The Protective Effect Of Exenatide On The Apoptosis Of Osteoblasts Induced By Palmitic Acid

Backgrounds and ObjectiveThe occurrence and development of osteoporosis have close relatetionship with obesity.The high level of free fatty acids in obese patients has an obvious lipid toxicity on osteoblasts.Our previous study had found that palmitic acid can induce the apoptosis of osteoblasts through the way of endoplasmic reticulum stress.It also suggests that inhibition of endoplasmic reticulum stress can improve the osteoblast apoptosis induced by high fat.Increasingly studies have found that GLP-1 receptor agonists can improve the apoptosis of endothelium,cardiomyocytes and hepatocytes by inhibiting endoplasmic reticulum stress.Additionally,other studies have confirmed that GLP-1 receptor agonists have a direct protective effect on OVX rats with osteoporosis.To explore the mechanism of GLP-1 receptor agonists on bone protection,we used GLP-1 receptor agonist(Exenatide)to interfere with osteoblast apoptosis induced by high fat.Constantly,the protective role of Exenatide could be investigated in high-fat environment.Materials and MethodsIn vitro we cultivated murine osteoblast MC3T3-E1 14 with complete medium containing 500 ?mol/L Palmitic acid(PA)mimicking high-fat environment in vivo for 24 huors.We divided six groups: normal control group,PA group,PA + Exenatide(1,10,100,1000nmol/L)groups.According to the experimental results,the optimal concentration of 100nmol/L was selected for follow-up experiments.We divided four groups: normal control group,Exenatide group,PA + Exenatide group,PA group to observe the effects of Exenatide on the proliferation and apoptosis of osteoblasts.Cell viability was detected by CCK-8 assay.Annexin V-FITC/PI Apoptosis Detection Kit was used for detecting apoptosis rate.RT qPCR was used for detecting the GRP78,CHOP and Caspase-12 mRNA expression.Results1.The results of CCK-8 showed that:(1)Compared with the normal control group,the OD values of the cells in the PA group(P<0.01)and the PA + Exenatide 1nmol/L(P<0.01)group were decreased,and the difference was statistically significant.Compared with the PA group,the OD values of cells in the PA+ Exenatide 1000 nmol / L(P<0.01),PA+ Exenatide 100nmol/L(P<0.01),and PA+ Exenatide 10nmol/L(P<0.05)were significantly increased.There was no difference between PA + Exenatide 1000 nmol / L and PA + Exenatide 100 nmol / L(P>0.05)groups.Test results suggested that 100 nmol / L of Exenatide can be used as the optimal concentration for interventing cells.(2)The OD value of the PA+ Exenatide 100 nmol / L group was significantly increased,which is to say that the osteoblasts proliferation activity was significantly increased(P<0.05).2.In the PA group,the apoptosis rate of osteoblasts increased significantly(P<0.01);the apoptosis rate of PA + Exenatide group decreased significantly(P<0.01).3.In the PA group,the expression of GRP78 and CHOP mRNA in the endoplasmic reticulum stress-related genes was significantly increased(P<0.01),and the expression of Caspase-12 mRNA was significantly decreased(P<0.01);PA + Exenatide group,the expression of GRP78 and CHOP mRNA in the endoplasmic reticulum stress-related genes was significantly decreased(P<0.01),and the expression of Caspase-12 mRNA was increased(P<0.05).ConclusionsExenatide,a GLP-1 receptor agonist,improves the occurrence of osteoblasts apoptosis through the way of endoplasmic reticulum stress possibly.