European journal of pain : EJP
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Conditioned pain modulation (CPM) is a validated measure of the function of endogenous pain inhibitory pathways. Placebo effects reflect top-down inhibitory modulation of pain. CPM and placebo effects are both influenced by expectations, albeit to varying degrees, and are related to neurotransmitter systems such as the endogenous opioid system, and it can be speculated that CPM responses are positively associated with the magnitude of placebo effects. Yet, no studies have tested this. ⋯ Conditioned pain modulation and placebo effects are endogenous pain-modulating phenomena that are influenced by some of the same mechanisms. This study suggests that CPM and placebo effects in neuropathic pain are independent phenomena that may be mediated by different mechanisms.
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Pregabalin is a first-line agent for neuropathic pain treatment whose abuse liability remains controversial. Surprisingly, studies exploring the reinforcing properties of pregabalin in operant mouse models are missing. ⋯ This study shows that mice with a nerve injury self-administer pregabalin at doses effective reducing nociceptive hypersensitivity and depressive-like behaviour associated with the neuropathic pain model. Interestingly, mice without neuropathy also develop operant self-administration behaviour, suggesting potential abuse liability of this first-line drug for neuropathic pain treatment.