European journal of pain : EJP
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Unilateral injection of Complete Freund's Adjuvant (CFA) into the intra-plantar surface of the rodent hindpaw elicits chronic inflammation and hyperalgesia in the ipsilateral hindlimb. Mechanisms contributing to this hyperalgesia may act over multiple time courses and can include changes in ion channel expression and post-translational SUMOylation. Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels mediate the hyperpolarization-activated current, Ih . An HCN2-mediated increase in C-nociceptor Ih contributes to mechanical hyperalgesia in the CFA model of inflammatory pain. Changes in HCN2 post-translational SUMOylation and protein expression have not been systematically documented for a given dorsal root ganglia (DRG) throughout the time course of inflammation. ⋯ Nociceptor HCN2 channels mediate an increase in Ih that is necessary for mechanical hyperalgesia in a CFA model of chronic pain, but the mechanisms producing the increase in nociceptor Ih have not been resolved. The data presented here suggest that the increase in Ih during the early stages of inflammation may be mediated by an increase in HCN2 protein expression and post-translational SUMOylation.
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Diffuse noxious inhibitory controls (DNIC) as measured in rat and conditioned pain modulation (CPM), the supposed psychophysical paradigm of DNIC measured in humans, are unique manifestations of an endogenous descending modulatory pathway that is activated by the application of a noxious conditioning stimulus. The predictive value of the human CPM processing is crucial when deliberating the translational worth of the two phenomena. ⋯ This study provides novel evidence that a comparable noxious cuff pressure paradigm activates a unique form of endogenous inhibitory control in healthy rat and man. This has important implications for the forward translation of bench and experimental pain research findings to the clinical domain. If translatable mechanisms underlying dysfunctional endogenous inhibitory descending pathway expression (previously evidenced in painful states in rat and man) were revealed using cuff pressure algometry, the identification of new analgesic targets could be expedited.
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Stress-related dissociation has been shown to negatively co-vary with pain perception in current borderline personality disorder (cBPD). While remission of the disorder (rBPD) is associated with normalized pain perception, it remains unclear whether dissociation proneness is still enhanced in this group and how this feature interacts with pain sensitivity. ⋯ Both current (cBPD) and remitted borderline personality disorder (rBPD) patients show enhanced proneness to dissociation. This feature is significantly linked with pain hyposensitivity in cBPD in a paradigm that induces stress using a script-driven imagery approach, whereas this connection cannot be observed in rBPD. However, in the stress compared to the neutral condition, rBPD participants also show pain hyposensitivity compared to healthy controls. This study provides new insights into the pain processing mechanisms of BPD and its remission.
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Recent evidence suggests that insomnia negatively influences the occurrence of generalized pain. This study examined whether insomnia is a risk factor for the transition from local pain (LP) to generalized pain (i.e. spreading of pain). ⋯ This study shows that people with LP conditions are at much higher risk of developing WSP if they also have significant insomnia symptoms. The elevated risk is evident after 24 months and increases in a dose-dependent manner regarding the degree of exposure to insomnia symptoms. Local pain conditions are quite common in primary care, and an evaluation of the insomnia symptoms is highly recommended since the most common sleep problems can be treated effectively if detected.
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Attending towards pain is proposed as a key mechanism influencing the experience and chronification of pain. Persistent attention towards pain is proposed to drive poor outcomes in both adults and children with chronic pain. However, there are no validated self-report measures of pain-related attention for children. ⋯ Pain-related attention is proposed as a key factor influencing fear-avoidance outcomes in both adults and youth with chronic pain, yet no self-report measures of pain-related attention have been validated for children. This paper presents a child version of the Pain Vigilance and Awareness Questionnaire (PVAQ-C), which indicates strong internal consistency, criterion validity and unique predictive validity, and provides evidence to support the Fear-Avoidance Model in youth with chronic pain.