Possible Interaction: Capsaicin and Serotonin

“Similar to PGE(2), an intraplantar injection of capsaicin (0.1 mg) produced a robust thermal hypersensitivity that was paralleled by a 3-fold increase in levels of 5-HT in the RVM.”

“… 5-HT (… capsaicin in an insurmountable way.6.The effect of very high concentrations of 5-HT (>10−5 mol/l) could be partially antagonised by … from the ileum of adult guinea-pigs a contractile action of 5-HT can be mediated by the activation of three independent receptors.”

“Tetrodotoxin (1 µM), NG-nitro-l-arginine (100 µM) and capsaicin (1 µM) were ineffective in antagonising the relaxation induced by 5-HT.”

“The scratching induced by 5-HT (100 nmol site(-1), peak effective dose) was suppressed by capsaicin (repeated administration) and the opioid antagonist naloxone, features being similar to human itching.”

“In intact ilea, however, tetrodotoxin (TTX) and capsaicin reduced significantly the maximum values of Isc stimulated by 5-HT , and the nitric oxide synthase inhibitor N omega-nitro-L-arginine methyl ester (L-NAME) caused a significant decrease in the maximum response to 5-HT.”

“Extracellular concentrations of aspartate, glutamate and serotonin increased significantly following capsaicin injection into the ipsilateral limb.”

“Responses evoked by brief applications of … threshold concentrations of bradykinin or capsaicin to the … enhanced by 5-hydroxytryptamine and the 5-hydroxytryptamine1C/5-hydroxytryptamine2-receptor agonist alpha-methyl-5-hydroxtryptamine but not by the …-hydroxytryptamine3-receptor agonist 2-methyl-5-hydroxytryptamine or the 5-hydroxytryptamine1-receptor agonist 5-carboxamidotryptamine.”

“ Capsaicin pretreatment of the animals resulted in rightward shifts of the dose-response curves to serotonin , 2-methyl-serotonin and TFMPP, but not to 5-methoxytryptamine or alpha-methyl-serotonin.”

“ Capsaicin treatment after sensitization reduced the bronchial reactivity to challenge with OA aerosol and serotonin iv.”

“Treatment of ovalbumin-sensitized rats with capsaicin resulted in altered bronchial reactivity to both ovalbumin and serotonin.”