Abstract
1. 1. Serotonin (5-HT) induced a linear increase in paw weight in rats within 1hr of an intraplantar injection (50μ1 vol) over a concentration range of 0.005–0.2mg/ml. At the 0.2 mg/ml concentration, a 16-fold increase in paw weight was observed as compared to saline-injected controls. 2. 2. Serotonin antagonists, such as LY53857, were the most effective antagonists of 5-HT induced paw swelling, producing near complete antagonism and an approximate ED 50 of 0.1 mg/kg. A mixed 5-HT/histamine antagonist, cyproheptadine, also produced a nearly complete inhibition of the 5-HT response with an approximate ED 50 of 1.3 mg/kg. 3. 3. Dopamine agonists (pergolide, quinpirole), yohimbine, dexamethasone and nifedipine also produced a significant degree of antagonism of the 5-HT response. 4. 4. Clonidine, prazocin, chlorpheniramine, cimetidine, various dopamine antagonists, imipramine, cyclosporine A, piroxicam and superoxide dismutase were all ineffective at altering the paw swelling response to 5-HT.
Published Version
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