The Effects And Mechanisms Of Gas Signaling Molecule Hydrogen Sulfide Protects Doxorubicin-induced Dilated Cardiomyopathy

Objective:To investigate whether H2S can attenuate the development of doxorubicin-induced dilated cardiomyopathy and to explore the potential mechanisms involved.Methods:we generated a rat model of DCM induced by doxorubicin hydrochloride administered intraperitoneally.Two weeks after cessation of doxorubicin injection,rats were examined by transthoracic echocardiography to confirm the formation of DCM.The rats were then divided into 4 groups:control group,DCM group,DCM + H2S group(DCM rats were administrated with NaHS solution at a dose of 15 ?mol/kg/d),and H2S group(normal rats were administered with H2S donor NaHS).Oxidative stress was assessed by detecting malondialdehyde(MDA)levels,superoxide dismutase(SOD)and glutathione peroxidase(GSH-Px)activities,and reactive oxygen species(ROS)production in the myocardium,the nuclear expression of Nrf2 protein and its downstream targets(NQO1 and GCLM)were detected by western blotting to assess the ability of antioxidation.Cardiomyocyte apoptosis was assessed by detecting the expression of apoptotic regulatory proteins(Bax,Bcl-2,caspase3,etc.).The PI3K activity was determined by uenzyme-linked immunosorbent assay(ELISA),the expression of phospho-Akt and its downstream target proteins,phospho-caspase-9 and phospho-Bad were detected by western blotting.We transfected myocardial cells with Nrf2 siRNA to downregulate its expression,and then subjected them to doxorubicin and NaHS,Compared to cells without Nrf2 siRNA transfection in the level Oxidative stress.Afterwards,we transfected cardiomyocytes with PI3K siRNA and then subjected them to doxorubicin and NaHS.Compared PI3K siRNA-transfected cells with cells without PI3K siRNA transfection in the expression of PI3K and apoptotic regulatory proteins.Results:LVEDD and LVESD were significantly increased in the DCM group and decreased in the DCM+ H2S group.Moreover,LVFS and LVEF were found to be markedly lower in the DCM group,whereas exogenous administration of H2S could improve left ventricular systolic function.There were significant increase in MDA levels and decrease in SOD and GSH-Px activities in DCM rats,while NaHS administration could reduce MDA levels and increase SOD and GSH-Px activities.Moreover,the ROS generation in cardiac tissue was elevated in the DCM group and decreased in the DCM +H2S group,the nuclear expression of Nrf2 protein was significantly increased in the myocardium of DCM rats following treatment with NaHS.In addition,the protein expression of downstream targets of Nrf2,NQO1 and GCLM,was markedly upregulated in the DCM + H2S group.Nrf2 siRNA-transfected cells that exposed to doxorubicin and NaHS exhibited decreased expression of Nrf2 and increased generation of ROS compared to cells without Nrf2 siRNA transfection.The apoptotic regulatory proteins Bax/Bcl-2 ratio and cleaved caspase-3 expression were significantly increased in the myocardium of DCM rats and reduced after treatment with NaHS.PI3K activity was found to be remarkably decreased in the DCM group and elevated in the DCM + H2S group.In addition,the expression of phospho-Akt and its downstream target proteins,phospho-caspase-9 and phospho-Bad,was downregulated in the DCM rats and upregulated following administration of NaHS.The PI3K siRNA-transfected cells that exposed to doxorubicin and NaHS exhibited reduced expression of PI3K and increased apoptotic rate compared to cells without Nrf2 siRNA transfection.Conclusions:Our study demonstrates that H2S alleviates the development of DCM via attenuation of oxidative stress and apoptosis.H2S may reduce doxorubicin-induced oxidative stress by activating Nrf2 signaling and may exert antiapoptotic effects in DCM by activating PI3K/Akt pathway.