Protective Effect Of Exenatide On H9C2 Cardiomyocytes Cultured With High Glucose By Regulating Adiponectin And Its Receptors，oxidative Stress And Endoplasmic Reticulum Stress

Objective:To observe the effect of exenatide on the adiponectin and its receptors(AdipoR),oxidative stress and endoplasmic reticulum stress in cardiomyocytes cultured with high glucose,and to explore the protective effects and mechanism of exenatide on the cardiomyocytes.Methods:H9C2 cardiomyocytes were randomly divided into following four groups(n=3): group A: cardiomyocytes were cultured in normal glucose(5.6 mmol/L);group B:cardiomyocytes were cultured in high glucose(25.5 mmol/L);group C: cardiomyocytes were cultured in high glucose and 10 nmol/L GLP-1;group D: cardiomyocytes were cultured in high glucose and 100 nmol/L GLP-1.Four groups were continued to be cultured for 24 h.Then,cell apoptosis rate was assayed.The level of adiponectin in the cell supernatant was measured by enzyme immunoassay(ELISA).The mRNA expressions of myocardial adenine dinucleotide(NADPH)oxidase subunit p22 phox,nuclear factor E2-related factor2(Nrf2),heme oxygenase-1(HO-1),Glucose-regulated protein78(GRP78),C/EBP homologous protein(CHOP)were assessed by real-time fluorescent quantitative PCR.Western blot analyzed AdipoR1,Phosphorylated AMP activated protein kinase(PAMPK)and Glucose transporter 4(GLUT4)protein expression.Results:1.Compared with group A,the rate of apoptosis was increased in group B(25.90±0.55 vs 5.60±0.25,χ2=10.958,P<0.05).The level of adiponectin,the protein expression of AdipoR1,PAMPK and GLUT4,and the mRNA expression of Nrf2 and HO-1 were significantly decreased in group B than those in group A(760±145 vs 1 490±168;0.59±0.08 vs 0.91±0.07;0.48±0.08 vs 1.00±0.00;0.63±0.08 vs 0.86±0.08;0.56±0.02vs1.00±0.00;0.48±0.08vs1.00±0.00;t=7.942,6.922,13.255,4.536,10.689,13.627;a ll P<0.05).The protein expression of p22 phox,and the m RNA expression of GRP-78 and CHOP were significantly increased in group B than those in group A(0.87±0.02 vs0.56±0.09;1.33±0.08 vs 1.00±0.00;1.58±0.16 vs 1.00±0.00;t=7.591,5.138;5.994;all P<0.05).2.Group C can effectively reduce the rate of apoptosis than this in group B(12.2±2.2,χ2=6.814,P<0.05).The level of adiponectin,the protein expression of AdipoR1,PAMPK and GLUT4,and the mRNA expression of Nrf2 and HO-1 of group C(1070±142,0.69±0.02,0.72±0.03,0.78±0.08,0.71±0.09,0.64±0.07)were obviously higher than those of group B(t=3.372,2.263,6.477,2.897,3.633,4.225;all P<0.05).The protein expression of p22phox(0.66±0.04),and the mRNA expression of GRP-78(0.99±0.16)and CHOP(1.26±0.28)of group C were obviously lower than those of group B(t=4.716,4.892,3.272;all P<0.05).3.The rate of apoptosis(8.7±0.8)was obviously lower in group D than those in group C(χ2=2.265,P<0.05).The levels of adiponectin(1306±178),the protein expression of AdipoR1(0.82±0.09)and PAMPK(0.88±0.20),and the mRNA expression of Nrf2(0.91±0.11)and HO-1mRNA(0.88±0.08),were increased in group D than those in group C(t=2.575,2.349,7.822,4.792,6.518;all P<0.05).The mRNA expression of CHOP(0.96±0.09)was decreased in group D than those in group C(t=3.185,P<0.05).However,there was no significant change in p22phox(0.60±0.14),GLUT4(0.89±0.05)and GRP-78(1.10±0.12)mRNA(t=1.323,1.702,1.348;均 P>0.05).Conclusions:1.The expression of adiponectin in cultured cardiomyocytes was decreased,while therate of apoptosis was increased.2.The expression of myocardial cells cultured in high glucose were decreased on PAMPK and GLUT4,with p22 phox expression increased,Nrf2 and its downstream antioxidant gene expression decreased,and the expression of GRP78 and its related factors levels increased,which suggested that high glucose induced energy metabolism,oxidative stress and endoplasmic reticulum stress.3.Exenatide may plays protective role on cardiomyocytes cultured with high glucose by increasing the level of adiponectin and its receptors,regulating the energy metabolism,inhibiting oxidative stress and endoplasmic reticulum stress.