e Medical Biochemistry Department, Faculty of Medicine-Zagazig University, Zagazig, Egypt f Department of Pharmacology, Faculty of Medicine-Zagazig University, Zagazig, Egypt

Ulcerative colitis (UC) is a global inflammatory bowel disease. This study aimed to assess the effects of icosapent ethyl on acetic acid-induced colitis in rats as well as the underlying mechanisms involved. 36 male Wister rats were equally divided into six groups: control, UC, mesalamine 100 mg/kg, icosapent 150mg/kg, icosapent 300 mg/kg, and EX527-icosapent 300 mg/kg groups. Except for control group, UC was induced by acetic acid instillation into colon. Drugs were administered once daily for one week then under thiopental anaesthesia, colons were excised. Colitis macroscopic and microscopic scores were assessed. A part of colon was homogenized for detection of malondialdehyde (MDA), inerleukin1 (IL-1 beta), tumor necrosis factor (TNF-alpha), superoxide dismutase (SOD), phosphorylated Akt (pAkt) and caspase 3 levels. Silent information regulator 1 (SIRT1), heme oxygenase 1 (HO-1), and nuclear factor erythroid 2 (Nrf2) mRNA expressions were detected. Mallory-stained colonic sections were examined for collagen fibres detection. Immunohistochemistry of NF-kappa B and p53 expressionsin colonic sections were assessed. Acetic acid induced colitis with increments in MDA, IL-1 beta, TNF-alpha, and caspase 3 levels while decreased SOD, pAkt, SIRT1, HO-1, and Nrf2 with increased collagen fibres as well as NF kappa B and p53. Icosapent decreased macro& microscopic colitis scores, MDA, IL-1 beta, TNF-alpha, and caspase 3 levels while increased SOD, pAkt, SIRT1, HO-1, and Nrf2 with decreased collagen fibres as well as NF-kappa B and p53. The effects of icosapent 300 mg/kg were similar to mesalamine. Icosapent effects were antagonized by EX527. Icosapent alleviated acetic acid-induced colitis via its anti-inflammatory, antioxidant, and anti-apoptotic effects mediated in part by SIRT1 pathway activation.