Objective:To investigate the protective effect of lovastatin on liver injury in the rats induced by hyperlipidemia,and to elucidate its possible mechanism.Methods:Fifteen SD rats were randomly divided into control group,hyperlipidemia model group,and lovastatin group,with 5 rats in each group.The rats in control group were fed with standard diet,while the rats in hyperlipidemia model group and lovastatin group were fed high-fat diet for 12 weeks.Starting from the 8th week,the rats were administered treatments via gavage once a day for 4 weeks:the rats in lovastatin group received 2 mng·kg-1 lovastatin,while the rats in control group and hyperlipidemia model group received an equal volume of normal saline.The body weights of the rats in various groups were measured at weeks 1,8,9,10,11,and 12 after the experiment began;the histopathology of liver tissue of the rats in various groups was observed using HE staining;the serum levels of total cholesterol(TC),triglycerides(TG),high-density lipoprotein cholesterol(HDL-C),low-density lipoprotein cholesterol(LDL-C),malondialdehyde(MDA),as well as the activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px),aspartate aminotransferase(AST),and alanine aminotransferase(ALT),and the levels of interleukin-2(IL-2),interleukin-6(IL-6),interleukin-12(IL-12),and tumor necrosis factor-a(TNF-α)of the rats in various groups were detected using commercial kits;the composition of the gut microbiota of the rats in various groups was analyzed by 16S rRNA sequencing.Results:Compared with control group,the body weight of the rats in hyperlipidemia model group was significantly increased from the 8th week of high-fat diet feeding(P＜0.05 or P＜0.01 or P＜0.001).Compared with hyperlipidemia model group,the body weight of the rats in lovastatin group was significantly decreased at weeks 11 and 12(P＜0.05).Compared with control group,the livers of the rats in hyperlipidemia model group appeared rough,pale,enlarged,with blunt edges,and had a granular and greasy texture.Compared with hyperlipidemia model group,the livers of the rats in lovastatin group were light brownish-red,soft,with slightly blunt edges,reduced volume,and less granularity and greasiness.Compared with control group,the liver cells of the rats in hyperlipidemia model group were swollen and disorganized,with pyknotic nuclei,extensive inflammatory cell infiltration,and numerous vacuolar degenerations.Compared with hyperlipidemia model group,the rats in lovastatin group showed significantly reduced hepatocyte swelling and degeneration,more orderly and intact liver cell arrangement,decreased inflammatory cell infiltration,and reduced vacuolar degeneration.Compared with control group,the serum levels of TC,TG,and LDL-C of the rats in hyperlipidemia model group were significantly increased(P＜0.05),and the serum HDL-C level was decreased(P＜0.05).Compared with hyperlipidemia model group,the serum levels of TC,TG,and LDL-C of the rats in lovastation group were significantly decreased(P＜0.05),and the serum HDL-C level was increased(P＜0.05).Compared with control group,the serum MDA levels and the ALT and AST activities of the rats in hyperlipidemia model group were significantly increased(P＜0.05),and the SOD and GSH-Px activities were significantly decreased(P＜0.05).Compared with hyperlipidemia model group,the serum MDA levels and ALT and AST activities of the rats in lovastatin group were decreased(P＜0.05),and the SOD and GSH-Px activities were increased(P＜0.05).Compared with control group,the serum levels of IL-2,IL-6,IL-12,and TNF-α of the rats in hyperlipidemia model group were significantly increased(P＜0.05).Compared with hyperlipidemia model group,the serum levels of IL-2,IL-6,IL-12,and TNF-α of the rats in lovastatin group were significantly decreased(P＜0.05).Compared with control group,the ACE and Chao1 indexes of the rats in hyperlipidemia model group were significantly decreased(P＜0.05).Compared with hyperlipidemia model group,the ACE and Chao1 indexes of the rats in lovastatin group were significantly increased(P＜0.05 or P＜0.01).Compared with control group,the relative abundances of Firmicutes and Proteobacteria of the rats in hyperlipidemia model group were significantly increased(P＜0.001),and the relative abundances of Bacteroidetes and Actinobacteria were decreased(P＜0.001).Compared with hyperlipidemia model group,the relative abundances of Firmicutes and Proteobacteria of the rats in lovastatin group were significantly decreased(P＜0.05 or P＜0.01),while the relative abundances of Bacteroidetes and Actinobacteria showed no significant changes.Compared with control group,the relative abundance of Lactobacillus of the rats in hyperlipidemia model group was significantly decreased(P＜0.001),and the relative abundances of Bacteroides,Desulfovibrio,and Clostridium were significantly increased(P＜0.01 or P＜0.001).Compared with hyperlipidemia model group,the relative abundance of Lactobacillus of the rats in lovastatin group showed no significant change but the relative abundances of Bacteroides,Desulfovibrio,and Clostridium were significantly decreased(P＜0.05 or P＜0.01 or P＜0.001).Conclusion:Lovastatin ameliorates liver injury induced by hyperlipidemia,and the mechanism may be related to its ability to improve gut microbiota composition and inhibit oxidative stress and inflammatory damage.