University of Manitoba, Department of Chemistry, Centre for Oil and Gas Research and Development (COGRAD), 586 Parker Building, 144 Dysart Rd., Winnipeg, MB, R3T 2N2, Canada.
Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK, S7N 5B3, Canada.
Chemosphere. 2022 Feb;288(Pt 2):132522. doi: 10.1016/j.chemosphere.2021.132522. Epub 2021 Oct 11.
The aim of this study was to determine the kynurenine (KYN) to tryptophan (TRP) ratio (KTR) in fish tissue to assess its usefulness as a biomarker of acute stress. Laboratory held rainbow trout (Oncorhynchus mykiss) were subjected to an acute stressor and KYN, TRP and cortisol were measured in liver and brain tissues at 4- and 48-h post-stress. The analytical method used to determine our analytes was based on lyophilization, and liquid-solid extraction followed by isotope dilution high-performance liquid chromatography positive ion electrospray tandem mass spectrometry. The [KYN]/[TRP] ratio (KTR) was greater in fish liver and brain in the 48-h post-stress exposure group (n = 8) relative to controls (n = 8, p < 0.05); a similar increase was not observed in fish in the 4-h post-stress exposure group. Hepatic and brain cortisol levels were also elevated in fish from both stress-induced groups relative to their respective controls implying that cortisol responded more quickly to the stressful stimulus than KYN and TRP. Our results suggest that the KTR is a promising acute stress diagnostic biomarker in fish. Efforts are ongoing to assess whether the KTR can be used as a biomarker for chronic stress in fish exposed to aquatic contaminants and other environmental stressors and if similar assessments can be made on tissues collected via non-lethal approaches.
本研究旨在测定鱼类组织中的犬尿氨酸（KYN）与色氨酸（TRP）比值（KTR），以评估其作为急性应激生物标志物的有用性。实验室饲养的虹鳟（Oncorhynchus mykiss）受到急性应激源的刺激，在应激后 4 小时和 48 小时分别测量肝脏和脑组织中的 KYN、TRP 和皮质醇。用于测定我们分析物的分析方法基于冻干，以及液-固萃取，随后是同位素稀释高效液相色谱-正离子电喷雾串联质谱法。与对照组（n=8）相比，应激后 48 小时暴露组（n=8）的鱼肝脏和脑组织中的 [KYN]/[TRP] 比值（KTR）更高（p<0.05）；在应激后 4 小时暴露组中未观察到类似的增加。来自两个应激诱导组的鱼的肝和脑皮质醇水平也升高，这意味着皮质醇对应激刺激的反应比 KYN 和 TRP 更快。我们的研究结果表明，KTR 是鱼类急性应激的一种有前途的诊断生物标志物。目前正在努力评估 KTR 是否可以用作暴露于水生污染物和其他环境应激源的鱼类慢性应激的生物标志物，以及是否可以通过非致死性方法采集的组织进行类似的评估。
