Anti-obesity Effect Of COS And CTS On Epididymal WAT Browning In Obese Rats And Its Mechanism

Obesity refers to a state of obvious overweight or a thick layer of fat,which is closely related to the content and distribution of body fat tissue.White adipose tissue?WAT?browning is an important mechanism for the body to increase heat production and increase energy release,and the research on WAT browning has become a hot spot in the treatment of obesity and related fields.Chitosan?CTS?and chitosan oligosaccharides?COS?are marine source animal polysaccharides,and their excellent physiological activities are widely used in many fields such as biomedicine,food,and chemical industry.This study used HFD?High-fat diets?to induce the establishment of SD rat obesity model and 3T3-L1 adipocyte model.Through the intervention of two specific molecular weight COS APIs?COST,COSM?and CTS APIs,the weight loss activities of COST,COSM and CTS on obese SD rats were explored at the overall and cellular levels of animals,as well as explored the effects of COST,COSM and CTS on WAT browning and its mechanism.Overall animal level:?1?The obese model of SD rats was induced by HFD,and the weight loss activities of COST,COSM and CTS were evaluated.The results showed that COST,COSM and CTS significantly reduced the body weight gain of obese rats without affecting food intake,effectively inhibited the adipose tissue hypertrophy and hyperplasia of obese rats,and significantly reduced the fat/body ratio of obese rats,showed a good weight loss activity.?2?In order to study the effects of COST,COSM and CTS on lipid metabolism in obese rats,the blood lipid and blood glucose levels of obese rats were determined.The results showed that COST,COSM and CTS could significantly reduce the levels of TC,TG,LDL-C,AST,ALT,free fatty acids and glucose in the serum of obese rats,and significantly increase the serum level of HDL-C in the obese rats,suggesting COST,COSM and CTS have a certain regulatory effect on blood glucose and cholesterol in obese rats.?3?To further study the effects of COST,COSM and CTS on energy metabolism in obese rats,the energy metabolism levels of obese rats were determined.The results showed that COST,COSM and CTS significantly increased O₂ consumption,CO₂ release,respiratory entropy,heat production and rectal temperature,and significantly increased the body temperature compensatory ability of obese rats,suggesting that COST,COSM and CTS can effectively increase the heat production capacity of obese rats.?4?In order to further study the effects of COST,COSM and CTS on genes,gene sequencing of epididymal fat was performed.It was found that COST,COSM and CTS could produce differentially expressed genes in obese rats.Further analysis by Gene Ontology and KEGG pathway revealed that differential gene expression was mainly reflected in the difference in cell protein binding and biomolecular composition,and differences occur in metabolism,cell signaling,and lipid synthesis enrichment pathways.?5?Based on the results of gene sequencing,this paper studied the WAT browning mechanism from the cAMP-PKA pathway.It was found that COST,COSM and CTS significantly increased the expression levels of UCP1,PGC1?,PRMD16,ATF2 protein and mRNA in epididymal fat of obese rats,and significantly increased the expression levels of UCP1,PGC1?,PRMD16 protein and mRNA in BAT.These results suggest that COST,COSM and CTS can promote the expression of thermogenic genes in BAT and promote the expression of browning genes in WAT by activating cAMP-PKA signaling pathway,which promotes browning of epididymis WAT in obese rats and increases BAT production.Cellular molecular level:To further influence the effects of COST and COSM on WAT browning,this study used induced 3T3-L1 preadipocytes to differentiate into mature adipocytes for COST and COSM intervention.The results showed that COST and COSM could promote the adipogenic differentiation rate of 3T3-L1 to over 90%,and significantly reduce the formation of lipid droplets.In addition,COST and COSM significantly increased the expression levels of UCP1,PGC1?and PRAM16 in 3T3-L1 adipocytes in a concentration-dependent manner,suggesting that COST and COSM can promote the expression of browning genes in WAT at the cellular level.Conclusion:?1?HFD-induced obese rats have the potential to down-regulate WAT browning;?2?COST,COSM and CTS may induce epididymal fat browning in obese rats to lose weight;?3?COST and COSM may promote the expression of thermogenic genes and browning genes such as UCP1,PGC1?,and PRAM16 by activating the cAMP-PKA pathway to promote WAT browning.