Abstract: AIM: To explore the role and mechanism of silent mating type information regulator 2 homolog 3 (SIRT3) in attenuation of intestinal ischemia-reperfusion (I/R) injury by dexmedetomidine in mice. METHODS: Twenty-four healthy male C57BL mice were divided into 4 groups randomly (n=6): sham operation group (Sham group), intestinal ischemia-reperfusion group (I/R group), dexmedetomidine group (Dex group), SIRT3 inhibitor 3-TYP group (3-TYP group). Superior mesenteric artery was clamped for 45 min followed by reperfusion for 2 h to establish intestinal I/R model in I/R group, Dex group, and 3-TYP group. Sham group received sole sham operation. 1 h prior to onset of ischemia, 3-TYP was injected into mice in 3-TYP group intraperitoneally (5 mg/kg, diluted to 0.3 mL), and 0.3 mL normal saline into mice in Dex group intraperitoneally. 30 min prior to onset of ischemia, dexmedetomidine was injected into mice in 3-TYP group and Dex group intraperitoneally (25 μg/kg, diluted to 0.3 mL). 1 h and 30 min prior to onset of ischemia, 0.3 mL normal saline was injected into mice in Sham group and I/R group intraperitoneally, respectively. 2 h of after reperfusion, the mice were sacrificed under anesthesia. Intestinal tissues were took and observed for pathological changes under light microscope after HE staining, and the injury was assessed via the Chiu's score method, and activities of SIRT3 and superoxide dismutase 2 (SOD2)   were detected via spectrophotometry, and malondialdehyde (MDA) via spectrophotometry. RESULTS: The pathological injury was exacerbated, and the Chiu's score, the MDA level elevated remarkably, while the activity level of SIRT3 and SOD2 declined remarkably in I/R group, Dex group and 3-TYP group compared to Sham group (P<0.05). The pathological injury was alleviated, and the Chiu's score declined remarkably in Dex group and 3-TYP group compared to I/R group (P<0.05); and the MDA level declined remarkably, while activity level of SIRT3 and SOD2 elevated remarkably in Dex group compared to I/R group (P<0.05); and there was no significant difference both in the activity level of SIRT3 and SOD2 and in the MDA level between 3-TYP group and I/R group. The pathological injury was exacerbated, and the Chiu's score, the MDA level elevated remarkably, while the activity level of SIRT3 and SOD2 declined remarkably in 3-TYP group compared to Dex group (P<0.05). CONCLUSION: SIRT3 and its downstream SOD2 are involved in mediating the effect of attenuation of intestinal ischemia-reperfusion injury through inhibiting oxidative stress response by dexmedetomidine.

Key words: SIRT3, oxidative stress response, dexmedetomidine, reperfusion injury, intestine