The journal of pain : official journal of the American Pain Society
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Altered nociception, a key feature of nociplastic pain, often involves central sensitization. We previously found that central sensitization underlying a nociplastic pain state in female mice depends on the ongoing activity of TRPA1 agonist-responsive afferents. Here, we investigated how the activity of these afferents induces and maintains central sensitization at the spinal level. ⋯ These results suggest that the activity of TRPA1 agonist-responsive afferents induces and maintains central sensitization by activating dorsal horn SSTn and suppressing GABAn via SST2A-R, resulting in altered nociception that manifests as mechanical hypersensitivity. PERSPECTIVE: This article presents experimental evidence that TRPA1 agonist-responsive afferents induce and maintain central sensitization at the spinal level by activating SST-expressing excitatory interneurons and suppressing GABAergic inhibitory interneurons via SST2A-R. Spinal SST2A-R may represent a promising target for treating mechanical pain hypersensitivity due to central sensitization by TRPA1 agonist-responsive afferents.
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Biomedical and clinical research has traditionally focused on binary sex assignments as opposed to gender identity. This oversight has resulted in other gender minority populations being understudied. As a result, there is limited literature on chronic pain and mental health in transgender populations. ⋯ Therefore, it is crucial to include transgender individuals, as well as other gender minority people, in research in order to fully understand the impact of gender minority status on pain and quality of life. PERSPECTIVE: This review explores the intersectional impact of stress and mental health on chronic pain development and the unequal risk for transgender individuals. Promoting inclusion of gender minority individuals in research is a critical step to understanding the factors contributing to minority stress.
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Monitoring recovery during acute pain episodes is useful for identifying youth at risk for pain persisting. Subjective and objective measures can assess function postinjury, but associations among these different measures and pain patterns in the acute period are unknown. To fill this gap, we examined associations among self-reported activity limitations, objectively measured physical activity, and pain intensity in 176 youth (age 11-17, 46% male) seeking health care for acute musculoskeletal pain. ⋯ Future work should examine how physical activity and activity limitations change longitudinally and predict pain persistence. PERSPECTIVE: This study examined daily associations between pain intensity, self-reported activity limitations, and objectively assessed physical activity in youth during the acute recovery period following a musculoskeletal injury. Self-reported activity limitations and objective physical activity represent 2 distinct, yet related, aspects of physical functioning that are associated with pain.
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Negative expectations can increase pain, but can they promote the development of central sensitization? This study used an inert treatment and verbal suggestions to induce expectations of increased high-frequency electrical stimulation (HFS)-induced pain and assessed their effects on pain ratings during HFS and HFS-induced pinprick hypersensitivity. Fifty healthy volunteers were randomly allocated to either a control group (N = 25) or a nocebo group (N = 25). Participants in both groups received a patch containing water on the right forearm. ⋯ HFS increased pinprick sensitivity but no group differences were found. Because of the lack of differences in expected pain and pain intensity ratings for HFS between groups, no firm conclusions can be drawn regarding their effect on pinprick hypersensitivity. PERSPECTIVE: This study shows that sham treatment combined with verbal suggestions induces a nocebo effect but does not necessarily change expectations and experience of upcoming pain.
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Multiple large longitudinal cohorts provide opportunities to address questions about predictors of pain and pain trajectories, even when not anticipated in design of the historical databases. This focus article uses two empirical examples to illustrate the processes of assessing the measurement properties of data from large cohort studies to answer questions about pain. In both examples, data were screened to select candidate variables that captured the impact of chronic pain on self-care activities, productivity and social activities. ⋯ In conjunction with its supplementary material, this focus article aims to encourage exploration of these valuable prospectively collected data; to support researchers to make explicit the relationships between items in the databases and constructs of interest in pain research; and to use empirical methods to estimate the possible biases in these variables. PERSPECTIVE: This focus article outlines a theory-driven approach for fitting new measurement models to data from large cohort studies, and evaluating their psychometric properties. This aims to help researchers develop an empirical understanding of the gains and limitations connected with the process of re-purposing the data stored in these datasets.