Harper A E, Peters J C
Department of Nutritional Sciences, College of Agricultural and Life Sciences, University of Wisconsin, Madison 53706.
J Nutr. 1989 May;119(5):677-89. doi: 10.1093/jn/119.5.677.
Analysis of evidence of associations among dietary protein content, brain amino acid and serotonin concentrations, and protein self-selection by rats suggests that 1) protein intake is not regulated precisely, although rats will select between low and high protein diets to obtain an adequate, but not excessive, amount of protein; 2) associations between brain serotonin concentration and protein intake are weak, although consumption of single meals of protein-deficient diets will elevate brain serotonin concentration; 3) the nature of signals that drive rats to avoid diets containing inadequate or excessive amounts of protein remains obscure; (4) whole brain amino acid and serotonin concentrations are quite stable over the usual range of protein intakes, owing to competition among amino acids for uptake across the blood-brain barrier and effective metabolic regulation of blood amino acid concentrations; 5) protein intake and preference are not in themselves regulated, but what appears to be regulation of intake and preference is a reflection of the responses of systems for control of plasma amino acid concentrations; and (6) the relative stability of the average protein intake of groups of self-selecting rats (which gives the appearance of regulation) results from averaging the variable behavioral responses--learned aversions and preferences--of rats to the variety of sensory cues arising from diets that differ in protein content.
对大鼠饮食蛋白质含量、脑氨基酸和血清素浓度以及蛋白质自我选择之间关联证据的分析表明：1）尽管大鼠会在低蛋白和高蛋白饮食之间进行选择以获取适量而非过量的蛋白质，但蛋白质摄入量并未得到精确调节；2）脑血清素浓度与蛋白质摄入量之间的关联较弱，尽管食用单一餐次的蛋白质缺乏饮食会提高脑血清素浓度；3）驱使大鼠避免摄入蛋白质含量不足或过量饮食的信号本质仍不清楚；4）由于氨基酸在血脑屏障上的摄取竞争以及对血液氨基酸浓度的有效代谢调节，在通常的蛋白质摄入范围内，全脑氨基酸和血清素浓度相当稳定；5）蛋白质摄入量和偏好本身并未受到调节，看似对摄入量和偏好的调节反映的是控制血浆氨基酸浓度系统的反应；6）自我选择蛋白质的大鼠群体平均蛋白质摄入量的相对稳定性（这给人一种调节的表象）是将大鼠对蛋白质含量不同的饮食所产生的各种感官线索的可变行为反应（习得的厌恶和偏好）进行平均的结果。
