Peripheral 5-carboxamidotryptamine induces hindlimb scratching by stimulating 5-HT1A receptors in rats.
Treatment of rats with 5-carboxamidotryptamine (5-CT) or 5-methoxy-tryptamine (5-MeOT) induces a hindlimb scratch response. These compounds have high affinity for 5-HT1A and 5-HT1D receptors. The selective 5-HT1A receptor agonist N,N-dipropyl-5-CT (DP-5-CT) also induced hindlimb scratching while the selective 5-HT1D receptor agonist, sumatriptan, did not. 5-CT-induced hindlimb scratching was inhibited dose-dependently by several 5-HT1A antagonists (BMY 7378, NAN-190, MDL 73005EF and pindobind-5-HT1A) as well as the non-selective 5-HT antagonist, methiothepin. Pretreatment of rats with the serotonin (5-HT) synthesis inhibitor, p-chlorophenylalanine (PCPA) or the 5-HT depleting agent, reserpine, markedly attenuated 5-CT-induced hindlimb scratching. These data suggest that hindlimb scratching induced by 5-HT agonists may not be centrally mediated but rather may be mediated by a neuronal 5-HT1A receptor localized outside the blood-brain barrier.
Eison
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CNS Special Projects, Bristol-Myers Squibb Company, Wallingford, Connecticut 06492.
Wright
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Freeman
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D008735:5-Methoxytryptamine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D006614:Hindlimb; D007211:Indoles / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D018170:Sumatriptan; D014363:Tryptamines / Q000494:pharmacology
D007211:Indoles; D011985:Receptors, Serotonin; D013449:Sulfonamides; D014363:Tryptamines; D012701:Serotonin; D008735:5-Methoxytryptamine; C055895:N,N-dipropylcarboxamidotryptamine; D018170:Sumatriptan; C047087:5-carboxamidotryptamine