European journal of pain : EJP
-
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.
-
Smad-interacting protein 1 (also named Zeb2 and Zfhx1b) is a transcription factor that plays an important role in neuronal development and, when mutated, causes Mowat-Wilson syndrome (MWS). A corresponding mouse model carrying a heterozygous Zeb2 deletion was comprehensively analysed in the German Mouse Clinic. The most prominent phenotype was the reduced pain sensitivity. In this study, we investigated the role of Zeb2 in inflammatory and neuropathic pain. ⋯ Our data suggest that the under-reaction to pain observed in MWS patients results from a reduced responsivity to nociceptive stimulation rather than an inability to communicate discomfort.
-
Expectations for recovery are a known predictor for returning to work. Most studies seem to conclude that the higher the expectancy the better the outcome. However, the development of expectations over time is rarely researched and experimental studies show that realistic expectations rather than high expectancies are the most adaptive. This study aims to explore patterns of stability and change in expectations for recovery during the first weeks of a back-pain episode and how these patterns relate to other psychological variables and outcome. ⋯ Decreases in expectancies for recovery seem as important as baseline values in terms of outcome, which has clinical and theoretical implications.
-
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.
-
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.