Ulcerative colitis (UC) is a chronic inflammatory disease of intestinal tract, and Periplaneta americana has been found to be effective in the treatment for UC. The purpose of the study was to investigate the therapeutic effect of Periplaneta americana extract Ento-A on UC in rats induced by 2,4,6-trinitrobenzene sulfonic acid (TNBS) and to explore its mechanism. The Sprague-Dawley (SD) rats were randomly divided into normal control group; TNBS-treated group; sulfasalazine (SASP) treated group; Ento-A low- (50 mg/kg), medium- (100 mg/kg), and high-dose (200 mg/kg) groups, respectively. The UC model of rats was induced via TNBS. Disease activity index (DAI) was used to evaluate the severity of UC in rats. The macroscopic and microscopic damages of colon were accessed by colon mucosa damage index (CMDI) and histopathological score (HS), respectively. The levels of interleukin-4 (IL-4), interleukin-17 (IL-17), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in serum and the contents of myeloperoxidase (MPO), transforming growth factor-β1 (TGF-β1), and epidermal growth factor (EGF) in colonic mucosa were measured by enzyme-linked immunosorbent assay (ELISA). Compared with the normal control group, the TNBS-treated group showed increase in DAI, CMDI, HS, IL-17, TNF-α, IFN-γ as well as MPO and decrease in the levels of IL-4, EGF, and TGF-β1. However, Ento-A-administrated groups reversed the changes in the DAI, CMDI, HS, and the cytokines caused by TNBS. The study indicates that Periplaneta americana extract Ento-A can effectively alleviate the inflammation in TNBS-induced UC of rats, and the mechanism of that may be related to restoring the balance of T helper 1 (Th1)/Th2/Th17/T regulatory (Treg) cytokines.

Purpose: To investigate the effects of Periplaneta americana L. on ulcerative colitis (UC) induced by a combination of chronic stress (CS) and 2,4,6-trinitrobenzene sulfonic acid enema (TNBS) in rats. Methods: The experiment UC model with CS was established in rats by a combination of chronic restraint stress, excess failure, improper, and TNBS. The body weight, disease activity index (DAI), colonic mucosal injury index (CMDI), histopathological score (HS) and pro-inflammatory mediators were measured. The content of corticotropin-releasing hormone (CRH) in hypothalamus or adrenocorticotropic hormone (ACTH) and corticosteroids (CORT) in plasma were evaluated by enzyme-linked immunosorbent assay. The proportion of T lymphocyte subsets was detected by flow cytometry, and gut microbiota was detected by 16S rDNA amplicon sequencing. Results: Weight loss, DAI, CMDI, HS and proinflammatory mediators were reversed in rats by P. americana L. treatment after UC with CS. Increased epidermal growth factor (EGF) was observed in P. americana L. groups. In addition, P. americana L. could reduce the content of CRH and ACTH and regulate the ratio of CD3 + , CD3 + CD8 + and CD3 + CD4 + CD25 + /CD4 + in spleen. Comparably, P. americana L. changes composition of gut microbiota. Conclusions: The ethanol extract of Periplaneta Americana L. improves UC induced by a combination of CS and TNBS in rats.