シロネズミ脳のチロシン水酸化酵素活性に及ぼすニコチン酸とトリプトファンの影響 (第2報)
1979 年 37 巻 3 号 p. 107-115
詳細
1979 年 37 巻 3 号 p. 107-115
Tyrosine hydroxylase activity in the brain homogenate increased and nicotinic acid content in the brain and liver decreased in rats fed a tryptophan-imbalanced diet. In order to clarify the function of nicotinic acid, we studied the causes of increase in tyrosine hydroxylase activity in the tryptophan-imbalanced rats.
1) Tyrosine hydroxylase activity in the brain and nicotinic acid content in the liver and brain were not changed by the administration of nicotinic acid to rats fed on a 7% casein diet. However, tyrosine hydroxylase activity increased and nicotinic acid content decreased in rats fed on a 7% casein diet supplemented with methionine (0.3g/100g diet) and threonine (0.36g/100g diet), but normal activity and content were recovered by the administration of nicotinic acid or tryptophan.
2) In tryptophan-deficient rats, tyrosine hydroxylase activity and nicotinic acid content were not changed by the administration of nicotinic acid.
3) In protein-deficient rats, tyrosine hydroxylase activity and nicotinic acid content were not changed by the administration of nicotinic acid.
4) Tyrosine hydroxylase activity was increased and nicotinic acid content was decreased by the administration of tryptophan to tryptophan or protein-deficient rats.
5) A positive correlation was observed between the tryptophan content in the diet and the total nicotinic acid content in the brain. A negative correlation was noted between the total nicotinic acid content in the brain and the level of tyrosine hydroxylase activity. It was therefore, considered that the level of tyrosine hydroxylase activity in the brain was directly influenced by the nicotinic acid content in it, and that the level of nicotinic acid was maintained by tryptophan.
