Metabolic Effects of Histidine-Deficient Diets Fed to Growing Rats by Gastric Tube

Abstract

Effects of histidine deficiency on muscle carnosine and anserine levels and on activities of enzymes associated with histidine catabolism and protoporphyrin synthesis were investigated. Male Sprague-Dawley (150 g) rats were tubefed isonitrogenous, isocaloric, defined diets containing 0%, low (0.013%) or adequate (0.45%) histidine for 8–13 days. While histidine-deficient animals maintained body weight, muscle and plasma histidine and carnosine concentrations decreased rapidly and remained low following a 3-day histidine repletion period. Hepatic histidine ammonia-lyase and histidine-pyruvate transaminase activities were decreased in histidine-deficient animals, whereas formiminotransferase activity was unchanged. Hematocrit levels and hemoglobin concentrations declined progressively during histidine depletion and the activity of erythrocyte and hepatic δ-aminolevulinic acid dehydratase also decreased relative to controls. Evidence is presented indicating that decreased histidine catabolism combined with carnosine and hemoglobin degradation can provide sufficient histidine to explain the slow onset of negative nitrogen balance associated with histidine deficiency and that impaired protoporphyrin synthesis may partially explain the anemia observed in the absence of dietary histidine.