氨氮胁迫下饥饿与复投喂对黄颡鱼肝脏中脂质代谢相关酶活性及相关基因表达的影响

为了研究氨氮胁迫下饥饿与复投喂对黄颡鱼脂质代谢的影响,将360尾黄颡鱼幼鱼初始体重为(14.95±0.03)g]随机分配到12个养殖桶中,每桶30尾.对照组人工饱食投喂42 d,试验组饥饿14 d后恢复投喂28 d.对照组和试验组分别被暴露到总氨氮浓度为0(低氨氮处理,正常养殖环境)和5.70 mg/L(高氨氮处理,...

Effects of Starvation and Re-Feeding on Enzyme Activities and Gene Expression Involved in Liver Lipid Metabolism of Yellow Catfish(Pelteobagrus fulvidraco)under Ammonia Nitrogen Stress

This experiment was conducted to study the effects of starvation and re-feeding on lipid metabolism of yellow catfish(Pelteobagrus fulvidraco)under ammonia nitrogen stress.Three hundred and thirty-six yellow catfishinitial body weight:(14.95±0.03)g]were randomly distributed into 12 culture buckets with 30 fish per bucket.The fish in the control group were fed on satiation for 42 days,and the fish in the trial group were starved for 14 days,then re-feeding to satiation for 28 days.The control group and trial group were exposed to 0(low ammonia nitrogen treatment,normal culture environment)and 5.70 mg/L ammonia nitrogen(high ammonia nitrogen treatment,ammonia nitrogen stress),respectively,and each group had 3 buckets of fish.The results showed as follows:after 14 days of starvation,the activities of 6-phosphogluconate dehydrogenase(6PGD)and fatty acid synthase(FAS),and the mRNA relative expression levels of 6PGD,glucose 6-phosphate dehydrogenase(G6PD),FAS,sterol-regulatory element binding protein-1(SREBP-1),peroxisome proliferator-activated receptorα(PPARα)and peroxisome proliferator-activated receptorγ(PPARγ)genes in the liver of fish in the high ammonia nitrogen treatment were significantly lower than those of fish in the low ammonia nitrogen treatment,but the activities of carnitine palmitoyltransferase(CPT)and lipoprotein lipase(LPL),and the mRNA relative expression levels of carnitine palmitoyltransferase 1(CPT1)and LPL genes were significantly higher than those of fish in the low ammonia nitrogen treatment(P<0.05).Under the ammonia nitrogen stress or normal culture environment,after 28 days of starvation,the activities of 6PGD and FAS,and the mRNA relative expression levels of 6PGD,G6PD,FAS,SREBP-1 and PPARγgenes in the liver of fish in the trial group were significantly lower than those of fish in the control group(P<0.05),but the activities of CPT and LPL,and the mRNA relative expression levels of PPARα,CPT1 and LPL genes were significantly higher than those of fish in the control group(P<0.05).After 28 days of re-feeding,the activities of 6PGD and FAS,and the mRNA relative expression levels of 6PGD,G6PD,FAS and PPARαgenes in the liver of fish in the high ammonia nitrogen treatment were significantly lower than those of fish in the low ammonia nitrogen treatment(P<0.05),but the activities of CPT and LPL,and the mRNA relative expression levels of CPT1 and LPL genes were significantly higher than those of fish in low ammonia nitrogen treatment(P<0.05).Under the ammonia nitrogen stress or normal culture environment,after 28 days of re-feeding,the activity of 6PGD and the mRNA relative expression levels of 6PGD and G6PD genes in the liver of fish in the trial group were significantly higher than those of fish in the control group(P<0.05),but the activity of LPL was significantly lower than that of fish in the control group(P<0.05).Moreover,under the ammonia nitrogen stress,the mRNA relative expression levels of FAS,SREBP-1 and PPARγgenes in the liver of fish in the trial group were significantly higher than those of fish in the control group(P<0.05),but the mRNA relative expression level of LPL gene was significantly lower than that of fish in the control group(P<0.05).The results indicate that both ammonia nitrogen stress and starvation stress can promote the lipid catabolism and inhibit the lipid anabolism of yellow catfish,and re-feeding after starvation can restore the lipid metabolism homeostasis of yellow catfish under ammonia nitrogen stress.