Dunn A J
Department of Neuroscience, University of Florida College of Medicine, Gainesville 32610.
Life Sci. 1988;42(19):1847-53. doi: 10.1016/0024-3205(88)90023-9.
Brain concentrations of tryptophan, serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) and plasma amino acids were measured after 15 or 30 minutes of intermittent footshock. Footshock treatment significantly decreased the content of 5-HT in prefrontal cortex and hypothalamus, but not brainstem at 15 min, but the decreases were reversed by 30 min. 5-HIAA, the major catabolite of 5-HT, increased in prefrontal cortex after 15 min, and in prefrontal cortex and hypothalamus after 30 min footshock. 5-HIAA:5-HT ratios were increased at both timepoints in all three brain regions. Concomitant changes in the ratios of 3,4-dihydroxyphenylacetic acid (DOPAC) to dopamine and 3-methoxy,-4-hydroxyphenylethyleneglycol (MHPG) to norepinephrine were also observed. Brain concentrations of tryptophan increased progressively during the footshock in all three brain regions. Plasma concentrations of both tryptophan and tyrosine were also significantly increased, while those of histidine and lysine were decreased. It is possible that the stress-related changes in 5-HT metabolism are due to increased plasma tryptophan, in turn causing increased brain tryptophan and 5-HT synthesis. However, the transient decreases in 5-HT suggest a footshock-induced increase of 5-HT release, depleting existing stores of 5-HT, that are replenished by the increased systemic availability of tryptophan.
在间歇性足部电击15或30分钟后，测量了大脑中色氨酸、血清素（5-羟色胺，5-HT）和5-羟吲哚乙酸（5-HIAA）的浓度以及血浆氨基酸浓度。足部电击处理在15分钟时显著降低了前额叶皮质和下丘脑，但未降低脑干中5-HT的含量，但在30分钟时这些降低情况得到了逆转。5-HT的主要分解代谢产物5-HIAA在足部电击15分钟后在前额叶皮质中增加，在30分钟后在前额叶皮质和下丘脑中增加。在所有三个脑区的两个时间点，5-HIAA:5-HT比率均升高。同时还观察到3,4-二羟基苯乙酸（DOPAC）与多巴胺的比率以及3-甲氧基-4-羟基苯乙二醇（MHPG）与去甲肾上腺素的比率的伴随变化。在所有三个脑区中，色氨酸的大脑浓度在足部电击期间逐渐增加。血浆中色氨酸和酪氨酸的浓度也显著增加，而组氨酸和赖氨酸的浓度则降低。5-HT代谢中与应激相关的变化可能是由于血浆色氨酸增加，进而导致大脑色氨酸和5-HT合成增加。然而，5-HT的短暂降低表明足部电击诱导了5-HT释放增加，耗尽了现有的5-HT储备，而这些储备由色氨酸全身可用性的增加来补充。
