Development of the animal model of trauma brain injury coupled with acute lung injury induced by seawater drowning

Objective To establish an animal model of traumatic brain injury coupled with acute lung injury induced by seawater drowning. Methods A total of 80 male Sprague-Dawley rats were randomly divided into 4 groups: sham group, traumatic brain injury (TBI) group, seawater drowning-induced acute lung injury (SWD-ALI) group and traumatic brain injury coupled with seawater drowning- induced acute lung injury (TBI+ SWD-ALI) group, each consisting of 20 animals. The TBI model group was established with impact power of 450 g×1.5 m by method. The SWD-ALI group was established by pumping artificial seawater into rat trachea at a rate of 3 ml/kg. The TBI+ SWD-ALI group was established on basis of TBI. The data of arterial blood gases were detected 10, 30, 60, 120 and 240 minutes after trauma injury. Wet/dry weight of lung was detected 240min after injury, and pulmonary pathological changes were also observed after HE staining. Pathological changes in brain tissue after HE staining and expression levels of β-APP and NF-L after immunohistochemical (IHC) staining were observed 24 hours after injury. Results The levels of PaO2 after injury during observation period generally displayed an increasing trend in TBI, SWD-ALI and TBI+ SWD-ALI groups. The levels of PaO2 10 minutes after injury were lowest, which were respectively (85.12±2.03) mmHg, (37.75±1.17) mmHg and (33.38±1.92) mmHg, and were obviously lower than that of sham group (95.25±2.05) mmHg, with statistical significance (P 0.05). HE staining indicated that such pulmonary pathological lesions as wider alveolar septa, alveolar space fusion, inflammatory cell infiltration in various degrees could be observed in SWD-ALI and TBI+ SWD-ALI groups. In addition, brain tissue HE staining revealed that neuronal cell degeneration in cortex of brain tissue could be detected in TBI, SWD-ALI and TBI+ SWD-ALI groups, and immunohistochemical staining indicated that there were positive expressions of β-APP and NF-L in TBI and TBI+ SWD-ALI groups. Conclusion The impact with power of 450 g×1.5 m by the Marmarou method followed by pumping of seawater (3 ml/kg) into trachea could establish a stable and reproductive rat model of traumatic brain injury coupled with acute lung injury induced by seawater drowning. Key words: Animal model; Rat; Traumatic brain injury; Seawater drowning; Acute lung injury