Decrease in Appetite and Biochemical Changes in Amino Acid Imbalance in the Rat

Abstract

Rats fed imbalanced diets containing 10 and 15% of wheat gluten supplemented with lysine, to which a 3.1% mixture of essential amino acids lacking threonine was added, had lower “appetite quotient” values than control animals fed balanced diets. This confirms our assumption that decreased food intake is a primary effect of the imbalance. The plasma amino acid pattern produced by the imbalance was similar to that described in earlier experiments: the concentration of threonine, limiting amino acid of the diet decreased markedly, and the ratios between the concentration of other essential amino acids to threonine increased markedly. Animals fed the imbalanced diets showed an increased liver weight correlated with a high glycogen content, when expressed per 100 g of body weight. The liver lipid of imbalanced animals was decreased possibly as a consequence of the lipotropic effect of lysine and threonine that were ingested in amounts higher than needed for growth. These changes could be related to the mechanism responsible for food intake depression. The similarity between some of these observations and some of the changes occurring with kwashiorkor supports the theory that imbalance of amino acids in the diet plays an important role in the incidence of that disease.