Figure 5.

Effect of stress on expression of the genes encoding tumor necrosis factor α and receptors for adrenocorticotropic and corticotropin-releasing hormones in the ileum and colon of specific pathogen-free (SPF) and germ-free (GF) mice. CTRL, unstressed mice; STRESS, mice exposed to restraint stress for 2 h; Tnfα, tumor necrosis factor α; Crhr1, corticotropin-releasing hormone receptor type 1; Crhr2, corticotropin-releasing hormone receptor type 2; Mc2r, melanocortin-2 receptor. All data are expressed as mean ± SEM. Where an interaction effect was observed, the ampersand sign (^&p < 0.05) indicates a significant difference from the stressed GF mice and the plus sign (⁺⁺⁺p < 0.001, ⁺⁺p < 0.01, ⁺p < 0.05) indicates a significant difference relative to the unstressed SPF animals. Where no interaction effect was observed, a main effect of stress has been identified by placing a dashed horizontal line with an asterisk (^***p < 0.001) above the bars for the stress-exposed groups, whereas a main effect of microbiota by placing a dashed horizontal line with a hash sign (^#p < 0.05) above the bars for the SPF groups.