Department of Animal Sciences, Purdue University, West Lafayette, IN, USA.
Department of Biology, Hope College, Holland, MI, USA.
Poult Sci. 2022 Jan;101(1):101534. doi: 10.1016/j.psj.2021.101534. Epub 2021 Oct 13.
Some concerns have been raised recently about the assay of corticosterone vs. cortisol in poultry species. Thus, we tested the hypothesis that ducks secrete both glucocorticoids. First, we validated two commercially ELISA kits for the two glucocorticoids by first charcoal stripping duck serum in order to remove all steroid hormones. We ran serial dilutions of spiked, charcoal-stripped serum on kits of opposite glucocorticoid as well as a serial dilution using the respective ELISA buffer of the opposite assay kit. We found that the glucocorticoid standard curve in duck serum matched the respective curve in that kit's own buffer. However, when the opposite hormone was run in each kit in both duck serum or ELISA buffer, a near zero slope was obtained. Second, we further validated the presence of both glucocorticoids using mass spectrometry. Third, we tested the hypothesis that exogenous ACTH would stimulate the release of both corticosterone and cortisol. And, fourth, we tested the hypothesis that each glucocorticoid would have different serum levels in response to shipping stress. To test this hypothesis, we collected serum from 10 drakes and 10 hens from 2 flocks (N = 20 per time point per sex): 24 h prior to shipping, at shipping as ducks were walked off the truck, 24 h after shipping, and 1 wk after shipping. Data were analyzed by 2-way repeated measures ANOVA. Surprisingly, we also observed a sex difference in both glucocorticoid levels in that hens showed higher (P < 0.01) serum levels than did drakes at all-time points in response to either ACTH or transportation. Finally, no differences were observed in either glucocorticoid levels associated with shipping in either sex. The fact that both glucocorticoids are released in measurable amounts lends to the possibility that they may be differentially regulated, or at least there is a sex difference in the neural pathways associated with glucocorticoid release in ducks. Although corticosterone is the likely predominate glucocorticoid in ducks, serious attention should be given to the role of cortisol in poultry. Further consideration of sex, age, and timing of blood collection to stressor needs to be considered when assessing glucocorticoid levels in any avian species.
最近，人们对禽类中皮质酮与皮质醇的测定提出了一些担忧。因此，我们检验了以下假设：鸭子会分泌两种糖皮质激素。首先，我们通过首先对鸭血清进行炭吸附来去除所有类固醇激素，从而验证了两种商业 ELISA 试剂盒对这两种糖皮质激素的检测。我们对添加了皮质酮和皮质醇的血清进行了系列稀释，并在试剂盒的相反检测激素以及相反检测试剂盒的各自 ELISA 缓冲液中进行了系列稀释。我们发现，鸭血清中的糖皮质激素标准曲线与试剂盒自身缓冲液中的相应曲线相匹配。然而，当在每个试剂盒中使用鸭血清或 ELISA 缓冲液运行相反的激素时，获得了接近零斜率。其次，我们使用质谱进一步验证了两种糖皮质激素的存在。第三，我们检验了外源性 ACTH 会刺激皮质酮和皮质醇释放的假设。第四，我们检验了在运输应激下，每个糖皮质激素的血清水平会不同的假设。为了检验这个假设，我们从两个群体中采集了 10 只雄鸭和 10 只母鸡的血清（每个性别在每个时间点采集 20 只）：在运输前 24 小时、在鸭子从卡车上走下来的时候、运输后 24 小时和运输后 1 周。数据通过双向重复测量方差分析进行分析。令人惊讶的是，我们还观察到了两种糖皮质激素水平的性别差异，即在对 ACTH 或运输的反应中，母鸡的血清水平均高于雄鸭（P<0.01）。最后，在雄鸭和母鸡中，都没有观察到与运输相关的糖皮质激素水平的差异。事实上，这两种糖皮质激素都以可测量的量释放，这使得它们可能受到不同的调节，或者至少在与鸭糖皮质激素释放相关的神经通路中存在性别差异。虽然皮质酮可能是鸭的主要糖皮质激素，但皮质醇在禽类中的作用也应该得到重视。在评估任何禽类的糖皮质激素水平时，应该进一步考虑性别、年龄和采血时间与应激的关系。
