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| Effects of Carbohydrates on Transcription of Five Key Genes Involved in Lipid Metabolism in Hepatopancreas of Grass Carp Ctenopharyngodon idella |
| SUN Junjun,LU Ronghua,CHANG Zhiguang,QIN Chaobin,YANG Feng,NIE Guoxing |
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Abstract In current intensive aquaculture ,the hepatopancreatic lipid metabolic disorderis are serious in grass carp (Ctenopharyngodon idellus) ,and has caused the attention of people .The transcriptional effects of carbohydrates on the five key genes involved in lipid metabolism in hepatopancreas of grass carp were in‐vestigated in vivo and in vitro in order to get the exact regulatory mechanisms of carbohydrates on lipid me‐tabolism in grass carp .The expression levels of sterol regulatory element‐binding protein‐1c (SREBP‐1c) , peroxisome proliferator‐activated receptorα(PPARα) and acetyl‐CoA carboxylase (ACC) were analyzed in hepatopancreas of grass carp fed the diets containing low‐carbohydrates (24% ) and high carbohydrates (42% ) using quantitative real‐time fluorescent PCR technology .T he histological observation w as conduc‐ted in hepatopancreas of grass carp fed the diets containing low and high carbohydrates by H‐E staining . The SREBP‐1c ,fatty acid synthase (FAS) and lipoprotein lipase (LPL) gene expression patterns in vitro hepatocytes treated with different concentrations of glucose were detected by the quantitative real‐time flu‐orescent PCR .The results showed that there were significant higher relative expression levels of SREBP‐1c and ACC in the high carbohydrate group than in the control and in low carbohydrate group (P<0 .05) , without significantly differences in relative expression level of PPARα between the high carbohydrate group and the low carbohydrate group (P > 0 .05) .The histological observation revealed that fat accumu‐lation was induced in the hepatopancreas ,and the expression level of SREBP‐1c ,FAS and LPL was in‐creased first and then decreased with the increasing concentrations of glucose in the hepatocyte cultures , with the maximal level of SREBP‐1c at 10 mmol/L ,and the maximal FAS and LPL at 20 mmol/L in grass carp fed the high carbohydrate diet ( P< 0 .05 ) . T he findings suggested that the expression levels of SREBP‐1c ,FAS ,and LPL were adjusted by dietary glucose ,which may further regulate the transforma‐tion of carbohydrate into fat .T he research data can enrich the glucose metabolism regulation mechanism in fish ,and is expected to provide a theoretical basis for improvement of utilization efficiency of carbohydrates in fish feed .
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Received: 25 November 2015
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