Norwegian Institute for Nature Research (NINA), The Polar Environmental Centre, Tromsø, Norway.
J Exp Biol. 2010 Nov 15;213(Pt 22):3810-8. doi: 10.1242/jeb.045484.
The prolonged exposure of birds to environmental stressors known to affect energy status and glucocorticoid secretion may have several physiological consequences including a decrease in immunocompetence, further compromising the survival of individuals. However, the relationships between these parameters remain poorly understood. To this end, changes in body energy content, plasma corticosterone, adaptive (total plasma immunoglobulin Y; IgY) and innate (natural antibodies; NAbs) immune systems were assessed in female mallards (Anas plathyrhynchos) throughout prolonged fasts of different intensities and subsequent re-feeding. Plasma IgY and NAb scores were decreased by 36% and 50%, respectively, during phase II of fasting (protein-sparing phase) and by up to 40% and 80%, respectively, during phase III (protein-wasting phase), indicating a selective regulation of immune function. These results are consistent with the hypothesis of a trade-off between immune function and other energy-demanding activities. However, despite full repletion of fuel reserves and NAbs, only 76% of initial IgY levels were recovered, further supporting a trade-off between innate and adaptive branches of immunity. Although fasting induced significant increases in corticosterone levels to up to 6 times higher than baseline levels during phase III, baseline levels were recovered within 1 day of re-feeding. Our data do not support the hypothesis of a direct regulation of immunocompetence by corticosterone, at least during periods of energy repletion. Finally, the mismatch between the kinetics of body fuels and the two arms of the immune system during fasting and re-feeding suggests that variations in immune system components do not strictly covary with body mass under fluctuating food conditions.
鸟类长期暴露于已知会影响能量状态和糖皮质激素分泌的环境应激源中，可能会产生多种生理后果，包括免疫能力下降，进一步危及个体的生存。然而，这些参数之间的关系仍知之甚少。为此，我们在雌性绿头鸭（Anas plathyrhynchos）中评估了身体能量含量、血浆皮质酮、适应性（总血浆免疫球蛋白 Y；IgY）和固有（天然抗体；NAbs）免疫系统在不同强度的长期禁食和随后的再喂食过程中的变化。在禁食的第二阶段（蛋白质保护阶段），血浆 IgY 和 NAb 评分分别下降了 36%和 50%，而在第三阶段（蛋白质消耗阶段），分别下降了 40%和 80%，这表明免疫功能受到了选择性调节。这些结果与免疫功能和其他能量需求活动之间存在权衡的假设一致。然而，尽管燃料储备和 NAb 完全得到补充，但初始 IgY 水平仅恢复了 76%，这进一步支持了先天和适应性免疫分支之间的权衡。尽管禁食会导致皮质酮水平显著升高，最高可达基线水平的 6 倍，但在再喂食的第 1 天，基线水平就得到了恢复。我们的数据不支持皮质酮直接调节免疫能力的假设，至少在能量补充期间是这样。最后，在禁食和再喂食期间，身体燃料和免疫系统两个分支的动力学之间存在不匹配，这表明在食物波动的情况下，免疫系统成分的变化与体重不一定严格相关。
