Stereotaxic delivery of corticosterone to the amygdala modulates colonic sensitivity in rats.

Episodes of anxiety are often associated with the onset or exacerbation of visceral pain in patients with irritable bowel syndrome (IBS). The central amygdaloid nucleus (CeA) is a key limbic structure involved in the expression of anxiety as well as a major site for regulating autonomic and visceral responses to stress. Previous experiments have shown that glucocorticoids can act directly at the CeA to increase the level of anxiety in rats. Therefore, the goal of this study was to examine the effect of stereotaxic delivery of corticosterone into the CeA on the development of visceral hypersensitivity by measuring visceromotor response to colorectal distention in rats. Stereotaxic delivery of corticosterone to the CeA increases indices of anxiety and produces a hypersensitive colon as demonstrated by an exaggerated visceromotor response to colorectal distention in the F344 rat strain. Our findings suggest that modulation of anxiety by manipulating amygdala function with corticosterone induced colonic hypersensitivity via descending neuronal pathways from the CeA.