[Protective effects of 3-methyladenine on acute lung injury caused by multiple trauma in rats]

To investigate the role of autophagy in acute lung injury (ALI) caused by multiple trauma in rats via pretreat with 3-methyladenine (3-MA).

Forty-five Sprague-Dawley male rats, with age of 4 months and body weight of 250-300 g,were randomly divided into three groups. In the sham group, the rats received sphenotresia only;in the control group, the rats were made model of femur shaft fracture combined with brain injury, and treated with physiological saline by abdominal cavity at 1 hour before making model; in the 3-MA group, the rats were made model of femur shaft fracture combined with brain injury,and treated with 3-MA of 10 mg/kg by abdominal cavity at 1 hour before making model. Histologic changes and the concentration of related inflammatory factors in the damaged lung tissue were examined at 48 h after opteration, at the same time, the effect of 3-MA on the expression of LC-3 II and Beclin-1 was examined through reverse transcriptase polymerase chain reaction technique (RT-PCR).

Compared with sham group, LC-3 II and Beclin-1 level in control group at 48 h after operation were obviously increased (P < 0.01). Compared with control group, LC-3 II and Beclin-1 level in 3-MA group at 48 h after operation were obviously decreased (P < 0.01). Compared with sham group, the level of proinflammatory cytokines (TNF-α and IL-6) in control group obviously enhanced (P < 0.01). Compared with control group, above items in 3-MA group was obviously lower (P < 0.01). Compared with control group,the histopathological damage of lung in 3-MA group obviously reduced (P < 0.01).

Autophagy can aggravate the acute lung injury caused by fracture of shaft of femur combined with brain injuries,but 3-MA can reduce tissue damage by inhibiting the autophagy and inflammatory response.