The Antidiabetic Effects And Underlying Mechanisms Of Novel PPARγ Partial Activators Which Based On The Structure Of Thiazolidinedione

Background:Diabetes mellitus (DM) has been the major chronic disease throughoutthe world; and more than90%of diabetes is type2diabetes mellitus(T2DM) in the world. Thiazolidinediones (TZDs), as ligands forperoxisome proliferator-activated receptor γ (PPARγ), achieve their uniqueinsulin-sensitizing effect and are highly effective in treating insulinresistance and T2DM. However, a major problem with TZDs application isthe potential side effects, including weight gain, edema, increasedincidence of heart attack, and bone loss. It has been reported that optimalapproach to achieve insulin sensitization did not need full agonism ofPPARγ. Therefore, explorations of novel PPARγ ligands with moderatemodes of activation are required for the development of therapeutic agentsfor insulin resistance and T2DM.Our team have synthesized series of thiazolidinedione-derivatives,established an in vitro PPARγ ligand screening system. We found CMHX003and CMHX008to be novel compounds with the activity ofPPARγ partial agonism. The result of luciferase reporter assay suggestedthat compared with rosiglitazone, CMHX003and CMHX008displayed amodest PPARγ agonist activity. CMHX008significantly promoted3T3-L1preadipocytes differentiation and increased intracellular lipid accumulation.This effect can be inhibited by co-treatment with a PPARγ antagonist,GW9662. Moreover, CMHX008increased the expression of adiponectinand Glucose transporter4(Glut4), and CMHX008showed only25%aspotent as rosiglitazone for the induction of aP2.Method:3T3-L1preadipocytes were differentiated into adipocytesaccording to the standard protocols. CMHX003or rosiglitazone wasadministered at the initiation of differentiation, and was added with everyrenewal of medium therafter. Oil red O staining was performed at the endof differentiation. Adiponectin and aP2mRNA levels were determined byreal-time PCR. The secreted adiponectin levels in the culture medium weremeasured with mouse adiponectin ELISA kit.Male C57BL/6mice were fed with either high fat diet (HFD) or lowfat diet (LFD). After16weeks for HFD, mice were administered once dailywith CMHX008(3or10mg/kg/day), rosiglitazone (3mg/kg/day) or anequivalent volume of vehicle by intragastric gavage for additional5weeks.Four weeks after drug treatment, GTTs were performed for portions of theanimals. Serum biochemical assays were performed using automatic biochemistry equipment. Serum adiponectin levels were detected withmouse adiponectin ELISA kit. Others cytokines were detected by Milliplexmap multiplex Assay. H&E and oil-red O staining were performed in livertissue and WAT. Interested gene expressions in liver and WAT wereanalyzed by real-time quantitative PCR.Results: CMHX003promoted3T3-L1preadipocyte differentiationwith lower activity than rosiglitazone. CMHX003regulated the expressionof PPARγ target genes in a different manner from rosiglitazone. CMHX003increased the expression and secretion of adiponectin with the similarefficacy as rosiglitazone, however, was less potent for the induction of aP2compared with rosiglitazone.Treatment of CMHX008and rosiglitazone protected mice fromHFD-induced glucose intolerance, hyperinsulinemia and inflammation.CMHX008significantly decreased the weight of epididymal white adiposetissue (WAT) and the size of adipocytes. CMHX008significantly decreasedserum levels of triglyceride, low-density lipoproteins (LDL) and aspartateaminotransferase (AST). CMHX008reduced IL-6levels and TNF-α levels.Compare to rosiglitazone, CMHX008would not cause the increase of liverweight and improves lipid deposition in liver. CMHX008reduced themRNA expression of M1macrophage markers, and significantly increasedthe mRNA expression of M2macrophage markers. CMHX008switchedthe polarization of adipose macrophages from M1dominant to M2 dominant.Conclusion: CMHX008shared the similar insulin-sensitizing effectsas rosiglitazone in vivo. The improvement of metabolic abnormalities byCMHX008was associated its anti-inflammatory effects and inducing themacrophage M2-polarization. Compare to rosiglitazone, CMHX008showed no influence on the body weight and lipid deposition in the liver.These findings suggest that CMHX008may potentially be developed intoan effective and safe agent for the treatment of diabetes and metabolicdisorders.