背景:花生四酰基乙醇酰胺(AEA)和2-花生四酰基甘油(2-AG)是内源性大麻素系统的中心脂质介质。它们是高度相关的,因为它们参与了各种各样的炎症,代谢或恶性疾病。进一步阐明其作用方式,并在易于访问的矩阵中用作生物标志物,像血一样,受到血液采样过程中对偏差的敏感性和生理依赖性的限制,这导致报告浓度在低ng/mL范围内的高变异性。
目的:本综述的目的是确定分析前阶段的关键参数,并提出可靠测定血液样品中内源性大麻素(EC)的最低要求。
方法:报告的影响EC浓度的生理过程与已发表的分析前研究和来自生物分析方法验证的稳定性数据相结合。
结果:EC浓度变化的原因是多方面的。在某种程度上,它们是由个体间的因素引起的,比如性别,代谢状态和/或昼夜变化。然而,新鲜抽取的血液样品中的酶活性是改变AEA和2-AG浓度的主要原因,除了后者的额外非酶异构化。
结论:用于EC分析的血液样品需要在低温(>0°C)下立即处理以保持样品完整性。各自的血管或抗凝剂的标准化,采样时间点,施加的离心力和完整的处理时间可以进一步减少由样品处理引起的可变性。然而,需要对研究参与者进行广泛的表征,以减少因共变量导致的临床数据失真,并促进内源性大麻素系统的研究.
BACKGROUND: Arachidonoyl ethanolamide (AEA) and 2-arachidonoyl glycerol (2-AG) are central lipid mediators of the endocannabinoid system. They are highly relevant due to their involvement in a wide variety of inflammatory, metabolic or malign diseases. Further elucidation of their modes of action and use as biomarkers in an easily accessible matrix, like blood, is restricted by their susceptibility to deviations during blood sampling and physiological co-dependences, which results in high variability of reported concentrations in low ng/mL ranges.
OBJECTIVE: The objective of this review is the identification of critical parameters during the pre-analytical phase and proposal of minimum requirements for reliable determination of endocannabinoids (ECs) in blood samples.
METHODS: Reported physiological processes influencing the EC concentrations were put into context with published pre-analytical research and stability data from bioanalytical method validation.
RESULTS: The cause for variability in EC concentrations is versatile. In part, they are caused by inter-individual factors like sex, metabolic status and/or diurnal changes. Nevertheless, enzymatic activity in freshly drawn blood samples is the main reason for changing concentrations of AEA and 2-AG, besides additional non-enzymatic isomerization of the latter.
CONCLUSIONS: Blood samples for EC analyses require immediate processing at low temperatures (>0 °C) to maintain sample integrity. Standardization of the respective blood tube or anti-coagulant, sampling time point, applied centrifugal force and complete processing time can further decrease variability caused by sample handling. Nevertheless, extensive characterization of study participants is needed to reduce distortion of clinical data caused by co-variables and facilitate research on the endocannabinoid system.