European journal of pain : EJP
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The basolateral amygdala (BLA) contains a high density of cannabinoid CB1 receptors and is critically involved in pain and fear-related behaviour. We investigated the effects of bilateral intra-BLA administration of the CB1 receptor antagonist/inverse agonist, rimonabant, on formalin-evoked nociceptive behaviour, fear-conditioned behaviour including analgesia, and associated brain regional alterations in Fos expression in rats. Intra-BLA administration of rimonabant significantly reduced formalin-evoked nociceptive behaviour in the absence, but not presence, of conditioned fear. ⋯ Contextually-induced fear was associated with increased FI in the dorsal caudal periaqueductal grey in the absence, but not presence, of formalin-evoked nociceptive tone. In conclusion, bilateral intra-BLA administration of rimonabant reduces nociceptive behaviour in a model of tonic, persistent inflammatory pain, an effect associated with reduced activation of neurons in the CA2/3 hippocampus and rostral ventromedial medulla. The data also provide evidence for differential pain- and fear-related brain regional activity in the presence or absence of contextually-induced aversion and nociceptive tone.
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Cancer pain is one kind of the most common and severe kinds of chronic pain. No breakthrough regarding the mechanisms and therapeutics of cancer pains has yet been achieved. Based on the well established involvement of the NMDA (N-methyl-D-aspartate) receptor containing NR2B in inflammatory pain and neuropathic pain and the effective pain relief obtained with ketamine in cancer patients with intractable pain, we supposed that NR2B in the spinal cord was an important factor for cancer pain. ⋯ Intrathecal administration of 5 and 10 microg of NR2B subunit-specific NMDA receptor antagonist ifenprodil attenuated cancer-evoked spontaneous pain, thermal hyperalgesia and mechanical allodynia. These results suggest that NR2B in the spinal cord may participate in bone cancer pain in mice, and ifenprodil may be a useful alternative or adjunct therapy for bone cancer pain. The findings may lead to novel strategies for the treatment of bone cancer pain.
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Patients suffering from major depressive disorder (MDD) have been shown to exhibit increased thresholds towards experimentally induced thermal pain applied to the skin. In contrast, the induction of sad mood can increase pain perception in healthy controls. Here, we aimed to test the hypothesis that heat pain thresholds are further increased after sad mood induction in depressed patients. ⋯ From these data, we propose that the depressed mood as seen in MDD patients influences pain experience differently as compared to the shorter-lasting mood change after MIP. A differential interaction of both affective states with brain areas of the pain matrix might be assumed. Eventually, the induction of sad mood might mirror the increased number of pain complaints in depressed patients and thus adds to the current concept of adjuvant antidepressant treatment both in depressed patients with pain complaints and in chronic pain patients.
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Widespread pain has negative influence on outcome in low back pain (LBP) patients. Tender point (TP) examination is a standardized examination method to estimate diffuse tenderness. ⋯ The pain in patients with diffuse tenderness was rarely related to disc degeneration or nerve root affection, rather it may be caused by disturbed pain regulation.
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Multicenter Study
Reliability study in five languages of the translation of the pain behavioural scale Doloplus.
Non-verbal pain assessment scales are useful tools for pain evaluation in persons with communication disorders and moderate-severe dementia. The Doloplus was one of the first scales to be developed and validated as a pain assessment tool in older adults with dementia. ⋯ Results show that both tests are good or excellent for the English, Italian, Portuguese and Spanish versions and moderate for the Dutch version. These results bring a unique opportunity to include the translated Doloplus scale in daily assessment of elderly persons with communication disorders, and future studies should focus on enriching the validation of the scale in each language.