Abstract
We investigated the role of serotonin (5-hydroxytryptamine; 5-HT)2 and 5-HT3 receptor subtypes in acute itch-associated scratching behavior as well as in an allergic pruritus model in rats. Intradermal 5-HT evoked hind limb scratching directed toward the injection site in naïve rats. Scratching behavior was significantly reduced by pretreatment with the 5-HT2 receptor antagonist ketanserin. Intradermal injection of α-methylserotonin, a 5-HT2 receptor agonist, also elicited scratching behavior in a dose-dependent manner, indicating that acute 5-HT-induced scratching is mediated via peripheral 5-HT2 receptors. To produce a model of allergic pruritus, skin was sensitized by topical application of 5% dinitrofluorobenzene (DNFB). One month later, repeated challenge of the skin with 0.2% DNFB at weekly intervals elicited scratching as part of the immediate allergic response. Scratching was not affected by ketanserin or by the 5-HT3 receptor antagonist ondansetron, indicating that neither 5-HT2 nor 5-HT3 receptors is involved in itch-associated scratching behavior caused by allergic skin dermatitis in rats.
Footnotes
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This study was supported by grants from the California Tobacco-Related Disease Research Program (6RT-0231 and 11RT-0053) and National Institutes of Health (NS 35788 and DE 13685).
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DOI: 10.1124/jpet.103.049239.
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ABBREVIATIONS: 5-HT, 5-hydroxytryptamine (serotonin); DNFB; dinitrofluorobenzene; ANOVA, analysis of variance.
- Received January 15, 2003.
- Accepted April 4, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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