Department of Zoology, University of Delhi, Delhi 110 007, India.
Department of Zoology, CCS University, Meerut 250 004, India.
Comp Biochem Physiol A Mol Integr Physiol. 2020 Dec;250:110790. doi: 10.1016/j.cbpa.2020.110790. Epub 2020 Aug 12.
The molecular underpinnings of the spleen-mediated immune functions during the period of heightened energetic needs in the year are not known in avian migrants. We investigated this, in Palearctic-Indian migratory male redheaded buntings, which exhibited vernal (spring) premigratory / early testicular maturation states under artificial long days. This was evidenced by increased dio2 and decreased dio3 mRNA expression in the hypothalamus, elevated levels of circulating corticosterone and testosterone, and enlarged testes in long-day-photostimulated birds, as compared to unstimulated controls under short days. The concomitant decrease in both mass and volume of the spleen, and increase in the heterophil/ lymphocyte ratio suggested the parallel innate immunity effects in photostimulated buntings. Importantly, we found increased mRNA expression of genes coding for the cytokines (il15 and il34), steroid receptors (nr3c2) and oxidative stress marker enzymes (gpx1 and sod1) in the spleen, suggesting the activation of both immune and antioxidant molecular pathways during the early photostimulated state. However, the splenic expressions of il1β, il6, tgfβ, ar and nos2 genes were not significantly different between long-day stimulated and short-day unstimulated birds. The negative correlation of plasma corticosterone levels with spleen mass further indicated a role of corticosterone in the modulation of the spleen function, probably via nr3c2 gene encoded mineralocorticoid receptors. These results suggest the activation of the spleen-mediated innate immunity in anticipation of the heightened energetic stress state of the photostimulated spring migratory/breeding period in migratory songbirds.
在鸟类迁徙者中，尚不清楚在能量需求增加的时期，脾脏介导的免疫功能的分子基础。我们研究了 Palearctic-Indian 迁徙雄性红头金翅雀，它们在人工长日条件下表现出 vernal（春季）迁徙前/早期睾丸成熟状态。这表现在下丘脑中二碘氧嘧啶 2（dio2）和二碘氧嘧啶 3（dio3）mRNA 表达增加，循环皮质酮和睾酮水平升高，以及长日光照刺激鸟类的睾丸增大，而与短日对照相比，未受刺激的鸟类的睾丸则较小。脾脏的质量和体积同时减小，嗜中性粒细胞/淋巴细胞比例增加，这表明光照刺激的金翅雀中存在并行的固有免疫效应。重要的是，我们发现脾脏中编码细胞因子（il15 和 il34）、类固醇受体（nr3c2）和氧化应激标记酶（gpx1 和 sod1）的基因的 mRNA 表达增加，这表明在早期光照刺激状态下激活了免疫和抗氧化分子途径。然而，长日光照刺激和短日未刺激鸟类之间，脾脏中 il1β、il6、tgfβ、ar 和 nos2 基因的表达没有显著差异。血浆皮质酮水平与脾脏质量之间的负相关进一步表明皮质酮在调节脾脏功能中的作用，可能是通过 nr3c2 基因编码的盐皮质激素受体。这些结果表明，在迁徙鸣禽的光照刺激的春季迁徙/繁殖期间，为应对能量需求增加的压力状态，脾脏介导的固有免疫被激活。
