Lower Synthesis and Higher Catabolism of Liver and Muscle Protein Compensate for Amino Acid Deficiency in Severely Protein-Restricted Growing Rat

Severely low-protein (LP) diets induce a decrease in body weight and an increase relative food including intake (FI) rat. In the liver, changes anabolic catabolic protein pathways could transitorily participate to compensate for amino acid (AA) deficiency. The present study investigated these liver muscle metabolic on LP diet fed growing rats. Growing rats were three weeks different containing 3–5–8–12–15 or 20% energy from milk protein. Body FI measured daily. At end of experiment, injected with 13C valine tissues biological fluids collected gene expression measurement, blood AA UPLC analysis synthesis rate determination muscle. Statistical was done by 1- 2-factor ANOVA, when data repeated. P3, P5 P8% resulted significant growth retardation lean mass. Severe deficiency induced addition, results showed activation GCN2 pathway, via ATF4-CHOP-TRB3 both muscle, which suggests inhibition initiation translation at level binding RNAt-Met. Liver proteolytic up-regulated ubiquitin-proteasome, caspase system autophagy. ubiquitin-proteasome autophagy increased as well calpain system. activated confirming degradation pathways, portal vein, indispensable lower severe deficient whereas vena cava no difference observed. restriction lowered catabolism effect observed moderate restriction. These confirm that play major role supplying response This funded doctoral school ABIES AlimH-INRAE department.