ABSTRACT
Aim To explore the effect of adenylate cyclase(AC) antagonists SQ22536 and agonist forskolin on acute lung injury induced by lipopolysaccharide.Methods ICR mice were randomly divided into normal saline control group(N group), model group(group L), dexamethasone group(group D),AC antagonists s(group SQ) and AC agonist group(group F).The ALI mouse model was induced by instilling intratracheally with LPS(2 mg·kg-1), and 6 h later, the lung tissue and alveolar lavage fluid(BALF) were harvested, pathological changes in lung were observed, white blood cell and neutrophil, albumin content in BALF and myeloperoxidase(MPO) activity of lung tissue homogenate were determined, and tumor necrosis factor α(TNF-α), interleukin-1β(IL-1β), interleukin 6(IL-6) and cAMP content in lung homogenates were detected by ELISA.Results Compared with normal saline group, a large number of neutrophils infiltrated around the pulmonary vessel and airway 6 h after LPS intratracheal instillation in model group.White blood cells and neutrophils and protein content increased in BALF;MPO activity and cAMP levels increased in lung tissues.In the lung tissue TNF-α and IL-6, IL-1β content increased, compared with model group.Forskolin could improve the pathological changes of lung tissue, reduce the total number of leukocytes, number of neutrophils and protein content in BALF, and reduce MPO activity and TNF-α content in lung tissue, at the same time it increased the cAMP content;SQ22536 had no significant effect when compared with model group.Conclusion AC agonists have protective effects on LPS-induced acute lung injury in mice, and the mechanism may be related to elevating cAMP levels, inhibiting neutrophil adhesion and chemotaxis and reducing inflammatory factor levels.
