The journal of pain : official journal of the American Pain Society
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Chronic inflammation, which changes the neurotransmitter metabolism and kindles neuroendocrine system dysfunction in the central nervous system, might cause fibromyalgia (FM) formation. In FM patients without traditional FM risk factors, such as hypertension, hyperlipidemia, diabetes, sleep disorder, depression, and anxiety, the chronic inflammatory process is a possible risk factor for FM. Thus, we investigated whether chronic osteomyelitis (COM), a disease characterized by chronic inflammation, increases FM risk. ⋯ Younger people had an even greater risk (age younger than 35 years: aHR = 1.58, 95% CI, 1.03-2.44; age 60 years or older: aHR = 1.03, 95% CI, .78-1.36). To our knowledge, this is the first study to link COM to an enhanced risk of FM development. The results imply that COM is a predictor of FM, suggesting that close follow-up for patients with COM is required to prevent FM, especially in younger populations.
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The present study investigated the pain-reducing effects of various pictures in a sample of 88 patients receiving inpatient treatment for chronic pain. We investigated whether the pain-attenuating effects of the pictures were mediated by picture valence, arousal, or change in subjective social support. The study was carried out over 4 consecutive days. ⋯ Viewing photographs of loved ones reduced pain intensity more than viewing other picture types. The association between picture type and decrease in pain intensity was mediated by picture valence. These findings suggest an easy to implement supplementary intervention that could be used in multidisciplinary pain treatment.
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Synovitis is a key factor in joint disease pathophysiology, which affects a greater proportion of women than men. P2X7 receptor activation contributes to arthritis, but whether it plays a role in articular inflammatory pain in a sex-dependent manner is unknown. We investigated whether the P2X7 receptor blockade in the knee joint of male and female rats reduces the articular hyperalgesia and inflammation induced by a carrageenan knee joint synovitis model. ⋯ P2X7 receptor blockade by the articular coadministration of selective P2X7 receptor antagonist A740003 with carrageenan significantly reduced articular hyperalgesia, pro-inflammatory cytokine concentrations, and myeloperoxidase activity induced by carrageenan injection into the knee joint of male and estrus female rats. However, a lower dose of P2X7 receptor antagonist was sufficient to significantly induce the antihyperalgesic and anti-inflammatory effects in estrus female but not in male rats. These results suggest that P2X7 receptor activation by endogenous adenosine 5'-triphosphate is essential to articular hyperalgesia and inflammation development in the knee joint of male and female rats. However, female rats are more responsive than male rats to the antihyperalgesic and anti-inflammatory effects induced by P2X7 receptor blockade.
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Opioid-induced hyperalgesia (OIH) is one of the major problems associated with use of opioids in perioperative and chronic pain management. The mechanism underlying this paradoxical phenomenon needs to be fully elucidated. Laterocapsular division of the central nucleus of amygdale (CeLC) has emerged as an important brain center for pain modulation, so we hypothesize that the activation of extracellular signal-regulated kinase (ERK) in CeLC may modulate OIH through strengthening synaptic transmission between neurons in the CeLC. ⋯ In vitro whole-cell recordings evaluating the change in synaptic transmission found that the frequency as well as amplitude of miniature excitatory postsynaptic currents recorded on CeLC neurons from OIH rats were fundamentally increased and were completely reversed by acutely applied U0126 (10 μM in the recording well). In vivo microinjection of U0126 into the CeLC reversed the spinal long-term potentiation in OIH rats. These results showed that fentanyl-induced hypersensitivity may occur partly through the mechanism of ERK activation and followed by the strengthening of synaptic transmission in CeLC neurons.