The Role And Mechanism Of Melatonin In Lipopolysaccharide-induced Myocardial Injury

Background: Melatonin(MT) has been shown to protect against various cardiovascular diseases.However,the effect of MT on lipopolysaccharide(LPS)-induced myocardial injury is poorly understood.This study aims to evaluate the effects of MT on LPS-induced myocardial injury in vitro.Methods: H9C2 cells were divided into a control group,MT group,LPS group,and MT+ LPS group.The control group was treated with sterile saline solution,the LPS group received 8 μg/m L LPS for 24 h,MT + LPS cells were pretreated with 200 μmol/L MT for 2 h then with 8 μg/m L LPS for 24 h,and the MT group received only 200 μmol/L MT for 2 h.The CCK-8 assay and lactate dehydrogenase(LDH)activity assay were used to analyze cell viability and LDH release,respectively.Intracellular reactive oxygen species(ROS)and the rate of pyroptosis were measured using the fluorescent probe dichloro-dihydro-fluorescein diacetate(DCFH-DA)and propidium iodide(PI)staining,respectively.The cell supernatants were used to measure the levels of inflammatory cytokines,including IL-6,TNF-α,and IL-1βby enzyme-linked immunosorbent assay(ELISA).The protein levels of i NOS,COX-2,NF-κB,p-NF-κB,NLRP3,caspase-1,and GSDMD were detected by western blot.Results: MT pretreatment significantly improved LPS-induced myocardial injury by inhibiting inflammation and pyroptosis in H9C2 cells.Moreover,MT inhibited the activation of the NF-κB pathway,and reduced the expression of inflammation-related proteins(i NOS and COX-2),and pyroptosis-related proteins(NLRP3,caspase-1,and GSDMD).Conclusions: Our data suggests that MT can alleviate LPS-induced myocardial injury,providing novel insights into the treatment of sepsis-induced myocardial dysfunction.Furthermore,MT attenuates LPS-induced myocardial injury by inhibiting NF-κB/i NOS/COX-2-induced inflammation and ROS-dependent NLRP3-mediated pyroptosis in H9C2 cardiomyocytes.