AZ 242, a novel PPARα/γ agonist with beneficial effects on insulin resistance and carbohydrate and lipid metabolism in ob/ob mice and obese Zucker rats
2002; Elsevier BV; Volume: 43; Issue: 11 Linguagem: Inglês
10.1194/jlr.m200127-jlr200
ISSN1539-7262
AutoresBengt Ljung, Krister Bamberg, Björn Dahllöf, Ann Kjellstedt, Nicholas D. Oakes, Jörgen Östling, Lennart Svensson, Germán Camejo,
Tópico(s)Adipose Tissue and Metabolism
ResumoAbnormalities in fatty acid (333333333333382) metabolism underlie the development of insulin resistance and alterations in glucose metabolism, features characteristic of the metabolic syndrome and type 2 diabetes that can result in an increased risk of cardiovascular disease. We present pharmacodynamic effects of AZ 242, a novel peroxisome proliferator activated receptor (PPAR)α/γ agonist. AZ 242 dose-dependently reduced the hypertriglyceridemia, hyperinsulinemia, and hyperglycemia of ob/ob diabetic mice. Euglycemic hyperinsulinemic clamp studies showed that treatment with AZ 242 (1 μmol/kg/d) restored insulin sensitivity of obese Zucker rats and decreased insulin secretion. In vitro, in reporter gene assays, AZ 242 activated human PPARα and PPARγ with EC50 in the μmolar range. It also induced differentiation in 3T3-L1 cells, an established PPARγ effect, and caused up-regulation of liver fatty acid binding protein in HepG-2 cells, a PPARα-mediated effect. PPARα-mediated effects of AZ 242 in vivo were documented by induction of hepatic cytochrome P 450-4A in mice.The results indicate that the dual PPARα/γ agonism of AZ 242 reduces insulin resistance and has beneficial effects on FA and glucose metabolism. This effect profile could provide a suitable therapeutic approach to the treatment of type 2 diabetes, metabolic syndrome, and associated vascular risk factors. Abnormalities in fatty acid (333333333333382) metabolism underlie the development of insulin resistance and alterations in glucose metabolism, features characteristic of the metabolic syndrome and type 2 diabetes that can result in an increased risk of cardiovascular disease. We present pharmacodynamic effects of AZ 242, a novel peroxisome proliferator activated receptor (PPAR)α/γ agonist. AZ 242 dose-dependently reduced the hypertriglyceridemia, hyperinsulinemia, and hyperglycemia of ob/ob diabetic mice. Euglycemic hyperinsulinemic clamp studies showed that treatment with AZ 242 (1 μmol/kg/d) restored insulin sensitivity of obese Zucker rats and decreased insulin secretion. In vitro, in reporter gene assays, AZ 242 activated human PPARα and PPARγ with EC50 in the μmolar range. It also induced differentiation in 3T3-L1 cells, an established PPARγ effect, and caused up-regulation of liver fatty acid binding protein in HepG-2 cells, a PPARα-mediated effect. PPARα-mediated effects of AZ 242 in vivo were documented by induction of hepatic cytochrome P 450-4A in mice. The results indicate that the dual PPARα/γ agonism of AZ 242 reduces insulin resistance and has beneficial effects on FA and glucose metabolism. This effect profile could provide a suitable therapeutic approach to the treatment of type 2 diabetes, metabolic syndrome, and associated vascular risk factors. The metabolic syndrome and its associated increased risk of cardiovascular disease are responsible for a major worldwide health problem (1Grundy S. Benjamin I. Burke G. Chait A. Eckel R. Howard B. Mitch W. Smith S. Sowers J. Diabetes and cardiovascular disease: a statement for healthcare professionals from the American Heart Association.Circulation. 1999; 100: 1134-1146Google Scholar, 2Isomaa B. Almgren P. Tuomi T. Forsen B. Lahti K. Nissen M. Taskinen M.R. Groop L. Cardiovascular morbidity and mortality associated with the metabolic syndrome.Diabetes Care. 2001; 24: 683-689Google Scholar, 3Zimmet P. Alberti K. Shaw J. Global and societal implications of the diabetes epidemic.Nature. 2001; 414: 782-787Google Scholar). Systemic excess of fatty acids (FAs) impairs the ability of insulin to stimulate glucose metabolism in skeletal muscle, thus contributing to the whole-body insulin resistance of the metabolic syndrome (4Randle P.J. 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New drug targets for type 2 diabetes and the metabolic syndrome.Nature. 2001; 414: 821-827Google Scholar). PPARs are ligand-activated nuclear receptors that modulate the expression of genes involved in the transport and metabolism of lipids [for recent reviews see (8Fajas L. Debril M.B. Auwerx J. Peroxisome proliferator-activated receptor-gamma: from adipogenesis to carcinogenesis.J. Mol. Endocrinol. 2001; 27: 1-9Google Scholar, 9Torra I.P. Chinetti G. Duval C. Fruchart J.C. Staels B. Peroxisome proliferator-activated receptors: from transcriptional control to clinical practice.Curr. Opin. Lipidol. 2001; 12: 245-254Google Scholar)]. The relative distribution of PPAR subtypes and their transcriptional responses to activation vary in a tissue- and ligand-specific manner. PPARγ (NR1C3) is expressed mainly in adipose tissue, whereas PPARα (NR1C1) is most abundantly expressed in liver, skeletal muscle, and heart. Intact, postprandial insulin signalling is required, in concert with PPARγ-stimulated gene products, for storage of free fatty acids (FFA) primarily into adipose tissue triglycerides (TGs) and, to a lesser extent, to those of liver and muscle (10Auwerx J. PPARγ, the ultimate thrifty gene.Diabetologia. 1999; 42: 1033-1049Google Scholar, 11Willson T.M. Lambert M.H. Kliewer S.A. Peroxisome proliferator-activated receptor γ and metabolic disease.Annu. Rev. Biochem. 2001; 70: 341-367Google Scholar, 12Oakes N. Thalén P. Jacinto S. Ljung B. Thiazolidinediones increase plasma-adipose tissue FFA exchange capacity and enhance insulin-mediated control of systemic FFA availability.Diabetes. 2001; 50: 1158-1165Google Scholar). Activation of PPARα, on the other hand, appears to mediate FA oxidation in muscle and liver, a condition that seems to be most important during fasting (13Kersten S. Seydoux J. Peters J.M. Gonzalez F.J. Desvergne B. Wahli W. 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These agents also enhance glucose-metabolic insulin sensitivity, possibly secondary to reduced exposure to FA in skeletal muscle and hepatic tissues. These actions provide the rationale for the use of PPARγ agonists, like thiazolidinediones, for improvement of blood glucose control and dyslipidemia in patients with type 2 diabetes (15Lebovitz H.E. Dole J.F. Patwardhan R. Rappaport E.B. Freed M.I. Rosiglitazone monotherapy is effective in patients with type 2 diabetes.J. Clin. Endocrinol. Metab. 2001; 86: 280-288Google Scholar, 16Miyazaki Y. Mahankali A. Matsuda M. Glass L. Mahankali S. Ferrannini E. Cusi K. Mandarino L.J. DeFronzo R.A. Improved glycemic control and enhanced insulin sensitivity in type 2 diabetic subjects treated with pioglitazone.Diabetes Care. 2001; 24: 710-719Google Scholar). On the other hand, PPARα agonists in humans ameliorate the atherogenic lipoprotein profile of insulin resistance and reduce cardiovascular disease (17Fruchart J-C. Duriez P. Staels B. 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PPARα agonists also stimulate liver-specific genes required for secretion of apolipoprotein A-I (apoA-I) containing HDL and decrease apoC-III synthesis, thus improving VLDL triglyceride hydrolysis by lipoprotein lipase (22Staels B. Dallongeville J. Auwerx J. Schoonjans K. Leitersdorf E. Fruchart J.C. Mechanism of actions of fibrates on lipid and lipoprotein metabolism.Circulation. 1998; 98: 2088-2093Google Scholar). The important functions of PPARα and PPARγ in normal lipid and glucose metabolism have motivated the search for new agonists of these transcription factors that could decrease insulin resistance and its associated dyslipoproteinemia (23Shibata T. Matsui K. Yonemori F. Wakitani K. Triglyceride-lowering effect of a novel insulin-sensitizing agent, JTT-501.Eur. J. Pharmacol. 1999; 373: 85-91Google Scholar, 24Willson T. Brown P. Sternbach D. Henke B. The PPARs: from orphan receptors to drug discovery.J. Med. Chem. 2000; 43: 527-550Google Scholar, 25Pineda I. Chinetti G. 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Mochizuki T. Ohashi M. Akanuma Y. Yazaki Y. Kadowaki T. A novel insulin sensitizer acts as a ligand for peroxisome proliferator-activated receptor-alpha and PPAR-gamma.Diabetes. 1998; 47: 1841-1847Google Scholar, 30Etgen G.J. Oldham B.A. Johnson W.T. Broderick C.L. Montrose C.R. Brozinick J.T. Misener E.A. Bean J.S. Bensch W.R. Brooks D.A. Shuker A.J. Rito C.J. McCarthy J.R. Ardecky R.J. Tyhonas J.S. Dana S.L. Bilakovics J.M. Paterniti J.R. Ogilvie K.M. Liu S. Kauffman R.F. A tailored therapy for the metabolic syndrome—the dual peroxisome proliferator-activated receptor-alpha/gamma agonist LY465608 ameliorates insulin resistance and diabetic hyperglycemia while improving cardiovascular risk factors in preclinical models.Diabetes. 2002; 51: 1083-1087Google Scholar, 31Sauerberg P. Pettersson I. Jeppesen L. Bury P.S. Mogensen J.P. Wassermann K. Brand C.L. Sturis J. Woldike H.F. Fleckner J. Andersen A.S.T. Mortensen S.B. Svensson L.A. Rasmussen H.B. Lehmann S.V. Polivka Z. Sindelar K. Panajotova V. Ynddal L. Wulff E.M. Novel tricyclic-alpha-alkyloxyphenylpropionic acids: dual PPAR alpha/gamma agonists with hypolipidemic and antidiabetic activity.J. Med. Chem. 2002; 45: 789-804Google Scholar). We report here the effects of AZ 242, a novel agent that binds and activates PPARα and PPARγ with similar high potency (28Cronet P. Petersen J.F.W. Folmer R. Blomberg N. Sjoblom K. Karlsson U. Lindstedt E.L. Bamberg K. Structure of the PPAR[alpha] and -[gamma] ligand binding domain in complex with AZ 242; ligand selectivity and agonist activation in the PPAR family.Structure. 2001; 9: 699-706Google Scholar). To assess its potential for correction of lipid and glucose abnormalities associated with conditions of human insulin (HI) resistance, we studied the ability of AZ 242 to improve glucose control and ameliorate insulin resistance and hypertriglyceridemia in diabetic ob/ob mice and nondiabetic insulin-resistant obese Zucker rats. The results demonstrate that AZ 242 is potent and efficient in correcting the metabolic disorders in these disease models. To confirm functional activation of endogenous PPARα and PPARγ in relevant cell lines, AZ 242 effects were examined in human liver–derived HepG2 cells and 3T3-L1 murine pre-adipocytes. Evidence for specific PPARα activation in vivo was obtained by analyzing hepatic responses in lean mice. In normal mice, a number of enzymes for oxidizing FAs are under selective PPARα versus PPARγ control. This is in contrast to obese rodent models, where these same enzymes can also be regulated via PPARγ activation (32Edvardsson U. Bergström M. Alexandersson M. Bamberg K. Ljung B. Dahllöf B. Rosiglitazone (BR49653), a PPAR-gamma selective agonist, causes peroxisome proliferator-like liver effects in obese mice.J. Lipid Res. 1999; 40: 1177-1184Google Scholar). The present in vivo and in vitro experiments provide evidence that the metabolic effects of AZ 242 are mediated by activation of PPARα and PPARγ. Male lean (Ob/?) and obese, diabetic (ob/ob) mice, and lean B6C3F1 mice, 6-weeks-old, were bred and delivered by B&M A/S Breeding and Research Centre, Ry, Denmark. Male lean (Fa/?) and obese (fa/fa) Zucker rats, 8-weeks-of-age, were obtained from Charles River Wiga GmbH, Suffield, FRG, via Charles River Uppsala, Sweden. Animals were housed in the AstraZeneca Mölndal Laboratory Animal Resources Facility in transparent polycarbonate cages, with aspen wood chip bedding at a 12 h light/darkness cycle, a temperature of 21°C, and a relative humidity of 50% throughout the accommodation (at least 1 week) and dosing periods. Unless otherwise stated, all animals had free access to standard rodent chow (R3 Laktamin AB, Stockholm, Sweden) and tap water. All animal experiments were approved by the Local Ethics Review Committee on Animal Experiments, Göteborg Region. Cell lines 3T3-L1 and HepG2 were purchased from American Type Culture Collection (ATCC, Manassas, VA). The compound AZ 242, AstraZeneca code AR-H039242XX, an enantiomer-pure di-hydro cinnamate derivative with the chemical name (S)-2-ethoxy-3-[4-[2-(4-methylsulphonyloxyphenyl)ethoxy]phenyl]propanoic acid (Fig. 1)was synthesized at Medicinal Chemistry, AstraZeneca, Mölndal (Andersson, K., patent application WO 9962872-A). The reference compounds (rosiglitazone and pioglitazone, PPARγ agonists; WY14,643, a rodent-selective PPARα agonist; and bezafibrate, a human and rodent PPARα agonist) were obtained from the same source. In all experiments, analytical grade reagents were used. In vivo potency and efficacy were determined in groups of 7–10 ob/ob mice given a particular dose of test compound by gavage (10 ml/kg, vehicle 0.5% w/v methyl cellulose in water) once daily for 8 days. On the last day of dosing, food was removed and the final dose was given at 7 AM. Four hours later, blood was collected under inhalation anaesthesia from cut neck vessels and centrifuged. For each animal in the five test groups of an experiment, plasma levels of TGs, insulin, and glucose and the percentage weight gain during the test period were expressed as a percentage of those in the concurrent control group of 10–15 untreated ob/ob mice. In one experiment, a group of age-matched lean (Ob/?) mice were included for reference. The effects of AZ 242 on insulin sensitivity were analyzed in euglycemic hyperinsulinemic clamp experiments in anesthetized obese fa/fa Zucker rats (n = 6) pre-treated for 1 week with a daily oral dose of AZ 242, 1 μmol/kg/d in 0.5% methyl cellulose, 2.5 ml/kg. Matched vehicle-treated obese (n = 4) and lean (Fa/?) (n = 3) Zucker rats served as controls. On the day of the clamp experiment, the final gavage was given at 07:00 and food was removed. The animals were anesthetized with 180 (obese Zuckers) or 120 (lean Zuckers) mg/kg intraperitroneal Na-thiobutabarbitol (Inactin®, RBI/Sigma, St. Louis, MO). Following tracheotomy, the spontaneously breathing animals were fitted with a carotid artery catheter for blood sampling and recording of arterial blood pressure as well as three catheters in a jugular vein for infusions of insulin and glucose and for top-up doses of anaesthetic, if needed, respectively. Rectal temperature was maintained at 38°C by means of external heating. Blood pressure, heart rate, and body temperature were monitored on a custom-made computerized recording system (PC-Lab, AstraZeneca, Sweden). The following protocol was used in all experiments. A stabilization period of at least 120 min elapsed between completion of the surgical preparation and commencement of the clamp, 5–7 h after removal of food. Blood glucose levels were determined every 5 min (YSI 2700 glucose analyzer, YSI, Inc., Yellow Springs, OH) using a blood sampling method allowing minimal sampling volumes (15 μl/sample). The hyperinsulinemic clamp was commenced once three successive blood glucose readings were within 10% of their mean value, which was used as the target glucose level for the subsequent clamp. HI (Actrapid®Novo Nordisk A/S Bagsvaerd, Denmark), 10 mU/kg lean body mass/min, was infused using a syringe pump (CMA 1100, Carnegie Medicine, Solna, Sweden). Blood glucose was clamped to within 10% of the target glucose level by means of variable rate 20% (w/v) glucose (Glucos 200 mg/ml, Fresnius Kabi AB, Uppsala, Sweden) infusion, using another syringe pump (Model 22 I/W, Harvard Apparatus, Inc., South Natic, MA). A computer program (Gluclamp.V2.1A, AstraZeneca) was used to record blood glucose levels and the glucose infusion rate (GIR) and to set the glucose infusion pump according to the rate determined by the operator. The clamp period was defined as the earliest 30 min period during insulin infusion in which blood glucose (sampled once every 5 min) stayed within 10% of the target glucose level without any alteration in GIR. Immediately before insulin infusion was started and at the end of the clamp period, blood samples (200 μl) were collected from the arterial catheter directly into vials containing potassium-ethylenediaminetetraacetic acid (Microvette CB300, Sarstedt, Nümbrecht, Germany). Red blood cells were separated as rapidly as possible and plasma stored at −20°C for subsequent determination of TG, human and total insulin, C-peptide, glycerol and FFA. To normalize for differences in body composition and plasma insulin levels, an "insulin sensitivity index" was calculated according to the following formula: where GIR (μmol/min) is the steady state glucose infusion rate during clamp. The pancreatic insulin secretion, as assessed by the posthepatic insulin outflow rate, was estimated by the use of the selective insulin radio immunoassay (RIA) determination of exogenous HI and endogenous rat insulin (RI) plasma levels, based on the assumption that plasma clearance of HI and RI are equal in the rat. At steady state, the ratio of posthepatic insulin secretion (IS) and the entry of total insulin into the plasma [the sum of IS and exogenous insulin infusion rate (I)] would be as follows: During the clamp, IS could therefore be estimated, since I was known and RI and HI were measured. A basal insulin secretion rate ISBasal could also be calculated assuming a plasma clearance equal to that obtained during the clamp. For determination of liver cytochrome P450 4A activity (CYP4A), lean B6C3F1 mice were treated by gavage for 1 week once daily with AZ 242 (0.13 μmol/kg/d), the PPARγ agonist rosiglitazone (5 μmol/kg/d), and the PPARα agonist WY14, 643 (36 μmol/kg/d). The CYP4A-dependent lauryl ω-hydroxylase activity was measured in liver microsomes using 14C-labeled lauric acid. Separation and detection of the 11- and 12-hydroxy metabolites were performed using reverse-phase HPLC coupled to a radioactivity detector (33Romano M. Straub K. Yodis L. Eckhardt R. Newton J. Determination of microsomal lauric hydroxylase activity by HPLC with flow-through rediochemical quantification.Anal. Biochem. 1988; 170: 83-93Google Scholar). cDNAs containing the ligand binding domains of human PPARα or murine PPARα and PPARγ were amplified by PCR. Maintaining an open reading frame, the fragments were cloned 3′ to the GAL4 DNA binding domain and the nuclear localization sequence from T-antigen of Polyoma Virus in pSG5 (Stratagene, CA). A luciferase reporter plasmid was constructed by inserting five upstream activating sequences elements into the truncated SV40 promoter of pGL3-P (Promega, WI). U-2 OS cells (ATCC catalog no. HTB-96) were cultivated in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with resin-charcoal–stripped fetal calf serum (FCS) and transfected with the PPAR expression vectors and the luciferase reporter plasmid by electroporation using a Gene Pulser™ (BioRad, Hercules, CA). After electroporation, approximately 25,000 cells/well were seeded in triplicate 96-well plates in DMEM without phenol red. The test agents were added to the medium, and the plates were incubated for 40 h and then lysed using LucLite™ (Packard, CT) buffer. The luciferase signal was recorded in a Victor2™ plate reader (Wallach, Finland). The signals were normalized against plate-specific controls (DMSO for 0%; 16 μM pioglitazone, 4 μM WY14,643, 16 μM 5,8,11,14-eicosatetrayemoic acid for 100% activation of PPARγ, mPPARα, and hPPARα, respectively) and the values from the triplicate plates were averaged. Xlfit (ID Business Solutions) was used for fitting curves to the experimental points and to determine EC50. Murine preadipocyte 3T3-L1 cells were cultured in DMEM with 25 mM glucose, 10% FCS and 2 mM l-glutamine at 10% CO2. For the experiments, cells were seeded in 24-well plates, 0.5 × 104 cells/cm2. After reaching confluence, usually after 5 to 6 days, cells were stimulated to differentiate by the addition of 0.05 mM 1-methyl-3-isobuthylxanthine (MIX) and 2 μg/ml dexamethasone (DEX), essentially as described (34Garcia de Herreros A. Birnbaum M.J. The acquisition of increased insulin-responsive hexose transport in 3T3-L1 adipocytes correlates with expression of a novel transporter gene.J. Biol. Chem. 1989; 264: 19994-19999Google Scholar). After 2 days, the DEX/MIX medium was removed, cells were washed three times with medium, and fresh medium with or without the test agent was added (duplicate wells for each drug concentration). Five days later, uptake of 2-deoxy-d-[3H]glucose was measured as a marker of adipocyte differentiation (34Garcia de Herreros A. Birnbaum M.J. The acquisition of increased insulin-responsive hexose transport in 3T3-L1 adipocytes correlates with expression of a novel transporter gene.J. Biol. Chem. 1989; 264: 19994-19999Google Scholar). Cells were washed twice with 0.5 ml serum-free DMEM and incubated with 1 ml serum-free DMEM for 2 h. Thereafter, cells were washed twice with 0.5 ml Dulbecco's phosphate buffered saline (DPBS), and incubated with 1 ml DPBS in a water bath at 37°C for 10 min. Insulin (human; 1 μM) was added, and incubation continued at 37°C. After 20 min, 0.1 ml DPBS with 1 mM deoxyglucose and 6 μCi/ml 2-deoxy-d-[3H]glucose was added, and incubation continued for another 10 min. Thereafter, cells were washed three times with 1 ml cold DPBS and finally solubilized with 0.75 ml 1% Triton X-100 at 37°C for 20 min. The radioactivity was determined by liquid scintillation counting using a 0.5 ml aliquot of the Triton/cell solution mixed with 0.5 ml Optiphase "Supermix" (Wallac, Turku, Finland). Human liver derived HepG2 cells were seeded in a 12-well plate in triplicate at 1.5 × 105 cells/well and grown in Modified Eagle's Medium (MEM) supplemented with 10% FCS and 2 mM l-glutamine. Drug treatment was for 72 h. For metabolic labeling, medium was removed from the wells and 0.5 ml labeling medium (0.5 ml methionine-free MEM, supplemented with 10% FCS and 2 mM glutamine plus 21 μl [35S]met Redivue PRO-MIX, [Amersham Pharmacia Biotech, Uppsala, Sweden]) was added to each well (corresponding to 0.3 mCi per well). Cells were lysed by adding 1 ml 2D-sample solution containing 8 M urea, 0.3% dithiothreitol, 0.5% IPG 3-10NL ampholytes, and 4% CHAPS (Amersham Pharmacia Biotech) to each well. Analysis of cellular HepG2 proteins by proteomics was done essentially as described using 3-10NL IPG strips in the first dimension in an IPG-Phor unit and a Hoeffer-Dalt tank for the second dimension (Amersham Pharmacia Biotech) (35Lanne B. Potthast F. Hoglund A. Brockenhuss von Löwenhielm H. Nystrom A.C. Nilsson F. Dahllöf B. Thiourea enhances mapping of the proteome from murine white adipose tissue.Proteomics. 2001; 1: 819-828Google Scholar). Gels were dried, and images of exposed screens were captured using an FX molecular imager (BioRad) and analyzed using PDQuest (BioRad). Protein spots were identified using mass fingerprinting and MALDI-TOF (Applied Biosystems, Framingham, MA) as described (32Edvardsson U. Bergström M. Alexandersson M. Bamberg K. Ljung B. Dahllöf B. Rosiglitazone (BR49653), a PPAR-gamma selective agonist, causes peroxisome proliferator-like liver effects in obese mice.J. Lipid Res. 1999; 40: 1177-1184Google Scholar). Total plasma insulin was determined by RIA (Rat Insulin RIA Kit, Linco Research, Inc., St. Charles, MO). HI, administered in clamp experiments, was selectively determined with the Human Insulin RIA Kit (Linco Research, Inc.); plasma C-peptide concentrations were determined using a rat C-peptide RIA kit (Linco Research, Inc.). Colorimetric kit methods were used for the determination of plasma TGs, total protein, glucose (Glucose HK, Roche Diagnostics, Stockholm, Sweden), and plasma FFA (NEFA C, Wako, Richmond, VA). Photometric assays were performed using a centrifugal analyzer (Cobas Bio, F. Hoffman-La Roche & Co., Basel, Switzerland). CETP mass was measured by ELISA (Wako Chemie, Bad Homburg, Germany). Where appropriate, results were evaluated using paired parametric t-test. ANOVA was used when more than two groups were compared. The characteristically elevated plasma levels of TGs, insulin, and glucose, and increases in body weight in obese, diabetic (ob/ob) control mice, compared with those of lean (Ob/?) control mice after are shown in Fig. 2. Treatment with AZ 242 (1μmol/kg/d) for 1 week resulted in normalization of the hyperglycemia and a concomitant reduction in insulin levels, indicating greatly increased insulin sensitivity. At this dose, plasma TG levels were lowered to a level below that of lean mice. There was no AZ 242 treatment–related effect on body weight. The oral in vivo potency and efficacy of AZ 242 in ob/ob mice following 1 week administration of graded doses was compared with that of the PPARγ agonist rosiglitazone and the rodent-selective PPARα agonist WY14,643 (Fig. 3). On the last day of dosing, 4 h after final gavage and removal of food, plasma levels of TGs, glucose, and i
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