Effects of Bifidobacterium infantis on intestinal corticotropin releasing factor receptors and mast cells activation in a murine model of irritable bowel syndrome

Abstract

Objective To investigate the effects of Bifidobacterium infatn ison the expression of in -testinal corticotropin releasing factor （ CRF） receptors and how the peripheral CRF receptors activate mast cells in a murine model of irritable bowel syndrome （IBS）.Methods Thirty BALB/c male mice were ran-domly divided into three groups including control group , model group and Bifidobacterium infantis group. The mouse model of IBS was established by using chronic restraint stress .Mice in Bifidobacterium infantis group received daily intragastrical administration of Bifidobacterium infantis for 14 days.Mice in control and model groups were treated with equal volume of saline .Then all mice were killed after the assessment of weight and abdominal withdrawal reflex （ AWR） .The levels of histamine , tryptase and tumor necrosis fac-tor-α（ TNF-α） in serum samples were detected by ELISA .The expression of CRF in colonic mucosa was analyzed by immunohistochemistry .The expression of CRF-R1 and CRF-R2 in mast cells and the number of mast cells in colonic mucosa were detected by double immunofluorescence staining assay .The expression of CRF-R1 and CRF-R2 at mRNA level in colon were detected by reverse transcription polymerase chain reac-tion （ RT-PCR） .Results Compared with control group , the levels of histamine , tryptase and TNF-αin pe-ripheral blood samples , the expression of CRF-R1 and CRF-R2 at mRNA level , and the number of mast cells, CRF-R1＋mast cells and CRF-R2＋mast cells in colonic mucosa were increased significantly in model group （P〈0.05）, but were remarkably down-regulated with the treatment ofB ifidobacterium infantis （P〈0.05）.Conclusion Bifidobacterium infantis could reduce the activation of mast cells in a murine model of IBS by inhibiting the expression of CRF-R1 and CRF-R2 in intestinal mast cells . Key words: Irritable bowel syndrome; Probiotics; Corticotropin releasing factor; Mast cell