Previously preclinical
pain research has focused on simple behavioral endpoints to assess the efficacy of
analgesics in acute and
chronic pain models, primarily reflexive withdrawal from an applied mechanical or thermal stimulus. However recent research has been aimed at investigating other behavioral states in the presence of
pain, including spontaneous, non-elicited
pain. One approach is to investigate the reinforcing effects of
analgesics in animals with experimental
pain, which should serve as reinforcers by virtue of their ability to alleviate the relevant subjective states induced by
pain. The gold standard for assessing drug reinforcement is generally accepted to be drug
self-administration, and this review highlights the ability of drugs to serve as reinforcers in animals with experimental
neuropathic pain, and the extent to which this behavior is altered in
chronic pain states. Additionally, intracranial self-stimulation is an operant procedure that has been used extensively to study drug reinforcement mechanisms and the manner in which
neuropathic pain alters the ability of drugs to serve as reinforcers in this paradigm will also be discussed. Drug
self-administration and intracranial self-stimulation have promise as tools to investigate behavioral effects of
analgesics in animals with
chronic pain, particularly regarding the mechanisms through which these drugs motivate consumption in a
chronic pain state.