title: Chronic stress-induced alterations in mouse colonic 5-HT and defecation responses are strain dependent.
abstract: Mood disorders and chronic stress are frequently associated with gastrointestinal (GI) symptoms including diarrhoea or constipation. Locally produced serotonin [5-hydroxytryptamine (5-HT)] regulates GI motility and is a key factor in the pathophysiology of stress-associated GI disorders. We aimed to establish whether chronic stress can differentially affect faecal output and colon 5-HT concentration in two inbred mouse strains: BALB/c and C57BL/6 which differ in their ability to cope with stress. Adult male BALB/c and C57BL/6 mice were restrained for 2 h daily for 10 days. Defecation was monitored during each stress session. Twenty-four hours after the last session of stress, plasma corticosterone concentration was higher than control in both strains, indicative of a physiological effect of chronic stress; however, stress-induced diarrhoea was more persistent in C57BL/6 mice. Basal concentration of colon 5-HT was higher in C57BL/6 mice, and stress elicited an increase in colon 5-HT only in this strain. Finally, naïve BALB/c mice had a higher sensitivity (incidence of diarrhoea) to 5-HT (0.33 mg/kg, i.p.) than C57BL/6 mice. Our results suggest that differential defecation responses to stress may be associated with colon 5-HT concentration, which may in turn reflect the individual sensitivity to 5-HT. In addition, C57BL/6 mice emerge as a relevant model for studying GI alterations induced by chronic stress.
authors.affiliation: Laboratory of Neurogastroenterology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
authors.forename: Marcela
authors.initials: M
authors.lastname: Julio-Pieper
authors.forename: Cliona M
authors.initials: CM
authors.lastname: O'Mahony
authors.forename: Gerard
authors.initials: G
authors.lastname: Clarke
authors.forename: Javier A
authors.initials: JA
authors.lastname: Bravo
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Dinan
authors.forename: John F
authors.initials: JF
authors.lastname: Cryan
mesh_terms: D000818:Animals; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D003672:Defecation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D012149:Restraint, Physical; D012701:Serotonin / Q000378:metabolism* / Q000494:pharmacology; D013045:Species Specificity; D013312:Stress, Physiological / Q000502:physiology*; D013315:Stress, Psychological
chemical_list: D012701:Serotonin; D003345:Corticosterone