Fokidis H Bobby, Hurley Laura, Rogowski Christopher, Sweazea Karen, Deviche Pierre
School of Life Sciences, Arizona State University, Tempe, Arizona 85281, USA.
Physiol Biochem Zool. 2011 Nov-Dec;84(6):595-606. doi: 10.1086/662068. Epub 2011 Sep 1.
The acute stress response involves the secretion of catabolic glucocorticoids, such as corticosterone (CORT) in birds, that mobilize intrinsic energy stores primarily through a gluconeogenic pathway involving fat breakdown, thus linking body condition and stress. We measured changes in CORT and gluconeogenic metabolites (triglycerides, free glycerols, glucose) during handling stress in curve-billed thrashers Toxostoma curvirostre from two habitats (urban vs. desert) that may differ in food abundance in the wild, in captivity, and in response to both food restriction and subsequent recovery. Urban thrashers were heavier and secreted more CORT than desert birds in the field, but differences did not persist in captivity. Decreased access to food resulted in decreased body mass and a diminished ability to elevate plasma CORT in response to handling stress. However, the opposite effect was observed as these birds recovered from food restriction. Plasma levels of glucose and triglycerides did not change with stress. Food restriction also increased locomotor activity, which likely further exacerbated energy loss. These observations suggest that body condition and stress differences between urban and desert birds may be related to differences in their relative energetic states, possibly due to food availability. Body condition may affect the extent to which an individual can elevate CORT and use free glycerol as energy during acute stress.
急性应激反应涉及分解代谢糖皮质激素的分泌，比如鸟类体内的皮质酮（CORT），它主要通过一条涉及脂肪分解的糖异生途径来调动内在能量储备，从而将身体状况与应激联系起来。我们测量了来自两种栖息地（城市与沙漠）的弯嘴矢嘲鸫（Toxostoma curvirostre）在处理应激过程中CORT和糖异生代谢物（甘油三酯、游离甘油、葡萄糖）的变化，这两种栖息地在野生、圈养条件下的食物丰富度可能存在差异，并且在食物限制及随后恢复过程中的反应也可能不同。在野外，城市矢嘲鸫比沙漠矢嘲鸫更重，分泌的CORT也更多，但在圈养条件下这种差异并未持续存在。食物获取减少导致体重下降，并且对应激处理时升高血浆CORT的能力减弱。然而，当这些鸟类从食物限制中恢复时，观察到了相反的效果。血浆葡萄糖和甘油三酯水平不会因应激而改变。食物限制还增加了运动活动，这可能进一步加剧了能量损失。这些观察结果表明，城市和沙漠鸟类之间的身体状况和应激差异可能与它们相对能量状态的差异有关，这可能是由于食物可获得性造成的。身体状况可能会影响个体在急性应激期间升高CORT以及利用游离甘油作为能量的程度。
