The journal of pain : official journal of the American Pain Society
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The purpose of this study was to examine exercise-induced pain modulation in diabetic adults with painful diabetic neuropathy (PDN) compared to diabetic adults without PDN. Eighteen adults diagnosed with type 2 diabetes with and without PDN (mean age of 49 years) completed 2 sessions. During the familiarization session, participants completed questionnaires, were familiarized with the pain testing protocols, and completed maximal isometric contractions. During the exercise session, experimental pain testing was completed before and following exercise consisting of 3 minutes of isometric exercise performed at 25% maximal voluntary contraction. Ratings of perceived exertion and muscle pain were assessed every 30 seconds during exercise. Results indicated that ratings of perceived exertion and muscle pain during exercise were significantly higher (P < .05) for diabetic adults with PDN versus diabetic adults without PDN. Diabetic adults with PDN did not experience changes in thermal pain ratings following exercise, whereas diabetic adults without PDN reported significantly lower pain ratings following exercise. It is concluded that diabetic adults with PDN experienced high levels of muscle pain during exercise and a lack of exercise-induced hypoalgesia following exercise, in comparison to diabetic adults without PDN, who experienced lower levels of muscle pain during exercise and a hypoalgesic response following exercise. ⋯ Very little research has been conducted examining the impact of exercise on pain modulation in diabetic adults with PDN. This study provides support that adults with PDN exhibit exercise-induced endogenous pain modulatory system dysfunction.
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The aim of the present study was to analyze differences between men and women in the experience of chronic pain. Resilience, fear-avoidance of pain, and pain acceptance were included in a hypothetical model as variables involved in chronic pain adjustment. A sample of 400 chronic spinal pain patients (190 men and 210 women) attending primary care units participated in the study. Student's t-test analyses showed that the women's scores were significantly higher than men's scores on pain intensity, pain anxiety, and current functioning. A LISREL multisample analysis of the theoretical model across genders was conducted. As expected, statistically significant associations were found between resilience and confrontation in both samples. Thus, resilient people will probably develop accepting behavior when faced with chronic pain. Confrontation yielded 3 statistically significant path coefficients: to pain intensity, functional status, and negative mood. Statistically significant associations were found between fear-avoidance and negative mood in both samples, but no association was found between fear-avoidance and functional status in either sample. Finally, fear-avoidance was associated with pain intensity in the sample of men alone. Despite this difference, the results suggest that the theoretical model had an adequate fit across both groups. ⋯ In the context of fear-avoidance models, this article analyzed differences between men and women with spinal pain in relation to the pain experience. The fear-avoidance model appeared to be a good theoretical reference model in both men and women.
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Opioids are standard therapy for the treatment of pain; however, adverse effects limit their use. Voltage-gated calcium channel blockers may be used to increase opioid analgesia, but their effect on opioid-induced side effects is little known. Thus, the goal of this study was to evaluate the action of the peptide Phα1β, a voltage-gated calcium channel blocker, on the antinociceptive and adverse effects produced by morphine in mice. A single administration of morphine (3-10 mg/kg) was able to reduce heat nociception as well as decrease gastrointestinal transit. The antinociception caused by a single injection of morphine was slightly increased by an intrathecal injection of Phα1β (30 pmol/site). Repeated treatment with morphine caused tolerance, hyperalgesia, withdrawal syndrome, and constipation, and the Phα1β (.1-30 pmol/site, intrathecal) was able to reverse these effects. Finally, the effects produced by the native form of Phα1β were fully mimicked by a recombinant version of this peptide. Taken together, these data show that Phα1β was effective in potentiating the analgesia caused by a single dose of morphine as well as in reducing tolerance and the adverse effects induced by repeated administration of morphine, indicating its potential use as an adjuvant drug in combination with opioids. ⋯ This article presents preclinical evidence for a useful adjuvant drug in opioid treatment. Phα1β, a peptide calcium channel blocker, could be used not only to potentiate morphine analgesia but also to reduce the adverse effects caused by repeated administration of morphine.
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The effects of minocycline or riluzole treatment on spinal root avulsion-induced pain in adult rats.
Spinal root avulsion produces tactile and thermal hypersensitivity, neurodegeneration, and microglial and astrocyte activation in both the deafferented and the adjacent intact spinal cord segments. Following avulsion of the fifth lumbar spinal root, immediate and prolonged treatment with riluzole or minocycline for 2 weeks altered the development of behavioral hypersensitivity. Riluzole delayed the onset of thermal and tactile hypersensitivity and partially reversed established pain behavior. Minocycline effectively prevented and reversed both types of behavioral change. Histologic analysis revealed that both drugs reduced microglial staining in the spinal cord, with minocycline being more effective than riluzole. Astrocyte activation was ameliorated to a lesser extent. Surprisingly, neither drug provided a neuroprotective effect on avulsed motoneurons. ⋯ Immediate treatment of spinal root avulsion injuries with minocycline or riluzole prevents the onset of evoked pain hypersensitivity by reducing microglial cell activation. When treatment is delayed, minocycline, but not riluzole, reverses pre-established hypersensitivity. Thus, these drugs may provide a new translational treatment option for chronic avulsion injury pain.