Effect of dexmedetomidine on mitochondrial dynamics in mice with endotoxin-induced acute lung injury

Objective To evaluate the effect of dexmedetomidine on mitochondrial dynamics in mice with endotoxin-induced acute lung injury (ALI). Methods Thirty clean-grade healthy adult male C57BL/6 mice, weighing 20-25 g, aged 2 months, were divided into 3 groups (n=10 each) using a random number table method: control group (group C), endotoxin-induced ALI group (group LPS) and endotoxin-induced ALI plus dexmedetomidine group (group LPS+ DEX). In LPS and LPS+ DEX groups, lipopolysaccharide (LPS) 10 mg/kg was injected via the caudal vein to establish the model of endotoxin-induced ALI.In group LPS+ DEX, dexmedetomidine 50 μg/kg was intraperitoneally injected at 30 min before injection of LPS, while the equal volume of normal saline was given instead in C and LPS groups.The mice were sacrificed at 6 h after LPS administration, and lung tissues were obtained for examination of the pathological changes (with a light microscope) which were scored and for determination of the level of reactive oxygen species (ROS) and expression of mitochondrial fusion proteins mitofusin 1 (Mfn1), Mfn2, optic atrophy 1 (OPA1), dynamin-related protein 1 (Drp1) and fission protein 1 (Fis1)(using Western blot). Results Compared with group C, the lung injury scores and ROS level in lung tissues were significantly increased, the expression of Mfn1, Mfn2 and OPA1 was down-regulated, and the expression of Drp1 and Fis1 was up-regulated in LPS and LPS+ DEX groups (P<0.05). Compared with group LPS, the lung injury scores and ROS level in lung tissues were significantly decreased, the expression of Mfn1, Mfn2 and OPA1 was up-regulated, and the expression of Drp1 and Fis1 was down-regulated in group LPS+ DEX (P<0.05). Conclusion Dexmedetomidine can reduce endotoxin-induced ALI through maintaining the mitochondrial fusion-fission balance in mice. Key words: Dexmedetomidine; Acute lung injury; Endotoxemia; Mitochondria