title: Influence of high dietary threonine on growth and amino acids in blood and tissues of rats.
abstract: Diets containing 8 or 15% protein from casein plus limiting amino acids, 25% fat and adequate levels of other nutrients for rat growth were supplemented with 0, 0.5, 1.0, 2.0 or 4% of excess L-threonine. Addition of up to 1% excess threonine had little effect on weight gains or food intakes of weanling rats, but addition of 2 and 4% threonine caused a drastic reduction in weight gains or food intakes (up to 41%); the adverse effect being more severe in rats fed lower protein diets. Addition of graded levels of excess threonine resulted in (5 to 47-fold and 4 to 20-fold) increase in concentration of free threonine in rat plasma and brain, respectively. Addition of excess threonine also caused up to 5-fold increase in plasma level of 3-methylhistidine, suggesting increased muscle protein breakdown.
authors.affiliation: Health Protection Branch, Food Directorate, Banting Building, Tunney's Pasture, Health and Welfare Canada, K1A OL2, Ottawa, Ontario, Canada.
authors.forename: G
authors.initials: G
authors.lastname: Sarwar
authors.forename: R W
authors.initials: RW
authors.lastname: Peace
authors.forename: H G
authors.initials: HG
authors.lastname: Botting