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One aspect of the Reactive Scope Model is wear-and-tear, which describes a decrease in an animal’s ability to cope with a stressor, typically because of a period of chronic or repeated stressors. We investigated whether wear-and-tear due to chronic stress would accelerate a transition from phase II to phase III of fasting. We exposed house sparrows (Passer domesticus) to three weeks of daily fasts combined with daily intermittent repeated acute stressors to create chronic stress, followed by two weeks of daily fasts without stressors. We measured circulating glucose, β-hydroxybutyrate (a ketone), and uric acid in both fasted and fed states. We expected birds to be in phase II (high fat breakdown) in a fasted state, but if wear-and-tear accumulated sufficiently, we hypothesized a shift to phase III (high protein breakdown). Throughout the experiment, the birds exhibited elevated β-hydroxybutyrate when fasting but no changes in circulating uric acid, indicating that a transition to phase III did not occur. In both a fasted and fed state, the birds increased glucose mobilization throughout the experiment, suggesting wear-and-tear occurred, but was not sufficient to induce a shift to phase III. Additionally, the birds exhibited a significant decrease in weight, no change in corticosterone, and a transient decrease in neophobia with chronic stress. In conclusion, the birds appear to have experienced wear-and-tear, but our protocol did not accelerate the transition from phase II to phase III of fasting.
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Neophobia, but not perch hopping, is sensitive to long‐term chronic stress intensity
Abstract To further elucidate the role that wear‐and‐tear plays in the transition from acute to chronic stress, we manipulated the intensity and duration of applied chronic stress to determine if behavior would respond proportionately. We brought wild house sparrows into captivity and subjected them to high‐stress, medium‐stress, low‐stress, or captivity‐only. We varied the number of stressors per day and the duration of stress periods to vary wear‐and‐tear, and thus the potential to exhibit chronic stress symptoms. The behaviors we assessed were neophobia (the fear of the new; assessed via food approach latency) and perch hopping (activity). We predicted that our birds would show proportionate decreases in neophobia and activity throughout a long‐term chronic stress paradigm. Our results indicate that neophobia is sensitive to the intensity of chronic stress, however, the birds became more neophobic, which was the opposite of what we expected. Conversely, perch hopping did not differ across treatment groups and is thus not sensitive to the intensity of chronic stress. Together, these data show that different behavioral measurements are impacted differently by chronic stress.
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- Award ID(s):
- 1655269
- PAR ID:
- 10469512
- Publisher / Repository:
- Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
- Date Published:
- Journal Name:
- Journal of Experimental Zoology Part A: Ecological and Integrative Physiology
- ISSN:
- 2471-5638
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1002/jez.2752
