Effects of low doses of glucocorticoid on acute lung injury in rats

Objective To investigate the efficacy of low doses of glucocorticoid in pulmonary acute lung injury(ALI)induced by Escherichia coli(E.coli)in rats.Methods ALI model was induced in rats by intratracheal E.coli injection[3ml/kg,O111B4,(4.4～5.6)×1012CFU/L],then the rats were randomly divided into hydrocortisone group(HC)treated with hydrocortisone(5mg/kg,intraperitoneally) and pulmonary ALI control group(C)treated with normal saline(intraperitoneally).And there was a normal control group (N).Twelve,twenty-four and thirty-six hours later,mechanical ventilation was applied.The blood gas,blood pressure,lung-thorax compliance were monitored,the lung index was calculated,the levels of protein,IL-8,IL-10 and TNF-α in BALF were measured.Results The blood pressure in group HC was significantly higher than that in group C (P<0.05).There was no difference in mortality between group HC (21%) and C (23%).At 12 hour,the lung index in group HC [(0.333±0.082)%] was significantly lower than that in group C [(0.432±0.137)%].At 24 and 36 hour,total protein in BALF of group HC [(874.55±426.97)mg/L,(735.95±244.33)mg/L] were significantly lower than those in group C [(1468.52±433.38)mg/L,(1350.95±681.66)mg/L];IL-8 in group HC [(69.66±13.07)ng/L,(61.49±15.27)ng/L] were significantly lower than those in group C [(91.37±24.59)ng/L,(98.97±17.77)ng/L].At 36 hour,IL-10 in group HC [(173.92±38.28)ng/L] was significantly higher than that in group C [(136.46±34.00)ng/L].At 12,24 and 36 hour,the levels of TNF-α in group HC [(343.13±50.19)ng/L,(277.92±84.51)ng/L,(305.87±61.59)ng/L] were significantly lower than those in group C [(467.51±76.09)ng/L,(360.12±34.69)ng/L,(375.26±25.79)ng/L].Conclusion Low dose of hydrocortisone can relieve pulmonary edema,decrease the production of pro-inflammatory cytokines and maintain blood pressure in rats with E.coli-induced ALI. Key words: Acute lung injury; Glucocorticoid; Compliance; Cytokine; Escherichia coli