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Chang van Oordt DA, Taff CC, Pipkin MA, Ryan TA, Vitousek MN. Experimentally elevated corticosterone does not affect bacteria killing ability of breeding female tree swallows (Tachycineta bicolor). Horm Behav 2024; 160:105500. [PMID: 38316079 DOI: 10.1016/j.yhbeh.2024.105500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 01/19/2024] [Accepted: 01/29/2024] [Indexed: 02/07/2024]
Abstract
The immune system can be modulated when organisms are exposed to acute or chronic stressors. Glucocorticoids (GCs), the primary hormonal mediators of the physiological stress response, are suspected to play a crucial role in immune modulation. However, most evidence of stress-associated immunomodulation does not separate the effects of glucocorticoid-dependent pathways from those of glucocorticoid-independent mechanisms on immune function. In this study, we experimentally elevated circulating corticosterone, the main avian glucocorticoid, in free-living female tree swallows (Tachycineta bicolor) for one to two weeks to test its effects on immune modulation. Natural variation in bacteria killing ability (BKA), a measure of innate constitutive immunity, was predicted by the interaction between timing of breeding and corticosterone levels. However, experimental elevation of corticosterone had no effect on BKA. Therefore, even when BKA is correlated with natural variation in glucocorticoid levels, this relationship may not be causal. Experiments are necessary to uncover the causal mechanisms of immunomodulation and the consequences of acute and chronic stress on disease vulnerability. Findings in other species indicate that acute increases in GCs can suppress BKA; but our results support the hypothesis that this effect does not persist over longer timescales, during chronic elevations in GCs. Direct comparisons of the effects of acute vs. chronic elevation of GCs on BKA will be important for testing this hypothesis.
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Affiliation(s)
- David A Chang van Oordt
- Dept. of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, 159 Sapsucker Woods Rd, Ithaca, NY 14850, USA.
| | - Conor C Taff
- Dept. of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, 159 Sapsucker Woods Rd, Ithaca, NY 14850, USA
| | - Monique A Pipkin
- Dept. of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, 159 Sapsucker Woods Rd, Ithaca, NY 14850, USA
| | - Thomas A Ryan
- Dept. of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, 159 Sapsucker Woods Rd, Ithaca, NY 14850, USA
| | - Maren N Vitousek
- Dept. of Ecology and Evolutionary Biology, Cornell University, 215 Tower Rd, Ithaca, NY 14853, USA; Cornell Lab of Ornithology, 159 Sapsucker Woods Rd, Ithaca, NY 14850, USA
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Assis VR, Titon SCM, Voyles J. Ecoimmunology: What Unconventional Organisms Tell Us after Two Decades. Integr Comp Biol 2022; 62:icac148. [PMID: 36250609 DOI: 10.1093/icb/icac148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/13/2022] [Accepted: 09/18/2022] [Indexed: 02/18/2024] Open
Affiliation(s)
- Vania R Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo SP 05508-090, Brasil
| | - Stefanny C M Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, São Paulo SP 05508-090, Brasil
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, Reno, NV 89557, USA
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