Phenotypic flexibility of glucocorticoid signaling in skeletal muscles of a songbird preparing to migrate

摘要: Abstract Glucocorticoids are commonly associated with responses to stress, but other important functions include homeostatic regulation, energy metabolism and tissue remodeling. At low circulating levels, glucocorticoids bind high-affinity mineralocorticoid receptors (MR) activate repair homeostasis (anabolic pathways), whereas at elevated glucocorticoid (GR) catabolic pathways. Long distance migrations, such as those performed by Gambel's white-crowned sparrows (Zonotrichia leucophrys gambelii), require modification of anatomy, physiology behavior. Plasma corticosterone (CORT) increases in association impending departure flight may promote muscle-specific anabolic states. To test this idea, we explored signaling the pectoralis (flight) gastrocnemius (leg) muscles male on wintering grounds three stages leading up spring departure: winter (February), pre-nuptial molt (March), pre-departure (April). CORT was detected plasma both muscles, measures differed across stages. Expression 11β-hydroxysteroid dehydrogenase (11β-HSD) Type 2 (inactivates CORT) increased pre-departure, 11β-HSD 1 (regenerates did not change. Neither two isoforms detectable gastrocnemius. MR, GR, while only GR expression These data suggest that predominate activity is undetected either muscle pre-departure.