Oluwagbenga E M, Tetel V, Tonissen S, Karcher D M, Fraley G S
Animal Sciences, Purdue University, West Lafayette, IN, United States.
Front Physiol. 2023 Mar 17;14:1132728. doi: 10.3389/fphys.2023.1132728. eCollection 2023.
During chronic stress, there is an initial increase in glucocorticoid (GC) levels, but they then return to low, albeit not baseline, levels. Recent studies have renewed interest in cortisol in that it may also have important roles in the stress response. The purpose of our study was to test the hypothesis that chronic treatment with low levels of either corticosterone or cortisol would alter HLR and immune organ morphometrics. Further, we wanted to determine if chronic treatment with either GC would elicit an increase in cortisol levels in egg albumen. To test our hypotheses, we implanted silastic capsules that contained corticosterone, cortisol, or empty capsules as controls (N = 5/sex/treatment). Blood serum, smears, body weights, and egg quality data were collected. Ducks were then euthanized and body weight, weights of spleens, livers, and the number of active follicles were recorded. Albumen GC levels were assessed using mass spectrometry. Data were analyzed using a 2- or 3-way ANOVA as appropriate and post-hoc with Fishers PLSD. No treatment elicited differences in egg quality measures or body weight compared to controls. Corticosterone treatment did elicit an increase in serum corticosterone ( < 0.05), but not cortisol, levels compared to controls in both sexes. Both cortisol and corticosterone treatments increased ( < 0.05) serum levels of cortisol compared to controls. Relative spleen weights were higher ( < 0.05) in hens following corticosterone but not cortisol treatment. No other organs showed any differences among the treatment groups. Both GCs elicited an increase ( < 0.001) in HLR in hens at all time-points over the 2-week treatment period compared to controls. Cortisol, not corticosterone, only elicited an increase in HLR for drakes ( < 0.05) compared to controls but only at day 1 after implants. Chronic treatment with cortisol, but not corticosterone, elicited an increase ( < 0.01) in egg albumen cortisol levels compared to other groups. Corticosterone was not detected in any albumen samples. Our results suggest that glucocorticoids elicit differential effects and although corticosterone has been stated to be the predominant GC in avian species, cortisol may provide critical information to further understand bird welfare.
在慢性应激期间，糖皮质激素（GC）水平最初会升高，但随后会降至较低水平，尽管并非基线水平。最近的研究重新引发了对皮质醇的兴趣，因为它在应激反应中可能也具有重要作用。我们研究的目的是检验以下假设：长期用低剂量的皮质酮或皮质醇处理会改变血液淋巴细胞比率（HLR）和免疫器官形态学指标。此外，我们想确定长期用任何一种GC处理是否会导致蛋清中皮质醇水平升高。为了验证我们的假设，我们植入了含有皮质酮、皮质醇的硅橡胶胶囊或作为对照的空胶囊（每组性别各5只）。收集血清、涂片、体重和蛋品质数据。然后对鸭子实施安乐死，并记录体重、脾脏重量、肝脏重量和活跃卵泡数量。使用质谱法评估蛋清中的GC水平。根据情况使用双向或三向方差分析对数据进行分析，并采用Fisher最小显著差异法进行事后检验。与对照组相比，没有任何处理在蛋品质指标或体重方面引起差异。与对照组相比，皮质酮处理确实使两性血清皮质酮水平升高（<0.05），但未使皮质醇水平升高。与对照组相比，皮质醇和皮质酮处理均使血清皮质醇水平升高（<0.05）。皮质酮处理后的母鸡相对脾脏重量较高（<0.05），而皮质醇处理的母鸡则不然。各处理组之间其他器官未显示出任何差异。与对照组相比，在为期2周的处理期内，两种GC在所有时间点均使母鸡的HLR升高（<0.001）。与对照组相比，仅皮质醇而非皮质酮使公鸭的HLR升高（<0.05），但仅在植入后第1天。与其他组相比，长期用皮质醇而非皮质酮处理使蛋清皮质醇水平升高（<0.01）。在任何蛋清样本中均未检测到皮质酮。我们的结果表明，糖皮质激素会产生不同的影响，尽管皮质酮被认为是鸟类中的主要GC，但皮质醇可能为进一步了解鸟类健康提供关键信息。
