高脂饮食诱导肥胖和游泳运动对小鼠心脏脂质沉积的影响

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

目的明确高脂饮食诱导肥胖和游泳运动对小鼠心脏脂质沉积的影响。方法 C57BL/6J小鼠分为普通饲料组(NC)、高脂饲料诱导肥胖组(DIO)、肥胖低运动组(DIO+LE)、肥胖高运动组(DIO+HE),DIO+LE小鼠每天自由游泳30分钟,DIO+HE小鼠游泳3×30分钟,间隔15分钟。连续游泳运动4周后,油红O染色检测心脏脂质沉积,RT-qPCR分析基因表达变化,免疫组织染色观察线粒体标记物MTCO2水平变化。结果 NC小鼠心脏可见少量脂滴,DIO小鼠心肌细胞内脂滴的数量显著减少(P<0.05)。DIO+HE小鼠心肌细胞内脂滴的数量较DIO显著增加(P<0.05)。DIO小鼠心脏中乙酰辅酶A羧化酶1(ACC1)、脂肪酸合酶(FAS)等基因表达较NC组显著下降(P<0.05),肉毒碱棕榈酰转移酶(CPT1和CPT2)、3-磷酸甘油脱氢酶(GPD-1)和甘油激酶(GyK)基因表达较NC显著升高(P<0.05)。DIO+HE进一步增加CPT1和CPT2表达,但是逆转DIO小鼠的GPD-1和GyK升高(P<0.05)。DIO+HE小鼠MTCO2免疫染色较DIO组显著增强(P<0.05)。结论单纯高脂饲料诱导的肥胖模型小鼠并未增加心脏脂质沉积,反而出现脂质减少,一定运动量可逆转此种变化。本研究为高脂饮食和运动影响心脏脂质沉积提供了新的认识。

AIM To clarify the effects of high fat diet-induced obesity and swimming on mouse myocardial lipid accumulation. METHODS C57 BL/6 J 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.