Neuroendocrine Control Of The Stress Response

应激反应的神经内分泌控制

• 批准号: 7594140
• 负责人: Greti Aguilera
• 金额: $ 165.25万
• 依托单位: EUNICE KENNEDY SHRIVER NATIONAL INSTITUTE OF CHILD HEALTH & HUMAN DEVELOPMENT
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7594140
• 关键词: Acute; Address; Adrenal Glands; Adrenergic Agents; Affect; Attenuated; Behavioral; Biological Assay; CREB1 gene; Calcium; Cell Line; Cells; Chronic; Chronic stress; Condition; Corticosterone; Corticotropin; Corticotropin-Releasing Hormone; Cyclic AMP; Cyclic AMP Response Element; Development; Diagnostic; Disease; Dominant-Negative Mutation; Elevation; Exposure to; Feedback; Forskolin; Genes; Genetic Transcription; Glucocorticoids; Goals; Homeostasis; Hormonal; Hormones; Hour; Hypothalamic structure; Incubated; Infusion procedures; Investigation; Laboratory Study; Lead; Measures; Mediating; Mental Depression; Messenger RNA; Metabolic; Minor; Molecular; Neurons; Neuropeptides; Neurosecretory Systems; Neurotransmitters; Numbers; Pathology; Peptides; Personal Satisfaction; Phase; Phorbol Esters; Phospholipids; Phosphorylation; Pituitary Gland; Play; Production; Purpose; RNA Interference; Rattus; Receptor, Angiotensin, Type 1; Regulation; Relative (related person); Renin-Angiotensin System; Reporter; Reporter Genes; Repression; Research; Role; Signal Transduction; Steroid biosynthesis; Stress; Tetradecanoylphorbol Acetate; Therapeutic; Translational Regulation; V1b vasopressin receptor; Vasopressins; Wistar Rats; adrenergic; base; biological adaptation to stress; candesartan; gene repression; hypothalamic-pituitary-adrenal axis; paraventricular nucleus; parvocellular; prevent; promoter; receptor; receptor binding; response; subcutaneous; synergism; tool

Summary: Studies of this laboratory have been pivotal for understanding the interaction between CRH and vasopressin (VP) in the regulation of pituitary ACTH, and the regulation of the expression of these peptides in the PVN during stress and other alterations of the HPA axis. Both peptides co-expressed in the same parvocellular neuron of the paraventricular nucleus (PVN) are differentially regulated during stress or exposure to glucocorticoids. CRH coordinates behavioral, autonomic and hormonal responses to stress and is the main regulator of ACTH secretion in acute and chronic conditions. Following CRF release, activation of CRF transcription is required to restore mRNA and peptide levels, but termination of the response is essential to prevent pathology associated with chronic elevation of CRF and glucocorticoid production. While glucocorticoid feedback plays an important role in regulating CRF expression, the relative importance of direct transcriptional repression of the CRF gene by glucocorticoids in the overall feedback mechanism is not clear. In addition to glucocorticoids, intracellular feedback mechanisms in the CRF neuron, involving induction of repressor forms of cAMP response element modulator (CREM) limit CRF transcriptional responses by competing with the positive regulator, phospho-CREB. Research during the past year supports the hypothesis that induction of ICER is part of an intracellular feedback mechanism limiting CRH transcription. In these studies inhibition of endogenous ICER production using silencing RNA (siRNA) enhanced forskolin-induced CRH promoter activity in reporter gene assays, and attenuated the inhibitory phase of CRH transcription in primary hypothalamic neuronal cultures incubated with forskolin. Rapid repression of CRF transcription following stress-induced activation is likely to contribute to limiting the stress response and to preventing disorders associated with excessive CRF production. While it is well established that cAMP-dependent signaling is the major regulator of CRH transcription, the most recognized receptors mediating stimulation of CRH neurons, alpha adrenergic and glutamaergic receptors, act through mechanisms other than via cAMP. To determine whether synergism between calcium phospholipid signaling and small elevations of intracellular cAMP mediate activation of CRH transcription during stress, we investigated the effects of the phorbol ester, PMA, and the cAMP stimulator, forskolin, on CRH transcription and CREB phosphorylation in the hypothalamic cell line, 4B, and in hypothalamic neuronal cultures. Incubation of 4B cells transfected with a CRH promoter-driven reporter with forskolin, increased phospho-CREB (pCREB) levels and CRH promoter activity. PMA alone increased pCREB to similar levels but had no effect on CRH promoter activity. However, PMA potentiated the stimulatory effect of small concentrations of forskolin. The CREB dominant negative, A-CREB, reduced forskolin-stimulated CRH promoter activity in the absence or presence of PMA, indicating that pCREB is required but not sufficient to activate CRH transcription. PMA also potentiated the stimulatory effect of forskolin on CRH transcription (measured by intronic qRT-PCR) in primary cultures of hypothalamic cells. The potentiating effect of calcium/phospholipid-signaling on cAMP-mediated transcription provides a mechanism by which non-cAMP dependent neurotransmitters mediate activation of CRH transcription in presence of minor increases in intracellular cAMP. The relevance of these observations to the regulation of CRH expression by neurotransmitters activated during stress is under current investigation. We have shown that stress activates the renin-angiotensin system and increases the number of type angiotensin (AT1) receptors in the PVN. Sustained pretreatment with AT1 receptor antagonists prevents the sympathoadrenal and hormonal responses to 24 hours isolation stress. To examine the mechanism of the anti-stress effects of AT1 receptor antagonism, we investigated the effect of chronic treatment subcutaneous infusion of candesartan, a non-competitive AT1 receptor antagonist, on HPA axis responses to 24h isolation stress in Wistar rats. In vehicle rats, 24 h isolation stress increased pituitary ACTH, adrenal corticosterone content and AT1 receptor binding in the PVN but decreased CRH mRNA and CRH content in the PVN, changes similar to those found in depression. Candesartan pretreatment prevented the effects of stress, suggesting that activation of AT1 receptors is permissive for the HPA axis response to isolation. These results support the view that inhibition of central AT1 receptors limits the CRF response to stress and could serve as a therapeutic tool to preserve homeostasis under stress chronic conditions.

摘要：对该实验室的研究对于理解垂体ACTH调节中CRH和加压素（VP）之间的相互作用至关重要，以及在压力和HPA轴的其他变化过程中，这些肽在PVN中的表达调节。两种肽在脊髓核体（PVN）的相同副细胞神经元中共表达的肽在压力或暴露于糖皮质激素期间均受到差异调节。 CRH协调对压力的行为，自主和激素反应，是急性和慢性条件下ACTH分泌的主要调节剂。 CRF释放后，需要CRF转录的激活以恢复mRNA和肽水平，但是终止反应对于预防与CRF慢性升高和糖皮质激素产生相关的病理至关重要。尽管糖皮质激素反馈在调节CRF表达中起着重要作用，但尚不清楚糖皮质激素对CRF基因直接转录抑制的相对重要性在整体反馈机制中尚不清楚。除糖皮质激素外，CRF神经元中的细胞内反馈机制涉及CAMP响应元件调节剂（CREM）的诱导形式，通过与阳性调节剂磷酸化磷酸磷酸磷酸磷酸化反应限制了CRF转录响应。过去一年的研究支持以下假设：ICER的诱导是限制CRH转录的细胞内反馈机制的一部分。在这些研究中，使用沉默RNA（siRNA）抑制内源性ICER的产生，在报告基因测定中增强了Forskolin诱导的CRH启动子活性，并减弱了原发性下丘脑神经元培养物中CRH转录的抑制阶段。压力引起的激活后CRF转录的快速抑制可能有助于限制压力反应并预防与过度CRF产生相关的疾病。 虽然可以很好地确定cAMP依赖性信号传导是CRH转录的主要调节剂，但最公认的受体介导了CRH神经元，α肾上腺素能和谷氨酸能受体的刺激，通过通过CAMP以外的机制起作用。 To determine whether synergism between calcium phospholipid signaling and small elevations of intracellular cAMP mediate activation of CRH transcription during stress, we investigated the effects of the phorbol ester, PMA, and the cAMP stimulator, forskolin, on CRH transcription and CREB ​​phosphorylation in the hypothalamic cell line, 4B, and in hypothalamic neuronal cultures.用CRH启动子驱动的报告基因与Forskolin，磷酸-CREB（PCREB）水平升高和CRH启动子活性一起孵育4B细胞。单独使用PMA将PCREB提高到类似水平，但对CRH启动子活性没有影响。然而，PMA增强了少量福斯科蛋白的刺激作用。在不存在或存在PMA的情况下，CREB主导的负a-CREB降低了Forskolin刺激的CRH启动子活性，这表明PCREB是必需的，但不足以激活CRH转录。 PMA还增强了孔科林对下丘脑细胞原代培养物中CRH转录（通过内含子QRT-PCR测量）的刺激作用。钙/磷脂信号对cAMP介导的转录的增强作用提供了一种机制，通过这种机制，在细胞内cAMP中有较小的增加的情况下，非依赖性神经递质介导CRH转录的激活。这些观察结果与在压力期间激活的神经递质调节CRH表达的相关性是在当前的研究下。 我们已经表明，应激会激活肾素 - 血管紧张素系统，并增加PVN中血管紧张素（AT1）受体类型的数量。 AT1受体拮抗剂的持续预处理防止了对24小时隔离应激的副作用和激素反应。为了检查AT1受体拮抗作用的抗压力作用的机制，我们研究了慢性治疗皮下注射Candesartan（一种非竞争激烈的AT1受体拮抗剂）对Wistar大鼠中HPA轴对24H隔离应激的反应的影响。在车辆大鼠中，24小时的分离应力增加了垂体ACTH，肾上腺皮质酮含量和PVN中AT1受体结合，但PVN中的CRH mRNA和CRH含量降低，与抑郁症发现的变化相似。坎迪沙坦预处理阻止了应力的影响，表明AT1受体的激活对于HPA轴对分离的响应允许。这些结果支持这样一种观点，即抑制中央AT1受体会限制CRF对压力的反应，并可以作为在压力慢性条件下保存稳态的治疗工具。