不同糖及糖水平对松浦镜鲤养殖过程中糖代谢相关基因表达的影响

Effects of different carbohydrates and different carbohydrate levels on mRNA expression of glucose metabolism related genes in different feeding stages of Songpu mirror carp(Cyprinus carpio)

为探讨在养殖不同阶段,不同糖及糖水平对松浦镜鲤肝脏糖酵解酶(GK和HK)、糖异生酶(G6Pase和PEPCK)和糖代谢相关基因(IGF-Ⅰ和GHR)m RNA表达水平的影响,实验采用2×2双因素设计实验,选择淀粉和葡萄糖2种糖源,2个糖水平(25%和50%),共4个实验组,分别为低淀粉组(LS)、高淀粉组(HS)、低葡萄糖组(LG)和高葡萄糖组(HG)。选用初始体质量为(8.30±0.15)g的松浦镜鲤420尾,随机分为4组,每组3个重复,每个重复35尾鱼。实验周期为7周。结果显示,不同养殖阶段,HK基因和IGF-Ⅰ基因在不同实验组中的表达趋势基本一致,HK基因在养殖1周时表达量显著升高,之后开始降低,IGF-Ⅰ基因在养殖3周时表达量显著升高。在不同养殖阶段,GK、PEPCK、G6Pase和GHR基因的表达趋势受糖水平和糖种类的影响。在低糖水平下(LS组和LG组),这些基因表现了相同的变化趋势,GK和GHR基因在1周时表达量最高,之后开始下降;PEPCK基因在3周时表达量最高;G6Pase在1周时表达量升高,之后下降,在7周时表达量又有上升趋势。在高糖水平下,HS组的GK基因的表达量在各个养殖阶段差异不显著,而HG组的GK基因则在1周时表达量显著升高;HS组和HG组的PEPCK基因的表达量在各个养殖阶段差异不显著;HS组的G6Pase基因的表达量在各个养殖阶段差异不显著,而HG组的G6Pase基因则在3周时表达量显著升高;HG组的GHR基因的表达量在各个养殖阶段差异不显著,而HS组的GHR基因则在3周时表达量显著升高。在养殖初期(1周),高糖饲料显著促进了HK基因的表达,并抑制了PEPCK、G6Pase和GHR基因的表达。

This experiment was aimed to study the effect of different carbohydrates and different carbohydrate levels on m RNA expression of glycolytic enzyme（glucose kinase, GK; hexokinase, HK）, gluconeogenesis enzyme（Glucose-6-phosphatase, G6 Pase; phosphoenolpyruvate carboxykinase, PEPCK）, glucose metabolism related genes（Insulin-like Growth Factor-Ⅰ, IGF-Ⅰ; Growth Hormone Receptor, GHR） in different feeding stages of Songpu mirror carp（Cyprinus carpio）. Four experimental diets were formulated to contain two carbohydrates（starch and glucose） diets with two levels（250 g/kg and 500 g/kg）（Low level starch group： LS; High level starch group： HS; Low level glucose group： LG; High level glucose group： HG） two carbohydrates（glucose and starch）and two carbohydrate levels（25% and 50%）（LS/HS/LG/HG） using 2×2 double factor experimental design, 420 Songpu mirror carp（mean weight=[8.30±0.15] g） were randomly divided into 4 dietary treatments with 3 triplicates and 35 fish per triplicate and were reared for 7 weeks. The results showed that in different feeding stages, the m RNA expression levels of HK gene and IGF-Ⅰ gene in different experimental groups were basically in the same trend. The m RNA expression levels of HK gene at feeding 1 W was significantly increased and then decreased. The m RNA expression level of IGF-Ⅰ gene was significantly increased at feeding 3 W. IGF-Ⅰ gene expression increased significantly at feeding 3 W. In different feeding stages, the m RNA expression levels of GK, PEPCK,G6 Pase and GHR genes were affected by carbohydrate levels and carbohydrate types. At low carbohydrate level（LS group and LG group）, the m RNA expression levels of these genes showed the same trend. The m RNA expression levels of GK and GHR genes were significantly higher at feeding 1 W and then began to decline. The m RNA expression level of PEPCK gene was the highest at feeding 3 W. The m RNA expression level of G6 Pase genes were significantly higher at feeding 1 W, then began to decline and showed a rising trend at feeding 7 W. At high carbohydrate levels, the m RNA expression level of GK gene in HS group was not significantly different at different feeding stages. But the m RNA expression level of GK gene in HG group was increased significantly at feeding1 W. The m RNA expression level of PEPCK gene in HS group and HG group had no significant difference at different feeding stages. The m RNA expression level of G6 Pase gene in HS group had no significant difference at different feeding stages. But the m RNA expression level of G6 Pase gene in HG group was increased significantly at feeding 3 W. The m RNA expression level of GHR gene in HG group had no significant difference at different feeding stages, while the m RNA expression level of GHR gene in HS group was increased significantly at feeding3 W.In the early feeding stage（1 W）, the m RNA expression level of HK gene was significantly promoted by high carbohydrate diet. While, the m RNA expression levels of PEPCK, G6 Pase and GHR genes were suppressed by high carbohydrate diet. In conclusion, this study investigated the effects of different carbohydrates and carbohydrate levels on the expression trend of enzymes and genes involved in glucose metabolism at different feeding stages. It provides a theoretical basis for the application of carbohydrate in feed.