Participation of chemical mediators other than histamine in nasal allergy signs: a study using mice lacking histamine H 1 receptors

Abstract

The purpose of this study was to investigate the involvement of chemical mediators other than histamine in nasal allergic signs using histamine H 1 receptor-deficient mice. In passively sensitized mice, antigen instillation into the nasal cavity induced significant increases in sneezing and nasal rubbing in wild-type mice, but no such increases were observed in histamine H 1 receptor-deficient mice. In actively sensitized mice, both sneezing and nasal rubbing were also significantly increased in a dose-dependent manner in both wild-type and histamine H 1 receptor-deficient mice. Histamine H 1 receptor antagonists such as cetirizine and epinastine significantly inhibited antigen-induced nasal allergic signs in wild-type mice, although the effects were incomplete. In addition, the thromboxane A 2 receptor antagonist ramatroban also inhibited these responses in wild-type mice. However, the leukotriene receptor antagonist zafirlukast showed no effects in wild-type mice. These results suggested that in the acute allergic model (passive sensitization), only histamine H 1 receptors are related to nasal signs induced by antigen, whereas in the chronic allergic model (active sensitization), both histamine H 1 receptors and thromboxane A 2 receptors were involved in the responses.