MacLeod K J, Langkilde T, Heppner J J, Howey C A F, Sprayberry K, Tylan C, Sheriff M J
Department of Ecosystem Science and Management, Pennsylvania State University, Forest Resources Building, University Park, PA 16802, USA; Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA; Department of Biology, Lund University, Sölvegatan 37, Lund 223 62, Sweden.
Department of Biology, Pennsylvania State University, Mueller Laboratory, University Park, PA 16802, USA.
Horm Behav. 2021 Nov;136:105072. doi: 10.1016/j.yhbeh.2021.105072. Epub 2021 Oct 7.
Reproduction is a critical part of an animal's life history, but one which incurs significant costs to survival and future reproductive potential. These physiological consequences are likely to be influenced by context - for example, if an individual is subject to environmental stressors, physiological and behavioral changes associated with reproduction may be altered. Glucocorticoids, hormones produced as part of the physiological response to stressors, may alter how reproduction affects female physiology and behavior, and therefore the outcomes of reproductive trade-offs. Glucocorticoids prioritize immediate survival over reproduction, for example through changes in immune function, metabolic rate, and foraging, which may reduce energy expenditure or increase energy gain. However, we previously found that female eastern fence lizards (Sceloporus undulatus) experiencing elevated glucocorticoid levels during gestation were nevertheless able to maintain reproductive output and body condition. Here we investigate compensatory mechanisms by which eastern fence lizard females may maintain reproduction under experimental increases in a glucocorticoid, corticosterone (CORT). We found that, although CORT-treated females had similar immune function and behavior, they had reduced metabolic rates 3-5 days post-parturition compared to control females. Given that CORT-treated females spent a similar time basking and had equal food intake compared to control females, we suggest that the reduced metabolic rate is a mechanism by which CORT-treated females maintain their energy balance and reduce the energetic costs of gestation during periods of stress. This study suggests that physiological responses to reproduction may be context-dependent and could act to minimize costs of reproduction in situations where CORT is elevated (such as during periods of environmental stress).
繁殖是动物生命历程中的关键部分，但这一过程会给生存及未来的繁殖潜力带来巨大代价。这些生理后果可能会受到环境背景的影响——例如，如果个体面临环境压力源，与繁殖相关的生理和行为变化可能会被改变。糖皮质激素是作为对应激源生理反应的一部分而产生的激素，它可能会改变繁殖对雌性生理和行为的影响，进而影响繁殖权衡的结果。糖皮质激素将即时生存置于繁殖之上，例如通过改变免疫功能、代谢率和觅食行为，这可能会减少能量消耗或增加能量获取。然而，我们之前发现，妊娠期糖皮质激素水平升高的雌性东部围栏蜥蜴（Sceloporus undulatus）仍能够维持繁殖产出和身体状况。在此，我们研究东部围栏蜥蜴雌性在实验性增加一种糖皮质激素——皮质酮（CORT）的情况下可能维持繁殖的补偿机制。我们发现，尽管接受CORT处理的雌性具有相似的免疫功能和行为，但与对照雌性相比，它们在产后3 - 5天的代谢率降低。鉴于接受CORT处理的雌性与对照雌性晒太阳的时间相似且食物摄入量相同，我们认为代谢率降低是接受CORT处理的雌性维持能量平衡并在应激期间降低妊娠能量成本的一种机制。这项研究表明，对繁殖的生理反应可能取决于环境背景，并且在CORT升高的情况下（如在环境应激期间）可能会起到将繁殖成本降至最低的作用。
