmacological effects of JTT-553 [trans-5'-(4-amino-7,7-dimethyl-2-trifluoromethyl-7H-pyrimido[4,5-b][1,4]oxazin-6-yl)-2',3'-dihydrospiro(cyclohexane-1,1'-inden)-4-yl]acetic acid monobenzenesulfonate, a novel DGAT1 inhibitor, are reported. To measure the inhibitory activity of JTT-553 against DGAT1, TG synthesis using [(14)C]-labeled oleoyl-CoA was evaluated. Similarly, the inhibitory activity of JTT-553 against DGAT2, an isozyme of DGAT1, and acyl-CoA cholesterol acyltransferase (ACAT) 1, which is highly homologous to DGAT1, were evaluated. JTT-553 selectively inhibited human DGAT1 and showed comparable inhibitory effects on the activity of human, rat, and mouse DGAT. In vivo, JTT-553 suppressed plasma TG and chylomicron TG levels after olive oil loading in Sprague-Dawley (SD) rats. JTT-553 also inhibited TG synthesis in epididymal fat after [(14)C] oleic acid injection in C57BL/6J mice. Food intake was evaluated in SD rats fed 3.1%, 13%, or 35% (w/w) fat diets. In rats fed the 35% fat diet, JTT-553 reduced food intake. This reduction of food intake was observed 2 h after feeding, lasted for 24 h, and correlated with dietary fat content. Furthermore, JTT-553 reduced daily food intake and body weight gain in diet-induced obese rats after 4-week repeated administration. JTT-553 exerted multiple effects on intestinal fat absorption, adipose fat synthesis, and food intake, and consequently induced body weight reduction. Therefore, JTT-553 is expected to be an effective novel therapeutic agent for the treatment of obesity.

JTT-130, a novel intestine-specific inhibitor of microsomal triglyceride transfer protein, reduces food preference for fat.

Microsomal triglyceride transfer protein (MTP) is involved in the assembly and secretion of triglyceride-rich lipoproteins from enterocytes and hepatocytes. JTT-130 is a novel intestine-specific MTP inhibitor, which has been shown to be useful in the prevention and treatment of dyslipidemia, obesity, and diabetes. JTT-130 has also been shown to suppress food intake in a dietary fat-dependent manner in rats. However, whether JTT-130 enables changes in food preference and nutrient consumption remains to be determined. Therefore, the aim of the present study was to investigate the effects of JTT-130 on food preference in rat under free access to two different diets containing 3.3% fat (low-fat diet, LF diet) and 35% fat (high-fat diet, HF diet). JTT-130 decreased HF diet intake and increased LF diet intake, resulting in a change in ratio of caloric intake from LF and HF diets to total caloric intake. In addition, macronutrient analysis revealed that JTT-130 did not affect carbohydrate consumption but significantly decreased fat consumption (P < 0.01). These findings suggest that JTT-130 not only inhibits fat absorption, but also suppresses food intake and specifically reduces food preference for fat. Therefore, JTT-130 is expected to provide a new option for the prevention and treatment of obesity and obesity-related metabolic disorders.

Discovery of 6-phenylpyrimido[4,5-b][1,4]oxazines as potent and selective acyl CoA:diacylglycerol acyltransferase 1 (DGAT1) inhibitors with in vivo efficacy in rodents.

The discovery and optimization of a series of acyl CoA:diacylglycerol acyltransferase 1 (DGAT1) inhibitors based on a pyrimido[4,5-b][1,4]oxazine scaffold is described. The SAR of a moderately potent HTS hit was investigated resulting in the discovery of phenylcyclohexylacetic acid 1, which displayed good DGAT1 inhibitory activity, selectivity, and PK properties. During preclinical toxicity studies a metabolite of 1 was observed that was responsible for elevating the levels of liver enzymes ALT and AST. Subsequently, analogues were synthesized to preclude the formation of the toxic metabolite. This effort resulted in the discovery of spiroindane 42, which displayed significantly improved DGAT1 inhibition compared to 1. Spiroindane 42 was well tolerated in rodents in vivo, demonstrated efficacy in an oral triglyceride uptake study in mice, and had an acceptable safety profile in preclinical toxicity studies.

Diabetic peripheral neuropathy in Spontaneously Diabetic Torii-Lepr(fa) (SDT fatty) rats.

Spontaneously Diabetic Torii (SDT) rat is a hereditary model of diabetes. Although the SDT rat shows severe diabetic complications, the onset of hyperglycemia is late. SDT fatty rat, established by introducing the fa allele of the Zucker fatty rat to SDT rat, develops diabetes much faster than SDT rat. In the present study, diabetic peripheral neuropathy (DPN) was evaluated to show the further usefulness of this animal model. Motor nerve conduction velocity (MNCV) was delayed, and the number of sural nerve fibers was decreased in SDT fatty rat. Treatment of pioglitazone lowered blood glucose level and prevented delay of MNCV in SDT fatty rats. SDT fatty rat is a useful animal model for studies of DPN in type 2 diabetes.

JTT-130, a novel intestine-specific inhibitor of microsomal triglyceride transfer protein, suppresses food intake and gastric emptying with the elevation of plasma peptide YY and glucagon-like peptide-1 in a dietary fat-dependent manner.

The microsomal triglyceride transfer protein (MTP) takes part in the mobilization and secretion of triglyceride-rich lipoproteins from enterocytes and hepatocytes. In this study, we investigated the effects of diethyl-2-({3-dimethylcarbamoyl-4-[(4'-trifluoromethylbiphenyl-2-carbonyl) amino] phenyl}acetyloxymethyl)-2-phenylmalonate (JTT-130), a novel intestine-specific MTP inhibitor, on food intake, gastric emptying, and gut peptides using Sprague-Dawley rats fed 3.1% fat, 13% fat, or 35% fat diets. JTT-130 treatment suppressed cumulative food intake and gastric emptying in rats fed a 35% fat diet, but not a 3.1% fat diet. In rats fed a 13% fat diet, JTT-130 treatment decreased cumulative food intake but not gastric emptying. In addition, treatment with orlistat, a lipase inhibitor, completely abolished the reduction of food intake and gastric emptying by JTT-130 in rats fed a 35% fat diet. On the other hand, JTT-130 treatment increased the plasma concentrations of gut peptides, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) but not cholecystokinin, in the portal vein in rats fed a 35% fat diet. These elevations in PYY and GLP-1 were also abolished by treatment with orlistat. Furthermore, JTT-130 treatment in rats fed a 35% fat diet increased the contents of triglycerides and free fatty acids in the intestinal lumen, which might contribute to the elevation of PYY and GLP-1 levels. The present findings indicate that JTT-130 causes satiety responses, decreased food intake, and gastric emptying in a dietary fat-dependent manner, with enhanced production of gut peptides such as PYY and GLP-1 from the intestine.