Research Unit in Environmental and Evolutionary Biology (URBE), Institute of Life, Earth & Environment, University of Namur, Rue de Bruxelles 61, Namur, B-5000, Belgium.
Animal and Functionality of Animal Products Research Unit (URAFPA), University of Lorraine, Boulevard des Aiguillettes, BP 236, 54506, Vandoeuvre-Les-Nancy, France.
Sci Rep. 2020 Feb 14;10(1):2650. doi: 10.1038/s41598-020-59568-1.
Melatonin is considered as the time-keeping hormone acting on important physiological functions of teleosts. While the influence of melatonin on reproduction and development is well described, its potential role on immune functions has little been considered. In order to better define an immune modulation by the melatonin hormone, we hypothesized that natural variations of photoperiod and subsequent changes in melatonin release profile may act on immune status of pikeperch. Therefore, we investigated during 70 days the effects of two photoperiod regimes simulating the fall and spring in western Europe, on pikeperch physiological and immune responses. Samples were collected at 04:00 and 15:00 at days 1, 37 and 70. Growth, plasma melatonin levels, innate immune markers and expression of immune-relevant genes in head kidney tissue were assessed. While growth and stress level were not affected by the seasonal simulated photoperiods, nocturnal levels of plasma melatonin were photoperiod-dependent. Innate immune markers, including lysozyme, complement, peroxidase and phagocytic activities, were stimulated by the fall-simulated photoperiod and a significant correlation was made with plasma melatonin. In addition to bring the first evidence of changes in fish immunocompetence related to photoperiod, our results provide an additional indication supporting the immunomodulatory action of melatonin in teleosts.
褪黑素被认为是作用于鱼类重要生理功能的计时激素。虽然褪黑素对繁殖和发育的影响已有详细描述，但它对免疫功能的潜在作用却鲜为人知。为了更好地定义褪黑素激素的免疫调节作用，我们假设光周期的自然变化及其引发的褪黑素释放模式的改变可能会影响欧鲈的免疫状态。因此，我们在 70 天内研究了模拟西欧秋季和春季的两种光周期对欧鲈生理和免疫反应的影响。在第 1、37 和 70 天的 04:00 和 15:00 采集样本。评估了生长、血浆褪黑素水平、固有免疫标志物和头肾组织中免疫相关基因的表达。虽然生长和应激水平不受季节性模拟光周期的影响，但夜间血浆褪黑素水平依赖于光周期。包括溶菌酶、补体、过氧化物酶和吞噬活性在内的固有免疫标志物被模拟秋季的光周期刺激，并且与血浆褪黑素之间存在显著相关性。本研究除了首次证明与光周期相关的鱼类免疫能力变化外，还提供了另一个支持褪黑素在鱼类中具有免疫调节作用的证据。
