Effects of Qingluo Tongbi Compound on Pain Behavior and Expression of COX-2 in Dorsal Root Ganglion and Blood PGE₂

OBJECTIVE To study the effects of Qingluo Tongbi Compound(QLT) on pain behavior and COX-2 mRNA expression in dorsal root ganglion(DRG) and blood PGE₂ concentration， and to explore the mechanisms of pain in rheumatoid arthritis. METHODS The mice were randomly divided into control group， celecoxib 30mg/kg，QLT 4.35g/kg， QLT 8.70g/kg and QLT 17.4g/kg groups. The mice pain threshold change were measured by hot plate method， and body torsion times were tested by acetic acid twisting method. The collagen-induced arthritis(CIA) was induced by collagenⅡ in DBA/1 mice. The mice were randomly divided into control group， CIA group， celecoxib 30mg/kg group， QLT 8.70g/kg. The paws swelling， mechanical withdrawal threshold(MWT) and thermal withdrawal latency(TWL) were recorded. After treated with corresponding drugs by intragastric administration for four weeks， COX-2 mRNA in DRG and PGE₂ in mice were quantified. RESULTS QLT reduced pain threshold and body torsion times in pain model mice(P<0.01); compared with the CIA group， the QLT group decreased the paws swelling(P<0.05)， up-regulated MWT(P<0.01) and PWL(P<0.05)， down-regulated the expression level of COX-2 mRNA in DRG and PGE₂ concentrations in blood. CONCLUSION QLT shows certain analgesic action， which might be related to the inhibitory effect of COX-2 mRNA expression in DRG and PGE₂ in blood.