Effect of Picrorrhizae Rhizoma Aqueous Extracts on Paw Chronic Inflammation In Mice

Abstract

Objectives:The purpose of this study was to examine the efficacy of Picrorrhizae Rhizoma (PR) aqueous extracts on the formalin-induced paw chronic inflammation in mice. Methods: PR extracts (500, 250 and 125mg/kg) or distilled water (DW) were orally administered once a day for 10 days to formalin-injected chronic inflammatory mice. The paw thicknesses and volumes were measured daily and the paw wet-weight and histological profiles were conducted at termination with paw tumor necrosis factor (TNF)-α contents measurement. The anti-inflammatory effects of PR extracts were compared with dexamethasone. Results: In DW treated control group, the paw thickness, paw wet-weights and paw TNF-α contents were markedly increased. Severe chronic inflammation signs such as severe fibrosis, the formation of necrotic debris, and infiltration of inflammatory cells were detected in histopathological observations. However, these formalin-induced changes were dramatically decreased by treatment of dexamethasone and all three different dosages of PR extracts. The anti-inflammatory effects of PR at highest dose were slighter than that of dexamethasone, but it did not show any harmful effects on the body weight contrary to dexamethasone. Conclusion: These results suggest that PR extracts have safe and favorable effects on formalin-induced chronic inflammation.