Keywords: 5-HT; serotonin; CCI; chronic constriction injury; COX-2; cyclooxygenase-2; DLPT; dorsolateral pontine tegmentum; DOI; (±)-2.5-dimethoxy-4-iodoamphetamine; GSH; glutathione; HPLC; high performance liquid chromatography; l-NMMA; NG-monomethyl-l-arginine;