Experimental Studies Of The Effect And Mechanism Of Melatonin On Atherosclerotic Lesions Based On Ferroptosis

Background Cardiovascular diseases（CVD）already rank first among the leading causes of death in China,and the burden of cardiovascular diseases will continue to increase as China’s population ages and metabolic risk factors continue to increase.Atherosclerosis（AS）is the main pathological basis of many cardiovascular and cerebrovascular diseases.It is of great significance to study and explore potential targets for delaying the progression of atherosclerotic lesions from multiple aspects.Objective To investigate the effect of melatonin on atherosclerotic lesions,and preliminarily explore the specific pathway of melatonin action on atherosclerosis.Methods A total of 6 male wild type（WT）mice and 24 of Apo E^-/-mice on a C57BL/6 background（6-to 8-week old,18–22 g）were purchased from the Rat Laibao（Wuhan）biotechnology company.After two-week adptation,24 Apo E^-/-mice were randomized into four groups:Apo E^-/-,Apo E^-/-+MLT,Apo E^-/-+RSL3 and Apo E^-/-+RSL3+MLT groups and the wild-type mice were considered as control mice.For AS modeling,the Apo E^-/-mice received high-fat-diet for 16 months.The Apo E^-/-+RSL3 and the Apo E^-/-+RSL3+MLT groups mice were received 100 mg/kg of RSL3 twice a week from the 9^th week to 12^th week.The Apo E^-/-+MLT and the Apo E^-/-+RSL3+MLT groups mice were received 20mg/kg of melaton every day from the 13^th week to 16^th week.After 2 months treatment,the mice were scarificed.And we collected the blood samples and vascular tissue samples for further analysis.Results（1）The atherosclerosis model was successfully constructed;（2）There were significant differences in blood lipid levels and serum iron levels among all groups,and the concentrations of low-density lipoprotein and triglyceride in melatonin treatment group were significantly lower than those of the Apo E^-/-group（P<0.01）;The concentrations of low density lipoprotein and triglyceride of the Apo E^-/-+RSL3+MLT group were significantly lower than those of the Apo E^-/-+RSL3 group（P<0.01）.（3）Melatonin treatment down-regulated lipid peroxidation level and increase antioxidant capacity in atherosclerotic mice;The levels of MDA and LPO in the Apo E^-/-+MLT group were significantly lower than those in the Apo E^-/-group,and those in the Apo E^-/-+RSL3+MLT group were significantly lower than those of the Apo E^-/-+RSL3 group.The GSH/GSSG ratio of melatonin treatment group was significantly higher than that of Apo E^-/-group（P<0.05）,and the GSH/GSSG ratio of Apo E^-/-+RSL3+MLT group was significantly higher than that of Apo E^-/-+RSL3 group（P<0.05）.（4）Melatonin treatment up-regulated the expression levels of GPX4 and SLC7A11in aorta of atherosclerotic mice;The m RNA and protein expression levels of SLC7A11 and GPX4 in melatonin treatment group were significantly higher than those in control group,respectively.The m RNA and protein expression levels of SLC7A11 in Apo E^-/-+RSL3+MLT group were significantly higher than those of the RSL3 treated group.Conclusion The level of ferroptosis increases during the occurrence and development of atherosclerosis.Melatonin can improve blood lipid levels in atherosclerosis and Atherosclerotic plaque.Melatonin can improve atherosclerosis by reducing lipid peroxidation level,increasing GSH/GSSG ratio,SLC7A11 and GPX4 expression,and melatonin can improve atherosclerosis by inhibiting ferroptosis through GSH/SLC7A11/GPX4 axis.