Relationship between SIRT3 and mitochondrial function in mice with endotoxin-induced lung injury / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the relationship between silent information regulator 2 homologue 3 (SIRT3) and mitochondrial function in mice with endotoxin-induced lung injury.Methods:Twenty clean-grade healthy adult male wild C57BL/6 (SIRT3 + /+ ) mice, 20 SIRT3 knockout (SIRT3 -/-) mice, weighing 20-25 g, aged 6-8 weeks, were studied.SIRT3 + /+ mice and SIRT3 -/- mice were divided into 4 groups ( n=5 each) according to the random number table method: blank control group (group C, group SIRT3 -/-C), endotoxin-induced lung injury group (group L, group SIRT3 -/-L), endotoxin-induced lung injury plus resveratrol group (group L+ R, group SIRT3 -/-L+ R), and resveratrol group (group R, group SIRT3 -/-R). Resveratrol 15 mg/kg was intraperitoneally injected once a day for 7 consecutive days in L+ R, R, SIRT3 -/-L+ R and SIRT3 -/-R groups, while the equal volume of normal saline was injected in the rest groups.Lipopolysaccharid 15 mg/kg was injected via the tail vein to develop a mouse model of endotoxin-induced lung injury at 30 min after resveratrol injection on 7th day, in L+ R and SIRT3 -/-L+ R groups and at the corresponding time points in L and SIRT3 -/-L groups, while the equal volume of normal saline was injected in the other groups.Blood samples were collected from the orbital venous plexus at 12 h after injection of normal saline or lipopolysaccharid for determination of serum total oxidation state (TOS) and total antioxidant state (TAS) levels by the xylenol orange method and ABTS colorimetric method, and the oxidative stress index (OSI) was calculated.After the mice were sacrificed, the lung tissues were taken for microscopic examination of the pathological changes which were scored and for determination of the mitochondrial membrane potential (MMP) (by JC-1 method), cellular oxygen consumption rate (OCR) (by the specific fluorescent probe method), and expression of SIRT3 (by Western blot). Results:Compared with group C or group SIRT3 -/-C, the lung injury score, serum TOS concentration and OSI were significantly increased, TAS concentration, MMP and OCR were decreased, and SIRT3 expression was down-regulated in L, L+ R, SIRT3 -/-L and SIRT3 -/-L+ R groups ( P<0.05). Compared with group L, the lung injury score, serum TOS concentration and OSI were significantly decreased, TAS concentration, MMP and OCR were increased, and SIRT3 expression was up-regulated in group L+ R, and lung injury score, serum TOS concentration and OSI were significantly increased, TAS concentration, MMP and OCR were decreased, and SIRT3 expression was down-regulated in group SIRT3 -/-L ( P<0.05). Compared with group L+ R, the lung injury score, serum TOS concentration and OSI were significantly increased, the TAS concentration, MMP and OCR were decreased, and the expression of SIRT3 was down-regulated in group SIRT3 -/- L+ R ( P<0.05). There was no significant difference in the indicators mentioned above between group SIRT3 -/-L+ R and group SIRT3 -/-L ( P>0.05). Conclusions:Down-regulation of SIRT3 expression can lead to impaired mitochondrial function, which is involved in the pathophysiological mechanism of endotoxin-induced lung injury.