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ABSTRACT: The present study was performed to study the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on scratching behavior in hairless mice, which are highly sensitive to pruritogens (mediators causing itching), except for histamine, and are suitable for time-course studies due to their hairless skin. TCDD is a well-known environmental pollutant that causes skin diseases with itching; therefore, we examined whether TCDD induced itching. Oral administration of TCDD caused no increase in scratching behavior when used alone, whereas TCDD in combination with distilled water or acetone/olive oil application caused a significant increase in scratching behavior. Furthermore, nerve growth factor (NGF) content in the skin increased significantly. A single administration of chlorpheniramine (histamine H1 receptor antagonist), tranilast (chemical mediator release inhibitor) and olopatadine (histamine H1 receptor antagonist) had no effect on scratching behavior induced by TCDD in combination with acetone/olive oil application. With repeated administration for 7 days, chlorpheniramine and tranilast had no effect on scratching behavior, whereas olopatadine significantly inhibited scratching behavior. In addition, only olopatadine significantly inhibited NGF content in the skin. From these findings, it can be concluded that TCDD is not a pruritogen but causes alloknesis (itchy skin) with the simultaneous use of trivial external stimulation. In addition, it was found that drugs which decreased skin NGF contents may inhibit this scratching behavior.
International immunopharmacology 12/2009; 10(3):304-7. · 2.21 Impact Factor
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ABSTRACT: The aim of this study was to clarify the effect of histamine H(4) receptor antagonist, JNJ7777120 (1-[(5-Chloro-1H-indol-2-yl)carbonyl]-4-methyl-piperazine) on allergic rhinitis in mice. We measured allergic symptoms (sneezing and nasal rubbing), serum total IgE and the levels of cytokines in nasal lavage fluid. Histamine H(4) receptor antagonist, JNJ7777120, caused the dose-dependent inhibition of nasal symptoms by single and repeated intranasal administrations; however, JNJ7777120 caused no inhibition of serum total IgE by single and repeated intranasal administrations. Therefore, we investigated the effect of JNJ7777120 by oral administration. JNJ7777120 also caused a significant inhibition of nasal symptoms by both single and repeated oral administrations. In addition, repeated oral administration of JNJ7777120 caused significant inhibition of serum total IgE. Furthermore, JNJ7777120 caused a significant decrease in the levels of IL-4 and a significant increase in the levels of IFN-gamma in nasal lavage fluid. These results indicated that histamine H(4) receptor is closely related with allergic rhinitis and is important in the pathogenesis of allergic rhinitis. From these results, it can be concluded that histamine H(4) receptor antagonist might be a new strategy to treat allergic rhinitis with immunomodulatory function.
International immunopharmacology 04/2009; 9(6):734-8. · 2.21 Impact Factor
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ABSTRACT: We investigated the character of histamine H(1) receptor and H(4) receptor in allergic conjunctivitis. Histamine is the most important mediator in allergic conjunctivitis. We measured eye scratching behavior and allergic-like symptoms score, that is, hyperemia and edema in ICR mice, and examined which receptors intimately involved in allergic conjunctivitis. Histamine caused a dose-dependent eye scratching behavior and allergic-like symptoms. Histamine H(1) receptor antagonist (levocabastine) and H(4) receptor antagonist (JNJ7777120) inhibited eye scratching behavior and histamine H(1) receptor antagonist inhibited allergic-like symptoms induced by histamine. Additionally, combination of levocabastine and JNJ7777120 caused more potent inhibition in allergic conjunctivitis. On the other hand, both selective histamine H(1) receptor agonist (HTMT) and selective H(4) receptor agonist (4-methylhistamine) induced a dose-dependent eye scratching behavior and allergic-like symptoms. JNJ7777120 inhibited the effect of HTMT. However, levocabastine caused no inhibition on the response of 4-methylhistamine. H(4) receptor was closely related with allergic conjunctivitis. H(4) receptor antagonists may be effective in allergic conjunctivitis which showed no inhibition by histamine H(1) receptor antagonists.
European journal of pharmacology 03/2009; 608(1-3):71-5. · 2.59 Impact Factor
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ABSTRACT: We investigated the character of histamine H1 receptor and H4 receptor in allergic conjunctivitis. Histamine is the most important mediator in allergic conjunctivitis. We measured eye scratching behavior and allergic-like symptoms score, that is, hyperemia and edema in ICR mice, and examined which receptors intimately involved in allergic conjunctivitis. Histamine caused a dose-dependent eye scratching behavior and allergic-like symptoms. Histamine H1 receptor antagonist (levocabastine) and H4 receptor antagonist (JNJ7777120) inhibited eye scratching behavior and histamine H1 receptor antagonist inhibited allergic-like symptoms induced by histamine. Additionally, combination of levocabastine and JNJ7777120 caused more potent inhibition in allergic conjunctivitis. On the other hand, both selective histamine H1 receptor agonist (HTMT) and selective H4 receptor agonist (4-methylhistamine) induced a dose-dependent eye scratching behavior and allergic-like symptoms. JNJ7777120 inhibited the effect of HTMT. However, levocabastine caused no inhibition on the response of 4-methylhistamine. H4 receptor was closely related with allergic conjunctivitis. H4 receptor antagonists may be effective in allergic conjunctivitis which showed no inhibition by histamine H1 receptor antagonists.
European Journal of Pharmacology.
