Gupta Neelu Jain, Nanda Ranjan Kumar, Das Samya, Das Mrinal Kumar, Arya Rakesh
Department of Zoology, Chaudhary Charan Singh University, Meerut 250004 Uttar Pradesh, India.
Translational Health Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India.
ACS Omega. 2020 Oct 22;5(43):28088-28095. doi: 10.1021/acsomega.0c03691. eCollection 2020 Nov 3.
Aerobic metabolism in night migratory songbirds exhibit seasonal plasticity, which depends not only on annual life history stages (LHSs), viz., migratory/nonmigratory or breeding/nonbreeding, but also on the time of the day. Initially, we studied daily changes in behavior/physiology alongside aerobic metabolism intermediates using gas chromatography-mass spectrometry-based chemometric analyses of serum of migratory male redheaded buntings during low-energy wintering, that is, the nonmigrating LHS. Then, the metabolic phenotype of nonmigrating birds was compared with that of photostimulated migrating buntings, the latter representing the high-energy LHS. Diurnal changes such as daytime feeding and activity were reflected by increased fatty acid (FA, viz., palmitic, oleic, and linoleic acids) levels and protein catabolites, whereas higher night-time levels of short-chain FAs indicated lipolysis in night-fasted birds. High night-time levels of taurine, a sulfur amino acid, suggested the endogenous metabolite rendering an adaptive advantage to hyperglycaemic night migratory songbirds during the LHS with low daily energy expenditure. Conversely, migrating birds, largely night-active, exhibited higher circulatory FA, its mobilization, and increased aerobic catabolism, and the adipocyte-secreted lipid, palmitoylethanolamide (PEA), capable of activating the peroxisome proliferator-activated receptor α-PGCα axis, showed elevated levels throughout the day. PEA is known for anti-inflammatory and cannabinomimetic properties, and we show, for the first time, circadian changes in PEA levels in any migrating bird. Significantly higher levels of pyridoxal phosphate also suggested the bird's protective ability to combat metabolic stress through high aerobic capacity during migration. This study elucidates putative "serum biomarkers" with a protective role in stress accrued by enhanced aerobic capacity requirements at the organismal level.
夜间迁徙鸣禽的有氧代谢具有季节性可塑性，这不仅取决于年度生活史阶段（LHSs），即迁徙/非迁徙或繁殖/非繁殖阶段，还取决于一天中的时间。最初，我们使用基于气相色谱 - 质谱的血清化学计量分析方法，研究了低能量越冬期间（即非迁徙LHS）迁徙雄性红头鹀行为/生理的每日变化以及有氧代谢中间产物。然后，将非迁徙鸟类的代谢表型与光刺激迁徙鹀的代谢表型进行比较，后者代表高能量LHS。白天进食和活动等昼夜变化表现为脂肪酸（FA，即棕榈酸、油酸和亚油酸）水平和蛋白质分解代谢产物增加，而夜间短链FA水平较高表明夜间禁食鸟类发生了脂肪分解。夜间高浓度的牛磺酸（一种含硫氨基酸）表明，这种内源性代谢产物在每日能量消耗较低的LHS期间，为高血糖的夜间迁徙鸣禽提供了适应性优势。相反，主要在夜间活动的迁徙鸟类表现出循环FA水平更高、其动员增加以及有氧分解代谢增强，并且脂肪细胞分泌的脂质棕榈酰乙醇胺（PEA）能够激活过氧化物酶体增殖物激活受体α - PGCα轴，其水平在一整天中都有所升高。PEA以其抗炎和类大麻素特性而闻名，我们首次展示了任何迁徙鸟类中PEA水平的昼夜变化。显著更高水平的磷酸吡哆醛也表明，鸟类在迁徙过程中通过高有氧能力来抵抗代谢应激的保护能力。这项研究阐明了在机体水平上因有氧能力需求增加而产生的应激中具有保护作用的假定“血清生物标志物”。
