School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, USA.
Integr Comp Biol. 2017 Dec 1;57(6):1184-1193. doi: 10.1093/icb/icx112.
To maximize fitness, organisms must invest energetic and nutritional resources into developing, activating, and maintaining reproductive physiology and behavior. Corticosterone (CORT), the primary avian glucocorticoid, regulates energetic reserves to meet metabolic demands. At low (baseline) plasma levels, CORT activates avian mineralocorticoid receptors and may stimulate lipid mobilization, foraging activity, and feeding behavior. During stress in birds, elevated plasma CORT also stimulates glucocorticoid receptors and may promote glycemia, lipolysis, and proteolysis. Furthermore, CORT orchestrates physiological and behavioral adjustments to perceived threats. While many avian studies demonstrate effects of CORT on reproduction, few studies have elucidated the mechanisms, including receptor activation and site(s) of action, which underlie these effects. Even fewer studies have investigated how low and elevated plasma CORT regulates energetic reserves to meet the metabolic demands of reproduction. Here, we propose several hypotheses to clarify the direct and indirect effects of CORT on avian reproductive physiology and behavior. In addition, we emphasize the need for new manipulative studies involving alterations of endogenous plasma CORT levels and/or food availability to elucidate how CORT regulates the energetic demands of reproduction.
为了最大限度地提高适应性，生物必须投入能量和营养资源来发展、激活和维持生殖生理学和行为。皮质酮（CORT）是主要的鸟类糖皮质激素，调节能量储备以满足代谢需求。在低（基线）血浆水平下，CORT 激活鸟类盐皮质激素受体，并可能刺激脂质动员、觅食活动和摄食行为。在鸟类的应激反应中，血浆 CORT 水平升高也会刺激糖皮质激素受体，并可能促进血糖、脂肪分解和蛋白质分解。此外，CORT 协调对感知威胁的生理和行为调整。尽管许多鸟类研究表明 CORT 对生殖有影响，但很少有研究阐明其机制，包括受体激活和作用部位，这些机制是这些影响的基础。更少的研究调查了低和高血浆 CORT 如何调节能量储备以满足生殖的代谢需求。在这里，我们提出了几个假设，以阐明 CORT 对鸟类生殖生理学和行为的直接和间接影响。此外，我们强调需要进行新的操纵研究，涉及改变内源性血浆 CORT 水平和/或食物供应，以阐明 CORT 如何调节生殖的能量需求。
