Journal article
Migratory state and patterns of steroid hormone regulation in the pectoralis muscle of a nomadic migrant, the pine siskin (Spinus pinus)
General and comparative endocrinology, Vol.309, pp.113787-113787
08/01/2021
Handle:
https://hdl.handle.net/2376/117757
PMID: 33862052
Abstract
•Changes in endocrine signaling are thought to mediate the migratory transition.•We investigated changes in endocrine signaling in a nomadic migrant.•We examined gene expression of steroid hormone receptors and biosynthesis enzymes.•Gene expression in flight muscle of nomadic migrant did not differ across transition.•Migratory strategies may shape evolution of endocrine signaling and integration.
The endocrine system is known to mediate responses to environmental change and transitions between different life stages (e.g., a non-breeding to a breeding life stage). Previous works from the field of environmental endocrinology have primarily focused on changes in circulating hormones, but a comprehensive understanding of endocrine signaling pathways requires studying changes in additional endocrine components (e.g., receptor densities) in a diversity of contexts and life stages. Migratory birds, for instance, can exhibit dramatic changes in their physiology and behavior, and both sex steroids as well as glucocorticoids are proposed mediators of the transition into a migratory state. However, the role of changes in endocrine signaling components within integral target tissues, such as flight muscles, in modulating the transition into a migratory state remains poorly understood. Here, we examined changes in gene expression levels of and correlational patterns (i.e., integration) between 8 endocrine signaling components associated with either glucocorticoids or sex steroid signaling in the pectoralis muscles of a nomadic migratory bird, the pine siskin (Spinus pinus). The pectoralis muscle is essential to migratory flight and undergoes conspicuous changes in preparation for migration, including hypertrophy. We focus on endocrine receptors and enzymes (e.g., 5α-reductase) that modulate the signaling capacity of circulating hormones within target tissues and may influence either catabolic or anabolic functioning within the pectoralis. Endocrine signaling components were compared between captive birds sampled prior to the expression of vernal migratory preparation and during the expression of a vernal migratory state. While birds exhibited differences in the size and color of the flight muscle and behavioral shifts indicative of a migratory state (i.e., zugunruhe), none of the measured endocrine components differed before and after the transition into the migratory state. Patterns of integration amongst all genes did, however, differ between the two life stages, suggesting the contrasting demands of different life stages may shape entire endocrine signaling networks within target tissues rather than individual components. Our work aligns with previous endocrine studies on pine siskins and, viewed together, suggest additional studies are needed to understand the endocrine system’s role in mediating the development and progression of the vernal migratory state in this species. Further, the patterns observed in pine siskins, a nomadic migrant, differ from previous studies on obligate migrants and suggest that different mechanisms or interactions between endocrine signaling components may mediate the migratory transition in nomadic migrants.
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Details
- Title
- Migratory state and patterns of steroid hormone regulation in the pectoralis muscle of a nomadic migrant, the pine siskin (Spinus pinus)
- Creators
- Ben J Vernasco - School of Biological Sciences, Washington State University, Pullman, WA, USAMichael G Emmerson - Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USAElizabeth R Gilbert - Animal and Poultry Sciences Department, Virginia Tech, Blacksburg, VA, USAKendra B Sewall - Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USAHeather E Watts - School of Biological Sciences, Washington State University, Pullman, WA, USA
- Publication Details
- General and comparative endocrinology, Vol.309, pp.113787-113787
- Publisher
- Elsevier Inc
- Identifiers
- 99900574624401842
- Language
- English
- Resource Type
- Journal article