Animal models of acute and chronic inflammatory and nociceptive pain.

To facilitate the study of pain transmission and the characterization of novel analgesic compounds, an array of experimental animal pain models has been developed mainly in rodents. In these preclinical models, nociceptive pain can be measured by both spontaneous and evoked behaviors. Acute pain (seconds to hours) can be more easily measured, albeit still with some difficulty, by spontaneous behaviors (nocifensive behaviors such as licking, flinching), or by stimulation of the injured paw. Chronic pain (lasting at least several days) is most readily measured by evoked stimulation (thermal, mechanical, chemical). Experimental measures of evoked pain are well characterized and are analogous to clinical diagnostic methods. This chapter will focus on rodent models of inflammatory and nociceptive pain that are most used in our laboratory for identification of novel antinociceptive compounds in drug discovery.