Kershaw Joanna L, Hall Ailsa J
Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife. KY16 8LB, UK.
Sci Rep. 2016 Feb 24;6:21889. doi: 10.1038/srep21889.
Cortisol is one of the main glucocorticoid hormones involved in both the mammalian stress response, and in fat metabolism and energy regulation, making it of increasing interest as a biomarker for stress, health and overall physiological state. However, transient stress responses to animal handling and sampling may be important sources of measurement artefact when investigating circulating concentrations of this hormone in wildlife. Here, cortisol concentrations were measured in the plasma and, for the first time, in the blubber of live captured adult harbour seals (Phoca vitulina). Plasma cortisol concentrations were positively correlated with capture time, suggesting that they were largely driven by a stress response to the capture event. In contrast, blubber cortisol concentrations were shown not to be significantly affected by capture time and varied significantly by sex and by season, with higher concentrations during natural fasting periods of their life cycle, particularly during the moult. These results suggest that cortisol may play a key role in increased fat metabolism during highly energetically demanding periods, and that blubber concentrations have the potential to be used as physiological state indicators in phocid seals.
皮质醇是参与哺乳动物应激反应、脂肪代谢和能量调节的主要糖皮质激素之一，这使得它作为应激、健康和整体生理状态的生物标志物越来越受到关注。然而，在研究野生动物体内这种激素的循环浓度时，对动物处理和采样的短暂应激反应可能是测量假象的重要来源。在此，对活体捕获的成年港海豹（Phoca vitulina）的血浆以及首次对其脂肪中的皮质醇浓度进行了测量。血浆皮质醇浓度与捕获时间呈正相关，这表明它们在很大程度上是由对捕获事件的应激反应驱动的。相比之下，脂肪中的皮质醇浓度不受捕获时间的显著影响，且因性别和季节而有显著差异，在其生命周期的自然禁食期，尤其是换毛期，浓度较高。这些结果表明，皮质醇可能在能量需求高的时期增加脂肪代谢中起关键作用，并且脂肪中的皮质醇浓度有可能被用作海豹生理状态的指标。
