This damage is formed through TNF‐α, because increased TNF‐α level in gastric tissue damages gastric tissue mucosal cells (Konturek et al. 2000; Baraka et al. 2010) In an ulcer study, it was reported that TNF‐α level increased in the indomethacin group when compared to the control group (Thong‐Ngam et al. 2012) In our study, it was observed that TNF‐α level expression was highest in the indomethacin group. The gene discussed is TNF; the disease is ulcer disease.