• amino acids
  • Groups of rats were deprived of food overnight and then given free access to diets designed to raise (carbohydrate) or lower (carbohydrate and large neutral amino acids) brain tryptophan concentrations. (biochemj.org)
  • Correlations were made between brain tryptophan and (1) free serum tryptophan, (2) the ratio of free serum tryptophan to the sum of the other large neutral amino acids in serum that compete with it for uptake into the brain, (3) total serum tryptophan or (4) the ratio of total serum tryptophan to the sum of its circulating competitors. (biochemj.org)