| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1997: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1996: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
The role of substance P in experimental allergic conjunctivitis induced by egg albumin was investigated with guinea pigs. Increase in vascular permeability of the conjunnctiva induced by antigen was significantly inhibited after repeated application of capsaicin. Substance P contents in the conjunctiva of guinea pig were decreased by topical instillation of antigen to the eyes, suggesting that substance P was released from the conjunctiva due to antigen-antibody reaction. Moreover, subconjunctival injection or topical application of substance P resulted in a dose-related conjunctivitis, and vascular permeability in the conjunctiva was also increased by substance P.In substance P-induced conjunctivitis, a significant edema was observed in the bulbar and palpebral conjunctiva, but no hyperemia was noted in all instances. Histamine contents of the conjunctiva and tears were not influenced by subconjunctival injection of substance P.However topical application of antigen and subconjunctival injection of compound 48/80 caused a significant decrease in hitamine contents, and that of tear was increased by both treatments. An increase in vascular permeability induced by antigen application was significantly inhibited by intravenous injection of FK888, which is a specific and potent NK-1 receptor antagonist. From these results, it is indicated that substance P is responsible for allergic conjunctivitis to some extent, and the conjunctival hyperpermeability induced by substance P is occurred through NK-1 receptor on the blood vessels, rather than by the direct action on the conjunctival mast cells during allergic conjunctival reactions. In addition, effects of certain drugs on substance P-induced conjunctivitis were investigated. H_1-antagonists such as ketotifen, chlorpheniramine and levocabastine caused a potent inhibitory effect, however, cromolyn sodium and tranilast showed no inhibitory effect on substance P-induced conjunctivitis even at high concentrations.
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