To investigate the anti-inflammatory effect and mechanism of all trans retinoic acid (ATRA) on intestinal ischemia/reperfusion (I/R) injury induced by superior mesenteric artery occlusion (SMAO).

Twenty-four Sprague-Dawley male rats were randomly divided into three groups (8 in each group): Sham group, I/R group and ATRA pretreatment group. Rat intestinal I/R models were made by clamping superior mesenteric artery for 60 min. After allowing reperfusion for 120 min, samples of distal ileum and serum were collected. Histological changes and Chiu's scores on the ileum mucosa were evaluated under light microscope. Serum diamine oxidase (DAO) and ileum myeloperoxidase (MPO) activity were analyzed by colorimetry. Ileum tumor necrosis factor (TNF)-α and interleukin(IL)-1β were detected by enzyme-linked immunosorbent assay method. Ileum protein of nuclear factor kappa B (NF-κB) p65 in nucleus and inhibitor NF-κB-α (IκBα) in cytoplasm was assessed by Western blot.

Compared with I/R group, ATRA significantly downgraded the mucosal Chiu's scores [(2.54±0.69) vs. (3.86±0.83), P < 0.05], lessened the serum DAO content [(18.09±4.21)U/L vs. (24.56±4.92)U/L, P < 0.05], suppressed the NF-κB p65 expression [(3.71±0.83) vs. (6.59±1.05), P < 0.05] and increased the IκBα expression [(0.56±0.12) vs. (0.26±0.05), P < 0.05] in ileum. Subsequently, the levels of TNF-α and IL-1β or the activity of MPO in ileum were effectively reduced [(61.37±18.66)pg/g vs. (97.21±24.67) pg/g, P<0.05; (115.24±30.82)pg/g vs. (219.83±54.31) pg/g, P < 0.05; (4.62±1.18) U/g vs. (7.16±1.50) U/g, P < 0.05; respectively].

With the mechanism of inhibiting NF-κB activation, ATRA pretreatment can alleviate the excessive inflammation response which result in attenuating intestinal ischemia/reperfusion injury induced by SMAO in rat.