Zaltoprofen inhibits bradykinin-induced responses by blocking the activation of second messenger signaling cascades in rat dorsal root ganglion cells

Abstract

Bradykinin interacts with the bradykinin B2 receptor on dorsal root ganglion (DRG) neurons, setting off a series of reactions inside the cells that ultimately make the vanilloid receptor 1 more sensitive to a normal stimulus by activating various enzymes coupled with second messenger signaling cascades. Zaltoprofen, a propionic acid derivative non-steroidal anti-inflammatory drug (NSAID), was proved to inhibit bradykinin-induced pain responses in vivo experimental systems more potently than indomethacin or other NSAIDs, but the molecular mechanisms underlying its action are not yet fully understood. Currently it appears unlikely that zaltoprofen binds to specific sites on the protein of the bradykinin B2 receptor, hence we have examined the effect of zaltoprofen on bradykinin-induced responses of adult DRG neurons to investigate possible interaction sites. Compared with several other NSAIDs, such as indomethacin, loxoprofen and diclofenac, zaltoprofen most potently inhibits bradykinin-enhancement of capsaicin-induced 45Ca2+ uptake into DRG neurons. Zaltoprofen also significantly inhibits bradykinin-induced 12-lipoxygenase (12-LOX) activity and the slow bradykinin-induced onset of substance P release from DRG neurons. These data indicate zaltoprofen may produce its analgesic effects through the inhibition of bradykinin B2 receptor-mediated bradykinin responses of not only cyclooxygenases (COXs) but also bradykinin induced 12-LOX inhibitors.