Effects Of Cold Exposure On Lipid Metabolism In Obese Mice Induced By High-fat Diet

Modern intensive livestock was mainly carried out in an open or semi-open culture model.Livestock and poultry have a high sensitivity to low temperature,and cold stress of animals occured frequently.As a result,the development of animal husbandry faces severe challenges of low temperature climate.A number of studies have shown that while cold stress inhibits the growth of livestock and poultry,it also has a tendency to reduce adipose deposition and affect the body's lipid metabolism function.As an important hub of various metabolic pathways in the body,how does liver tissue participate in the regulation of lipid balance and regulate lipid metabolism during the development of cold stress? This has not been reported yet.Therefore,in-depth study of the effects of cold exposure on liver tissue structure and lipid metabolism-related functions of mice,analysis of the mechanism of cold exposure on mice lipid metabolism disorders,and in-depth exploration of molecular biological mechanisms of pathogenic mechanism of cold stress and the body's response to cold stress injury of great significance.In order to elucidate the mechanism of cold exposure affecting the lipid metabolism disorder in mice,this study selected 5-week-old male C57 BL / 6J mice as experimental subjects to construct an animal model of obese mice induced by high-fat diet.After the successful construction of the obese mice model,the experimental mice were given acute or chronic cold exposure.Acute cold exposure conditions were: low temperature 4? for 6hours;chronic cold exposure conditions were: low temperature 4? for 4weeks.After the cold exposure,measured the body weight,waist circumference,liver weight,weight of mice epididymal fat(eWAT),subcutaneous groin fat(subcWAT),and scapular brown fat(iBAT)of each experimental group;then used qRT-PCR,Western-Blot,HE staining,ELISA and other technologies to detect the biochemical indexes and oxidative stress related indexes of serum lipid metabolism in mice of each experimental group,as well as mRNA and protein expression levels of the de novo fatty acid synthesis related enzymes,fatty acid ?-oxidation related enzymes and oxidative stress-related indicators in liver tissue.The results show that chronic cold exposure can reduce the weight,waist circumference,liver weight,and eWAT,subcWAT and iBAT weight of mice to relieve obesity,but acute cold exposure has no effect on the above indicators.Acute cold exposure can increase the concentration of corticosterone,adiponectin and MDA in serum,and reduce the concentration of leptin,LDL-C,NEFA,SOD and GPx in serum.Chronic cold exposure can increase the concentration of adiponectin,SOD,GPx in serum,and reduce the concentration of insulin,LDL-C,HDL-C,TCHO,TG,NEFA,GPx in serum.Both acute and chronic cold exposure can inhibit the expression of DNL-related genes and proteins(SREBP-1c,ACC1,FAS,and ACLY)in livers of obese mice;promote liver fatty acid ?-oxidation-related genes and proteins(CPT1,in normal mice and obese mice)CPT2,Adipor2 and PPAR?)expression.Acute cold exposure reduces the gene and protein expression of mice liver(Nrf2,HO-1),and chronic cold exposure can increase the gene and protein expression of mice liver(Nrf2,HO-1).The above results indicate that chronic cold exposure can alleviate dyslipidemia and oxidative stress in obese mice induced by high-fat diet.Both acute and chronic cold exposure can inhibit the expression of genes and proteins related to de novo synthesis of fatty acids in the liver of high-fat obese mice,and promote the expression of genes and proteins related to lipolysis,thereby inhibiting lipid synthesis and promoting lipid breakdown.