Pain
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Treatment of neuropathic pain is a clinical challenge likely due to the time-dependent changes in many neurotransmitter systems, growth factors, ionic channels, membrane receptors, transcription factors as well as recruitment of different cell types. Conversely, an increasing number of reports have shown the ability of extended and regular physical exercise in alleviating neuropathic pain throughout a wide range of mechanisms. In the present study we investigate the effect of swim exercise on molecules associated to the initiation and maintenance of nerve injury-induced neuropathic pain. ⋯ Finally, prolonged swim exercise reversed astrocyte and microglia hyperactivity in the dorsal horn after nerve lesion which persisted normalized after training cessation. Together, these results demonstrate that exercise therapy induces long-lasting analgesia through various mechanisms associated to the onset and advanced stages of neuropathy. Moreover, the data support further studies to clarify whether appropriate exercise intensity, volume, and duration can also cause long-lasting pain relieve in patients with neuropathic pain.
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The role of endogenous analgesic mechanisms has largely been viewed in the context of gain modulation during nociceptive processing. However, these analgesic mechanisms may play critical roles in the extraction and subsequent utilization of information related to spatial and temporal features of nociceptive input. To date, it remains unknown if spatial and temporal filtering of nociceptive information is supported by similar analgesic mechanisms. ⋯ In the brain stem, CPM consistently produced reductions in activity, while OA produced increases in activity. Conjunction analysis confirmed that CPM-related activity did not overlap with that of OA. Thus, dissociable mechanisms support inhibitory processes engaged during spatial vs temporal filtering of nociceptive information.
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A sound strategy for improving the clinical efficacy of opioids involves exploiting positive interactions with drugs directed at other targets in pain pathways. The current study investigated the role of dopamine receptor D2 (D2R) in modulation of spinal dorsal horn excitability to noxious input, and interactions therein with μ-opioid receptor (MOR) in an animal model of neuropathic pain induced by spinal nerve ligation (SNL). C-fiber-evoked field potentials in the spinal dorsal horn were depressed concentration dependently by spinal superfusion with the D2R agonist quinpirole both in nerve-injured and sham-operated (control) rats. ⋯ Co-administration of 1 μmol/L quinpirole, insufficient per se to alter evoked potentials, dramatically enhanced inhibition of evoked potentials by MOR agonist DAMGO, reducing the IC50 value of DAMGO by 2 orders of magnitude. The present data provide evidence of profound functional and subcellular changes in D2R-mediated modulation of noxious input after nerve injury, including positive interactions with spinal MOR. These results suggest D2R co-stimulation as a potential avenue to improve MOR analgesia in sustained pain states involving peripheral nerve injury.
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Review Meta Analysis
Incidence, Prevalence and Predictors of Chemotherapy Induced Peripheral Neuropathy: a Systematic Review and Meta-Analysis.
Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling pain condition resulting from chemotherapy for cancer. Severe acute CIPN may require chemotherapy dose reduction or cessation. There is no effective CIPN prevention strategy; treatment of established chronic CIPN is limited, and the prevalence of CIPN is not known. ⋯ Although CIPN prevalence decreases with time, at 6months 30% of patients continue to suffer from CIPN. Routine CIPN surveillance during post-chemotherapy follow-up is needed. A number of genetic and clinical risk factors were identified that require further study.
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Randomized Controlled Trial
Effect of vitamin D on musculoskeletal pain and headache: A randomized, double-blind, placebo-controlled trial among adult ethnic minorities in Norway.
Immigrants from South Asia, the Middle East, and Africa living in Northern Europe frequently have low vitamin D levels and more pain compared to the native Western population. The aim of this study was to examine whether daily vitamin D3 (25 μg/d or 10 μg/d) supplementation for 16 weeks would improve musculoskeletal pain or headache compared to placebo. This randomized, double-blind, placebo-controlled, parallel-group trial recruited 251 participants aged 18 to 50 years, and 215 (86%) attended the follow-up visit. ⋯ At follow-up, vitamin D level, measured as serum 25(OH)D3, increased from 27 nmol/L to 52 nmol/L and from 27 nmol/L to 43 nmol/L in the 25-μg and 10-μg supplementation groups, respectively, whereas serum 25(OH)D3 did not change in the placebo group. Pain scores and headache scores were improved at follow-up compared with baseline. The use of vitamin D supplements, however, showed no significant effect on the occurrence, anatomical localization, and degree of pain or headache compared to placebo.