Olfactory preference and neuronal activation. A, Time spent chemoinvestigating clean, male-soiled, and female-soiled-bedding by control and ARNesCre mice (n = 20 per genotype). A significant effect of bedding (F(2,76) = 143.58, p < 0.0001) but not of genotype was found; post hoc analysis showed differences in the time spent sniffing the three beddings (ap < 0.001 vs clean bedding; bp < 0.001 vs male-soiled bedding). B, C, Representative c-fos immunostaining in the medial amygdala (B) and medial preoptic area (C) of control and ARNesCre males exposed to clean or female-soiled beddings for 1 h. CA, Cortical amygdala; AC, anterior commissure; V3, third ventricle.