Injection stauntoniae inhibits chronic inflammatory pain responses by changing COX-2 expression in carrageenan-inflamed mice

AIM：To investigate the effect of injection stauntoniae (IS) on inflammatory pain responses in mice. METHODS：The carrageenan test was used to determine the anti-inflammatory and analgesic effects of IS. Except for control group, the mice in other groups received an injection of λ-carrageenan solution (1%, 50 μL) into the plantar region of the left hind paws, followed by a subcutaneous injection of IS at doses of 12.5%, 50% and 100% or equal volume of 0.9% NaCl. Both paw edema and hyperalgesia to thermal stimulation were measured 4 h, 12 h, 24 h and 48 h after the injection of λ-carrageenan solution. The lumbar-5 (L5) dorsal root ganglions (DRGs) of the mice were taken to investigate the cyclooxygenase 2 (COX-2) expression by immunohistochemical staining. RESULTS：Subcutaneous injection of IS potently inhibited paw edema and hyperalgesia induced by λ-carrageenan in the mice accompanied with the inhibition of COX-2 protein expression in L5 DRGs. CONCLUSION：IS exerts the anti-inflammatory and analgesic effects on the inflammatory responses by inhibiting the protein expression of COX-2 in DRGs.