The journal of pain : official journal of the American Pain Society
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Irritable bowel syndrome (IBS), characterized mainly by abdominal pain, is a functional bowel disorder. The present study aimed to examine changes in the excitability and the activity of the voltage-gated K(+) channel in dorsal root ganglia (DRG) neurons innervating the colon of rats subjected to neonatal maternal separation (NMS). Colonic DRG neurons from NMS rats as identified by FAST DiI™ labeling showed an increased cell size compared with those from nonhandled (NH) rats. Whole cell current-clamp recordings showed that colonic DRG neurons from NMS rats displayed: 1) depolarized resting membrane potential; 2) increased input resistance; 3) a dramatic reduction in rheobase; and 4) a significant increase in the number of action potentials evoked at twice rheobase. Whole cell voltage-clamp recordings revealed that neurons from both groups exhibited transient A-type (I(A)) and delayed rectifier (I(K)) K(+) currents. Compared with NH rat neurons, the averaged density of I(K) was significantly reduced in NMS rat neurons. Furthermore, the Kv1.2 expression was significantly decreased in NMS rat colonic DRG neurons. These results suggest that NMS increases the excitability of colonic DRG neurons mainly by suppressing the I(K) current, which is likely accounted for by the downregulation of the Kv1.2 expression and somal hypertrophy. ⋯ This study demonstrates the alteration of delayed rectifier K current and Kv1.2 expression in DRG neurons from IBS model rats, representing a molecular mechanism underlying visceral pain and sensitization in IBS, suggesting the potential of Kv1.2 as a therapeutic target for the treatment of IBS.
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Substantial literature suggests that diverse biological, psychological, and sociocultural mechanisms account for differences by race and ethnicity in the experience, epidemiology, and management of pain. Many studies have examined differences between Whites and minority populations, but American Indians (AIs), Alaska Natives (ANs), and Aboriginal peoples of Canada have been neglected both in studies of pain and in efforts to understand its biopsychosocial and cultural determinants. This article reviews the epidemiology of pain and identifies factors that may affect clinical assessment and treatment in these populations. We searched for peer-reviewed articles focused on pain in these populations, using PubMed, CINAHL, Cochrane, and the University of New Mexico Native Health Database. We identified 28 articles published 1990 to 2009 in 3 topic areas: epidemiology of pain, pain assessment and treatment, and healthcare utilization. A key finding is that AI/ANs have a higher prevalence of pain symptoms and painful conditions than the U.S. general population. We also found evidence for problems in provider-patient interactions that affect clinical assessment of pain, as well as indications that AI/AN patients frequently use alternative modalities to manage pain. Future research should focus on pain and comorbid conditions and develop conceptual frameworks for understanding and treating pain in these populations. ⋯ We reviewed the literature on pain in AI/ANs and found a high prevalence of pain and painful conditions, along with evidence of poor patient-provider communication. We recommend further investigation of pain and comorbid conditions and development of conceptual frameworks for understanding and treating pain in this population.
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Preliminary reports suggest that acceptance of pain is an important construct when assessing and treating adolescents with chronic pain. Although the Chronic Pain Acceptance Questionnaire, Adolescent version (CPAQ-A) appears to be a promising tool, it has been evaluated in only 1 study. The current results present a confirmatory analysis of the CPAQ-A and validity data collected independently from the developers of the scale. A sample of 109 adolescents with chronic pain completed the CPAQ-A, as well as measures of pain characteristics, functional impairment, depression, anxiety, and pain self-efficacy. Results of the confirmatory factor analysis indicate the previously reported 2-factor solution provides a good fit to the data, and has acceptable internal consistency. The CPAQ-A correlated strongly with disability, depression, anxiety, and self-efficacy. It correlated only moderately with pain intensity and was not correlated with pain frequency or duration of pain. When entered last into a hierarchical regression model predicting disability, acceptance accounted for more variance than pain intensity, depression, anxiety, and self-efficacy. Results supported the internal consistency and validity of the CPAQ-A as a measure of pain acceptance in this sample of adolescents with chronic pain. Use of the CPAQ-A may provide valuable insight into the manner in which adolescents adapt to chronic pain and can guide acceptance-based treatment. ⋯ This article strengthens the psychometric support for a measure of chronic pain acceptance in adolescents. Acceptance-based treatment has been shown to reduce disability in preliminary research targeting adolescents with chronic pain; the CPAQ-A may be useful for assessing the degree to which acceptance-based approaches may be indicated for a given patient.
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Non-adherence to opioid prescriptions can decrease the safety and efficacy of opioid therapy. Identifying factors associated with over- and under-use of opioids in patients presenting with pain may improve prescribing and pain management. Patients presenting with pain often also present with somatization, and somatization is associated with both excessive use of and non-adherence to medications. This study examines the relationship between somatization and non-adherence (over- and under-use) to opioid prescriptions in the Veteran sample. One hundred and ninety-one Veterans who received an opioid prescription at a Veterans Affairs Palo Alto Health Care System in the prior year participated by completing a 1.5 hour semistructured interview which included assessments of depressive symptoms, somatization, medication side effects, and opioid pain medication usage. The percentage of patients non-adherent to opioid prescriptions increased as a function of somatization: Compared to no somatization, all levels of somatization were associated with higher rates of underuse, while severe somatization was associated with increased rates of overuse. Consistent with previous studies of medication non-adherence, increased depression and medication side effects were associated with decreased adherence to opioid prescriptions. However, in exploratory analyses, somatization mediated the relationship between depressive symptoms and opioid-use patterns as well as medication side effects and opioid use patterns. ⋯ This article sought to explore the relationship between somatization and adherence to prescription opioid medications. Our findings suggest that pain management treatment plans may be optimized by addressing patient distress about physical symptoms when considering the use of prescription opioid medications.
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The aims of this study were: 1) to examine race and sex differences in primary pain appraisals and catastrophizing; 2) to test the unique ability of race, sex, primary pain appraisals, and catastrophizing to predict experimental pain outcomes; and 3) to conduct mediational analyses testing pain appraisals and catastrophizing as explanatory mechanisms for race and sex differences in pain. One hundred and fifty-five college students at The University of Alabama completed a cold pressor experimental pain task and a questionnaire battery. Statistical methods included multivariable regression models and nonparametric bootstrapping methods for tests of mediation. African-Americans reported higher catastrophizing and had lower pain tolerance than white Americans. Males demonstrated higher challenge appraisals, lower pain intensity, and longer pain tolerance. Challenge appraisals were positively related to pain tolerance, threat/harm appraisals were inversely related to pain tolerance, and pain catastrophizing was positively related to both pain intensity and pain unpleasantness. Pain catastrophizing partially mediated race differences in pain tolerance and mediated sex differences in intensity, whereas primary pain appraisals did not significantly mediate race or sex differences in pain variables. Primary appraisals and catastrophizing appear to be separable constructs related to different aspects of the pain experience. ⋯ This study found that important race and sex differences exist in relation to pain appraisals and catastrophizing, and that these cognitive variables play unique roles in different aspects of the pain experience. Cognitive-behavioral therapies for pain may be enhanced by including a focus on both pain appraisals and pain catastrophizing.