Stimulation of inflammatory mediators secretion by chemotactic peptides in rat colitis model.

Colonic inflammation was produced in rats by chemotactic peptides acting on polymorphonuclear leucocytes. Instillation during one hour of formylated tripeptide: formylmethionyl-leucyl-phenylalanine (FMLP) and a tetrapeptide: alanine-glycine-sefine-glutamine (AGSG) into rat colon caused erosions and exulcerations. Neutrophils increased secondary to instillation, predominantly with FMLP, and mucus depletion was marked in the cecum. Chloride ion secretion and mucosal permeability were significatively greater in the colonic lumen with the chemotactic peptides. Histamine and serotonin concentration were greater in the colonic fluid in animals treated with the peptides. These observations could suggest that the presence of chemotactic peptides at the colonic lumen produce changes at the mucosal wall, that would participate in generation and perpetuation of the colonic inflammation.