Effects Of High Fat Diet On Lipid Accumulation,oxidative Stress And Autophagy In The Liver Of Chinese Softshell Turtle

In this paper,Chinese softshell turtle was used to study the effect of high fat diet of lipid accumulation,oxidative stress and autophagy in the liver.Experimental turtles were fed for 8 weeks using normal fat diet(NFD,control group,6.38% lipid)and high fat(HFD,high fat group,13.89% lipid).Then their growth index(weight gain rate,specific growth rate,feed conversion rate,hepatosomatic index and the survival rate),lipid accumulation index(TG,TC,LDL-C and HDL-C),injury index(AST and ALT),oxidation index(ROS,MDA and PC),antioxidant index(T-SOD,GSH-PX,CAT,GST,GSH and ASA)in the liver of Chinese softshell turtle were measured.The relative expression levels of antioxidant-related genes(SOD,CAT,GST,Keap1,Nrf2,m TOR and S6K1)and the relative expression(MAP1LC3,m TOR,AMPK and ULK1)levels of autophagy m RNA were analyzed.The effects of high fat diet on liver lipid accumulation,oxidative stress and autophagy in Chinese softshell turtle were analyzed.Following is the main outcome of the study:(1)Effect of high fat diet on growth performance of Chinese softshell turtleThe final weight in HFD was significantly higher than NFD,and the weight gain rate,specific growth rate and hepatosomatic index(P <0.05)were significantly higher than NFD.The feed conversion rate was lower than NFD but there was no significant difference,indicating that high fat diet can promote the growth of Chinese softshell turtle.(2)Effect of high fat diet on lipid accumulation in Chinese softshell turtle liverCompared with NFD,the Chinese softshell turtle bred with high fat group indicated a significant increase in liver triglyceride(TG),total cholesterol(TC)and low-density lipoprotein cholesterol(LDL-C)levels(P <0.05).While the liver high-density lipoprotein cholesterol(HDL-C)content were decreased remarkably(P <0.05).Meanwhile,the levels of triglyceride(TG),low-density lipoprotein cholesterol(LDL-C)and total cholesterol(TC)in the serum were increased remarkably(P <0.05).While the level of high-density lipoprotein cholesterol(HDL-C)in the serum were decreased remarkably(P <0.05).The liver fat droplets of Chinese softshell turtle in the high fat group and the control group was observed by oil red staining.The number of lipid droplets of the high fat group was significantly more than the control group.These results indicate that high fat diet exacerbates the accumulation of liver and serum lipids in Chinese softshell turtle.High fat diet bred to Chinese softshell turtle,the levels of enzymatic activities of alanine amino transferase(ALT)and aspartate amino transferase(AST)in the serum was increased significantly(P <0.05),indicating that high fat diet also induced liver injury in Chinese softshell turtle.(3)Effect of high fat diet on oxidative stress of Chinese softshell turtle liverCompare with NFD,high fat diet group fed to Chinese softshell turtle,its liver reactive oxygen species(ROS)increased significantly(P <0.05).Malondialdehyde(MDA)and protein carbonyl(PC)levels were also increased greatly(P <0.05).At the same time,liver antioxidant enzymes were decreased significantly,including reducing catalase(CAT),glutathione(GSH)content,total superoxide dismutase(T-SOD),glutathione Peroxidase(GPX),glutathione-S transferase(GST)enzymatic activity and superoxide anion(ASA)ability(P <0.05),indicating that high fat diet induces Chinese softshell turtle liver oxidation system injury.Moreover,the corresponding m RNA expressions of the antioxidant genes T-SOD,CAT,GST and GPX of Chinese softshell turtle were also significantly decreased(P <0.05),which may be attributed to a significant up-regulation of Kelch-like epichlorohydrin-related protein 1(Keap1)and down-regulation of NF-E2-related nuclear factor(Nrf2)expression(P<0.05).(4)Effect of high fat diet on autophagy of Chinese softshell turtle liverCompared to NFD,high fat diet group fed to Chinese softshell turtle,its autophagy-associated gene AMP-activated protein kinase(AMPK),Unc-51autophagy-activated kinase(ULK1)and microtubule-associated protein 1A/1B light chain 3(MAP1LC3)m RNA expression levels was remarkably up-regulated(P <0.05).However,mammalian target of rapamycin(m TOR)gene expression level was significantly decreased(P <0.05),and by the outcome of electron microscopy,high fat diet group autophagosomes were increased compared with the control group.The results showed that high fat diet can induce autophagy in the liver.