title: Importance of stress receptor-mediated mechanisms in the amygdala on visceral pain perception in an intrinsically anxious rat.
abstract: BACKGROUND
  Stress worsens abdominal pain experienced by patients with irritable bowel syndrome (IBS), a chronic disorder of unknown origin with comorbid anxiety. Previously, we have demonstrated colonic hypersensitivity in Wistar-Kyoto rats (WKYs), a high-anxiety strain, which models abdominal pain in IBS. In low-anxiety rats, we have demonstrated that the central nucleus of the amygdala (CeA) regulates colonic hypersensitivity and anxiety induced by selective activation of either glucocorticoid receptors (GR) or mineralocorticoid receptors (MR), which is also mediated by the corticotropin releasing factor (CRF) Type-1 receptor. The goal of the present study was to test the hypothesis that the CeA through GR, MR, and/or CRF-1R regulates colonic hypersensitivity in WKYs.
  
  
  METHODS
  One series of WKYs had micropellets of a GR antagonist, an MR antagonist or cholesterol (control) stereotaxically implanted onto the CeA. Another series were infused in the CeA with CRF-1R antagonist, or vehicle. Colonic sensitivity was measured as a visceromotor response (VMR) to graded colorectal distension (CRD).
  
  
  RESULTS
  The exaggerated VMR to graded CRD in WKYs was unaffected by GR or MR antagonism in the CeA. In contrast, direct CeA infusion of CRF-1R antagonist significantly inhibited the VMR to CRD at noxious distension pressures.
  
  
  CONCLUSIONS
  Stress hormones in the CeA regulate colonic hypersensitivity in the rat through strain-dependent parallel pathways. The colonic hypersensitivity in WKYs is mediated by a CRF-1R mechanism in the CeA, independent of GR and MR. These complementary pathways suggest multiple etiologies whereby stress hormones in the CeA may regulate abdominal pain in IBS patients.
authors.affiliation: Oklahoma Center for Neuroscience, University of Oklahoma Health Science Center, Oklahoma City, OK, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Johnson
authors.forename: L
authors.initials: L
authors.lastname: Tran
authors.forename: J
authors.initials: J
authors.lastname: Schulkin
authors.forename: B
authors.initials: B
authors.lastname: Greenwood-Van Meerveld
mesh_terms: D000679:Amygdala / Q000503:physiopathology*; D000818:Animals; D001007:Anxiety / Q000503:physiopathology* / Q000523:psychology*; D002404:Catheterization; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D003627:Data Interpretation, Statistical; D006930:Hyperalgesia / Q000503:physiopathology / Q000523:psychology; D008297:Male; D058748:Pain Perception; D010812:Physical Stimulation; D051381:Rats; D011916:Rats, Inbred F344; D011921:Rats, Inbred WKY; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000502:physiology; D018161:Receptors, Mineralocorticoid / Q000502:physiology; D013238:Stereotaxic Techniques; D013315:Stress, Psychological / Q000503:physiopathology* / Q000523:psychology*; D059265:Visceral Pain / Q000503:physiopathology*; D000099052:CRF Receptor, Type 1
chemical_list: D018019:Receptors, Corticotropin-Releasing Hormone; D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone