Costanzo Alessandra, Ambrosini Roberto, Parolini Marco, Caprioli Manuela, Secomandi Simona, Rubolini Diego, Fusani Leonida, Canoine Virginie
Department of Environmental Science and Policy, University of Milan, via Celoria 26, I-20133 Milan, Italy.
Department of Behavioral and Cognitive Biology, University of Vienna, Althanstr. 14, 1090 Vienna, Austria.
Curr Zool. 2021 Mar 9;68(1):93-101. doi: 10.1093/cz/zoab020. eCollection 2022 Feb.
When vertebrates face stressful events, the hypothalamic-pituitary-adrenal (HPA) axis is activated, generating a rapid increase in circulating glucocorticoid (GC) stress hormones followed by a return to baseline levels. However, repeated activation of HPA axis may lead to increase in oxidative stress. One target of oxidative stress is telomeres, nucleoprotein complexes at the end of chromosomes that shorten at each cell division. The susceptibility of telomeres to oxidizing molecules has led to the hypothesis that increased GC levels boost telomere shortening, but studies on this link are scanty. We studied if, in barn swallows , changes in adult erythrocyte telomere length between 2 consecutive breeding seasons are related to corticosterone (CORT) (the main avian GC) stress response induced by a standard capture-restraint protocol. Within-individual telomere length did not significantly change between consecutive breeding seasons. Second-year individuals showed the highest increase in circulating CORT concentrations following restraint. Moreover, we found a decline in female stress response along the breeding season. In addition, telomere shortening covaried with the stress response: a delayed activation of the negative feedback loop terminating the stress response was associated with greater telomere attrition. Hence, among-individual variation in stress response may affect telomere dynamics.
当脊椎动物面临应激事件时，下丘脑-垂体-肾上腺（HPA）轴被激活，导致循环中的糖皮质激素（GC）应激激素迅速增加，随后恢复到基线水平。然而，HPA轴的反复激活可能导致氧化应激增加。氧化应激的一个靶点是端粒，它是染色体末端的核蛋白复合体，在每次细胞分裂时都会缩短。端粒对氧化分子的敏感性导致了这样一种假说，即GC水平升高会加速端粒缩短，但关于这一联系的研究很少。我们研究了在家燕中，连续两个繁殖季节之间成年红细胞端粒长度的变化是否与标准捕捉-束缚方案诱导的皮质酮（CORT）（鸟类主要的GC）应激反应有关。个体内的端粒长度在连续繁殖季节之间没有显著变化。第二年的个体在束缚后循环CORT浓度增加最多。此外，我们发现雌性在繁殖季节的应激反应有所下降。另外，端粒缩短与应激反应相关：终止应激反应的负反馈回路的延迟激活与更大的端粒损耗有关。因此，个体间应激反应的差异可能会影响端粒动态。
