Expression Of P-ERK1/2 And ERK2 MRNA In Lung Tissues Of Asthmatic Rats

Objective To investigate the correlation of the airway smooth muscle cells proliferation with the expression of ERK in the lung tissues of asthmatic rats.Methods Eighteen Wistar rats were randomly divided into three groups: the control group,the asthma model group and the dexamethasone group. The asthma model group and the dexamethasone group were sensitized by intraperitoneal injection with ovalbumin(OVA) and exposed to aerosolized OVA two weeks later to be challenged,and the rats in the dethamethasone group inhaled dexamethasone before the challenge. Control group was injected with saline and exposed to aerosolized saline two weeks later. Immunohistochemistry and In situ hybridization were used to measure the level of p-ERK and ERK2 mRNA in the rats'lung tissues. The wall area and the thickness of the airway smooth muscle were estimated by a computerized digital image analyzer.Results (1) The wall area and the thickness of the airway smooth muscle in the asthma model group were higher than in the other groups (P<0.05). (2) The expressions of p-ERK1/2 and ERK2 mRNA in the lung tissues of the asthma model group were highter than that in the other groups (P<0.05). (3) p-ERK1/2 expressions were positively correlated with the wall area and the airway smooth muscle thickness(r=0.858,r=0.848,respectively); ERK2 mRNA expressions were positively correlated with the wall area and the airway smooth muscle thickness(r=0.918, r=0.860,respectively). (4) The wall area and the thickness of the airway smooth muscle in the dexamethasone group were higher than in the the control groups (P<0.05). (5) The expressions of p-ERK1/2 and ERK2 mRNA in the lung tissues of the dexamethasone group were highter than that in the control groups (P<0.05).Conclusion The expressions of p-ERK1/2 and ERK2 mRNA were increased in the lung tissues of asthmatic rats and positively correlated with the proliferation of airway smooth muscle. ERK may take part in the process of airway smooth muscle proliferation in the airway remodeling of asthma.Early treatment with dexamethasone partly reduces the expression of p-ERK1/2 and ERK2 mRNA in the lung tissues of the asthma induced by OVA exposure, and probably prevents the process of airway remodeling in asthma.