Activation Of Liver X Receptors Inhibites H9c2Cardiomyocyte Apoptosis Induced By Hypoxia/reoxygenation Through Endoplasmic Reticulum Stress Pathway

Objective：1.To construct the Hypoxia/reoxygenation model mimicking ischemiareperfusion injury in vitro based on rat H9c2cardiomyocytes;2.To detect the cell viability and apoptosis level of each group afterpreconditioning with T0901317(LXRs agonists) in H/R injury, and analysis the ERSrelevant indicators. To clarify the effect of Liver X receptors on ERS signalingpathways on H/R injury in H9c2cardiomyocytes.Methods：1. Rat H9c2cardiomyocytes were cultured in vitro and subjected to an H/Rmodel(Hypoxia for3h and reoxygenation for10h)．2. All H9c2cardiomyocytes were randomly divided into three groups:Controlgroup;H/R(Hypoxia and reoxygenation)group; T0901317(10μmol/L) preconditioninggroup;3. The rate of H9c2cardiomyocytes cell viability of each group were detected byCCK-8detection kit; the rate of H9c2cardiomyocytes apoptosis were detected byAnnexin-FIFC/PI kit and Hoechest33342/PI detection kit.4. The expression of the ERS marker GRP78and ERS induced apoptosis-relatedprotein CHOP/GADD153,Caspase-12of rat H9c2cardiomyocytes were detected byqRT-PCR and Western blot.Results：1. After Hypoxia/reoxygenation in H9c2cardiomyocytes cells, the cell viabilityin H/R group and T0901317preconditioning group, compared with that in controlgroup, significantly decreased(P＜0.01). And compared with that in H/R group,thecell viability in T0901317preconditioning group increased with significantdifferences(P＜0.01).2. The average rate of apoptosis of each group were detected byAnnexin-FIFC/PI kit and Hoechest33342/PI detection kit, it was found that theapoptosis index of the H/R group and T0901317preconditioning group were significantly increased(P＜0.01).But in T0901317preconditioning group, theapoptosis index was significantly decreased compared with that in H/R group(P＜0.01)..3. Both the expression of mRNA and the protein of GRP78, CHOP/GADD153,Caspase-12in H/R group and T0901317preconditioning group were significantlyup-regulated(P＜0.01),and compared with those in H/R group, all the GRP78,CHOP/GADD153,Caspase-12mRNA and protein were significantly decreased inT0901317(10μmol/L) preconditioning group(P＜0.01)Conclusions：1. T0901317pretreatment can significantly improve the cell viability and reducethe apoptosis rate of H9c2cardiomyocytes in H/R injury；2. H/R-induced the increase in mRNA expression and protein content ofGRP78,CHOP/GADD153,Caspase-12can be significantly suppressed by thepretreatment with T0901317,which indicated that LXRs activation may inhibit H/Rinduced apoptosis through Endoplasmic Reticulum Stress pathway.