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U.S. Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND 58202
Brain amino acids were measured in 30-day-old male Long-Evans rats subsequent to feeding a 20% egg white biotin-enriched zinc-deficient diet for 9 days. The zinc-deficient (ZD) group was given distilled deionized water. Zinc-supplemented control groups included pair-fed (PF), ad libitum-fed (AL) and ad libitum-fed, over-night fasted (OF) animals. Brain tyrosine concentrations and related amino acid ratios tended to be higher when food was consumed in all groups. Brain tryptophan concentrations and a brain amino acid ratio (glycine + serine + glutamine + taurine:leucine + isoleucine + valine + methionine) were not related to food intake in ZD rats in contrast to zinc-adequate controls. Also the brain ratio of tryptophan to the sum of large neutral amino acids minus tryptophan was not related to food intake in the ZD and AL-OF groups in contrast to the PF group. There were some differences in brain amino acid concentrations between ZD rats and the control groups; however, the pattern of the brain amino acids in ZD rats did not suggest that food intake was directly influenced by them.
KEY WORDS: zinc deficiency appetite brain amino acids
1 This investigation was supported in part by the U.S. Department of Agriculture Cooperative Agreement No. 12-14-3001-294.
Manuscript received 21 May 1982.