Inflammatory effects of acute and chronic capsaicin treatment on rat paw

Abstract

Abstract Capsaicin extracted from natural sources ( Capsicum frutescens ) and standard capsaicin (Sigma Chemicals) were used in this study. On acute treatment capsaicin produced a dose‐related inflammatory response in rat paw as measured by the volume displacement method. This response was found to be synergestic when injected with carrageenan. Preliminary experiments showed that pretreatment with diphenhydramine‐HCl produced a significant inhibition of this acute capsaicin induced paw oedema, whereas indomethacin and methysergide were ineffective in blocking paw oedema. On the other hand, chronically capsaicin treated rats (for 10 days) showed a significant inhibition of paw oedema when treated with either carregeenan or a single high dose of capsaicin. Both the extracted and the standard capsaicin showed a similar type of response in all experiments.