Effects of high fat diet-induced obesity and swimming on mouse myocardial lipid accumulation

  AIM  To clarify the effects of high fat diet-induced obesity and swimming on mouse myocardial lipid accumulation.

  METHODS   C57BL/6J mice were divided into 4 groups: normal chow diet group (NC), high fat diet-induce obesity group (DIO), DIO in combination with low amount of exercise group (DIO+LE) and DIO in combination with high amount of exercise group (DIO+HE). DIO+LE mice performed swimming exercise for 30 minutes per day and DIO+HE mice swam for 3×30 minutes with 15 minutes interval per day. After finishing the 4-week swimming, the mice were sacrificed, and the myocardial lipid accumulation was observed by oil red O staining. The change in gene expression was analyzed by RT-qPCR and the change in MTCO2 levels, the marker protein of mitochondria, was observed by immunohistochemical staining.

  RESULTS  A small amount of lipid droplets existed in the myocardium in NC mice and the amount of lipid droplets significantly reduced in the myocardium of DIO mice. The lipid droplets in myocardium were restored in DIO+HE mice and showed significant increase as compared with those in DIO mice. The expressions of Acetyl CoA carboxylase 1 (ACC1) and fatty acid synthase (FAS) were significantly decreased, while the expressions of carnitine acyl transferase-1 and 2 (CPT1 and 2), glycerol-3-phosphate dehydrogenaase 1 (GPD1) and glycerol kinase (GyK) were significantly decreased in DIO mice as compared with those in NC mice. The expressions of CPT1 and CPT2 expression were further increased and the expressions of GPD1 and GyK were significantly decreased in DIO+HE mice as compared with those in DIO mice. MTCO2 levels were significantly increased in DIO+HE mice as compared with those in DIO mice.

  CONCLUSION  The DIO mice that are induced by high fat diet alone do not show the increase in myocardial lipid accumulation but exhibit reduction of myocardial lipid accumulation, and suitable amount of exercise reverses the DIO-induced changes in myocardial lipid accumulation. This study gives a new view of the influence of DIO and exercise on myocardial lipid accumulation.