Aim: The study is to understand histopathological abnormalities in neonatal Sprague-Dawley (SD) rats with acute lung injury (ALI) induced by different doses of lipopolysaccharide (LPS) and to explore suitable doses of LPS to develop ALI model of neonatal SD rats in 12-48 hours (h).
Methods: (1) 180 neonatal SD rats were randomly assigned into one of six groups: LPS 1mg group, LPS 1.5 mg group, LPS 2 mg group, LPS 2.5 mg group, LPS 3 mg group and control group (n=30 for each group). The rats were inoculated intraperitoneally with 1, 1.5, 2, 2.5, 3 mg/kg LPS and NS. We observed survival rate in each group within 48h. (2) 72 newly-born SD rats were randomly divided into LPS and control groups according to the above method (n=12 for each group). Each group rats were killed at 24, 36, and 48 h. Lungs were collected and used for histological analysis, histological score, determination of wet-dry ratio and radial alveolar cunt (RAC).
Results: (1) The rats in the control group alive all the time. However, the 24-36 h survival rate in the LPS groups were 67 %, 40 %, 23 %, 10 % and 0 respectively; The 48 h survival rate were 33.3%, 6.7%, 0, 0 and 0. (2) LPS aggravated degrees of ALI in neonatal SD rats in a dose-dependent manner. With increasing the dose of LPS and prolonged time, histological score and the ratio of W/D were increased, RAC count was decreased.
Conclusion: The 2, 2.5 mg/kg of LPS induced ALI model of neonatal SD rats might be used to study for the ALI within 24 h. The 1, 1.5 mg/kg of LPS induced ALI model of neonatal SD rats might be used to study for the ALI in 24-36 h. The 1 mg/kg of LPS induced ALI model of neonatal SD rats might be used to study for the ALI in 36-48 h.