Study On The Mechanism Of Sturgeon Peptide LLLE Improving Permethrin-induced Obesity In High-fat Diet Mice

Marine fish is a good source of bioactive peptides,with a variety of functional characteristics,such as antioxidant,antibacterial,anti-inflammatory,anti-obesity and anti-diabetes and so on,which is conducive to the prevention and treatment of obesity,diabetes and cardiovascular diseases and other chronic diseases.Previous in vitro and in vivo studies have shown that permethrin exposure promotes fat accumulation,insulin abnormalities and dyslipidemia,as well as dysbacteriosis.On account of this,in this study,C57BL/6J male mice fed with a high-fat diet under permethrin exposure were used as model animals to explore the anti-obesity activity of LLLE,a bioactive polypeptide derived from sturgeon cartilage.The main research contents are as follows:(1)The study aimed to investigate the effect of supplementing LLLE peptide solution on a high-fat diet-induced obesity mouse model exposed to permethrin,with a daily dose of 10mg/kg body weight via gavage.The results showed that LLLE significantly reduced weight gain and lipid accumulation induced by high-fat diet and permethrin exposure,without affecting energy intake.LLLE also inhibited the increase of triglycerides(TG),total cholesterol(TC),and low-density lipoprotein(LDL-c)levels in mouse serum(p < 0.05)and improved the decreasing trend of highdensity lipoprotein(HDL-c)levels.Additionally,LLLE improved the levels of TG and TC in the liver(p < 0.05),reducing lipid accumulation.LLLE also improved glucose tolerance abnormalities and insulin resistance induced by permethrin exposure,maintaining glucose metabolism homeostasis.These findings suggest that sturgeon peptide LLLE has good anti-obesity activity.(2)After LLLE intervention in high-fat diet mice exposed to permethrin,the diversity of intestinal microbial flora was enriched and the composition and abundance of the microbial community changed significantly at the phylum and genus levels.At the phylum level,the level of Firmicutes decreased while that of Bacteroidetes increased.At the genus level,the levels of Lachnoclostridium and Faecalibacterium decreased while that of Bacteroides increased.Analyzing the changes in the abundance of differentially metabolizing bacterial species and correlating them with body weight and blood lipid indicators,the results showed that Clostridium scindens,Lactobacillus johnsonii,and Bacteroides thetaiotaomicron were negatively correlated with HDL-c,TG,and TC,respectively(p < 0.05).Predicted functional analysis of the gut microbiota metabolism pathway showed that LLLE intervention down-regulated hexitol fermentation and methane production.These findings suggest that LLLE intervention can regulate the imbalance of intestinal microbiota caused by permethrin exposure and change the gut microbiota that is closely related to obesity in mice.(3)This study used RNA-seq transcriptomics sequencing to analyze the changes in liver transcriptomes of high-fat diet mice before and after exposure to permethrin under LLLE intervention.The significantly enriched metabolic pathways obtained through GSEA analysis showed that after LLLE intervention,cholesterol metabolism,primary bile acid biosynthesis,and insulin signaling pathways were significantly upregulated,while Toll-like receptor(TLR)and Nod-like receptor(NLR)signaling pathways were upregulated under permethrin exposure(p <0.05),which was reversed by LLLE intervention.Hierarchical clustering analysis of enriched genes for each pathway showed that LLLE intervention upregulated CYP7A1 and CYP27A1 to promote cholesterol metabolism and primary bile acid biosynthesis,which in turn promoted bile acid secretion,upregulated LDLR expression to promote low-density lipoprotein generation,and thus decreased total cholesterol levels.In addition,LLLE intervention upregulated PIK3R1 to promote glucose transport and alleviate insulin resistance,and regulated the expression activity of MYD88 and RELA/p65 to affect the transcription of downstream inflammatory factors,thus alleviating the inflammation caused by permethrin exposure exacerbating mouse obesity.The results showed that sturgeon peptide LLLE has anti-obesity activity and can alleviate the abnormal glucose and lipid metabolism caused by permethrin exposure.The sequencing of gut microbiota and transcriptomics analysis further showed that the anti-obesity effect of LLLE is closely related to the regulation of gut microbiota and metabolic regulation.The study results provide a possible molecular mechanism for the weight-loss and lipid-lowering effects of sturgeon peptide LLLE,while also increasing the value of sturgeon byproducts and promoting the development of bioactive peptide products in the food and pharmaceutical industries.