Objective  To evaluate the role of autophagy in apoptosis of neurons in brain tissue of rats induced by mechanical ventilation.

  Methods  A total of 24 healthy adult male Wistar rats were divided into 4 groups (n=6) by random number table method, including control group (C group), mechanical ventilation group (MV group), mechanical ventilation combined with 6-amino-3-methylindole treatment group (3MA group), and mechanical ventilation plus rapamycin treatment group (R group). Group C retained spontaneous breathing after endotracheal intubation without mechanical ventilation. MV group, 3MA group and R group were performed mechanical ventilation. 3MA group and the R group received intraperitoneal injection of 30 mg/kg 3-MA and 1 mg/kg rapamycin, respectively, at 15 min before MV, while the C group was given intraperitoneal injection of the same amount of normal saline at 15 min before MV. At the end of mechanical ventilation, 6 rats were sacrificed for brain tissue to observe pathological changes under light microscope. TUNEL assay was used to detect the apoptosis of neurons in the hippocampus CA1 region and calculate the apoptosis index. Using Western blot method to detect the expression of Bax, Bcl-2, activated Caspase-3, LC3 Ⅰ, LC3 Ⅱ, p62, and calculate the ratios of Bax to Bcl-2, LC3 Ⅱ to LC3 Ⅰ.

  Results  Compared with group C, the rest three groups had severe pathological damage, with higher hippocampus neuron apoptosis index and Bax/Bcl-2 ratio, up-regulated expression of activated Caspase-3, increased Beclin-1, LC3Ⅱ/Ⅰand decreased p62 (P < 0.05); compared with MV group, pathological damage, the hippocampus neuron apoptosis index and Bax/Bcl-2 ratio, the expression of activated Caspase-3, Beclin-1, LC3 Ⅱ/Ⅰ was decreased, p62 was up-regulated in 3MA group(P < 0.05); compared with MV group, the changes of above indicators in the R group was contrary to 3M group (P < 0.05).

  Conclusion  Autophagy is involved in the apoptosis of neurons in rat brain tissue induced by high tidal volume ventilation.