Maes M, Scharpé S, Verkerk R, D'Hondt P, Peeters D, Cosyns P, Thompson P, De Meyer F, Wauters A, Neels H
University Department of Psychiatry, Clinical Research Center-Mental Health, Antwerp, Belgium.
Arch Gen Psychiatry. 1995 Nov;52(11):937-46. doi: 10.1001/archpsyc.1995.03950230051008.
To investigate the seasonal variation in levels of plasma L-tryptophan and competing amino acids (CAAs) in healthy humans in relation to climatic variables, total serum protein levels, and violent suicide occurrence.
Twenty-six healthy volunteers (13 men and 13 women; mean [+/- SD] age, 38.7 +/- 13.4 years) had monthly blood samplings for assays of L-tryptophan, valine, leucine, isoleucine, tyrosine, and phenylalanine during 1 calendar year.
Significant annual rhythms were detected in L-tryptophan, the L-tryptophan/CAA ratio, phenylalanine, valine, and leucine, and semiannual rhythms in L-tryptophan values and in L-tryptophan/CAA ratios. Plasma L-tryptophan and the L-tryptophan/CAA ratio were significantly lower in the spring than in the other seasons. The peak-trough differences in the yearly variation expressed as a percentage of the mean were 17.1% and 16.1% for L-tryptophan values and L-tryptophan/CAA ratios, respectively. The amplitude of the yearly variation in all CAAs was low, ie, less than 7%. An important part of the variance in L-tryptophan availability (ie, 12% to 14%) could be explained by the composite effects of present and past climatic factors; higher ambient temperature and relative humidity in the face of lower air pressure are the most important predictors of low L-tryptophan availability. Important and positive time relationships were noted between total serum protein level and all amino acid concentrations, and a significant time relationship was also noted between the seasonal variation in L-tryptophan availability and the occurrence of violent suicide in Belgium.
Our results show a bimodal seasonal pattern in the availability of plasma L-tryptophan that matches seasonal patterns in the prevalence of violent suicide in the local population and depression in other studies.
研究健康人体内血浆L-色氨酸及竞争性氨基酸（CAA）水平的季节性变化，及其与气候变量、血清总蛋白水平和暴力自杀发生率的关系。
26名健康志愿者（13名男性和13名女性；平均年龄[±标准差]为38.7±13.4岁）在1个日历年内每月进行一次血液采样，以检测L-色氨酸、缬氨酸、亮氨酸、异亮氨酸、酪氨酸和苯丙氨酸。
检测到L-色氨酸、L-色氨酸/CAA比值、苯丙氨酸、缬氨酸和亮氨酸有显著的年度节律，L-色氨酸值和L-色氨酸/CAA比值有半年节律。春季血浆L-色氨酸和L-色氨酸/CAA比值显著低于其他季节。以平均值的百分比表示的年度变化峰谷差异，L-色氨酸值和L-色氨酸/CAA比值分别为17.1%和16.1%。所有CAA的年度变化幅度较低，即小于7%。L-色氨酸可用性差异的一个重要部分（即12%至14%）可由当前和过去气候因素的综合作用来解释；环境温度较高、相对湿度较大且气压较低是L-色氨酸可用性较低的最重要预测因素。血清总蛋白水平与所有氨基酸浓度之间存在重要的正时间关系，并且在比利时，L-色氨酸可用性的季节性变化与暴力自杀发生率之间也存在显著的时间关系。
我们的结果显示血浆L-色氨酸可用性存在双峰季节性模式，这与当地人群暴力自杀患病率的季节性模式以及其他研究中抑郁症的季节性模式相匹配。
