Impact Of Treatment With Swimming Exercise And Metformin On Serum Chemerin And Chemerin Protein Expression Levels In Different Tissues Of High-fat-diet-fed Obesity Rats

Objective To investigate the effects of swimming exercise, metformin and the combination of both interventions on serum chemerin levels, metabolic parameters and chemerin protein expression levels in epididymis adipose tissue (EAT) , subcutaneus adipose tissue(SAT) and muscle tissue (MT) of high-fat-diet induced obesity rats and to explore the relationship between chemerin and obesity-related metabolic disorders.Methods 70 SD rats were randomly divided into two groups in which 10 rats were fed with normal control diet as the NC group, and the remaining 60 were fed with high fat diet as the HD group. The rats'body weight was measured every two weeks. After 16 weeks obesity model(n=40) was established from HD group and was randomly divided into four groups: high fat group(HF) , swimming group(SWI) , metformin group(MET) , and the combination of swimming and metformin group(SAM) with 10 rats in each group. Body weight(BW), fasting blood glucose(FBG), fasting insulin(FINS), total cholesterol(TCH), triglyceride(TG), very low density lipoprotein(VLDL), HOMA-IR and fasting chemerin were detected before and after 6 weeks of treatment. Chemerin protein expression levels in EAT, SAT and MT were determined by Western Blot.Resultsâ‘ After 16 weeks high fat diet induced obesity, the levels of BW, FBG, FINS, TCH, TG, HOMA-IR and chemeirn in each group were increased significantly in contrast to those in NC group (P<0.05). There were no statistical differences in the parameters among the four groups of the obesity model (P>0.05). Chemerin protein expression levels of obesity group in EAT, SAT and MT, especially that of EAT increased compared to ND group(P<0.05),and there was no statistical differences in chemerin protein expression levels between SAT and MT.â‘¡After 6 weeks intervention, the levels of BW, FBG, FINS ,TCH,TG,VLDL,HOMA-IR and chemerin in SWI group, MET group and SAM group were down-regulated compared to those in HF group(P<0.05), but the parameters showed no difference among the three intervention groups (P>0.05). In EAT and SAT, chemerin expression levels of the group of SWI, MET and SAM, especially SAM group decreased after intervention. Chemerin expression levels of the group of MET, SWI and SAM in MT decreased with no statistical difference.â‘¢The level of FINS correlated independently with that of chemerin regardless of before or after intervention(P<0.05). Serum chemerin levels were positively related to chemerin protein expression levels in EAT (r=0.89, P<0.05).Conclusionâ‘ High fat diet could induce SD rats obesity and also increase the levels of serum chemerin and chemerin protein expression levels in adipose tissue and muscle tissue.â‘¡Swimming, metformin and the combination of both intervention could down-regulate the level of chemerin, especially in visceral adipose tissue and improve metabolic disorders remarkably in obesity rats.â‘¢Chemerin may be a key participant element in the etiology and pathophysiology of obesity-related metabolic disorders.