enkephalin--ala(2)-mephe(4)-gly(5)- and seryl-leucyl-isoleucyl-glycyl--arginyl-leucinamide

Protease-activated receptor-2 (PAR-2) in the sensory neurons may be involved in nociceptive processing. We attempted to detect and characterize specific expression of spinal Fos, a marker of nociception, in mast cell-depleted rats. Intraplantar (i.pl.) administration of not only the PAR-2 agonist SLIGRL-NH2, but also the control peptide LSIGRL-NH2, induced Fos expression in naive rats, whereas only the former specifically produced Fos expression in mast cell-depleted rats. This Fos expression was blocked by intrathecal DAMGO, a mu-opioid agonist, and, in part, by i.pl. calphostin C, a protein kinase C (PKC) inhibitor. Thus, specific expression of spinal Fos following peripheral PAR-2 activation is detectable in mast cell-depleted rats, suggesting activation of spinal nociceptive neurons, which is partially mediated by activation of PKC.

Topics: Animals; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Gene Expression; Genes, fos; Male; Mast Cells; Oligopeptides; Posterior Horn Cells; Rats; Rats, Wistar; Receptor, PAR-2; Receptors, Opioid, mu; Receptors, Thrombin; Spinal Cord