Burgess Elizabeth A, Hunt Kathleen E, Kraus Scott D, Rolland Rosalind M
Anderson Cabot Center for Ocean Life, New England Aquarium, 1 Central Wharf, Boston, MA 02110, United States.
Anderson Cabot Center for Ocean Life, New England Aquarium, 1 Central Wharf, Boston, MA 02110, United States.
Gen Comp Endocrinol. 2017 Oct 1;252:103-110. doi: 10.1016/j.ygcen.2017.07.026. Epub 2017 Jul 27.
Until now, physiological stress assessment of large whales has predominantly focused on adrenal glucocorticoid (GC) measures. Elevated GC concentrations in feces (fGC) are known to reflect stressful disturbances, such as fishing gear entanglement and human-generated underwater noise, in North Atlantic right whales (Eubalaena glacialis). However, there can be considerable variation in GC production as a function of sex and life history stage, which may confound the interpretation of fGC levels. Additionally, GC antibodies used in immunoassays can cross-react with other fecal metabolites (i.e., non-target steroids), potentially influencing fGC data. Here, aldosterone concentrations (fALD; aldosterone and related metabolites) were measured in fecal samples from right whales (total n=315 samples), including samples from identified individuals of known life history (n=82 individual whales), to evaluate its utility as a complementary biomarker to fGC for identifying adrenal activation. Concentrations of fALD were positively correlated with fGCs in right whales (r=0.59, P<0.001), suggesting concurrent secretion of these hormones by the adrenal gland. However, fALD levels were less influenced by concentrations of reproductive steroids in feces, minimizing the potential confounder of assay cross-reactivity in samples with highly skewed hormone ratios. Across different life history states for right whales, fALD concentrations showed similar patterns to those reported for fGC, with higher levels in pregnant females (35.9±7.6ng/g) followed by reproductively mature males (9.5±0.9ng/g) (P<0.05), providing further evidence of elevated adrenal activation in these groups of whales. The addition of fALD measurement as a biomarker of adrenal activation may help distinguish between intrinsic and external causes of stress hormone elevations in large whales, as well as other free-living wildlife species, providing a more comprehensive approach for associating adrenal activation with specific natural and anthropogenic stressors.
到目前为止，对大型鲸鱼的生理应激评估主要集中在肾上腺糖皮质激素（GC）指标上。已知粪便中GC浓度升高（fGC）反映了北大西洋露脊鲸（Eubalaena glacialis）所遭受的应激干扰，如渔具缠绕和人为产生的水下噪音。然而，GC的产生会因性别和生活史阶段而有很大差异，这可能会混淆对fGC水平的解读。此外，免疫分析中使用的GC抗体可能会与其他粪便代谢物（即非目标类固醇）发生交叉反应，从而可能影响fGC数据。在此，测量了露脊鲸粪便样本中的醛固酮浓度（fALD；醛固酮及相关代谢物）（样本总数n = 315），包括已知生活史的个体样本（n = 82头个体鲸鱼），以评估其作为fGC的补充生物标志物用于识别肾上腺激活的效用。露脊鲸的fALD浓度与fGC呈正相关（r = 0.59，P < 0.001），表明这些激素由肾上腺同时分泌。然而，fALD水平受粪便中生殖类固醇浓度的影响较小，将激素比例高度失衡的样本中检测交叉反应的潜在干扰因素降至最低。在露脊鲸的不同生活史状态下，fALD浓度呈现出与fGC报道的类似模式，怀孕雌性的水平较高（35.9±7.6ng/g），其次是生殖成熟雄性（9.5±0.9ng/g）（P < 0.05），这为这些鲸鱼群体中肾上腺激活增强提供了进一步证据。添加fALD测量作为肾上腺激活的生物标志物，可能有助于区分大型鲸鱼以及其他自由生活的野生动物物种应激激素升高的内在和外在原因，为将肾上腺激活与特定自然和人为应激源联系起来提供更全面的方法。
