STRESS-INDUCED ADRENOCORTICOTROPIN SECRETION - DIURNAL RESPONSES AND DECREASES DURING STRESS IN THE EVENING ARE NOT DEPENDENT ON CORTICOSTERONE
STRESS-INDUCED ADRENOCORTICOTROPIN SECRETION - DIURNAL RESPONSES AND DECREASES DURING STRESS IN THE EVENING ARE NOT DEPENDENT ON CORTICOSTERONE
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DOI：
10.1210/endo-128-2-680
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发表时间：
1991-02-01
期刊：
影响因子：
4.8
通讯作者：
DALLMAN, MF
中科院分区：
文献类型：
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作者：
BRADBURY, MJ;CASCIO, CS;DALLMAN, MF
为了测试应激反应的昼夜节律是否依赖于皮质酮 (B) 介导的负反馈，比较了完整大鼠 (SHAM) 和肾上腺切除 (ADX) 大鼠对束缚 3-90 分钟或早上 (AM) 和晚上 (PM) 腹腔注射生理盐水的反应。 在 SHAM 和 ADX 大鼠中，AM 大鼠对束缚应激的 ACTH 反应更大。 在完整的大鼠中，这可能是由于快速负反馈（由于 PM 应激期间 B 的上升速率）和延迟负反馈（由于 PM 应激之前 B 的基础浓度高）造成的。 然而，这种应激反应性的昼夜模式并不依赖于 B，因为在 ADX 大鼠中发现了对约束和腹腔注射的相同相对反应。 为了确定 PM 中 ADX 大鼠对应激缺乏反应是否是由于对内源性促分泌素敏感性丧失所致，在束缚 30 分钟后，给予 ADX 大鼠 CRF + 精氨酸加压素 (AVP)，同时用乙醚麻醉。 在上午和下午，垂体都能对外源性促分泌素做出反应。 第二个新发现是，尽管缺乏 B 介导的负反馈，但在 PM（而不是 AM）中，ADX 大鼠的血浆 ACTH 浓度在限制期间大幅下降。 在上午和下午，ADX 大鼠被限制 30 分钟，然后用乙醚应激 6 分钟。 乙醚前后的 ACTH 浓度没有差异，这表明，尽管 ADX 大鼠的垂体能够在应激后对外源性 CRF + AVP 做出反应，但在一天中的任何时间限制 30 分钟后，乙醚暴露的额外应激不再刺激内源性 CRF 和 AVP 释放。 在 AM 和 PM 中抑制 90 分钟后，ACTH 和 B 之间的关系是正向的，而不是负向的，这没有提供 SHAM 大鼠中持续的 B 介导的负反馈的证据。 因此，导致 ADX 大鼠 ACTH 分泌减少的相同机制也可能发生在 SHAM 大鼠中。 从这些结果中，我们得出结论，应激反应性的昼夜节律以及 ADX 大鼠 PM 中应激期间血浆 ACTH 的减少在很大程度上与 B.
To test whether the diurnal rhythm in stress responsiveness is dependent on corticosterone (B)-mediated negative feedback, the responses of intact (SHAM) and adrenalectomized (ADX) rats to restraint for 3-90 minutes or ip injection with saline in the morning (AM) and the evening (PM) were compared. In both SHAM and ADX rats, ACTH responses to restraint stress were larger in the AM. In intact rats, this could have resulted from both fast negative feedback, due to the rate of rise of B during the stress in the PM, and delayed negative feedback, due to the high basal concentrations of B before the stress in the PM. However, this diurnal pattern of stress responsiveness was not dependent on B, as the same relative responses to restraint and ip injection were found in ADX rats. To determine whether the lack of response of ADX rats in the PM to stress was due to a loss of sensitivity to endogenous secretagogues, ADX rats were given CRF + arginine vasopressin (AVP) while anesthetized with ether after 30 min of restraint. In both the AM and the PM, the pituitaries were able to respond to exogenous secretagogues. A second novel finding was that in the PM, but not the AM, plasma ACTH concentrations in the ADX rats decreased substantially during the period of restraint, despite the lack of B-mediated negative feedback. In the AM and the PM, ADX rats were restrained for 30 min and then stressed with ether for 6 min. The ACTH concentrations were not different before and after ether, suggesting that, although the pituitaries of ADX rats are able to respond to exogenous CRF + AVP after stress, an additional stress of ether exposure no longer stimulates endogenous CRF and AVP release after 30 min of restraint at either time of day. After 90 min of restraint in the AM and the PM, the relationship between ACTH and B was positive, not negative, providing no evidence of ongoing B-mediated negative feedback in the SHAM rats. Therefore, the same mechanism responsible for the decrease in ACTH secretion in ADX rats may occur in SHAM rats as well. From these results, we conclude that the diurnal rhythm in stress responsiveness and, in the PM in the ADX rats, the decrease in plasma ACTH during stress, are largely independent of B.