Pain
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Excitatory interneurons account for the majority of neurons in the superficial dorsal horn, but despite their presumed contribution to pain and itch, there is still limited information about their organisation and function. We recently identified 2 populations of excitatory interneuron defined by expression of gastrin-releasing peptide (GRP) or substance P (SP). Here, we demonstrate that these cells show major differences in their morphological, electrophysiological, and pharmacological properties. ⋯ The 2 populations also differed in responses to neuromodulators, with most SP cells, but few GRP cells, responding to noradrenaline and 5-HT; the converse was true for responses to the μ-opioid agonist DAMGO. Although a recent study suggested that GRP cells are innervated by nociceptors and are strongly activated by noxious stimuli, we found that very few GRP cells receive direct synaptic input from TRPV1-expressing afferents, and that they seldom phosphorylate extracellular signal-regulated kinases in response to noxious stimuli. These findings indicate that the SP and GRP cells differentially process somatosensory information.
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Joint inflammation is present in a subpopulation of knee osteoarthritis (OA) patients. Proinflammatory cytokines are known to sensitize the peripheral and central pain pathways. This can be mechanistically assessed by pressure pain thresholds and temporal summation of pain (TSP). ⋯ In conclusion, this study found that mechanistic pain profiling can predict pain alleviation of NSAIDs and paracetamol. Facilitated TSP and low clinical pain scores before treatment are independent predictors of poor pain alleviation after NSAIDs and paracetamol. This study adds to the growing evidence that a subgroup of knee OA patients with manifested central sensitization may require special management attention.
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The patients with multiple sclerosis (MS) are at greater risk of pain than people without the disease; however, the occurrence and characteristics of pain among these patients are incompletely described. We aimed to assess characteristics of pain amongst MS patients using MS patients who were recruited to participate in 3 studies in Sweden (n = 3877) and were matched with individuals without MS (n = 4548) by sex, year of birth, and region of residence. The Prescribed Drugs Register identified prescribed pain medication, overall and restricted to those given 4 or more prescriptions in 1 year to assess chronic pain. ⋯ The HR for chronic pain treatment was 3.55 (3.27-3.84), indicating an increased effect size relative to any pain treatment. Chronic neuropathic pain showed the largest HR at 7.43 (6.21-8.89). Neuropathic pain was shown to be the primary mechanism leading to increased risk of pain in patients with MS.
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This study investigated the moderating role of parental pain-related attention-set shifting and heart rate variability (HRV) for parental distress and pain control behaviour when faced with their child's pain. Participants were 54 schoolchildren and one of their parents. Parental HRV was assessed at study commencement followed by a cued-switching task indexing parental ability to flexibly shift attention between pain-related and neutral attentional sets. ⋯ Parental ability to shift attention away (ie, disengage) from a pain-related set to a neutral set did not impact findings. Results further indicated that although high levels of parental HRV buffer the impact of child facial pain display on parental emotional distress and pain control behaviour, low levels of HRV constitute a risk factor for higher levels of parental distress and pain control behaviour when faced with increased child facial pain display. Theoretical/clinical implications and further research directions are discussed.
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Pain is ubiquitous, but effective pain relief eludes many. Research has shown that some pain behaviours are perceived as gendered, and this may influence the way men and women express and cope with pain, but such enquiries have not extended to specific methods of pain relief. Our aim was to explore perceptions of the most socially acceptable ways for men and women to relieve pain. ⋯ The overarching male stereotype suggested it is most acceptable for men to use pain relief aligned with stereotypical masculinity; however, a second stereotype also emerged, characterised by conventional and effective responses to pain, much like the overarching stereotype for women. These differing viewpoints seem to depend on whether gender norm conformity or perceived analgesic efficacy is believed to determine social acceptability. These studies provide initial evidence of both a gendered and ungendered lens through which pain relief can be viewed, which may influence how men and women use pain relief.