Estacion Experimental de Zonas Áridas (EEZA, CSIC), Almería, Spain.
Oecologia. 2012 Jun;169(2):385-94. doi: 10.1007/s00442-011-2220-9. Epub 2011 Dec 11.
Oxidative stress is increasingly recognized as a key selective force shaping evolutionary trade-offs. One such trade-off involves investing in immunity versus combating oxidative stress. While there is broad evidence that mounting an immune response causes increased oxidative stress, the effect that increased oxidative stress during development has at a later stage on immune responsiveness remains little known. The production of melanin-based coloration in vertebrates is influenced by oxidative stress and by hormones, such as the alpha-melanocyte-stimulating hormone (α-MSH). Oxidative stress could impair immunity, and this might be a cost associated with the production of melanin traits. α-MSH has immunomodulatory effects, with most evidence pointing towards an improvement of immunity (improved pro-inflammatory activity). Here, we investigated the effects of an oxidative challenge (exposure to a pro-oxidant compound, diquat) and of experimentally elevated α-MSH on the cell-mediated immune responses (CMIR) of growing young (1 month old) red-legged partridges Alectoris rufa in captivity. CMIR were assessed in response to primary and secondary challenges with phytohemagglutinin (PHA). We specifically tested whether an oxidative challenge during growth and development had a delayed effect (4 months after exposure) on immunity. We found that the diquat treatment did not affect primary CMIR, but significantly reduced secondary CMIR. Elevated α-MSH increased primary CMIR in males, but not in females. Our experimental results are consistent with a trade-off between investing in activities that generate oxidative stress (e.g., growth, reproduction, production of ornaments) versus investing in immunity, and shed new lights onto the inter-relationships between immunity, oxidative stress and the expression of melanin-based coloration in vertebrates, revealing a novel, delayed physiological cost that can contribute to ensuring honest signaling.
氧化应激越来越被认为是塑造进化权衡的关键选择力量。这种权衡之一涉及投资于免疫与对抗氧化应激。虽然有广泛的证据表明，免疫反应会导致氧化应激增加，但在发育过程中增加的氧化应激对后期免疫反应的影响知之甚少。脊椎动物的黑色素基着色的产生受氧化应激和激素（如α-黑色素细胞刺激素（α-MSH））的影响。氧化应激可能会损害免疫，这可能是与黑色素特征产生相关的成本。α-MSH 具有免疫调节作用，大多数证据表明它可以改善免疫（改善促炎活性）。在这里，我们研究了氧化应激（暴露于促氧化剂二氯二氢醌）和实验性升高的 α-MSH 对圈养生长中的年轻（1 个月大）红腿鹧鸪 Alectoris rufa 的细胞介导免疫反应（CMIR）的影响。CMIR 是对植物血凝素（PHA）的初级和次级挑战的反应进行评估的。我们特别测试了在生长和发育过程中氧化应激是否对免疫有延迟影响（暴露后 4 个月）。我们发现，二氯二氢醌处理不会影响初级 CMIR，但会显著降低次级 CMIR。升高的 α-MSH 增加了雄性的初级 CMIR，但对雌性没有影响。我们的实验结果与在产生氧化应激的活动（例如生长、繁殖、产生装饰物）与投资于免疫之间的权衡一致，并为脊椎动物中的免疫、氧化应激和黑色素基着色表达之间的相互关系提供了新的认识，揭示了一种新的、延迟的生理成本，这可能有助于确保诚实的信号传递。
