It has previously been suggested that auditory event related potentials (AEPs) are a potential marker of central serotonergic (5-HT) activity in man, with the slope of the AEP amplitude stimulus intensity function (ASF-slope) inversely correlating with 5-HT activity. However, two recent studies investigating this hypothesis in healthy subjects by rapidly lowering central 5-HT concentrations using the acute tryptophan depletion paradigm have found no effect on ASF-slope [Biological Psychology, 59 (2002) 121; Psychopharmacology (Berl), 146 (1999) 101]. These studies employed a 50g tryptophan depletion drink, which has been argued may not lower central 5-HT concentrations sufficiently. We here report the effect of tryptophan depletion on the AEP ASF-slope using 100g amino acid drinks with and without tryptophan in 14 healthy male subjects, employing a within subject, double blind, random, balanced order, cross-over design. No significant effect of tryptophan depletion was found on ASF-slope. These negative findings cast further doubt on the hypothesis that the ASF-slope is an indicator of central 5-HT function.

中文翻译：

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色氨酸消耗对健康志愿者听觉事件相关电位的响度依赖性缺乏影响

以前有人认为听觉事件相关电位 (AEP) 是人类中枢血清素 (5-HT) 活动的潜在标志物，AEP 振幅刺激强度函数 (ASF-斜率) 的斜率与 5-HT 呈负相关活动。然而，最近的两项研究通过使用急性色氨酸消耗范式快速降低中心 5-HT 浓度来在健康受试者中调查这一假设，但发现对 ASF 斜率没有影响 [生物心理学，59 (2002) 121; 精神药理学 (Berl), 146 (1999) 101]。这些研究使用了 50 克色氨酸消耗饮料，有人认为这可能无法充分降低中心 5-HT 浓度。我们在此报告了色氨酸消耗对 14 名健康男性受试者使用 100 克含和不含色氨酸的氨基酸饮料对 AEP ASF 斜率的影响，采用内主题、双盲、随机、平衡顺序、交叉设计。没有发现色氨酸消耗对 ASF 斜率有显着影响。这些负面发现进一步怀疑 ASF 斜率是中枢 5-HT 功能指标的假设。