OBJECTIVETo observe the effects of low-intensity pulsed ultrasound (LIPUS) pretreatment on pulmonary expression of high mobility group box-1 (HMGB1) in a rat model of lung ischemia-reperfusion (IR).

METHODSThirty-two male SpragueDawley rats weighing 250-300 g were randomly divided (=8) into sham-operated group, lung IR group, LIPUS pretreatment group and pretreatment with α7-nicotinic cholinergic receptor (α7nAChR) antagonist group. In the sham-operated group, the left pulmonary hilum was dissociated without occlusion; in the other 3 groups, the left pulmonary hilum was occluded for 45 min followed by reperfusion for 180 min; LIPUS pretreatment for 30 min and intraperitoneal injection of methyllycaconitine (2 mg/kg), an α7nAChR antagonist, were administered before the operation. The wet/dry weight ratio (W/D) and pulmonary permeability index (LPI) of the lung tissue were measured, and the lung histopathology was observed and scored. The contents of interleukin-1 (IL-1) and IL-6 in the lung tissues were measured using ELISA, and the pulmonary expression of HMGB1 protein was detected using immunofluorescence assay and Western blotting.

RESULTSCompared with those in the sham-operated group, the W/D of the lung tissue, LPI, pathological scores, IL-1 and IL-6 contents in the lung tissue, and pulmonary HMGB1 expression all significantly increased in the other 3 groups ( < 0.05). LIPUS preconditioning significantly lowered the W/D values, LPI, pathological score, IL-1 and IL-6 contents and HMGB1 expression in the lung tissues following lung IR, and these effects were significantly inhibited by administration of methyllycaconitine.

CONCLUSIONSLIPUS preconditioning can reduce lung IR injury possibly by activating α7nAChR-dependent cholinergic anti-inflammatory pathway to reduce lung tissue HMGB1 expression.