| Objectives 1. To establish the model of allergic rhinitis (AR) in SD rat. 2. To present the character of morphology in allergic rhinitis of rat. 3. To determine the expression of aquaporins (AQPs) in nasal mucosa of AR. 4. To observe the effect of dexamethasone (DEX) on the expression of AQPs in the allergic rhinitis. 5. To explore the relation of AQPs and the fluid transportation in allergic rhinitis rat.Methods: Forty-eight healthy adult rats whose weight 250~300g were randomly divided into the blank group (C1), control group (C2), model group(M), hormone-intervention group(D1,D2). Model group had 16 rats, the others had 8 rats each. The methods of establish the model : Group M and group D1,D2 were sensitized by injection of 1ml of physiological saline containing ovalbumin (1mg) and alum (2mg) into the four footpads on the first day. Five days later, they were boosted by subcutaneous injection of 1ml of physiological saline containing ovalbumin (0.5mg) in 10 sites on the back. Then local sensitization was performed every day by dripping the ovalbumin in physiological saline (1mg/ml, 20ul) into the bilateral nasal cavities using a micropipette from day 14 to the establishment which was defined by the symptom score. After the establishment of model, dexamethasone (1mg/kg) were administered to group D1,D2 by intramuscular injection once a day, group D1,D2 were treated for one week and two weeks, respectively. While group C2 were treated with physiological saline replacing ovalbumin, the others steps were same as group M. The group C1 remains virgin. Applying with history chemistry staining, we observed the histomorphologic character of AR. The expression and changes of AQPs in nasal mucosa in each group were investigated with immunohistochemical technique (SP method). All data are represented as means±SEM. Statistical analysis was performed using one-way ANOVA and Repeated measures with SPSS11.5 statistical package. A probability value of less than 0.05 was considered significant.Results :(1)A large number of neutrophil and eosinophile granulocyte present in nasal smear of group M. In nasal mucosa, EOS got increase obviously in group M, and then, decreased after DEX treatment. In group C1 and group C2, epithelium mucosa were composed of ciliated columnar epithelia ,goblet cell and pavement cells etc. by hemotoxylineosin (HE) staining, and submucosa without inflammatory cell infiltrated and few vessels is compact fibrous connective tissue adjacent to the surface of cartilage. While, group M shown a significant increase of mucosa thickness, vessels and glands, epithelium secretive cells, inflammatory cells, compared to group C1 and group C2. After the treatment of DEX, mucosa recovered slowly, and all of vessels expanding, glands hyperplasted and inflammatory cell infiltrated did lighten. (2)Applying with immunohistochemistry method, we observed that the expression of AQP1,4,5 is evident in nasal mucosa, and they were localized at different sites. AQP1 expressed intensively in capillary and blood sinus endothelial cells, and the fibroblasts.AQP4 was localized to the basaolateral membrane in the epithelial cells, endoepithelial gland and the part of subepithelial gland. AQP5 resided in apical membrane of the part of subepithelial obviously. (3)Computer-assisted gray scale date shown that in group M, the expression of AQP1 decreased, compared to group C1 and group C2. The group D1 had a significant increase versus group M (P<0.05), and the expression of AQP1 in group D2 increased versus group D1 (P<0.05). Computer-assisted gray scale date shown that the group M had no significant difference versus group C1 and group C2 (P>0.05), while, the expression of AQP4 in group D1 decreased versus group M (P<0.05). But there was no difference between group D1 and group D2 (P>0.05). Computer-assisted gray scale date shown that in group M, the expression of AQP5 increased obviously compared to group C1 and group C2 (P<0.05). And there was significant difference among the group M, D1, D2 (P<0.05).Conclusion: According to stimulate in nasal cavity repeatedly, we established the allergic rhinitis model in rat after the system sensibilization. Group M shown a significant increase of mucosa thickness, vessels and glands, epithelium secretive cells, inflammatory cell, including eosinophile granulocytes. Applying with immunohistochemistry method, we observed that the protein of AQP1,4,5 presented at different sites. We concluded that in circumstance of allergic rhinitis, the expression change of AQPs played an important role in fluid transportation. The possible reason that the treatment of DEX had an effect on the proceeding of allergic rhinitis was to regulate the expression of AQPs in nasal mucosa.
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