Vascular permeability in allergic conjunctivitis in mice lacking histamine H 1 receptors

Abstract

To clarify the role of histamine H 1 receptors in allergic conjunctivitis, changes in vascular permeability of the conjunctiva were measured in histamine H 1 receptor deficient mice. Wild-type mice showed a significant increase in vascular permeability of the conjunctiva induced by histamine. However, no such increase was found in histamine H 1 receptor deficient mice. On the other hand, no differences were observed between wild-type and histamine H 1 receptor deficient mice in response to serotonin. A significant increase in vascular permeability was observed in actively sensitized wild-type mice, whereas no increase was observed in histamine H 1 receptor deficient mice. Similar findings were noted in passively sensitized animals. Histamine contents of the conjunctiva were significantly decreased by topical application of antigen in both wild-type and histamine H 1 receptor deficient mice after active sensitization with antigen. These findings suggested that vascular permeability in the conjunctiva in allergic conjunctivitis is entirely regulated through histamine H 1 receptor.