Evaluation methods using tear volume in a conjunctivitis mice model

Allergic conjunctival disease is an immune-mediated inflammatory disease of the conjunctiva. To develop clinically useful drugs, it is necessary to develop quantitative evaluation methods that reflect the clinical symptoms in experimental animal models. Allergic conjunctivitis model mice were systemically sensitised with ovalbumin (OVA) administered intraperitoneally and locally sensitised with OVA eye drops between day 14–28. Next, conjunctivitis induced by ocular administration of OVA solution to sensitised mice was evaluated based on tear volume. Additionally, we evaluated increase in tear volume induced by direct ocular instillation of histamine, compound 48/80, and carrageenan. An increase in antigen-induced tear volume was observed in the mice model. Additionally, direct instillation of histamine, compound 48/80, and carrageenan increased tear volume. Furthermore, levocabastine inhibited the increase in tear volume in antigen-induced allergic conjunctivitis and histamine- and compound 48/80-induced conjunctivitis models. In contrast, betamethasone suppressed carrageenan-induced tear volume but not histamine- or compound 48/80-induced tear volume. Histamine may be involved in increased tear volume in allergic conjunctivitis. Betamethasone is not directly involved in the action of histamine and is thought to suppress increase in tear volume. Evaluation of tear volume in a conjunctivitis mice model is highly quantitative; therefore, it is possible to evaluate drug efficacy. This is considered a useful index compared with conventional methods.