Establishment of a rat chronic asthma model and its evaluation

This study is to establish a rat chronic asthma model. Sensitive SD rats were selected through histamine challenge. The asthmatic groups were sensitized by ih and ip with OVA, aluminium hydroxide gel and inactivated bacillus pertussis on day 1 and 14. From day 21, acute asthmatic group was aerosolized 1% OVA for 1 week, chronic asthmatic group was aerosolized 0.1% OVA for 12 weeks. The control groups received saline as the substitution of OVA. Twenty four hours after the last provocation, physiological monitoring equipment was used to detect the pulmonary function, then the rats were sacrificed. Bronchoalveolar lavage fluid (BALF) was collected to calculate the ratio of different inflammatory cells. ELISA was used to detect total IgE and OVA-specific IgE in serum. Microscopy was conducted to observe the histopathology of lung stained with haematoxylin and eosin staining. Collagen fibers were detected using Picric acid-Sirius red staining technique. The optical density at 610 nm of extractive from locus caeruleus was detected by passive cutaneous anaphylaxis (PCA). The results showed that the asthmatic characteristics were significantly developed in model groups, but not in control groups. Chronic asthmatic group had significantly higher indexes than acute asthmatic group, including the thickness of airway smooth muscle and bronchial basement membrane, and goblet cell hyperplasia, the area of collagen in airways, A610 of extractive from locus caeruleus, the concentration of total IgE and OVA-specific IgE in serum. However, inflammatory cell infiltrate in lungs and the percentage of eosinophils of white blood cells in BALF were lower in chronic asthmatic group than those in acute asthmatic group. Respiratory rate and respiratory flow showed no significant difference in both model groups. In conclusion, the rat chronic asthma model is established by the way in this study, which is comparable to the physiopathologic characteristics of human asthma.