Rao S B, Raghuram T C, Krishnaswamy K
Nutr Metab. 1975;18(5-6):318-25. doi: 10.1159/000175610.
Administration of leucine at 3% level in the diet has been shown to increase tryptophan oxygenase activity and to decrease kynureninase activity in the liver and to increase quinolinic acid excretion in the urine of rats fed low amounts of vitamin B6 (0.5 mug/g diet). Vitamin B6 at 3 mug/g of diet was able to reverse the effects of leucine on enzyme activities, but not on quinolinic acid excretion. Isoleucine at 0.2% level could counteract the leucine effect on kynureninase but not on tryptophan oxygenase. Administration of leucine also decreased the 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in the brain. Simultaneous administration of isoleucine could counteract the effects of leucine on brain 5-HT and 5-HIAA partially at low amount of vitamin B6 but completely at higher levels of vitamin B6 in the diet.
在饮食中添加3%的亮氨酸已被证明可提高色氨酸加氧酶的活性，降低肝脏中犬尿氨酸酶的活性，并增加低维生素B6（0.5微克/克饮食）喂养的大鼠尿液中喹啉酸的排泄量。饮食中添加3微克/克的维生素B6能够逆转亮氨酸对酶活性的影响，但不能逆转其对喹啉酸排泄的影响。添加0.2%的异亮氨酸可抵消亮氨酸对犬尿氨酸酶的影响，但不能抵消其对色氨酸加氧酶的影响。亮氨酸的摄入还会降低大脑中的5-羟色胺（5-HT）和5-羟吲哚乙酸（5-HIAA）。同时添加异亮氨酸可部分抵消亮氨酸在低维生素B6水平时对大脑5-HT和5-HIAA的影响，而在饮食中维生素B6水平较高时则可完全抵消。
