ABSTRACT
OBJECTIVE: To investigate the role of the PPARγ-PI3K/AKT-NO signaling pathway in cardiac hypertrophy induced by high glucose and insulin. METHODS: Cardiomyocyte hypertrophy induced by high glucose (25.5 mmol/L) and insulin (0.1 µmol/L) (HGI) was characterized in rat primary cardiomyocytes by measuring the cell surface area, protein content, and atrial natriuretic factor mRNA expression level. Protein and mRNA expressions were measured by Western blotting and real time RT-PCR, respectively. A spectrophotometric assay was used to measure the enzymatic concentration of endothelial NO synthase (eNOS), and the Griess assay measured the NO concentration. RESULTS: HGI induced significant cardiomyocyte hypertrophy and decreased the expression of PPARγ, AKT and eNOS at the mRNA and protein levels, which occurred in parallel with declining eNOS activity and NO concentration (P<0.05). The effects of HGI were inhibited by rosiglitazone (0.1 µmol/L), a selective PPARγ agonist (P<0.05). However, GW9662, a selective PPARγ antagonist, abolished the effects of rosiglitazone (P<0.05). LY294002, a PI3K/AKT inhibitor, and N(G)-nitro-L-arginine-methyl ester, an NOS inhibitor, partially blocked the effects of rosiglitazone (P<0.05). CONCLUSION: These results suggest that the PPARγ-PI3K/AKT-NO signal transduction pathway might be involved in HGI-induced cardiomyocyte hypertrophy.
Subject(s)
Glucose/pharmacology , Insulin/pharmacology , Myocytes, Cardiac/drug effects , PPAR gamma/metabolism , Proto-Oncogene Proteins c-akt/metabolism , Animals , Cells, Cultured , Hyperglycemia/complications , Hyperinsulinism/complications , Hypertrophy/etiology , Myocytes, Cardiac/metabolism , Myocytes, Cardiac/pathology , Nitric Oxide/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Rats , Rats, Sprague-Dawley , Signal TransductionABSTRACT
AIM:To investigate the role of peroxisome proliferator-activated receptor β( PPARβ)-nitric oxide (NO) signal pathway in cardiomyocyte hypertrophy induced by high glucose (25.5 mmol/L) and insulin (0.1 μmol/L) ( HGI) .METHODS: The cardiomyocyte hypertrophy was characterized in rat primary cardiomyocytes by measuring the cell surface area, protein content, and the mRNA expression of atrial natriuretic factor (ANF).The mRNA and protein ex-pression were measured by real-time PCR and Western blotting , respectively .The activity of NO synthase ( NOS) and NO content were measured by a reagent kit through ultraviolet spectroscopy .RESULTS:HGI induced profound change of hy-pertrophic morphology , and significantly increased the cell surface area , protein content and mRNA expression of ANF (P<0.01), but decreased the expression of PPARβat mRNA and protein levels (P<0.05).At the same time, the ex-pression of inducible NOS (iNOS) was obviously elevated (P<0.01), which occurred in parallel with the rising NOS ac-tivity and NO concentration (P<0.01).GW0742 (1 μmol/L), a selective PPARβagonist, inhibited the cardiomyocyte hypertrophy induced by HGI ( P<0.01 ) , and up-regulated the expression of PPARβat both mRNA and protein levels . Meanwhile, GW0742 also inhibited the increases in iNOS expression , NOS activity, and NO content induced by HGI , which were abolished by GSK0660 (1 μmol/L), a selective PPARβantagonist (P<0.01).CONCLUSION: PPARβdown-regulation and the following iNOS-NO activation are involved in the cardiomyocyte hypertrophy induced by HGI .
ABSTRACT
Aim To investigate the effect of polydatin on cardiomyocyte hypertrophy induced by high glucose (25.5 mmol·L -1 )and insulin (0.1 μmol ·L -1 ) (HGI)and its possible influence on peroxisome prolif-erator-activated receptor-β (PPARβ)/nuclear tran-scription factor-κB (NF-κB)/nitric oxide (NO)signa-ling pathway.Methods The cardiomyocyte hypertro-phy was characterized in rat primary cardiomyocytes by measuring the cell surface area,protein content,and atrial natriuretic factor (ANF)mRNA expression.The mRNA and protein expressions were measured by qRT-PCR and Western blotting,respectively.The activity of NO synthase (NOS)and NO content were measured by reagent kit through ultraviolet spectroscopy.Results HGI significantly induced cardiomyocyte hypertrophy which increased the cell surface area,protein content and ANF mRNA expression (P <0.01 ).Meanwhile, the expressions of PPARβmRNA and protein reduced while the NF-κB p65 and iNOS expressions increased significantly which occurred in parallel with rising NOS activity and NO concentration (P <0.01 ).Polydatin (0.1,1,10 μmol·L -1 )inhibited the cardiomyocyte hypertrophy induced by HGI (P <0.01 ),and re-versed the mRNA and protein expressions of PPARβ, NF-κB p65 and iNOS,and NOS activity,as well as NO content.These effects of polydatin were abolished by GSK0660 (1 μmol·L -1 ),a selective PPARβan-tagonist (P <0.05 ).Conclusion Polydatin resists HGI-induced cardiomyocyte hypertrophy,which may be mediated by PPARβup-regulation,and then NF-κB-iNOS-NO pathway inactivation.
ABSTRACT
Aim To investigate the role of fenofibrate (FF),a selective PPAR-? agonist,in cardiac hypertrophy induced by high glucose and insulin (HGI) and its mechanisms related to nitric oxided (NO) signal transduction pathway. Methods The cultured neonatal rat cardiomyocytes were used to observe the effects of FF on cardiomyocyte hypertrophy induced by HGI (glucose at 25.5 mmol?L-1 and insulin at 0.1 ?mol?L-1),and the cardiomyocyte hypertrophic responses were assayed by measuring the cell surface area,protein content,and atrial natriuretic factor (ANF) mRNA expression. The expressions of mRNA and protein were assayed by Real-time PCR and Western blot,as well as NOS activity and NO concentration in cultured media were determined by using the spectrophotometry and nitrate reluction method.Results In cultured cardiomyocytes,FF (at 0.1,0.3 and 1 ?mol?L-1) could inhibit the cardiomyocyte hypertrophy induced by HGI in a concentration-dependent manner (P
