The evaluation of the degree of intestinal inflammation in the experimental chemical induced colitis models with biochemical and histopathologic findings

Inflammatory bowel disease whose etiology is unknown, accompanied by chronic inflammation of bowels is an intestinal pathology. Experimental colitis models are used to unveil the etiopathogenesis. In the studies, acetic acid and trinitrobenzene sulphonic acid (TNBS) induced colitis models are most widely used. While acetic acid forms a colitis with acute effect, TNBS induces a colitis with chronic effect. In this study, it is aimed to form a new experimental colitis model, with acute and chronic effect, by using acetic acid and TNBS together and to research the severity of inflammation biochemically and histopathologically in comparison with the other models. In the study, 56 Wistar albino male rats were randomly divided into four groups as control, acetic acid, TNBS and combined and were sacrificed following the colitis induction on the 3rd and 7th days. All the rats were weighed at the beginning and at the end of the experiment. The serum amyloid A (SAA) and myeloperoxidase (MPO) in plasma samples, the tumour necrosis factor alpha (TNF- α), interleukin 33 (IL-33) and IL-33 receptor ST2 in colon tissue samples were analysed by ELISA. Microscopic damage scoring was done for histopathologic evaluation. A statistically significant different was found between the acetic acid group on the 3rd day and the control group in other parameters except the plasma SAA and the plasma MPO. On the other hand, on the 7th day there were no significant difference between the acetic acid and the control groups. A statistically significant different was found between the TNBS and control groups in all parameters except the plasma SAA on the 3rd day and in all parameters on the 7th day. There were statistically significant difference between the combined and the control group both on the 3rd day and on the 7th day in all parameters. While the weight gain was detected in the control groups and acetic acid group on the 7th day, the weight loss in acetic acid group on the 3rd day, TNBS and combined groups was found statistically significant different. In conclusion, the acetic acid model forms an acute colitis. The combined model compared with the other models is found more successful in forming inflammation and this model is recommended to be used in experimental studies.