Unpredictable warm spells in winter increase blood cortisol level but lengthen telomeres in a seasonal rodent Phodopus sungorus

TL;DR

Unpredictable winter warmth increases stress hormones in a rodent species but surprisingly lengthens telomeres, suggesting a potential to cope with climate change.

Contribution

The study reveals that warm spells in winter elevate cortisol but lengthen telomeres in a seasonal rodent, indicating a novel stress response mechanism.

Findings

Both winter phenotypes of Phodopus sungorus increased cortisol levels during warm spells.

Telomere length increased under warm spells, suggesting a potential to prevent telomere shortening.

Responding individuals showed higher torpor incidence, which may prevent telomere shortening.

Abstract

Global warming and the increased frequency of unpredictable weather events may disrupt the proper timing of seasonal adjustments of a phenotype. This may lead to the deterioration of the animal’s condition and shorten its lifespan. We tested whether warm spells in winter affect the baseline and stress-induced cortisol level and leukocyte relative telomere length in two winter phenotypes of Siberian hamster, Phodopus sungorus, responding and non-responding to short photoperiod. We found that both phenotypes increased cortisol levels in winter and that warm spells augmented this response. Under stable cold conditions, non-responding individuals were more vulnerable to short-term stress than responding ones. However, telomere length increased, suggesting that animals have a high potential to cope with stress and prevent telomere shortening or that these two variables are not directly related. In responding individuals, the higher incidence of torpor also prevented telomeres shortening. These results indicate that both phenotypes, responding and non-responding to short photoperiod, can overcome the challenges posed by an unpredictably changing environment.

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