Effects Of Living Low-training High On Lipophagy In Mice Adipose Tissue And Its Mechanism

PurposeLipid is the essential component of normal life.When the lipid accumulation in tissue cells causes the inner lipid imbalance,it is easy to cause obesity and obesity related metabolic diseases.Fatty acids that are in the fatty tissue are stored in the form of lipid droplets in the cell,and the storage and utilization of lipid droplets in the cells are the key to maintaining the lipid balance of the organism.Lipophagy is used as a way to dissolve the lipid droplets and cholesterol of the cells into the cells of glycerin and free fatty acids by the autophagy of the cells.Exercise and low oxygen can activate lipid droplets and regulate lipid storage in the body.A major intervention pattern that is Living Low-Training High is applied to reduce fat,but it is not yet known that the ability of high practice can be used to regulate the lipid decomposition of fat tissue by activating lipophagy.Therefore,this study aims to explore whether the low living high practice is to reduce lipid storage and possible molecular mechanism by activating fat cell liposuction,and provide theoretical basis for the regulation of lipid decomposition.MethodsThirty-two 2-month-old C57BL/6 healthy male mice were randomly divided into normoxic Control group(Control,group C,n=8)and Hypoxia Control group(Hypoxia,group H,n=8).Exercise group(group,n=8)and Living Low-Training High,Lo Hi,n=8.After a week of adaptive exercise,a 6-week hypoxic exercise training program was established according to previous experimental protocols.Group E underwent treadmill exercise under normal oxygen environment at a speed of 25m/min,1h/d,5d/week for 6 weeks of exercise training;Group H was exposed to hypoxia at 13.6% oxygen concentration from 8 to 18 o ’clock every day,and rested in normal oxygen environment for the rest of the day.The Lo Hi group lived at normoxic(21%)oxygen concentration and trained at hypoxic(13.6%)oxygen concentration,with the same training regimen as group E.After the 6-week hypoxic training,the body composition test was conducted.Before the body composition test,the weight of the mice was weighed.After 48 hours,the mice were anesthetized and sacrificed,and the subcutaneous fat and serum of the mice were taken.HE staining was used to observe the morphology of subcutaneous adipocytes in mice,LC3 and LAMP-2co-location levels were used to observe the clearance level of autophagosomes in adipocytes,the content of serum triglyceride was measured by dual-reagent direct method,and the expression levels of autophagy-related proteins and AMPK,AKT and other related molecular mechanisms were detected by Western blot.Results(1)After 6 weeks of intervention,compared with group C,the weight gain of mice in E,H and Lo Hi groups was decreased correspondingly,and the weight gain of mice in Lo Hi group was decreased more significantly(P<0.05);In addition,the change of body fat in mice was consistent with the change of body weight,which was also the decrease of body fat in the Lo Hi group,but not significant.(2)After 6 weeks of intervention,the serum triglyceride level(TG)in E,H and Lo Hi groups was significantly decreased compared with group C(p<0.01,p<0.01,p<0.01).Compared with group C,subcutaneous adipocyte diameter was significantly decreased in E,H and Lo Hi groups,and the number of adipocyte under the same field was significantly increased(p<0.01,p<0.01,p<0.01).(3)The effect of 6 weeks of intervention,compared with group C,colocalization coefficients of E,H and Lo Hi groups were significantly increased(p<0.01,p<0.05,p<0.01).The immunofluorescence co-location of Lo Hi was significantly higher than that of E and H groups(p<0.01,p<0.01).(4)The effect of 6 weeks of intervention,compared with group C,LC3 ⅱ / ⅰ and LAMP-2 protein expressions in E,H,Lo Hi groups were significantly increased regardless of the intervention methods(P <0.05,P <0.01,P <0.05).Compared with group C,the protein expression of Beclin1 in group E and H showed an increasing trend,but there was no significant difference(P >0.05),and the protein expression of Beclin1 in group Lo Hi was significantly increased compared with group C,E and H(p<0.05).Compared with group C,the protein expression of p62 in GROUP E and LOHI was significantly decreased(p<0.01),and the protein expression of p62 in group LOHI was significantly lower than that in group H(p<0.05).(5)After 6 weeks of intervention,compared with group C,exercise,hypoxia and their combined effects increased the phosphorylation level of AMPK,and the phosphorylation level of H and Lo Hi groups was more significant(p<0.05,p<0.01).Exercise and hypoxia training significantly reduced the phosphorylation level of AKT(p<0.05,p<0.01),but the phosphorylation level of group H was significantly higher than that of groups C,E and Lo Hi(p<0.01).Consistent with the protein expression of AKT,the intervention of low residence and high exercise significantly reduced the phosphorylation level of PI3K(p<0.05),but pure hypoxia and exercise intervention had no significant effect on PI3 K phosphorylation.Conclusion(1)The intervention of 6 weeks of exercise,hypoxia and living low-training high all reduced serum triglyceride level and promoted lipid drop metabolism in subcutaneous adipose tissue of mice,but living low-training high had a more significant effect.(2)The intervention of 6 weeks of exercise,hypoxia and living low-training high can activate lipophagy in subcutaneous adipose tissue.Exercise and hypoxia intervention can promote the degradation of lipid droplets in subcutaneous adipose tissue,which may be related to the activation of lipophagy,and living low-training high has a more significant activation effect than hypoxia and exercise alone.(3)The lipophagy activated by 6 weeks of exercise,hypoxia and living low-training high may be mainly related to AMPK and PI3K/AKT signaling pathway.