The integration of multiple tissues in physiological and ecological analyses can enhance methodological approaches, increase applications for data and extend interpretation of results. Previous investigations of the stress response in fish have focused primarily on cortisol levels in a single matrix—blood plasma—which confines interpretations of cortisol levels to a short temporal frame. Epidermal mucus has been proposed as an alternative or complement to plasma that may provide a view to cortisol levels over a different temporal window allowing comparative assessment. Here, we explore the potential for multi-tissue cortisol analysis using both plasma and epidermal mucus in Pacific halibut (Hippoglossus stenolepis). The relative timing at which cortisol increased and decreased in the two matrices as well as cortisol concentrations at estimated peak levels were compared in two trials after (i) inducing cortisol synthesis by adrenocorticotropic hormone (ACTH1–24) administration and (ii) inducing cortisol elimination using cortisol (hydrocortisone, 98%) injection. The ACTH treatment elicited a peak plasma cortisol response approximately 12 hours post-injection, while mucus cortisol concentrations peaked later at approximately 62 hours post-injection. Exogenous cortisol treatments suggested relatively little transfer of cortisol from plasma to mucus, potentially reflecting differential effects of endogenous and exogenous cortisol. Our results suggest the potential utility of mucus as a sampling matrix that provides an extended window for detection of the stress response as compared to plasma. Results also suggest the utility of a multi-tissue approach to cortisol analysis with potential applications to applied fisheries research. Increased understanding of the relative scale of the cortisol response to stress (e.g. capture) will allow researchers and managers to better interpret the physiological condition and survival outcome of fish subjected to regulatory discard.

中文翻译：

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探索使用多组织方法来表征野生捕获的太平洋大比目鱼（Hippoglossus stenolepis）压力的对照实验

在生理和生态分析中整合多种组织可以增强方法学方法，增加数据应用并扩展结果解释。先前对鱼类应激反应的研究主要集中在单一基质（血浆）中的皮质醇水平，这将皮质醇水平的解释限制在较短的时间框架内。已提出表皮粘液作为血浆的替代物或补充物，可以提供不同时间窗口内皮质醇水平的视图，从而进行比较评估。在这里，我们探索了使用太平洋大比目鱼（Hippoglossus stenolepis）的血浆和表皮粘液进行多组织皮质醇分析的潜力。在（i）通过促肾上腺皮质激素（ACTH1-24）给药诱导皮质醇合成和（ii）诱导皮质醇消除后的两项试验中，比较了两种基质中皮质醇增加和减少的相对时间以及估计峰值水平的皮质醇浓度使用皮质醇（氢化可的松，98%）注射液。ACTH 治疗在注射后约 12 小时引起血浆皮质醇反应峰值，而粘液皮质醇浓度在注射后约 62 小时后达到峰值。外源性皮质醇治疗表明皮质醇从血浆到粘液的转移相对较少，这可能反映了内源性和外源性皮质醇的不同作用。我们的结果表明粘液作为一种采样矩阵的潜在用途，与血浆相比，它为检测压力反应提供了一个扩展的窗口。结果还表明多组织方法对皮质醇分析的实用性，以及在应用渔业研究中的潜在应用。增加对皮质醇对压力（例如捕获）反应的相对规模的了解将使研究人员和管理人员能够更好地解释受到监管丢弃的鱼的生理状况和生存结果。