The Effects Of Different Activation Methods Of Brown Adipose Tissue On The Mice Energy Metabolism

The imbalance of the energy metabolism,which has become an increasingly important and serious public health concern worldwide,is a major risk factor for many diseases,such as obesity,type II diabetes,nonalcoholic fatty liver disease,and cardiovascular disease,etc.The brown adipose tissue(BAT)plays an important role in modulating energy balance of healh field due to its ability to enhance energy expenditure in a manner of uncoupling proteins dependent mitochondrial membrane potential reduction.Therefore,taking advantage of BAT activation to burn extra triglycerides is an attractive and effective way to improve energy metabolism balance.In the current research,we investigated the effects of three different methods,including physical,chemical and functional food activation,on BAT functions,the major findings are as follows:1.From the physical activation aspect,the mice were treated with 4? cold temperature.We found that the mRNA expression of FGF21 in BAT was significantly up-regulated upon 8 hours of cold exposure.Consistently,serum FGF21 levels also significantly increased upon 8 hours of cold exposure and kept in high levels during the entire experimental periods.In addition,the expression of beige cell mark CD 137 together with the histological results showed a strong positive correlation between FGF21 and BAT formation.Moreover,we found that at early time point of the cold exposure,the mobilization of triglyceride by BAT is the major phenotype,whereas at late stage of the cold exposure,it changed into sustained BAT activation.The results from BAT removal experiment further revealed that the mice without BAT still had the ability of beige formation,which indicated that beige cell formation was mainly controlled by neurological input.2.For chemical BAT activation,the diet induced obesity(DIO)mice were treated with Fosinopril,a third-generation drug of angiotensin-converting enzyme inhibitor(ACEI).We found that ACEI treatment could significantly activate BAT by up-regulation of BAT specific gene UCP1 and fatty acid oxidation related gene expression.In addition,ACEI significantly increased the resting metabolic rate,energy expenditure and heat production in DIO mice.Moreover,ACEI treatment prominently reduced adiposity,improved lipid metabolism,accelerated glucose homeostasis and alleviated insulin resistance in DIO mice.3.To explore the BAT activation ability of functional food ingredients,the DIO mice were treated with garlic extracts,alliin and allicin.We found alliin had no significant effects on BAT function.However,the allicin treatment significantly increased glucose expenditure and improved insulin sensitivity,leading to an efficient reduction in fasting plasma glucose level and effective protection for fatty liver.Through the alliin and allicin on spontaneous activity of mice DIO,energy intake,using infrared thermal image scanner,positron emission computed tomography imaging(PET-CT),and other comprehensive statistics and comparison,further validated the BAT activation by allicin.Taken together,multi-dimentional experiments including phisical,chemical and functional food ingredients treatments were performed on animal models in the current study.We found these methods could significantly activate BAT,thus improving energy metabolism,reducing adiposity,increasing insulin sensitivity and alleviating fatty liver.We believe the current study paves new ways to treat the metabolic diseases caused by the imbalance of energy metabolism.