Hypothesized mechanism of exacerbated symptoms and increased sympathetic nerve activity before defecation.

Abstract

The stress of abdominal pain activates the amygdala to release corticotrophin-releasing hormone (CRH), resulting in further exacerbation of abdominal pain by increasing colonic motility. These cascades “exacerbate the circle of pain.” Two minutes before defecation, the stress also activates sympathetic nerves as a stress response against abdominal pain. Increased sympathetic nerve activity can decrease colonic motility, which may have a protective role to hold back the defecation. This situation may be under competition between the accelerator of colonic motility caused by CRH and the brake caused by sympathetic nerve activation.</p