Antinociceptive effect of CNS peroxynitrite scavenger in a mouse model of orofacial pain

Peroxynitrite (ONOO(-)) and species derived from it can oxidize and nitrate lipids, proteins and DNA leading to changes in signaling molecules. The present study was carried out to elucidate possible effects of CNS peroxynitrite in a mouse model of orofacial pain. Mice that received facial carrageenan injection + intracerebroventricular (i.c.v.) injection of the peroxynitrite scavenger [5,10,15,20-Tetrakis (4-sulfonatophenyl) porphyrinato iron (III), chloride] (FeTPPS) showed significantly fewer face wash strokes upon probing the inflamed area of the face with a von Frey hair at 6 h after injection, compared to mice that received facial carrageenan alone, or facial carrageenan injection + i.c.v. injection of saline. Mice that received i.c.v. injection of FeTPPS without facial carrageenan injection showed no significant difference in response to von Frey hair stimulation, compared to mice that received i.c.v. injection of saline without facial carrageenan injection. These results indicate an anti-nociceptive effect of the peroxynitrite scavenger FeTPPS in carrageenan induced facial pain but no effect on normal tactile sensation and point to an important role of CNS peroxynitrite in nociception.