Peters J C, Harper A E
Physiol Behav. 1984 Nov;33(5):783-90. doi: 10.1016/0031-9384(84)90048-9.
Control of protein intake was studied in young rats that were allowed to choose between either protein-free and 55% casein diets or 15% and 55% casein diets. Animals on the protein-free vs. 55% casein regimen exhibited a lower weight gain, a lower cumulative energy intake and a greater cumulative total protein intake during the 13-day study compared to rats selecting between 15% and 55% casein. The daily average proportion of total food selected as casein by animals choosing between protein-free and 55% casein diets increased from 15% to 38% during the course of the study. In contrast, rats choosing between 15% and 55% casein chose 18-22% of total food as protein throughout the entire study. Long-term protein intake or protein selection did not correlate significantly with whole-brain contents of 5-HT or 5-HIAA. Our results suggest that protein intake is not regulated at a constant proportion of total calories, but is controlled between a minimum level that will support rapid growth and a maximum that, if exceeded, would require the animal to undergo substantial metabolic adaptation. The mechanism controlling protein selection may involve diet-induced changes in the brain content of total free indispensable amino acids.
在幼鼠中研究了蛋白质摄入量的控制情况，这些幼鼠可在无蛋白饮食和55%酪蛋白饮食之间，或15%和55%酪蛋白饮食之间进行选择。与在15%和55%酪蛋白之间进行选择的大鼠相比，采用无蛋白与55%酪蛋白饮食方案的动物在为期13天的研究中体重增加较低、累积能量摄入量较低且累积总蛋白摄入量较高。在研究过程中，在无蛋白和55%酪蛋白饮食之间进行选择的动物选择作为酪蛋白的总食物的每日平均比例从15%增加到38%。相比之下，在15%和55%酪蛋白之间进行选择的大鼠在整个研究过程中选择18 - 22%的总食物作为蛋白质。长期蛋白质摄入量或蛋白质选择与全脑5 - 羟色胺（5 - HT）或5 - 羟吲哚乙酸（5 - HIAA）含量无显著相关性。我们的结果表明，蛋白质摄入量并非以总热量的恒定比例进行调节，而是在支持快速生长的最低水平和如果超过该水平动物将需要进行大量代谢适应的最高水平之间受到控制。控制蛋白质选择的机制可能涉及饮食诱导的总游离必需氨基酸脑含量变化。
