The journal of pain : official journal of the American Pain Society
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Despite a common assumption that reductions in chronic pain intensity must precede improvements in other pain-relevant domains, there has been limited empirical inquiry into the temporal ordering of improvements in chronic pain treatment. Cross-lagged models using retrospective clinical data examined relationships between average pain intensity and symptoms of psychological distress, difficulties with sleep initiation and maintenance, and disability in 666 treatment-seeking patients with chronic pain who demonstrated improvement in pain intensity (≥1-point reduction on 0-10 numeric rating scale) over a 1-year span. Results indicated that decreased difficulties with sleep initiation, depressive and anxious symptoms, and disability predicted later improvement in pain intensity, whereas greater pain intensity predicted only later difficulties in sleep initiation and maintenance. ⋯ The current findings should be replicated using prospective studies utilizing structured approaches to maximize data capture, as well as uniform interventional approaches to permit greater inferences regarding causal and temporal aspects of the model. PERSPECTIVE: This study demonstrates that pain intensity scores are not robust predictors of psychosocial outcomes longitudinally. Instead, other factors such as sleep initiation, psychological distress and disability appear to be important targets for intervention that may promote effective pain reduction.
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Oxylipins are lipid peroxidation products that participate in nociceptive, inflammatory, and vascular responses to injury. Effects of oxylipins depend on tissue-specific differences in accumulation of precursor polyunsaturated fatty acids and the expression of specific enzymes to transform the precursors. The study of oxylipins in nociception has presented technical challenges leading to critical knowledge gaps in the way these molecules operate in nociception. ⋯ Together, these findings advance our understanding of molecular lipidomic systems linking oxylipins and their precursors to nociceptive and inflammatory signaling pathways in rats. PERSPECTIVE: We applied a systems approach to characterize molecular pathways linking precursor lipids and oxylipins to nociceptive signaling. This systematic, quantitative evaluation of the molecular pathways linking oxylipins to nociception provides a framework for future basic and clinical research investigating the role of oxylipins in pain.
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Pain is a common but potentially debilitating symptom, often requiring complex management strategies. To understand the molecular dynamics of peripheral inflammation and nociceptive pain, we investigated longitudinal changes in behavior, tissue structure, and transcriptomic profiles in the rat carrageenan-induced peripheral inflammation model. Sequential changes in the number of differentially expressed genes are consistent with temporal recruitment of key leukocyte populations, mainly neutrophils and macrophages with each wave being preceded by upregulation of the cell-specific chemoattractants, Cxcl1 and Cxcl2, and Ccl2 and Ccl7, respectively. ⋯ PERSPECTIVE: This study investigates the highly orchestrated biological response during tissue inflammation with precise assessment of molecular dynamics at the transcriptional level. The results identify transcriptional changes that define an evolving inflammatory state in rats. This study provides foundational data for identifying markers of, and potential treatments for, inflammation and pain in patients.