Gundlach Neele Hendrika, Schmicke Marion, Ludes-Wehrmeister Eva, Ulrich Sophia Arlena, Araujo Marcelo Gil, Siebert Ursula
J Zoo Wildl Med. 2018 Sep;49(3):556-563. doi: 10.1638/2017-0191.1.
Cortisol is known to reflect the level of the stress response. However, measuring the cortisol concentration only once fails to provide sufficient information about the duration of the stress exposure. Moreover, handling is an acute stressor and increases cortisol secretion especially in wildlife species. Yet, in phocids reliable indicators are missing that reflect potential chronic effects of stress. The adrenal-derived steroid hormone dehydroepiandrosterone (DHEA) has been described as biomarker for the assessment of the stress status but has not been applied to marine mammal stress research. Therefore, DHEA, the sulfated precursor DHEAS and the cortisol/DHEA ratio were determined in serum of different seals. One group consisted of harbor ( Phoca vitulina) and gray seals ( Halichoerus grypus) that were habituated to human handling. The other two groups included healthy and free-ranging seals suffering from a disease. Blood samples were taken from 11 habituated (six males, five females), 17 wild_healthy (13 males, four females), and nine wild_diseased seals (four males, five females). No differences in serum cortisol levels could be detected between wild_healthy and wild_diseased seals. On the contrary, wild_diseased seals showed the lowest DHEA concentration compared to the other two groups. Wild_diseased seals also revealed the highest cortisol/DHEA ratio compared to the habituated_zoo (2,074.7 ± 351.4 vs. 121.5 ± 26.8, P < 0.001) and wild_healthy seals (827.9 ± 214.3, P < 0.01). DHEA and the cortisol/DHEA ratio may reflect differences in the functionality of the hypothalamic-pituitary-adrenal axis and therefore represent valuable tools for the assessment of stress-related effects in seals.
已知皮质醇可反映应激反应的水平。然而，仅测量一次皮质醇浓度无法提供关于应激暴露持续时间的足够信息。此外，处理是一种急性应激源，会增加皮质醇分泌，尤其是在野生动物物种中。然而，在海豹科动物中，缺乏反映应激潜在慢性影响的可靠指标。肾上腺衍生的类固醇激素脱氢表雄酮（DHEA）已被描述为评估应激状态的生物标志物，但尚未应用于海洋哺乳动物应激研究。因此，测定了不同海豹血清中的DHEA、硫酸化前体DHEAS以及皮质醇/DHEA比值。一组由习惯人类处理的港海豹（Phoca vitulina）和灰海豹（Halichoerus grypus）组成。另外两组包括健康且自由放养的患病海豹。从11只习惯处理的海豹（6只雄性，5只雌性）、17只野生健康海豹（13只雄性，4只雌性）和9只野生患病海豹（4只雄性，5只雌性）采集了血样。野生健康海豹和野生患病海豹之间的血清皮质醇水平未检测到差异。相反，与其他两组相比，野生患病海豹的DHEA浓度最低。与习惯处理的动物园海豹（2,074.7±351.4对121.5±26.8，P<0.001）和野生健康海豹（827.9±214.3）相比，野生患病海豹的皮质醇/DHEA比值也最高。DHEA和皮质醇/DHEA比值可能反映下丘脑-垂体-肾上腺轴功能的差异，因此是评估海豹应激相关影响的有价值工具。
