The effects of the COX-2 inhibitor, parecoxib (intraperitoneal 10 mg kg<sup>-1</sup>), or the EP-1R antagonist, SC51089 (intraperitoneal 100 μg kg<sup>-1</sup>), on hyperalgesia and spinal PGE2 were examined.
These results demonstrate that spinal EP1 receptors are involved in the PGE2-induced allodynia and that spinal EP3 receptors are involved in the hyperalgesia induced by low doses of PGE2.