Short-term elevations in glucocorticoids do not alter telomere lengths: A systematic review and meta-analysis of non-primate vertebrate studies

Abstract

Background: The neuroendocrine stress response allows vertebrates to cope with stressors via the activation of the Hypothalamic-Pituitary-Adrenal (HPA) axis, which ultimately results in the secretion of glucocorticoids (CORT). Glucocorticoids have pleiotropic effects on behavior and physiology, and might influence telomere length dynamics. During a stress event, CORT mobilizes energy towards survival mechanisms rather than to telomere maintenance. Additionally, reactive oxidative species produced in response to increased CORT levels can damage telomeres, also leading to telomere shortening. In our systematic review and meta-analysis, we tested whether CORT levels impact telomere length and if this relationship differs among time frame, life history stage, or stressor type. We hypothesized that elevated CORT levels are linked to a decrease in telomere length. Methods: To test this hypothesis, we conducted a literature search for studies investigating the relationship between telomere length and CORT levels in non-human vertebrates using four search engines Web of Science, Google Scholar, Pubmed and Scopus, last searched on September 27th, 2020. This review identified 31 studies examining the relationship between CORT and telomere length. We pooled the data using Fishers Z for 15 of these studies. All quantitative studies underwent a risk of bias assessment. This systematic review study was registered in the Open Science Framework Registry (https://osf.io/rqve6). Results: The pooled effect size from fifteen studies and 1066 study organisms shows no relationship between CORT and telomere length (Fishers Z= 0.1042, 95% CI = 0.0235; 0.1836). While these results support some previous findings, other studies have found a direct relationship between CORT and telomere dynamics, suggesting underlying mechanisms or concepts that are not currently taken into account in our analysis. The risk of bias assessment revealed an overall low risk of bias with occasional instances of bias from missing outcome data or bias in the reported result.

Telomere length correlates with physiological and behavioural responses of a long-lived seabird to an ecologically relevant challenge

“…brood size/degree of competition [44]), interannual variation (presumably in resource availability [59,60]) or exposure to elevated glucocorticoids [28] can generate variation in telomere length. However, while challenging experiences during adulthood such as increased energy expenditure and elevated glucocorticoid exposure [18] can accelerate telomere attrition in some species (potential mechanisms reviewed in [34,35]), a recent meta-analysis suggests that short-term elevations in glucocorticoids, at least, do not consistently alter telomere length [61].…”

Effects of the social environment on vertebrate fitness and health in nature: Moving beyond the stress axis

“…However, much remains to be understood about the interplay among social stressors, GCs, oxidative stress, telomere dynamics and their consequences on individual performance in the wild. Notably, telomere length and shortening rate appear to be related to chronic, but not short-term (Zane et al, 2021), modifications in GCs in vertebrates (reviewed in Angelier et al, 2018), though the direction of this relation (shorter telomeres with increased or reduced GCs) is not always consistent. Understanding how telomere biology is regulated by the interplay between GC and ROS production (Casagrande and Hau, 2019) is the next logical step in our understanding of social effects on vertebrate senescence and decline in overall performances in the wild.…”

Tales of the Telomeres

“…It was explored that increased levels of IGF-1 are believed to be involved in telomeres attrition and cellular senescence in patients with acromegaly [2]. Glucocorticoids also influence the Telomere length (TL) in stressful conditions by producing the reactive oxygen species and mobilizing the energy towards survival mechanisms as compare to the telomere maintenance [3]. Moreover, postmenopausal reduction in estrogen level is crucial in the biology of senescence and was surely correlated with leukocyte telomere length (LTL) shortening [4].…”