Symptomatic and pathophysiological observations in a modified animal model of allergic rhinitis.

There are many animal models for studying allergic rhinitis. However, they either need a too long establishment period or fail to show significant late allergic responses. In the model described in this paper, guinea pigs were sensitized and challenged intranasally with ovalbumin according to a modified protocol. As controls, antihistamine-treatment and non-sensitized, non-treatment groups were studied in parallel. Early and late symptoms, passive cutaneous anaphylaxis (PCA) reaction, nitric oxide synthase (NOS) immunoreactivities, pathological changes in nasal mucosa and nasal lavage fluid (NLF), and histamine, TXB2 and p-LTs levels in NLF were evaluated. In contrast to the control groups, the model group exhibited typical symptoms, including late phase nasal blockage, and increased levels of IgG1 and IgE. Considerable eosinophil infiltration and eNOS immunoreactivities in nasal mucosa, and increased levels of histamine, TXB2 and p-LTs in NLF were also observed. This model was not only capable of showing satisfactory symptomatic and pathophysiological changes in allergic rhinitis but also showed good responses to antihistamine treatment. The model can be established in six weeks. For the first time, respiratory rate was employed as an index to reflect the nasal blockage of guinea pigs and it proved to be a reliable indicator.