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This study examined the cross-sectional associations among pain intensity, pain catastrophizing, and sleep disturbance among patients receiving methadone maintenance treatment (MMT) for opioid use disorder (OUD) and reporting co-occurring chronic pain.
Learn More >Nicotinic acetylcholine receptors (nAChRs) have emerged as a novel therapeutic strategy for pain and inflammatory disorders. In particular, α4β2∗, α7, and α9α10 nAChR subtypes have been investigated as potential targets to treat pain. The nAChRs are distributed on the pain transmission pathways, including central and peripheral nervous systems and immune cells as well. Several agonists for α4β2∗ nAChR subtypes have been investigated in multiple animal pain models with promising results. However, studies in human indicated a narrow therapeutic window for α4β2∗ agonists. Furthermore, animal studies suggest that using agonists for α7 nAChR subtype and antagonists for α9α10 nAChR subtypes are potential novel therapies for chronic pain management, including inflammatory and neuropathic pain. More recently, alternative nAChRs ligands such as positive allosteric modulators and silent agonists have shown potential to develop into new treatments for chronic pain.
Learn More >Delta opioid receptor (δ-receptor) agonists produce antihyperalgesia, antidepressant-like effects, and convulsions in animal models. However, the role of agonist efficacy in generating different δ-receptor-mediated behaviors has not been thoroughly investigated. To this end, efficacy requirements for δ-receptor-mediated antihyperalgesia, antidepressant-like effects, and convulsions were evaluated by comparing the effects of the partial agonist BU48 and the full agonist SNC80 as well as changes in the potency of SNC80 following δ-receptor elimination. Antihyperalgesia was measured in a nitroglycerin-induced thermal hyperalgesia assay. An antidepressant-like effect was evaluated in the forced swim test. Mice were observed for convulsions after treatment with SNC80 or the δ-opioid receptor partial agonist BU48. Ligand-induced G protein activation was measured by [35S]GTPγS binding in mouse forebrain tissue and δ-receptor number was measured by [3H]DPDPE saturation binding. BU48 produced antidepressant-like effects and convulsions but antagonized SNC80-induced antihyperalgesia. The potency of SNC80 was shifted to the right in δ-receptor heterozygous knockout mice and 5'-NTII treated mice, and the magnitude of potency shift differed across assays with the largest shift occurring in the thermal hyperalgesia assay followed by the forced swim test, and then convulsion observation. NTI antagonized these SNC80-induced behaviors with similar potencies suggesting that these effects are mediated by the same type of δ-receptor. These data suggest that δ-receptor-mediated behaviors display a rank order of efficacy requirement with antihyperalgesia having the highest requirement, followed by antidepressant-like effects and then convulsions. These findings further our understanding of the pharmacological mechanisms mediating the in vivo effects of δ-opioid receptor agonists. SIGNIFICANCE STATEMENT: Delta opioid receptor (δ-receptor) agonists produce antihyperalgesia, antidepressant-like effects, and convulsions in animal models. This study evaluates pharmacological properties, specifically the role of agonist efficacy and receptor reserve, underlying these δ-receptor-mediated behaviors. These data suggest that δ-receptor-mediated behaviors display a rank order of efficacy requirement with antihyperalgesia having the highest requirement, followed by antidepressant-like effects and then convulsions.
Learn More >Although migraine is recognized as one of the most common and disabling diseases in the world, it is nonetheless still underestimated, underdiagnosed, and undertreated. The fact that migraine patients often tend to access the Web to search for headache-related information hinders patient-doctor relationships and one should also bear in mind that, unfortunately, text readability and medical literacy in the overall population may be the reason why patients' understanding of health information is compromised.
Learn More >Exercise training is an effective therapy for many pain-related conditions, and trained athletes have lower pain perception compared to unconditioned people. Some painful conditions, including strenuous exercise, are associated with elevated levels of protons, metabolites and inflammatory factors, which may activate receptors and/or ion channels, including acid-sensing ion channels (ASICs), on nociceptive sensory neurons. We hypothesized that ASICs are required for immediate exercise-induced muscle pain (IEIP), and that exercise training diminishes IEIP by modulating ASICs within muscle afferents. We found high-intensity interval training (HIIT) reduced IEIP in C57BL/6 mice, diminished ASICs mRNA levels in lumber dorsal root ganglia (DRG), and this downregulation of ASICs correlated with improved exercise capacity. Additionally, we found that ASIC3 -/- mice did not develop IEIP, however the exercise capacity of ASIC3 -/- was similar to wild-type mice. These results suggest that ASICs are required for IEIP, and that diminishment of IEIP after exercise training correlates with downregulation of ASICs in sensory neurons.
Learn More >Oxaliplatin-induced peripheral neurotoxicity (OIPN) is a severe and potentially permanent side effect of cancer treatment affecting the majority of oxaliplatin-treated patients, mostly with the onset of acute symptoms, but also with the establishment of a chronic sensory loss that is supposed to be due to dorsal root ganglia neuron damage. The pathogenesis of acute as well as chronic OIPN is still not completely known, and this is a limitation in the identification of effective strategies to prevent or limit their occurrence. Despite intense investigation at the preclinical and clinical levels, no treatment can be suggested for the prevention of OIPN, and only limited evidence for the efficacy of duloxetine in the treatment setting has been provided. In this review, ongoing neuroprotection clinical trials in oxaliplatin-treated patients will be analyzed with particular attention paid to the hypothesis leading to the study, to the trial strengths and weaknesses, and to the outcome measures proposed to test the efficacy of the therapeutic approach. It can be concluded that 1) prevention and treatment of OIPN still remains an important and unmet clinical need, 2) further, high-quality research is mandatory in order to achieve reliable and effective results, and 3) dose and schedule modification of OHP-based chemotherapy is currently the most effective approach to limit the severity of OIPN.
Learn More >It has been reported that a GM-CSF→CCL17 pathway, originally identified in vitro in macrophage lineage populations, is implicated in the control of inflammatory pain, as well as arthritic pain and disease. We explore, in this study and in various inflammation models, the cellular CCL17 expression and its GM-CSF dependence as well as the function of CCL17 in inflammation and pain. This study used models allowing the convenient cell isolation from reporter mice; it also exploited both CCL17-dependent and unique CCL17-driven inflammatory pain and arthritis models, the latter permitting a radiation chimera approach to help identify the CCL17 responding cell type(s) and the mediators downstream of CCL17 in the control of inflammation and pain. We present evidence that 1) in the particular inflammation models studied, CCL17 expression is predominantly in macrophage lineage populations and is GM-CSF dependent, 2) for its action in arthritic pain and disease development, CCL17 acts on CCR4 non-bone marrow-derived cells, and 3) for inflammatory pain development in which a GM-CSF→CCL17 pathway appears critical, nerve growth factor, CGRP, and substance P all appear to be required.
Learn More >The most common and multifaceted migraine aura symptoms are visual disturbances. Health information is one of the most popular topics on the internet but the quality and reliability of publicized information is unknown. The aim of this study was to analyze images of migraine aura on Google to determine the frequency of correct presentations of visual aura and distribution of visual aura phenotypes.
Learn More >Depression is a frequent comorbid condition in patients with persistent back pain and is associated with substantial adverse consequences, including the risk of developing opioid use disorders. Shifting the focus from depression treatment to preventing depression might be a viable way to reduce the disease burden.
Learn More >People with migraine have historically been depicted as "frail and perfectionist women." While these presentations are from a different cultural context, we may today still be at risk of stereotyping and stigmatizing this patient group. Portrayals of people with migraine on the Internet and in mass media offer a window of how society today views this patient group. The aim of this study was to explore how persons with migraine are being portrayed according to 2 popular sources of photographic images.
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