Intrathecal administration of PD-98059 inhibits formalin (5%, 50 μl, i.p.)-induced inflammatory nociception. (A) Time course of formalin-induced nociceptive behavior. The nociceptive behavior by formalin injection was significantly inhibited by intrathecal administration of PD-98059 in a dose dependent manner. Values are expressed as mean ± SEM. *P < 0.01, and **P < 0.01 vs. control rats (vehicle-pretreated and formalin-treated). (B) Total times of nociceptive behavior were remarkably blocked during phase II, but not during phase I by intrathecal administration of PD-98059 in a dose-related fashion following intraplantar injection of formalin. Values are expressed mean ± SEM. *P < 0.01 vs. control rats (vehicle-pretreated and formalin-treated).