Contribution of neurokinin 1 receptors in the cutaneous orofacial inflammatory pain.

This study investigated the role of neurokinin 1 receptors (NK1R) in inflammatory cutaneous orofacial pain. The effects of subcutaneous and intracisternal administration of the NK1R antagonist SR140333 on the face rubbing response provoked by injection of 50 micro l of 1.5% formalin into the vibrissa pad were examined. Subcutaneous administration of SR140333 (5, 15, 30 mg/kg) induced a dose-related depressant effect on both the first and second phases of the formalin test. In contrast, intracisternal administration of SR140333 (10, 30, 60, 90 microg) produced a decrease only on the second phase with an apparent ceiling effect at approximately 50%. These data suggest that persistent nociceptive effects associated with orofacial cutaneous inflammation depend at least in part on the activation of NK1R.