Objective:To evaluate the role of α7 nicotinic acetylcholine receptor (α7nAChR) in penehyclidine hydrochloride-induced reduction of endotoxin-induced acute lung injury (ALI) in mice.Methods:Forty SPF healthy male C57BL/6 mice, aged 6-8 weeks, weighing 18-25 g, were divided into 4 groups ( n=10 each) using a random number table method: control group (group C), ALI group, penehyclidine hydrochloride group (PHC group), and α7nAChR inhibitor MLA group (MLA group). ALI was induced by intraperitoneal injection of lipopolysaccharide 15 mg/kg in anesthetized animals, while normal saline was given instead in group C. In PHC group, penehyclidine hydrochloride 2 mg/kg was intraperitoneally injected at 30 min before developing the model. MLA 10 mg/kg was intraperitoneally injected at 10 min before administration of penehyclidine hydrochloride in MLA group. Mice were sacrificed at 6 h after lipopolysaccharide administration, and lung tissues were collected for microscopic examination of the pathological changes (by HE staining) and for determination of the wet/dry weight ratio (W/D ratio), content of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and IL-10 (by enzyme-linked immunosorbent assay) and expression of α7nAChR (by Western blot). Results:Compared with C group, the W/D ratio and contents of TNF-α and IL-1β were significantly increased, the content of IL-10 was decreased, and the expression of α7nAChR was up-regulated in ALI, PHC and MLA groups ( P<0.05). Compared with ALI group, the W/D ratio and contents of TNF-α and IL-1β were significantly decreased, the content of IL-10 was increased, and the expression of α7nAChR was up-regulated in PHC group ( P<0.05). Compared with PHC group, the W/D ratio and contents of TNF-α and IL-1β were significantly increased, the content of IL-10 was decreased, and the expression of α7nAChR was down-regulated in MLA group ( P<0.05). Compared with ALI group, the pathological changes of lung tissues were significantly mitigated in PHC group, while this effect of PHC was partially reversed by α7nAChR inhibitor MLA. Conclusions:α7nAChR is involved in penehyclidine hydrochloride-induced reduction of endotoxin-induced ALI in mice.