Molinari Giovanni S, Wojno Michal, Kwasek Karolina
Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University, Carbondale, IL, USA.
Center for Fisheries, Aquaculture, and Aquatic Sciences, Southern Illinois University, Carbondale, IL, USA; Department of Biological Sciences, University of New Hampshire, Durham, NH, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2024 Dec;298:111742. doi: 10.1016/j.cbpa.2024.111742. Epub 2024 Sep 12.
Evidence suggests that fish are more tolerant than mammals to imbalanced dietary amino acid profiles. However, the behavioral and physiological responses of fish to individual deficiencies in dietary indispensable amino acids (IDAA) remain unclear. This study examined how stomachless fish respond to diets deficient in limiting IDAA (lysine, methionine, and threonine), using Zebrafish (Danio rerio) as a model. The response to deficient diets was assessed based on; 1) growth performance and feeding efficiency; 2) feed intake; 3) expression of appetite-regulating hormones and nutrient-sensing receptors; and 4) muscle postprandial free amino acid (FAA) levels. There were 6 treatments, each with 3 replicate tanks. A semi-purified diet was formulated for each group. The CG diet was based on casein and gelatin, while the FAA50 diet had 50 % of dietary protein supplied with crystalline amino acids. Both were formulated to contain matching, balanced amino acid profiles. The remaining diets were formulated the same as the FAA50 diet, with minor adjustments to create deficiencies in selected IDAA. The (-) Lys, (-) Met, and (-) Thr diets had lysine, methionine, and threonine withheld from the FAA mix, respectively, and the Def diet was deficient in all three. The juvenile Zebrafish were fed to satiation 3 times daily from 21 to 50 days-post-hatch. Results showed that 50 % replacement of dietary protein with crystalline amino acids significantly reduced growth of juvenile Zebrafish. There were no significant differences in growth between the FAA50 group and groups that received deficient diets. The deficiency of singular IDAA did not induce significant changes in feed intake; however, the combined deficiency in the Def diet caused a significant increase in feed intake. This increased feed intake led to decreased feeding efficiency. A significant decrease in feeding efficiency was also observed in the (-) Lys group. There was an observed upregulation of neuropeptide Y (NPY), an orexigenic hormone, in the Def group. Overall, results from this study suggest stomachless fish increase feed intake when challenged with IDAA-deficient diets, and the regulation of NPY might play a role in this response.
有证据表明，鱼类比哺乳动物对不均衡的膳食氨基酸谱更具耐受性。然而，鱼类对膳食必需氨基酸（IDAA）个体缺乏的行为和生理反应仍不清楚。本研究以斑马鱼（Danio rerio）为模型，研究了无胃鱼对缺乏限制性IDAA（赖氨酸、蛋氨酸和苏氨酸）的日粮的反应。基于以下方面评估对缺乏日粮的反应：1）生长性能和摄食效率；2）采食量；3）食欲调节激素和营养感应受体的表达；4）肌肉餐后游离氨基酸（FAA）水平。有6种处理，每种处理有3个重复水族箱。为每组配制了半纯化日粮。对照日粮（CG日粮）以酪蛋白和明胶为基础，而FAA50日粮有50%的膳食蛋白质由结晶氨基酸提供。两者都被配制为含有匹配、平衡的氨基酸谱。其余日粮的配制与FAA50日粮相同，但进行了微小调整以造成选定IDAA的缺乏。（-）赖氨酸、（-）蛋氨酸和（-）苏氨酸日粮分别从FAA混合物中 withheld 赖氨酸、蛋氨酸和苏氨酸，而缺乏日粮（Def日粮）在所有三种氨基酸上都缺乏。幼体斑马鱼在孵化后21至50天每天喂食3次至饱足。结果表明，用结晶氨基酸替代50%的膳食蛋白质显著降低了幼体斑马鱼的生长。FAA50组和接受缺乏日粮的组之间的生长没有显著差异。单一IDAA的缺乏没有引起采食量的显著变化；然而，Def日粮中的联合缺乏导致采食量显著增加。这种采食量的增加导致摄食效率降低。在（-）赖氨酸组中也观察到摄食效率显著降低。在Def组中观察到促食欲激素神经肽Y（NPY）上调。总体而言，本研究结果表明，无胃鱼在受到IDAA缺乏日粮挑战时会增加采食量，并且NPY的调节可能在这种反应中起作用。
