Dietary Aversion established by a deficient load: Specificity to the amino acid omitted from a balanced mixture

Abstract

Rats become averse to the odor of a protein-free diet presented after gastric administration of loads devoid of histidine and isoleucine but otherwise balanced in amino acid composition. The specific sensory aversion may in these cases explain the intake decrement seen shortly after loading. The suppression of intake shortly after a threonine-devoid load was, in contrast, not allied with an acquired aversion under the experimental conditions used. There were signs of aversion or anorexia following loads devoid of methionine, valine, phenylalanine of lysine. A complete balanced load, and to a lesser extent tryptophan- and perhaps glycine-devoid loads, induced a preference for the associated odor over an odor paired with saline intubation. Omission of leucine or arginine from the balanced mixture produced niether preference nor aversion. The results support a suggestion that reduced synthesis of a brain protein is aversion-inducing.