The journal of pain : official journal of the American Pain Society
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Despite accumulating evidence of the clinical effectiveness of acupuncture, its mechanism remains largely unclear. We assume that molecular signaling around the acupuncture needled area is essential for initiating the effect of acupuncture. To determine possible bio-candidates involved in the mechanisms of acupuncture and investigate the role of such bio-candidates in the analgesic effects of acupuncture, we conducted 2 stepwise experiments. First, a genome-wide microarray of the isolated skin layer at the GB34-equivalent acupoint of C57BL/6 mice 1 hour after acupuncture found that a total of 236 genes had changed and that extracellular signal-regulated kinase (ERK) activation was the most prominent bio-candidate. Second, in mouse pain models using formalin and complete Freund adjuvant, we found that acupuncture attenuated the nociceptive behavior and the mechanical allodynia; these effects were blocked when ERK cascade was interrupted by the mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (MAPK) inhibitor U0126 (.8 μg/μL). Based on these results, we suggest that ERK phosphorylation following acupuncture needling is a biochemical hallmark initiating the effect of acupuncture including analgesia. ⋯ This article presents the novel evidence of the local molecular signaling in acupuncture analgesia by demonstrating that ERK activation in the skin layer contributes to the analgesic effect of acupuncture in a mouse pain model. This work improves our understanding of the scientific basis underlying acupuncture analgesia.
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Randomized Controlled Trial
Reduction of bodily pain in response to an online positive activities intervention.
Inducing temporary positive states reduces pain and increases pain tolerance in laboratory studies. We tested whether completing positive activities in one's daily life produces long-term reductions in self-reported bodily pain in a randomized controlled trial of an online positive activities intervention. Participants recruited via the Web were randomly assigned to complete 0, 2, 4, or 6 positive activities administered online over a 6-week period. Follow-up assessments were collected at the end of 6 weeks and at 1, 3, and 6 months postintervention. We used linear mixed effects models to examine whether the intervention reduced pain over time among those who had a score <67 on the bodily pain subscale of the Short Form-36 at baseline (N = 417; pain scores range from 0 to 100; higher scores indicate less pain). Mean pain scores improved from baseline to 6 months in the 2-activity (55.7 to 67.4), 4-activity (54.2 to 71.0), and 6-activity (50.9 to 67.9) groups. Improvements were significantly greater (P < .05) in the 4-activity and 6-activity groups than in the 0-activity control group (54.1 to 62.2) in unadjusted and adjusted models. This study suggests that positive activities administered online can reduce bodily pain in adults with at least mild to moderate baseline pain. ⋯ This study demonstrates that teaching people simple positive activities can decrease reported levels of bodily pain; moreover, these activities can be administered over the internet, a potential avenue for broadly disseminating health interventions at relatively low costs and with high sustainability.
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Aromatase inhibitors (AIs), which are used to treat breast cancer, inhibit estrogen production in postmenopausal women. AI-associated musculoskeletal symptoms occur in approximately half of treated women and lead to treatment discontinuation in 20 to 30%. The etiology may be due in part to estrogen deprivation. In premenopausal women, lower estrogen levels have been associated with increased pain as well as with impairment of descending pain inhibitory pathways, which may be a risk factor for developing chronic pain. We prospectively tested whether AI-induced estrogen deprivation alters pain sensitivity, thereby increasing the risk of developing AI-associated musculoskeletal symptoms. Fifty postmenopausal breast cancer patients underwent pressure pain testing and conditioned pain modulation (CPM) assessment prior to AI initiation and after 3 and 6 months. At baseline, 26 of 40 (65%) assessed patients demonstrated impaired CPM, which was greater in those who had previously received chemotherapy (P = .006). No statistically significant change in pressure pain threshold or CPM was identified following estrogen deprivation. In addition, there was no association with either measure of pain sensitivity and change in patient-reported pain with AI therapy. AI-associated musculoskeletal symptoms are not likely due to decreased pain threshold or impaired CPM prior to treatment initiation, or to effects of estrogen depletion on pain sensitivity. ⋯ This article presents our findings of the effect of estrogen deprivation on objective measures of pain sensitivity. In postmenopausal women, medication-induced estrogen depletion did not result in an identifiable change in pressure pain threshold or CPM. Impaired CPM may be associated with chemotherapy.
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Racial disparities in pain treatment pose a significant public health and scientific problem. Prior studies have demonstrated that clinicians and nonclinicians are less perceptive of, and suggest less treatment for, the pain of African Americans relative to European Americans. Here we investigate the effects of explicit/implicit patient race presentation, patient race, and perceiver race on pain perception and response. African American and European American participants rated pain perception, empathy, helping motivation, and treatment suggestion in response to vignettes about patients' pain. Vignettes were accompanied by a rapid (implicit) or static (explicit) presentation of an African or European American patient's face. Participants perceived and responded more to European American patients in the implicit prime condition, when the effect of patient race was below the level of conscious regulation. This effect was reversed when patient race was presented explicitly. Additionally, female participants perceived and responded more to the pain of all patients, relative to male participants, and in the implicit prime condition, African American participants were more perceptive and responsive than European Americans to the pain of all patients. Taken together, these results suggest that known disparities in pain treatment may be largely due to automatic (below the level of conscious regulation) rather than deliberate (subject to conscious regulation) biases. These biases were not associated with traditional implicit measures of racial attitudes, suggesting that biases in pain perception and response may be independent of general prejudice. ⋯ Results suggest that racial biases in pain perception and treatment are at least partially due to automatic processes. When the relevance of patient race is made explicit, however, biases are attenuated and even reversed. We also find preliminary evidence that African Americans may be more sensitive to the pain of others than are European Americans.
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Although persistent pain occurs in a sociocultural context, the influence of personal devaluation and invalidation is often neglected. As such, the present study sought to consider whether individuals' experience, perception, or anticipation of negative social reactions to their pain may become internalized and affect the self. To examine this issue, 92 adults with chronic pain responded to a questionnaire exploring the presence of internalized stigma and its association with a range of psychological consequences. As predicted, a large percentage of people with chronic pain (38%) endorsed the experience of internalized stigma. The results showed that internalized stigma has a negative relationship with self-esteem and pain self-efficacy, after controlling for depression. Internalized stigma was also associated with cognitive functioning in relation to pain, in terms of a greater tendency to catastrophize about pain and a reduced sense of personal control over pain. Overall, this study presents a new finding regarding the application of internalized stigma to a chronic pain population. It offers a means of extending our understanding of chronic pain's psychosocial domain. Implications are discussed in terms of the potential to inform clinical treatment and resiliency into the future. ⋯ This article presents a novel finding regarding the presence of internalized stigma among people living with chronic pain. Internalized stigma is strongly associated with indicators of patient outcome. It presents an area for future work with the aim to improve our understanding and treatment of people living with pain.