Grass Juliane, Miller Robert, Carlitz Esther H D, Patrovsky Fabian, Gao Wei, Kirschbaum Clemens, Stalder Tobias
Technische Universität Dresden, Department of Psychology, Dresden, Germany.
Technische Universität Dresden, Department of Psychology, Dresden, Germany.
Psychoneuroendocrinology. 2016 Nov;73:109-116. doi: 10.1016/j.psyneuen.2016.07.221. Epub 2016 Jul 27.
Hair cortisol concentrations (hairF) are considered to be relatively robust to various confounding influences. However, a potentially important covariate factor that has received little attention in this context is hair exposure to ultraviolet/sunlight radiation. We conducted a detailed experimental investigation to examine the effects of light exposure on hair cortisol. In study I, a hydrocortisone-containing solution was subjected to short-term artificial light irradiation for 1, 3, 5, 10, 15, or 30min to evaluate the stability of cortisol molecules due to radiant energy. In study II, hair samples (N=12) were subjected to single short-term artificial light irradiation for 0, 1, or 5h to examine light-induced effects in the hair matrix. In study III, hair samples (N=25) were subjected to long-term naturalistic sunlight radiation over a period of two months (during summer) with daily exposure times of 0, 1, 3, or 6h, respectively. Besides cortisol, studies II & III also examined concentrations of cortisone (hairE), dehydroepiandrosterone (hairDHEA) and progesterone (hairP) in hair, quantified using LC-MS/MS technology. Results across the three studies consistently revealed effects of light irradiation on hair steroid concentrations: Longer light exposure resulted in a decrease of dissolved hydrocortisone (study I) as well as of hairF and hairE (studies II and III). Conversely, hairDHEA and hairP increased with longer natural sunlight exposure times (study III), while this effect was not observed for short-term artificial light irradiation (study II). Combined, our findings imply sunlight exposure as a potential confound in hair steroid research. Given the experimental character of this investigation, the magnitude of this effect under real-life testing conditions is difficult to estimate. To support future investigation into this, we designed a 'sunlight-exposure' questionnaire to share with the research community. The assessment and statistical accounting for sunlight exposure-related effects in future hair steroid research (using this or a similar questionnaire) may help to reduce the potential influence of this unwanted error source and could thus lead to more valid and reliable results. In addition, our data strongly suggest that hair samples for steroid analyses need to be stored in a dark environment.
头发皮质醇浓度（HairF）被认为对各种混杂影响具有相对较强的耐受性。然而，在这种情况下，一个潜在的重要协变量因素——头发暴露于紫外线/阳光辐射下——却很少受到关注。我们进行了一项详细的实验研究，以检验光照对头发皮质醇的影响。在研究I中，将含氢化可的松的溶液进行短期人工光照1、3、5、10、15或30分钟，以评估由于辐射能导致的皮质醇分子稳定性。在研究II中，对头发样本（N = 12）进行单次短期人工光照0、1或5小时，以检查头发基质中的光诱导效应。在研究III中，对头发样本（N = 25）在两个月（夏季）期间进行长期自然阳光辐射，每天暴露时间分别为0、1、3或6小时。除了皮质醇，研究II和III还使用液相色谱-串联质谱技术（LC-MS/MS）检测了头发中可的松（HairE）、脱氢表雄酮（HairDHEA）和孕酮（HairP）的浓度。三项研究的结果一致显示光照对头发类固醇浓度有影响：较长时间的光照导致溶解的氢化可的松（研究I）以及HairF和HairE（研究II和III）降低。相反，HairDHEA和HairP随着自然阳光暴露时间延长而增加（研究III），而短期人工光照未观察到这种效应（研究II）。综合来看，我们的研究结果表明阳光暴露是头发类固醇研究中的一个潜在混杂因素。鉴于本研究的实验性质，在实际测试条件下这种效应的大小难以估计。为支持未来对此的研究，我们设计了一份“阳光暴露”问卷，供研究界分享。在未来的头发类固醇研究中（使用此问卷或类似问卷）对与阳光暴露相关的效应进行评估和统计核算，可能有助于减少这种不必要误差来源的潜在影响，从而得出更有效和可靠的结果。此外，我们的数据强烈表明，用于类固醇分析的头发样本需要保存在黑暗环境中。
