Milner J D, Irie K, Wurtman R J
J Neurochem. 1986 Nov;47(5):1444-8. doi: 10.1111/j.1471-4159.1986.tb00777.x.
We examined the effect of phenylalanine (50-400 microM) on the electrically stimulated release of endogenous 3,4-dihydroxyphenylethylamine (dopamine or DA) from superfused rat striatal slices. In the absence of tyrosine, phenylalanine (25 microM) partially sustained DA release, but less well than an equimolar concentration of tyrosine. In the presence of tyrosine (50 microM), phenylalanine (in concentrations of greater than or equal to 200 microM) inhibited DA release into the superfusate. This inhibition was not associated with changes in tissue levels of tyrosine or DA, nor was it mimicked by addition of high concentrations of tyrosine or leucine to the medium. We conclude that phenylalanine is a less effective precursor of DA in rat striatum than tyrosine and that it can also act to inhibit DA synthesis, depending on its concentration.
我们研究了苯丙氨酸（50 - 400微摩尔）对电刺激下从离体大鼠纹状体切片中释放内源性3,4 - 二羟基苯乙胺（多巴胺或DA）的影响。在缺乏酪氨酸的情况下，苯丙氨酸（25微摩尔）能部分维持DA的释放，但效果不如等摩尔浓度的酪氨酸。在存在酪氨酸（50微摩尔）时，苯丙氨酸（浓度大于或等于200微摩尔）会抑制DA释放到灌流液中。这种抑制作用与组织中酪氨酸或DA水平的变化无关，向培养基中添加高浓度的酪氨酸或亮氨酸也不能模拟这种抑制作用。我们得出结论，在大鼠纹状体中，苯丙氨酸作为DA的前体不如酪氨酸有效，并且根据其浓度，它还可以抑制DA的合成。
