| In addition to promoting and maintaining male sexual characteristics,muscle mass and strength,and bone metabolic homeostasis,in recent years,an increasing number of studies have shown that hypoandrogenism/AR signaling is highly related to glucose and lipid metabolism disorders in obesity and obesity-related diseases.Numerous studies have confirmed that exercise could improve glycolipid metabolism,increase insulin sensitivity,and prevent and treat obesity and obesity-related diseases.Exercise increases serum testosterone and AR protein expression in insulin-sensitive peripheral tissues in men or male animals.This is one of the mechanisms by which exercise improves glucose and lipid metabolism and prevents obesity and obesity-related diseases in males.However,the mechanism by which exercise increases androgen / AR signal and how the increased androgen / AR signal regulates glucolipid metabolism in males has not been fully clarified.Metabolic regulators and enzymes play an important role in maintaining the balance of glucose and lipid metabolism,and their abnormal expression can lead to glucose and lipid metabolism disorders.It has been reported that androgen/AR can regulate a variety of metabolic regulators and enzymes including peroxisome proliferator-activated receptor-gamma coactivator-1 alpha(PGC-1α),Forkhead box protein O1(FOXO1),phosphoenolpyruvate carboxykinase(PEPCK),and stearoyl-Co A desaturase-1(SCD1).Among them,PGC-1α is involved in mitochondrial biogenesis,lipolysis,and fatty acid oxidation;FOXO1 plays an important role in maintaining glucose and lipid metabolic homeostasis,and FOXO1 mainly regulates the hepatic gluconeogenesis process by regulating its target gene PEPCK(gluconeogenesis rate-limiting enzyme);SCD1 is the rate-limiting enzyme that catalyzes the conversion of saturated fatty acids to monounsaturated fatty acids and is closely related to insulin resistance.However,whether the role of androgen/AR in exercise improving glucose and lipid metabolism in males is mediated by regulating the above metabolic regulators and enzymes is rarely reported.In addition,it is not clear how exercise increases androgen/AR signaling,thereby improving glucose and lipid metabolism and preventing and treating obesity and obesity-related diseases.Chemerin,a newly discovered adipokine,plays a vital role in the regulation of adipogenesis,insulin signaling,energy metabolism,appetite,inflammation,and cardiovascular function.Both animal experiments and human studies have shown that increasing the level of chemerin is closely related to glucose and lipid metabolism disorders in obesity and obesity-related diseases,and exercise could improve the metabolic dysfunction of glucose and lipid by reducing serum and tissue chemerin levels.Interestingly,recent studies have found that chemerin inhibits androgen synthesis,and serum chemerin levels are negatively correlated with male fertility and reproductive hormones.Therefore,we speculated that during exercise intervention in glucose and lipid metabolic diseases,exercise may enhance androgen/AR signaling by decreasing the expression of chemerin in male mice fed with high fat diet,which induce changes in its downstream metabolic regulators and key enzymes,and ultimately improves glucose and lipid metabolism disorders in male mice fed with high-fat diet.Purpose 1.To confirm the role of androgen/AR in the prevention of glucose and lipid metabolism disorders by exercise in male mice fed with high fat diet using castration surgery,AR antagonist,and agonist,and to further investigate whether this effect is also achieved by regulating the expression levels of FOXO1,PGC-1α,PEPCK and SCD1.2.After confirming the role of chemerin in the regulation of glucose and lipid metabolism using chemerin knockout mice and metabolomic techniques,we investigate the regulatory effects of chemerin on androgen/AR in non-exercised and exercised male mice fed with high fat diet,as well as the regulatory roles of chemerin on the above-mentioned metabolic regulators and enzymes.Study content and methods 1.Roles of androgen/AR in exercise prevention of glycolipid metabolism disorders in male mice fed with high fat diet,and its downstream metabolic regulators and enzymes 2.Changes in the expression of androgen/AR and its downstream metabolic regulators and enzymes in exercise prevention of glycolipid metabolism disorders induced by a high fat diet in male mice.Six-week-old C57BL/6 male mice were divided into normal diet group(C,n=8),high-fat diet group(HFD,n=8),and high-fat diet + exercise group(HFD+EX,n=8).HFD+EX mice were subjected to aerobic exercise for six weeks after two weeks of a high-fat diet(At this point,there were no significant changes in body weight and glucolipid metabolism disorders in mice).Food intake,body weight,body composition,endurance,and grip strength,as well as four physiological indicators of blood lipids,insulin sensitivity(OGTT),serum testosterone level(ELISA)were tested.Besides,the expression levels of AR and metabolic regulators and enzymes(FOXO1,PEPCK,PGC-1α,and SCD1)in liver and gastrocnemius were detected.2)Using surgical castration to study the roles of androgen in exercise prevention of glycolipid metabolism disorders induced by a high fat diet in male mice,and investigate whether these effects are related to androgen downstream metabolic regulators and enzymes.All six-week-old C57BL/6 male mice were fed with high fat diet and divided into control(Con,n=8),exercise(EX,n=8),castration(CAS,n=8),and castration+exercise(CAS+EX,n=8)groups.The mice in the EX and CAS+EX groups were fed with high fat diet for two weeks(At this point,there was no significant change in body weight and glucolipid metabolism disorders in mice)and were subjected to six weeks of aerobic exercise intervention,and the indicators measured were consistent with the above.3)Using AR antagonists flutamide to study the roles of AR in exercise prevention of glycolipid metabolism disorders induced by a high fat diet in male mice,and investigate whether these effects are related to AR downstream metabolic regulators and enzymes.AR function was inhibited by neck-embedded slow-release tablets(flutamide,F)in male mice.All 6-week-old male C57BL/6 mice were fed with high fat diet and divided into control(Con,n=8),exercise(EX,n=8),flutamide(F,n=8),and flutamide+exercise(F+EX,n=8)groups.The mice in the EX and F+EX groups were fed with high fat diet for 2 weeks(At this point,there was no significant change in body weight and glucolipid metabolism disorders in mice)and were subjected to 6 weeks of aerobic intervention,and the testing indicators were consistent with the above.4)Using AR agonists S4 to increase AR activity and investigate whether it could prevent glycolipid metabolism disorders induced by high fat diet under androgen deficient condition,and whether this effect is related to AR downstream metabolic regulators and enzymes.AR biological activity was activated by intraperitoneal injection of the selective androgen receptor modulator S4 in mice.All 6-week-old male C57BL/6 mice were fed with a high-fat diet and divided into control(Con,n=8),S4(S4,n=8),castration(CAS,n=8),and castration +S4 groups(CAS+S4,n=8).Mice in the S4 and CAS+S4 groups were fed with high fat diet for two weeks(At this point,mice did not have significant changes in body weight and glycolipid metabolism disorders)and were subjected to a six-week intraperitoneal injection of S4,the assays were consistent with the above.2.Using chemerin knockout mice to study the roles of chemerin in exercise prevention of glycolipid metabolism disorders induced by high fat diet in male mice,and investigate the regulation of chemerin on androgen/AR.1)After the successful establishment of the chemerin knockout mice model,the roles of chemerin on glucose and lipid metabolism disorders in male mice fed with a high fat diet were studied Five-week-old male flox mice and adipo-specific chemerin knockout mice(adipo-chemerin(-/-))were fed a regular diet and a high fat diet for five weeks,respectively.Blood glucose and lipid metabolism parameters were measured,as well as the changes in epididymal adipose tissue metabolites were analyzied by untargeted metabolomics technique.2)After confirming that chemerin could regulate androgen/AR and its downstream metabolic regulators and enzymes,we investigated the roles of chemerin in the regulation of androgen/AR in non-exercising and exercising mice fed with a high fat diet.Eight-week-old male wild-type(WT)and whole-body chemerin knockout(chemerin(-/-))mice were subjected to regular dietary and high-fat dietary interventions for 38 weeks,respectively.The mice were then randomized into non-exercise groups and exercise groups.The exercise group underwent six weeks of aerobic exercise intervention.Serum glycolipid metabolism indexes were measured by chemiluminescence method,and serum testosterone levels were measured by ELISA.The protein levels of chemerin,AR,FOXO1,PEPCK,PGC-1α,and SCD1 in gastrocnemius were detected by western blot.Results: 1.The roles and mechanisms of androgen/AR in the exercise prevention of disorders of glycolipid metabolism in mice fed with a high fat diet.1.1 Changes in androgen/AR and its downstream metabolic regulators and enzymes in aerobic exercise prevention of disorders of glycolipid metabolism in mice fed with high fat diet.After six weeks of aerobic exercise,serum testosterone,as well as AR protein expression in liver and gastrocnemius were significantly increased in the HFD+EX group mice,while the expression levels of FOXO1,PGC-1α,and SCD1 in liver and gastrocnemius were improved,and serum TC and TG levels were reduced and insulin sensitivity was significantly increased in the HFD+EX group male mice.1.2 Using surgical castration to confirm the roles of androgen in exercise prevention of glucose and lipid metabolism disorders induced by a high fat diet in male mice.Compared with Con group mice,serum testosterone level was significantly lower in CAS group mice,accompanied by a significant increase in serum TG level and the area under the curve of OGTT in CAS group mice.Androgen deficiency partially inhibited the exercise prevention of dyslipidemia disorders(TC,TG,HLD)and the development of insulin resistance in high fat mice,and confirmed the roles of androgen in exercise prevention of glucose and lipid metabolism disorders induced by high fat diet in male mice.1.3 Using AR antagonist and agonist to demonstrate the roles of AR in exercise prevention of glucose and lipid metabolism disorders induced by high fat diet in male mice.1.3.1 Effects of AR antagonist flutamide(F)on exercise prevention glycolipid metabolism disorders in male mice fed with high fat diet.Compared with the Con group,the serum LDL level and the area under the curve of OGTT were significantly increased in the F group mice.Compared with the EX group,serum TG and LDL levels were significantly increased in the F+EX group.1.3.2 Effects of AR agonist S4 on glycolipid metabolism in male mice fed a high fat diet Further,supplementation with selective androgen receptor agonist S4 in normal and castration(low androgen level)mice fed with high fat diet to confirm the roles of AR and investigate whether the activation of AR in low androgen could improve glycolipid metabolism in high fat fed mice.The results revealed that compared with the Con group mice,serum TC,TG,LDL and the area under the curve of OGTT were significantly reduced in the S4 group;Compared with the CAS group mice,serum TG,LDL and the area under the curve of OGTT were also significantly reduced in the CAS+S4 group.The above results suggest that 1)the roles of androgen/AR in preventing glucose and lipid metabolism disorders in male mice fed with high fat diet were at least partially mediated through regulating the protein levels of FOXO1,SCD1 and PGC-1α in the liver and gastrocnemius;2)The mechanisms of androgen/AR in exercise prevention glucose and lipid metabolism disorders in male mice fed with high fat diet were also related to the changes of protein levels of FOXO1,SCD1 and PGC-1α in liver and gastrocnemius.1.4 Mechanisms of androgen/AR in exercise prevention disorders of glycolipid metabolism in male mice fed with high fat diet.1.4.1 Effects of surgical castration on metabolic regulators and enzymes in male mice fed a high fat diet Compared with Con group mice,the protein levels of FOXO1 and SCD1 were significantly increased,and PGC-1α protein levels were significantly decreased in liver and gastrocnemius in the CAS group mice;however,the protein levels of FOXO1,SCD1 and PGC-1α in liver and gastrocnemius in CAS+EX group mice showed no significant changes(only a trend of change)compared with mice in the CAS group.1.4.2 Effects of AR antagonist F and agonist S4 on metabolic regulators and enzymes in mice fed with high fat diet.Compared with the Con group mice,the protein levels of FOXO1 and SCD1 were significantly increased and PGC-1α protein levels were significantly decreased in liver and gastrocnemius in the F group;Compared with mice in the CAS group,the protein levels of FOXO1 and SCD1 were significantly decreased,while the protein levels of PGC-1α were significantly increased in liver and gastrocnemius of the CAS+S4 group mice;Compared with the F group mice,the protein levels of FOXO1,SCD1 and PGC-1α in liver and gastrocnemius in the F+EX group mice were not substantially changed.2.Chemerin regulates androgen/AR and the roles of chemerin in exercise increase of androgen/AR in high fat fed male mice.2.1 Knockout chemerin improves glycolipid metabolism disorders in male mice fed with high fat diet,and its metabolomic analysis.Abnormal glycolipid metabolism was significantly improved in adipo-chemerin(-/-)male mice fed with a high fat diet,as evidenced by the significantly reduced serum TC,LDL and the increased insulin levels and insulin sensitivity in adipo-chemerin(-/-)mice,compared to flox mice.Non-targeted metabolomics analysis identified that 28 metabolites were significantly increased in epididymal adipose tissue,and these differential metabolites were mainly associated with arginine and proline metabolism,phenylalanine metabolism,and phenylalanine,tyrosine,and tryptophan biosynthetic pathways.2.2 Chemerin knockdown increases androgen/AR levels and alters the protein levels of glucose and lipid metabolism regulators and key enzymes in male mice fed with high fat diet.2.2.1 Under non-exercise conditions,Knockout chemerin increases androgen/AR levels and regulates glycolipid metabolism regulators and enzymes in mice fed with high fat diet.Under high fat diet conditions,serum testosterone and AR protein levels in gastrocnemius were significantly enhanced in chemerin(-/-)mice compared with WT group mice,accompanied by the reduced serum TG levels and the increased HDL levels.2.2.2 Under exercise conditions,the roles of exercise in increasing androgen/AR levels,regulating glucose and lipid metabolism regulators and enzymes are likely to be related to the reduction of chemerin levels.Along with the improvement of dyslipidemia in male mice fed with a high-fat diet(serum TC,TG,and LDL levels were reduced in WT+EX mice compared with WT),exercise significantly decreased their serum chemerin levels,and increased serum testosterone levels and gastrocnemius AR protein expression,and reduced the protein levels of metabolic regulators and enzymes in gastrocnemius(the protein levels of FOXO1 and SCD1 were significantly reduced,but the PGC-1α protein levels were significantly increased).The above results suggested that exercise is likely to improve glucose and lipid metabolism disorders in male mice fed with a high-fat diet through decreasing chemerin levels,which increasing androgen/AR and regulating metabolic regulators and enzymes.Conclusion 1.Using castration surgery,AR antagonist and agonist to confirm the roles of androgen/AR in exercise prevention of glycolipid metabolism disorders of male mice induced by high fat diet.2.The effects of increased and activated androgen/AR in preventing glucose and lipid metabolism disorders in high fat diet male mice are achieved by regulating the protein levels of FOXO1,PGC-1α and SCD1;Not only that,the roles of androgen/AR in exercise prevention of glycolipid metabolism disorders in male mice fed with high fat diet were also mediated by regulating the above-mentioned metabolic regulators and enzymes.3.knockdown chemerin could up-regulate androgen/AR levels and modulate the downstream target genes of AR-related metabolic regulators and enzymes,as well as improve serum lipid profiles in male mice fed with high fat diet.4.Exercise may enhance androgen/AR signaling by decreasing chemerin levels,which in turn modulates glycolipid metabolism regulators and enzymes,and improve glycolipid metabolism in male mice fed a high fat diet. |
