Objective To evaluate the role of cholinergic anti-inflammatory pathway in dexmedeto-midine pretreatment-induced reduction of acute lung injury in a rat model of intestinal ischemia-reperfusion ( I∕R) . Methods Twenty-four healthy male Sprague-Dawley rats, aged 2-3 months, weighing 200-250 g, were divided into 4 groups ( n=6) using a random number table method: sham operation group ( S group) , intestinal I∕R group ( II∕R group ) , dexmetomidine group ( DEX group) and α7 nicotinic acetyl-choline receptor antagonistα-bungarotoxin (α-BGT) group (α-BGT group) . Intestinal I∕R was produced by occlusion of the superior mesenteric artery ( SMA) for 60 min followed by 120 min of reperfusion in anesthe-tized rats. Dexmetomidine 5 μg·kg-1 ·h-1 was injected via the tail vein at 1 h before operation in DEX group andα-BGT group. α-BGT 1μg∕kg was intraperitoneally injected at 15 min before dexmetomidine in-jection in α-BGT group. Rats were sacrificed at 120 min of reperfusion, and lung tissues were obtained for microscopic examination of pathological changes ( with a light microscope) and for determination of wet∕dry weight ratio ( W∕D ratio) , tumor necrosis factor-alpha ( TNF-α) and interleukin-6 ( IL-6) contents ( using enzyme-linked immunosorbent assay) , malondialdehyde ( MDA) content ( using thiobarbital acid method) and superoxide dismutase ( SOD) activity ( by xanthine oxidase method) . Results Compared with group S, the W∕D ratio and contents of MDA, TNF-αand IL-6 were significantly increased, and the SOD activi-ty was decreased in II∕R and α-BGT groups, and TNF-α and IL-6 contents were significantly increased in group DEX ( P<0. 05) . Compared with group II∕R, the W∕D ratio and contents of MDA, TNF-αand IL-6 were significantly decreased, SOD activity was increased (P<0. 05), and the pathological changes were significantly attenuated in group DEX. Compared with group DEX, the W∕D ratio and contents of MDA, TNF-α and IL-6 were significantly increased, SOD activity was decreased ( P<0. 05) , and the pathological changes were accentuated in group α-BGT. Conclusion Activation of cholinergic anti-inflammatory path-way is involved in the mechanism by which dexmedetomidine pretreatment reduces acute lung injury in a rat model of intestinal I∕R.