Kumkhong Suksan, Marandel Lucie, Plagnes-Juan Elisabeth, Veron Vincent, Boonanuntanasarn Surintorn, Panserat Stephane
School of Animal Technology and Innovation, Institute of Agricultural Technology, Suranaree University of Technology, Nakhon Ratchasima, Thailand.
INRAE, Université de Pau et des Pays de l'Adour, E2S UPPA, Nouméa, France.
Front Physiol. 2020 Apr 17;11:286. doi: 10.3389/fphys.2020.00286. eCollection 2020.
The aim of this study was to explore for the first time in omnivorous fish the concept of nutritional programming. A nutritional stimulus was accomplished by microinjecting 2 M glucose into yolk reserves during the alevin stage in Nile tilapia (). At the molecular level in fry, at 1 week post-injection, glucose stimuli were associated with the up-regulation of genes involved in glycolysis (, , , and ), glucose transport () pathways and down-regulation of genes related to gluconeogenesis (, , and ) and amino acid catabolism (, ) ( < 0.05), demonstrating that the larvae well received the glucose stimulus at a molecular level. Moreover, 20 weeks after glucose injection, early glucose stimuli were always linked to permanent effects in juvenile fish, as reflected by a higher level of glycolytic enzymes [, and at both mRNA and enzymatic levels and pyruvate kinase (PK) activity]. Finally, the effects of the glucose stimulus history were also examined in fish fed with two different dietary carbohydrate/protein levels (medium-carbohydrate diet, CHO-M; high-carbohydrate diet, CHO-H) in juvenile fish (during weeks 20-24). As expected, the CHO-H diet induced the expression of glycolytic and lipogenic genes (, , , , , and ) and suppressed the expression of gluconeogenic and amino acid catabolism genes (, , , , , and ). Nevertheless, the early glucose stimulus led to persistent up-regulation of glycolytic enzymes (, , , and ) at both the mRNA and enzyme activity levels and glucose transporter as well as lower gluconeogenic gene expression ( < 0.05). More interestingly, the early glucose stimulus was associated with a better growth performance of juvenile fish irrespective of the diets. These permanent changes were associated with DNA hypomethylation in the liver and muscles, suggesting the existence of epigenetic mechanisms at the origin of programming. In conclusion, for the first time in tilapia, early glucose stimuli were found to be clearly associated with a positive metabolic programming effect later in life, improving the growth performance of the fish.
本研究的目的是首次在杂食性鱼类中探索营养编程的概念。通过在尼罗罗非鱼仔鱼期向卵黄储备显微注射2 M葡萄糖来实现营养刺激。在注射后1周的鱼苗分子水平上，葡萄糖刺激与糖酵解相关基因（、、、和）、葡萄糖转运（）途径的上调以及糖异生相关基因（、和）和氨基酸分解代谢相关基因（、）的下调相关（<0.05），表明幼体在分子水平上很好地接受了葡萄糖刺激。此外，在葡萄糖注射20周后，早期葡萄糖刺激始终与幼鱼的长期效应相关，这体现在糖酵解酶在mRNA和酶水平以及丙酮酸激酶（PK）活性上的更高水平。最后，还在幼鱼（20 - 24周期间）中研究了葡萄糖刺激历史对喂食两种不同碳水化合物/蛋白质水平日粮（中等碳水化合物日粮，CHO - M；高碳水化合物日粮，CHO - H）的鱼的影响。正如预期的那样，CHO - H日粮诱导了糖酵解和脂肪生成基因（、、、、、和）的表达，并抑制了糖异生和氨基酸分解代谢基因（、、、、、和）的表达。然而，早期葡萄糖刺激导致糖酵解酶在mRNA和酶活性水平以及葡萄糖转运蛋白上持续上调，同时糖异生基因表达降低（<0.05）。更有趣的是，无论日粮如何，早期葡萄糖刺激都与幼鱼更好的生长性能相关。这些永久性变化与肝脏和肌肉中的DNA低甲基化有关，表明在编程起源处存在表观遗传机制。总之，在罗非鱼中首次发现，早期葡萄糖刺激与后期生活中的积极代谢编程效应明显相关，改善了鱼的生长性能。
