Newman Amy E M, Pradhan Devaleena S, Soma Kiran K
Department of Psychology, University of British Columbia, 2136 West Mall, Vancouver, British Columbia, Canada V6T 1Z4.
Endocrinology. 2008 May;149(5):2537-45. doi: 10.1210/en.2007-1363. Epub 2008 Feb 14.
Stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of glucocorticoids can have detrimental effects on the brain. Dehydroepiandrosterone (DHEA), an androgen precursor synthesized in the adrenal glands or the brain itself, has anti-glucocorticoid properties, but little is known about the role of DHEA in the stress response, particularly in the brain. Here, we measured the effects of acute restraint on circulating corticosterone (CORT) and DHEA levels in wild song sparrows. Blood was collected from either the brachial or jugular vein. In songbirds, jugular plasma is enriched with neurally synthesized steroids, and therefore, jugular plasma is an indirect index of the neural steroidal milieu. Subjects were sampled during four times of year: breeding, molt, early nonbreeding, and mid-nonbreeding. Baseline CORT and DHEA levels showed similar seasonal changes; both steroids were elevated during the breeding season. Baseline CORT and DHEA levels were similar in jugular and brachial plasma. Acute stress had robust effects on CORT and DHEA that were season specific and vein specific. For CORT, during the molt, stress increased jugular CORT more than brachial CORT. For DHEA, during the breeding season, stress decreased jugular DHEA but not brachial DHEA. During the molt, stress increased jugular DHEA but not brachial DHEA. Acute stress did not affect brachial DHEA. These data suggest that acute stress specifically affects the balance between DHEA synthesis and metabolism in the brain. Furthermore, these results suggest that CORT and DHEA are locally synthesized in the brain during molt, when systemic levels of CORT and DHEA are low.
压力对肾上腺糖皮质激素的分泌有着众所周知的影响，而糖皮质激素的长期升高会对大脑产生有害影响。脱氢表雄酮（DHEA）是一种在肾上腺或大脑自身合成的雄激素前体，具有抗糖皮质激素特性，但人们对DHEA在应激反应中的作用知之甚少，尤其是在大脑中的作用。在此，我们测量了急性束缚对野生歌雀循环皮质酮（CORT）和DHEA水平的影响。血液从臂静脉或颈静脉采集。在鸣禽中，颈静脉血浆富含神经合成的类固醇，因此，颈静脉血浆是神经甾体环境的间接指标。在一年中的四个时期对研究对象进行采样：繁殖期、换羽期、非繁殖早期和非繁殖中期。基线CORT和DHEA水平呈现相似的季节性变化；两种类固醇在繁殖季节均升高。颈静脉和臂静脉血浆中的基线CORT和DHEA水平相似。急性应激对CORT和DHEA有显著影响，且具有季节特异性和静脉特异性。对于CORT，在换羽期，应激使颈静脉CORT升高幅度大于臂静脉CORT。对于DHEA，在繁殖季节，应激使颈静脉DHEA降低，但臂静脉DHEA未降低。在换羽期，应激使颈静脉DHEA升高，但臂静脉DHEA未升高。急性应激不影响臂静脉DHEA。这些数据表明，急性应激会特异性地影响大脑中DHEA合成与代谢之间的平衡。此外，这些结果表明，在换羽期，当全身CORT和DHEA水平较低时，CORT和DHEA是在大脑中局部合成的。
