Sexually dimorphic effects of SCFA-FFAR2 signaling on colitis-induced visceral hypersensitivity in mice

Sex differences in visceral hypersensitivity (VH) has been demonstrated, while the underlying mechanism needs to be elucidated. A sodium dextran sulfate (DSS)-induced acute colitis mouse model was constructed to identify sex differences in the histopathology and microbiota composition of the colon. Colitis-induced VH was also measured using a behavioral assay in both male and female mice. Acetate, a principal short-chain fatty acid (SCFA), was administered, and SCFA receptor-deficient mice (FFAR2^-/- mice) were used to determine the role of SCFA-FFAR2 signaling in colitis-induced VH in both sexes as well as the potential neurobiological pathways. This study revealed a sexually dimorphic VH-related response in a DSS-induced colitis mouse model. The expression of the SCFA receptor FFAR2 was downregulated more obviously in DSS-treated male mice than in female mice. Acetate supplementation alleviated the VH-related response in male and female colitis mice, whereas FFAR2 deficiency intercepted this alleviation only in males. FFAR2 deletion led to discrepancies in differential gene expression in the dorsal root ganglion (DRG) associated with inflammatory pathways between male and female mice. The expression of IL-17RA in the anterior cingulate cortex (ACC) of DSS-treated FFAR2^-/- male mice was greater than that in wild-type (WT) mice. Blockade of IL-17RA in the ACC significantly attenuated the FFAR2 deficiency-induced aggravation of VH in DSS-treated male mice. This study reveals the involvement of FFAR2 in sexually dimorphic VH. In males, but not females, IL-17RA may be a downstream target of SCFAs-FFAR2 signaling in the perception of VH in experimental colitis. PERSPECTIVE: This article represents the mechanisms underlying sex differences in VH in a mouse model of colitis induced by DSS. The finding provides a theoretical basis and new ideas for the clinical implementation of gender differentiated analgesic treatment.