Objective:To investigate the effect of atorvastatin preconditioning on intestinal ischemia-reperfusion (I/R) injury in mice and the relationship with phosphatidylinositol 3-kinase (PI3K)/serine-threonine kinase (Akt) signaling pathway.Methods:Twenty-four healthy male C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were divided into 4 groups ( n=6 each) using a random number table method: sham operation group (S group), I/R group, atorvastatin preconditioning group (A group), atorvastatin plus PI3K inhibitor LY294002 group (AL group). Atorvastatin 10 mg/kg was given by intragastric gavage for 3 consecutive days in A and AL groups, and in addition LY294002 0.3 mg/kg was intraperitoneally injected at 30 min before the last administration of atorvastatin in AL group.Intestinal I/R was produced by occlusion of superior mesenteric artery (SMA) for 45 min followed by 2 h reperfusion in anesthetized mice.The superior mesenteric artery was only isolated but not clamped in S group.The mice were sacrificed at the end of reperfusion, and small intestinal tissues were taken for determination of the pathological changes with a light microscope after HE staining and for determination of wet to dry weight ratio(W/D ratio) and expression of PI3K, phosphorylated Akt (p-Akt), autophagy-related proteins Beclin-1, microtubule-associated protein 1 light chain 3Ⅰ (LC3Ⅰ) and LC3Ⅱ.The intestinal damage was assessed and scored according to Chiu.The ratio of LC3Ⅱ expression to LC3Ⅰ expression (LC3Ⅱ/LC3Ⅰ) was calculated. Results:Compared with S group, Chiu′s scores and W/D ratio were significantly increased, the expression of PI3K and p-Akt was down-regulated, the expression of Beclin-1 was up-regulated, and LC3Ⅱ/LC3Ⅰ ratio was increased in I/R, A and AL groups ( P<0.05). Compared with I/R group, Chiu′s scores and W/D ratio were significantly decreased, the expression of PI3K and p-Akt was up-regulated, the expression of Beclin-1 was down-regulated, and LC3Ⅱ/LC3Ⅰ ratio was decreased in A group ( P<0.05). Compared with A group, Chiu′s scores and W/D ratio were significantly increased, the expression of PI3K and p-Akt was down-regulated, the expression of Beclin-1 was up-regulated, and LC3Ⅱ/LC3Ⅰ ratio was increased in AL group ( P<0.05). Conclusion:Atorvastatin preconditioning can mitigate intestinal I/R injury in mice, and the mechanism is related to activating PI3K/Akt signaling pathway and inhibiting the level of autophagy.

Objective:To evaluate the role of nuclear factor NF-E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway in atorvastatin-induced reduction of intestinal ischemia-reperfusion (I/R) injury in mice.Methods:Twenty-four healthy male C57BL/6 mice, aged 6-8 weeks, weighing 18-22 g, were divide into 4 groups ( n=6 each) using a random number table method: sham operation group (S group), intestinal I/R group (I/R group), atorvastatin group (ATV group) and atorvastatin+ Nrf2 inhibitor ML385 group (AM group). Intestinal I/R was produced by occlusion of superior mesenteric artery for 45 min followed by reperfusion.In ATV and AM groups, atorvastatin 10 mg/kg was given by gavage for 3 consecutive days daily at 3 day before establishment of the model, while the equal volume of normal saline was given by gavage in S and I/R groups.Nrf2 inhibitor ML385 30 mg/kg was intraperitoneally injected at 1 h before establishment of the model in group AM.The mice were sacrificed at 2 h of reperfusion, and intestine tissues were obtained for examination of the pathological changes of intestinal tissues (with a light microscope) which were scored according to Chiu, for determination of wet/dry weight ratio (W/D ratio), for detection of the activity of superoxide dismutase (SOD) and content of malondialdehyde (MDA) (by xanthine oxidase method and thiobarbituric acid condensation method) and for determination of the expression of Nrf2 and HO-1 (by Western blot). Results:Compared with S group, the Chiu score, W/D ratio and MDA content were significantly increased, the activity of SOD was decreased, and the expression of Nrf2 and HO-1 was up-regulated in the other 3 groups ( P<0.05). Compared with the group I/R, the Chiu score, W/D ratio and MDA content were significantly decreased, the SOD activity was increased, and the expression of Nrf2 and HO-1 was up-regulated ( P<0.05), and the pathological changes were significantly attenuated in group ATV, and no significant change was found in the parameters mentioned above in AM group ( P>0.05). Compared with the group ATV, the Chiu score, W/D ratio and MDA content were significantly increased, the SOD activity was decreased, the expression of Nrf2 and HO-1 was decreased ( P<0.05), and the pathological changes were significantly aggravated in group AM. Conclusion:The mechanism by which atorvastatin reduces intestinal I/R injury is related to activating Nrf2/HO-1 signaling pathway in mice.

Objective:To evaluate the role of peroxidase proliferator-activated receptor γ (PPARγ)/nuclear factor kappa B (NF-κB) signaling pathway in sodium butyrate-induced reduction of intestinal ischemia-reperfusion (I/R) injury in mice.Methods:Thirty-two SPF-grade healthy adult male C57BL/6J mice, aged 7-9 weeks, weighing 20-25 g, were divided into 4 groups ( n=8 each) using a random number table method: sham operation group (Sham group), intestinal I/R group (IIR group), sodium butyrate group (NaB group) and PPARγ inhibitor GW9662 group (GW9662 group). The model of intestinal I/R was established by occlusion of superior mesenteric artery for 45 min followed by 2-h reperfusion in anesthetized animals.GW9662 2 mg/kg was intraperitoneally injected at 1 h before ischemia in GW9662 group, and sodium butyrate 500 mg/kg was intraperitoneally injected at 30 min before ischemia in NaB and GW9662 groups.Blood samples were obtained via cardiac puncture at 2 h of reperfusion, and the animals were then sacrificed.The intestinal tissues were removed for determination of diamine oxidase (DAO), tumor necrosis factorα (TNF-α) and interleukins 6 (IL-6) concentrations in serum (by enzyme-linked immunosorbent assay) and the expression of PPAR and NF-κB p65 (by Western blot). The damage to intestinal mucous membrane was assessed and scored according to Chiu. Results:Compared with group Sham, the Chiu′s score was significantly increased, levels of DAO, TNF-α and IL-6 in serum and intestinal tissues were increased, expression of PPARγ was down-regulated, and expression of NF-κB p65 was up-regulated in group IIR ( P<0.05). Compared with group IIR, the Chiu′s score, levels of DAO, TNF-α and IL-6 in serum and intestinal tissues were decreased, and expression of PPARγ was up-regulated in group NaB, and expression of NF-κB p65 was up-regulated in NaB and GW9662 groups ( P<0.05). Compared with group NaB, the Chiu′s score, levels of DAO, TNF-α and IL-6 in serum and intestinal tissues were increased, and expression of PPARγ was down-regulated, and expression of NF-κB p65 was up-regulated in group GW9662 ( P<0.05). Conclusion:The mechanism by which sodium butyrate reduces intestinal I/R injury may be related to activating PPARγ/NF-κB signaling pathway and inhibiting inflammatory responses in mice.

AIM: To evaluate the effect of SLC7A11 in dexmedetomidine pretreatment induced reduction of ferroptosis caused by intestinal ischemia-reperfusion (II/R) injury in mice. METHODS: Twenty-four healthy meal SPF C57BL/6J mice, aged 8 weeks, weighing 22-25 g, were randomly divided into Sham operation group (S group), intestinal I/R group (II/R group), dexmedetomidine group (DEX group) and dexmedetomidine plus SLC7A11 inhibitior group (DIKE group), with 6 mice in each group. Intestinal ischemia was induced by occluding the superior mesenteric artery for 45 min followed by 30 min of reperfusion to establish the model of II/R injury. In DEX and DIKE groups, Dexmedetomidine 25 μg/kg was intraperitoneally injected at 30 min before clamping the superior mesenteric artery. The same amount of normal saline was injected in the S group and the II/R group. In DIKE group, SLC7A11 inhibitior Imidazole ketone erastin 50 mg/kg was intraperitoneally injected at 90 min before ischemia. Mice were sacrificed 30 min after reperfusion, and small intestinal tissues in length 5 cm away from the ileocecal valvum were obtained for microscopic examination of pathological changes of intestinal mucosa and for determination of contents of Fe

AIM: To observe the effect of paricalcitol on intestinal ischemia-reperfusion injury, and to explore the relationship with HMGB1/TLR4/NF-κB signaling pathway. METHODS: Twenty-four SPF-grade healthy adult male C57BL/6J mice were divided into 4 groups (n=6) by random number table: sham operation group (S group), paricalcitol pretreatment+sham operation group (SP group), intestinal ischemia-reperfusion group (IR group) and paricalcitol ischemic preconditioning group (P group). S group and SP group were separated the superior mesenteric artery, IR group and P group were clamped the superior mesenteric artery for 45 minutes and then followed by reperfusion for 2 hours to establish the intestinal ischemia-reperfusion model; SP group and P group were intraperitoneally injected with 0.3 μg/kg paricalcitol 24 hours before surgery, and the other two groups were given equal volume of normal saline. The mice were sacrificed at 2 h after reperfusion, and the intestinal tissue was obtained 5 cm from the terminal ileum. The pathological results were observed under light microscope. The intestinal mucosal injury was scored according to the Chiu's scoring standard. The intestinal tissue diamine oxidase (DAO) and tumor were detected by ELISA. Necrosis factor α (TNF-α) and interleukin 6 (IL-6) content; Western blot was used to detect the expression levels of HMGB1, TLR4 and NF-κB p65 protein in small intestine tissues.RESULTS: Compared with S group and SP group, Chiu's score was increased, the expression of Dao, TNF-α and IL-6 were increased, as well as the expression of HMGB1, TLR4 and NF-κB p65 protein increased significantly in IR group (P< 0.05); Compared with IR group, Chiu's score was decreased, the expression of Dao, TNF-α and IL-6 were decreased, as well as the expression of HMGB1, TLR4 and NF-κB p65 protein decreased significantly in P group (P< 0.05). CONCLUSION: Paricalcitol can alleviate intestinal ischemia-reperfusion injury by inhibiting HMGB1/TLR4/NF-κB signaling pathway and playing an anti-inflammatory role.