Oklahoma Center for Neuroscience, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
Am J Physiol Gastrointest Liver Physiol. 2012 Jan 15;302(2):G260-6. doi: 10.1152/ajpgi.00353.2011. Epub 2011 Nov 3.
Symptoms of irritable bowel syndrome (IBS) are exacerbated by stress. Previously, we demonstrated that the stress hormone corticosterone applied directly to the amygdala induced visceral hypersensitivity through the actions of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). However, the involvement of amygdaloid GR and MR in the regulation of visceral sensitivity following psychological stress is unknown; therefore, the goal of the present study was to determine the relative importance of amygdaloid GR and MR in the regulation of visceral sensitivity in a rodent model of behavioral stress. Male F-344 rats were stereotaxically implanted with micropellets bilaterally on the dorsal margin of the amygdala containing the GR antagonist mifepristone, the MR antagonist spironolactone, or cholesterol as a control. Animals were then exposed to 1 h of water-avoidance stress (WAS) or sham stress for 1 day (acute) or 7 days (repeated). Visceral sensitivity was assessed either 1 h or 24 h after the final session of WAS and quantified as the number of contractions of the external abdominal oblique, a visceromotor response, in response to colorectal distension at pressures of 0-60 mmHg. Acute stress induced transient visceral hyperalgesia, which was absent 24 h after WAS and independent of GR and MR. Conversely, repeated WAS induced sustained visceral hyperalgesia that was abolished by specifically targeting the amygdala with GR and MR antagonists. These results demonstrate that the amygdala corticosteroid system plays an essential role in mediating the effects of repeated WAS on visceral sensitivity. Furthermore, our findings suggest that amygdaloid GR and MR may be involved in IBS symptomatology.
肠易激综合征(IBS)的症状会因压力而加重。此前,我们已经证明,直接施加于杏仁核的应激激素皮质酮通过糖皮质激素受体(GR)和盐皮质激素受体(MR)的作用诱导内脏敏感性。然而,杏仁核 GR 和 MR 在心理应激后内脏敏感性的调节中的作用尚不清楚;因此,本研究的目的是确定杏仁核 GR 和 MR 在行为应激的啮齿动物模型中对内脏敏感性调节的相对重要性。雄性 F-344 大鼠被立体定向双侧植入含有 GR 拮抗剂米非司酮、MR 拮抗剂螺内酯或胆固醇作为对照的微球于杏仁核背缘。然后,动物暴露于 1 小时的避水应激(WAS)或假应激 1 天(急性)或 7 天(重复)。在 WAS 的最后一次会话后 1 小时或 24 小时评估内脏敏感性,并通过对外侧腹斜肌的收缩次数进行量化,这是对直肠扩张至 0-60mmHg 时的内脏运动反应。急性应激诱导短暂的内脏痛觉过敏,在 WAS 后 24 小时消失且与 GR 和 MR 无关。相反,重复的 WAS 诱导持续的内脏痛觉过敏,用 GR 和 MR 拮抗剂特异性靶向杏仁核可以消除这种过敏。这些结果表明,杏仁核皮质激素系统在介导重复 WAS 对内脏敏感性的影响中起关键作用。此外,我们的发现表明,杏仁核 GR 和 MR 可能与 IBS 症状有关。
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