Histamine H₁ receptors are involved in mouse nasal allergic responses: A demonstration with H₁ receptor-deficient mice

The role of histamine H₁ receptors in nasal allergic symptoms (sneezing and nasal rubbing) were studied using histamine H₁ receptor-deficient mice. Intranasal instillation of histamine solution resulted in significant increases in sneezing and nasal rubbing in wild-type mice, whereas no increases were observed in histamine H₁ receptor-deficient mice. The histamine H₁ receptor agonist 2-pyridylethylamine induced sneezing and nasal rubbing in a dose-dependent manner in wild-type mice, but no such increase was found in histamine H₁ receptor-deficient mice. On the other hand, the histamine H₂ receptor agonist dimaprit did not increase sneezing and nasal rubbing in wild-type mice. Histamine H₁ receptor antagonists such as chlorpheniramine and epinastine significantly inhibited nasal allergic symptoms caused by histamine, but the histamine H₂ receptor antagonists cimetidine and famotidine showed no effect. No additional effects were observed by combined use of chlorpheniramine and cimetidine or famotidine compared with cimetidine or famotidine alone. These results suggested that histamine H₁ receptors play an important role in nasal allergy symptoms induced by histamine.