European journal of pain : EJP
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Randomized Controlled Trial
Prevalence of cold-related musculoskeletal pain according to self-reported threshold temperature among the Finnish adult population.
Exposure to cold reportedly increases musculoskeletal pains. We assessed the prevalence of such pain and self-reported threshold temperature (TT) at which the pain emerges. ⋯ People suffering from musculoskeletal disorders and those living in the warmer areas of Finland need special advice to protect themselves against the cold. Our study provides preliminary information to support such advice.
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Innate responses against spontaneous pain are proposed to improve the predictive validity of preclinical analgesia models. Therefore, development and validation of novel readouts is necessary. To investigate whether innate rodent burrowing is a useful alternative behavioural readout for assessment of analgesic efficacy, a complete Freund's adjuvant (CFA)-induced model of sub-chronic inflammation was used to compare the effects of naproxen, ibuprofen and pregabalin in weight-bearing (WB), open-field (OF) and burrowing assays. ⋯ Burrowing performance is an alternative non-reflex readout relying on innate rodent behaviour that is affected by nociceptive behaviour and can be pharmacologically manipulated. The burrowing assay appears to be more sensitive than OF assays and is as sensitive as WB assays at distinguishing between analgesic doses and doses that impair locomotion.
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Pathological pain states are often associated with neuronal hyperexcitability in the spinal cord. Reducing this excitability could theoretically be achieved by amplifying the existing spinal inhibitory control mediated by GABAA receptors (GABAARs). In this study, we used the non-benzodiazepine anxiolytic etifoxine (EFX) to characterize its interest as pain killer and spinal mechanisms of action. EFX potentiates GABAAR function but can also increase its function by stimulating the local synthesis of 3α-reduced neurosteroids (3αNS), the most potent endogenous modulators of this receptor. ⋯ This preclinical study shows that stimulating the production of endogenous analgesics such as 3αNS represents an interesting strategy to reduce neuropathic pain symptoms. Since EFX is already prescribed as an anxiolytic in several countries, a translation to the human clinic needs to be rapidly evaluated.
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Fear-conditioned analgesia (FCA) is the profound suppression of pain during exposure to conditioned aversive stimuli and is mediated at spinal and supraspinal levels. The endocannabinoid system plays a key role in FCA. This study investigated brain and spinal cord expression of genes implicated in pain- and fear-related plasticity (Zif268 and Sgk1), following expression of formalin-evoked nociception, contextual fear or endocannabinoid-mediated FCA. ⋯ The present findings suggest that Zif268 in the DHSC is an important molecular correlate of endocannabinoid-mediated FCA, and that fear-related expression of Zif268 in the RVM is influenced by the presence of nociceptive tone.
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Inflammatory responses and morphological changes of radiofrequency-induced rat sciatic nerve fibres.
Recently, the pulsed radiofrequency (PRF, pulsed fashion) procedure was introduced for neuropathic pain management. Since PRF-induced lesions do not need high temperature compared with conventional continuous RF (CRF)-induced lesions, there is no significant loss of sensory fibres after application. ⋯ PRF-induced pain relief may be due to temporary blockage of nerve signals through the nerve pathway responsible for reversible neuronal depression. However, CRF-induced pain relief may be due to permanent blockage of nerve signals through other nerve pathways. Therefore, CRF could be applied to chronic inflammatory models used to study the mechanism of neuropathic pain.