Seasonal Changes in Muscle Gene Expression Associated with HPA Axis Signaling: A Migrant and Resident Songbird Comparison
AuthorWatkins, Trevor J.
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Significant expression patterns of glucocorticoid receptors and their metabolizing enzymes indicate that HPA axis mechanisms fluctuate over an annual cycle and must be considered in addition to corticosterone levels in muscle tissue. Our research further supports the emergence of 11?HSD2 as a highly dynamic gene with a likely critical role in muscular morphological events. Further research must be performed on 11?HSD2 to confirm its exact role in phenotypic flexibility across muscle tissues in migrating species. Additionally, significant changes in MR and GR expression across life history stages further implicate these receptors as critical players in avian endocrinology mechanisms. The myriad of main model effects observed in gastrocnemius and heart tissue indicate that these receptors must not be exclusively considered in the more prominent and dynamic pectoralis muscle. We believe our results should encourage further research into what may be an important aspect of phenotypic change in dynamic species.