Plasma binding proteins as mediators of corticosteroid action in vertebrates
Plasma binding proteins as mediators of corticosteroid action in vertebrates
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DOI：
10.1677/joe.0.1750099
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发表时间：
2002-10-01
影响因子：
4
通讯作者：
Orchinik, M
中科院分区：
文献类型：
--
作者：
Breuner, CW;Orchinik, M
应激源引发一系列复杂但多变的内分泌事件。应激反应的比较研究主要集中在肾上腺皮质对应激的反应，特别是糖皮质激素的血浆水平的测量。然而，许多其他因素有助于并改变细胞和生物体对糖皮质激素的反应。值得注意的是，血浆皮质类固醇结合球蛋白（CBG）可以调节类固醇对组织的一般可用性，和/或指导激素向特定部位的递送。在本文中，我们讨论了CBG的可能功能和CBG的作用机制，审查CBG的特点，脊椎动物之间，并讨论我们最近的研究表明，CBG确实可以调节应激反应。例如，在家雀中，我们发现总皮质类固醇（皮质醇或皮质酮）（CORT）的基础和应激诱导浓度随季节变化，但CBG浓度按比例变化，因此游离CORT浓度全年保持不变。相反，在白冠麻雀和树蜥蜴中，CBG浓度在总CORT水平不变的条件下发生变化，导致循环游离CORT发生显著变化。如果不考虑CBG，则游离CORT的这些差异被掩盖。我们还发现CBG的结合特性在物种之间变化很大，需要凭经验确定。这些研究导致观察到CBG在几个物种中也可以作为功能性雄激素结合蛋白;这对鸟类尤其重要，因为以前的研究得出结论，鸟类缺乏雄激素结合球蛋白。我们建议，CBG的考虑是至关重要的糖皮质激素介导的行为和生理反应的压力的作用。
Stressors elicit a complex but variable suite of endocrine events. Comparative studies of the stress response have focused primarily on the adrenocortical response to stress, in particular the measurement of plasma levels of glucocorticoids. However, a number of other factors contribute to and modify cellular and organismal responses to glucocorticoids. Notably, plasma corticosteroid binding globulins (CBGs) can regulate the general availability of steroid to tissues, and/or direct the delivery of hormones to specific sites. In this paper, we discuss possible functions of CBG and mechanisms of CBG action, review CBG characteristics among vertebrates, and discuss our recent studies indicating that CBG may indeed modulate responses to stressors. For example, in house sparrows, we found that basal and stress-induced concentrations of total corticosteroid (cortisol or corticosterone) (CORT) vary seasonally, but CBG concentrations change proportionally, so that free CORT concentrations appear static year-round. In contrast, in white-crowned sparrows and tree lizards, CBG concentrations change under conditions when total CORT levels do not, resulting in significant changes in circulating free CORT. These differences in free CORT are masked if CBG is not accounted for. We have also found that the binding properties of CBG vary considerably between species and need to be determined empirically. Such studies led to the observation that CBG in several species may also serve as a functional androgen binding protein; this is especially important for birds, because previous studies had concluded that birds lack androgen binding globulins. We propose that consideration of CBG is paramount to understanding the role of glucocorticoids in mediating behavioral and physiological responses to stress.