Viegas Ivan, Rito João, Jarak Ivana, Leston Sara, Caballero-Solares Albert, Metón Isidoro, Pardal Miguel A, Baanante Isabel V, Jones John G
CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Largo Marquês de Pombal,3004-517Coimbra,Portugal.
CFE - Center for Functional Ecology, Department Life Sciences, University of Coimbra, Calçada Martins de Freitas,3000-456Coimbra,Portugal.
Br J Nutr. 2015 May 14;113(9):1345-54. doi: 10.1017/S0007114515000574.
In the present study, the effects of partial substitution of dietary protein by digestible starch on endogenous glucose production were evaluated in European seabass (Dicentrarchus labrax). The fractional contribution of dietary carbohydrates v. gluconeogenesis to blood glucose appearance and hepatic glycogen synthesis was quantified in two groups of seabass fed with a diet containing 30% digestible starch (DS) or without a carbohydrate supplement as the control (CTRL). Measurements were performed by transferring the fish to a tank containing water enriched with 5% (2)H2O over the last six feeding days, and quantifying the incorporation of (2)H into blood glucose and hepatic glycogen by (2)H NMR. For CTRL fish, gluconeogenesis accounted for the majority of circulating glucose while for the DS fish, this contribution was significantly lower (CTRL 85 (SEM 4) % v. DS 54 (SEM 2) %; P < 0.001). Hepatic glycogen synthesis via gluconeogenesis (indirect pathway) was also significantly reduced in the DS fish, in both relative (CTRL 100 (SEM 1) % v. DS 72 (SEM 1) %; P < 0.001) and absolute terms (CTRL 28 (SEM 1) v. DS 17 (sem 1) μmol/kg per h; P < 0.001). A major fraction of the dietary carbohydrates that contributed to blood glucose appearance (33 (sem 1) % of the total 47 (SEM 2) %) had undergone exchange with hepatic glucose 6-phosphate. This indicated the simultaneous activity of hepatic glucokinase and glucose 6-phosphatase. In conclusion, supplementation of digestible starch resulted in a significant reduction of gluconeogenic contributions to systemic glucose appearance and hepatic glycogen synthesis.
在本研究中，评估了用可消化淀粉部分替代日粮蛋白质对欧洲海鲈（Dicentrarchus labrax）内源性葡萄糖生成的影响。在两组分别投喂含30%可消化淀粉（DS）日粮或不含碳水化合物补充剂作为对照（CTRL）日粮的海鲈中，定量分析了日粮碳水化合物与糖异生对血糖生成和肝糖原合成的贡献率。在最后六个投喂日，将鱼转移至装有富含5%（2）H2O的水的水箱中进行测量，并通过（2）H NMR定量分析（2）H掺入血糖和肝糖原中的情况。对于CTRL组鱼，糖异生占循环葡萄糖的大部分，而对于DS组鱼，这一贡献率显著降低（CTRL 85（标准误4）%对DS 54（标准误2）%；P<0.001）。DS组鱼通过糖异生（间接途径）进行的肝糖原合成在相对（CTRL 100（标准误1）%对DS 72（标准误1）%；P<0.001）和绝对（CTRL 28（标准误1）对DS 17（标准误1）μmol/kg每小时；P<0.001）方面也显著降低。对血糖生成有贡献的大部分日粮碳水化合物（占总量47（标准误2）%中的33（标准误1）%）与肝葡萄糖6-磷酸发生了交换。这表明肝葡萄糖激酶和葡萄糖6-磷酸酶同时发挥作用。总之，补充可消化淀粉导致糖异生对全身葡萄糖生成和肝糖原合成的贡献显著降低。
