| This study was conducted to determine the effects of high-fat dietary supplementation of resveratrol and quercetin on lipid metabolism,growth performance,antioxidant capability and hepatic apoptosis of blunt snout bream,in order to provide preventive approaches to control aquatic metabolic disorder disease through improving immunity,disease resistance and antioxidant capability for the sustainable development of aquaculture industry.And,this study has three parts.Series 1 Effects of resveratrol supplementation on growth performance,lipid accumulation and lipid metabolism of high-fat diet-fed blunt snout breamIn this study,we aimed to investigate whether RSV can ameliorate high-fat diet(HFD)-induced hepatic steatosis in fish.Blunt snout bream(Megalobrama amblycephala;n=320)were fed a normal diet(NFD,5%fat,w/w),a HFD(11%fat),or a HFD supplemented with 0.04%,0.36%,or 1.08%RSV for 10 weeks.As expected,fish fed a HFD developed hepatic steatosis,as shown by elevated hepatic and plasma triglycerides,and increased plasma alanine aminotransferase(ALT)and aspartate aminotransferase(AST).RSV supplementation alleviated increases in body mass,whole body fat,and visceral fat,development of hepatic steatosis,elevations of plasma TG and glucose,and abnormalities of ALT and AST in HFD fed fish.RSV supplementation increased SIRT1 mRNA expression and consequently hepatic mRNA expression of ATGL,CPTla,and MTTP,implying up-regulation of lipolysis,β-oxidation,and lipid transport,respectively,in the liver.Conversely,hepatic LPL,SREBP-1c,PPARy,and ACLY mRNA expression were decreased,implying suppression of fatty acid uptake,lipogenesis,and fatty acid synthesis.Additionally,RSV down-regulated GCK and SGLT2 and up-regulated GLUT2 mRNA expression,thus restoring normal glucose fluxes.Thus,RSV improves lipid and glucose metabolism in blunt snout bream,effects which are potentially mediated by activation of SIRT1,then the optimal dose of resveratrol was 1.08%.Series 2 Effects of resveratrol supplementation on antioxidant capability,immunity and disease resistance of blunt snout bream fed high-fat dietThis study was conducted to investigate the effects of Resveratrol(RSV)supplementation on specific growth rate(SGR),nonspecific immunity function,antioxidant capability and disease resistance of blunt snout bream fed high-fat diet.This experiment was designed with five kinds of diets:a normal fat diet(NFD,5%fat,),a high fat diet(HFD 11%fat),and a HFD supplemented with 0.04%,0.36%,and 1.08%RSV,respectively.At the end of 10-week feeding trial,fish were challenged by Aeromonas hydrophila at the concentration of 1 ×107 CFU/mL,and the survival rate was recorded for the next 96h.The results showed that HFD supplemented with 1.08%RSV significantly reduced the SGR and average daily feed intake of blunt snout bream when compared to the other groups,the similar trend found in feed efficiency rate of blunt snout bream.In comparison with NFD,HFD significantly increased the levels of plasma MDA and NO,and decreased the level of plasma GSH in blunt snout bream.QRT-PCR results demonstrated that long-term HFD consumption induced the up-regulation of TNF-a,HSP70 and HSP90,which means HFD potently weaken antioxidant defenses in blunt snout bream.HFD supplemented with RSV at 0.04%significantly suppressed the activities of the plasma SOD.And yet,it not only significantly reduced the contents of plasma MDA and NO,but also significantly inhibited the activities of plasma SOD and CAT when HFD supplemented with 0.36%and 1.08%RSV.Besides,the plasma GSH content increased significantly when the fish fed HFD supplemented with 1.08%RSV.HFD supplemented with RSV at 0.04%,0.36%and 1.08%all significantly increased plasma complement 3 content,enhanced lysozyme activities,and down-regulated the mRNA expressions of hepatic HSP70,HSP90 and TNF-a in blunt snout bream.After A.hydrophila challenge,the significant highest survival rate was observed in fish fed 1.08%RSV supplemented diet.In summary,when blunt snout bream was fed with high-fat diet for long time,the body was in a state of oxidative stress.And,the appropriate dose of RSV added could ameliorate the state of oxidative stress in the body,then the optimal dose of resveratrol was 1.08%.Series 3 Combined effects of resveratrol and quercetin on growth performance,antioxidant capability and hepatic apoptosis of blunt snout bream(Megalobrama amblycephala)under high-fat stressThis study aimed to determine the effects of Resveratrol(R)and Quercetin supplementation on growth performance,antioxidant capability and hepatic apoptosis of blunt snout bream juvenile fish fed high-fat diet.This experiment was designed eight kinds of diets:a normal fat diet(NFD,5%fat),a high fat diet(HFD,11%fat),HFD/0.4%Q,HFD/0.8%Q,HFD/0.4%Q/0.5%R,HFD/0.8%Q/0.5%R,HFD/0.4%Q/1.0%R,HFD/0.8%Q/1.0%R,respectively.At the end of the 8-week feeding trial,the plasma and hepatic physiological and biochemical indexes showed that the high fat intake resulted in a significantly higher level of plasma glucose,TG and TC,and significantly higher hepatic aspartate aminotransf--erase(AST)and EC:3.5.4.4 adenosine deaminase(ADA)activities;Supplementation of high-fat diet with resveratrol or quercetin could reverse the high-fat diet induced high level of plasma glucose,TG and TC,hepatic oxidative injury and apoptosis in blunt snount bream juvenile.In this study,the expression of genes relating to antioxidant capability,lipid and glucose metabolism,such as SIRT1,MaCu/Zn-SOD,MaCAT and MaGPx were up regulated,whereas the expressions of genes relating to inflammatory response and apoptosis were down-regulated in the liver of resveratrol or quercetin fed juvenile fish compared to HFD fed juvenile fish.As is known that resveratrol and quercetin are the agonist of SIRT1,and SIRT1 regulates the energy and substance metabolism in higher animals.On the whole,resveratrol and quercetin may relieve the state of abnormal metabolism of blunt snout bream juvenile under high-fat diet stress by activating SIRT1,then the best combination of composite groups was 0.5%resveratrol and 0.4%quercetin. |
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