Rats Rapidly Reject Diets Deficient in Essential Amino Acids

Abstract

Omnivores must obtain diets balanced with respect to amino acids to support growth and protein synthesis. The standard paradigm used to study behavioral responses to amino acid deficiency combines deficient diets with dietary novelty. The objective of this study was to examine the effects of amino acid deficiency on the first meal of rats without the confounding effects of novelty. We report on a series of five studies of feeding behavior in rats. Rats were fed low protein diets for 5-7 d and then exposed to diets with and without essential amino acids. Rats consistently demonstrated recognition of essential amino acid deficiency within the first meal by a significant reduction in first meal duration, rejecting the deficient diets after just 12-16 min exposure. This is the first report of a rapid effect of amino acid-deficient diets without the confounding effects of dietary novelty.

Threonine-deficient diets induced changes in hepatic bioenergetics

“…It has been shown that the rapid rejection of amino acid-decent diets corresponds to decreases in the level of the limiting indispensable amino acid in the anterior pyriform cortex of rats (3,28). The smaller depression in both food intake (see below) and weight gain values obtained in this study compared with those previously published can be explained by essentially three factors: 1) the age of the rats; 2) the protein selected to design the diet; and 3) the nutritional requirements for rat growth.…”

“…Recent studies showed that the response to amino acid deficiency takes 15 min to develop [if previously fed a low threonine (Thr) diet; Refs. 22,28], but few data exist to understand biochemical changes related to bioenergetics at longer periods and in organs other than brain.…”

Calcium-Dependent Eukaryotic Initiation Factor 2α Phosphatase Restores Control to Anterior Piriform Cortex Neural Circuitry after Activation by Essential Amino Acid Deficiency

“…For the in vitro studies, the tissue was taken without further dietary changes. For the gene-chip experiments, animals were fed BAS for the week prior to the experiment and then given a fresh food cup with either BAS, threonine devoid (Dev) or an IAA complete diet (corrected, COR i.e., Control, Cont) for 2 hr prior to collection of the APC tissue; for details and rationale for use of these diets see Koehnle et al [3].…”

“…Omnivorous mammals and birds show rapid sensing of IAA deficient food during the first meal; they reject a deficient diet within 20 min [3]. This adaptive behavioral response is associated with activation of neurons both in vivo [4] and in vitro [5], found in the ventro-rostral area of the APC (APCvr) [5][6][7].…”

Dependent on dietary treatments of mothers, rats showed individual preference of diets containing ingredients produced with different cultivation strategies

“…Amongst other factors playing a role for the choose are the nutritional content of the food and the taste of the food, and rats' capability to identify and avoid poison and to choose the more nutritional feed, combined with their tendency to investigate new food sources, which results in manifold and flexible feeding behaviour. Investigations concerning essential and/or dangerous contents using laboratory rats are based on these characteristics (Fromentin and Nicolaidis, 1996;Koehnle et al, 2003), which has proven efficient (Benett and Henderson, 1972). Some food preference tests with various bread, common beets, beet roots, carrots, apples, and wheat have shown that rats were able to discriminate between organic and conventional products (Plochberger, 1989;Plochberger and Velmirov, 1992;Mäder et al, 1993).…”