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Pathophysiology of Pain

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97 papers 0 to 25 followers
By Xander Zuidema MD, pharmD, Anesthesiologist, intensivist, pain specialist
Anthony Park, Olivia Uddin, Ying Li, Radi Masri, Asaf Keller
Pain after spinal cord injury (SCI-Pain) is one of the most debilitating sequelae of SCI, characterized as relentless, excruciating pain that is largely refractory to treatments. While it is generally agreed that SCI-Pain results from maladaptive plasticity in the pain processing pathway that includes the spinothalamic tract and somatosensory thalamus, the specific mechanisms underlying the development and maintenance of such pain are yet unclear. However, accumulating evidence suggests that SCI-Pain may be causally related to abnormal thalamic disinhibition, leading to hyperactivity in the posterior thalamic nucleus (PO), a higher order nucleus involved in somatosensory and pain processing...
February 23, 2018: Journal of Pain: Official Journal of the American Pain Society
Ru-Rong Ji, Andrea Nackley, Yul Huh, Niccolò Terrando, William Maixner
Chronic pain is maintained in part by central sensitization, a phenomenon of synaptic plasticity, and increased neuronal responsiveness in central pain pathways after painful insults. Accumulating evidence suggests that central sensitization is also driven by neuroinflammation in the peripheral and central nervous system. A characteristic feature of neuroinflammation is the activation of glial cells, such as microglia and astrocytes, in the spinal cord and brain, leading to the release of proinflammatory cytokines and chemokines...
February 19, 2018: Anesthesiology
Claudia Sommer, Mathias Leinders, Nurcan Üçeyler
Peripheral nerve injuries and diseases often lead to pain persisting beyond the resolution of damage, indicating an active disease-promoting process, which may result in chronic pain. This is regarded as a maladaptive mechanism resulting from neuroinflammation that originally serves to promote regeneration and healing. Knowledge on these physiological and pathophysiological processes has accumulated over the last few decades and has started to yield potential therapeutic targets. Key players are macrophages, T-lymphocytes, cytokines, and chemokines...
March 2018: Pain
Claudia Sommer
Although animal models of pain have brought invaluable information on basic processes underlying pain pathophysiology, translation to humans is a problem. This Review will summarize what information has been gained by the direct study of patients with chronic pain. The techniques discussed range from patient phenotyping using quantitative sensory testing to specialized nociceptor neurophysiology, imaging methods of peripheral nociceptors, analyses of body fluids, genetics and epigenetics, and the generation of sensory neurons from patients via inducible pluripotent stem cells...
November 4, 2016: Science
C Hu, Y Lu, X Chen, Z Wu, Q Zhang
BACKGROUND: Chronic post-surgical pain (CPSP) remains a major clinical problem and is often refractory to current treatments. New analgesic medications and strategies for pain relief are needed. Hepatocyte growth factor (HGF) is known to be a multi-functional growth factor and regulates various biological activities. METHODS: We investigated the analgesic effect and underlying mechanism of plasmid pUDK-HGF encoding human HGF gene on CPSP induced by skin/muscle incision and retraction (SMIR) in rats...
January 26, 2018: European Journal of Pain: EJP
Ghorbangol Ashabi, Mitra-Sadat Sadat-Shirazi, Ardeshir Akbarabadi, Nasim Vousooghi, Zahra Kheiri, Heidar Toolee, Solmaz Khalifeh, Mohammad-Reza Zarrindast
To investigate the effect of parental drug abuse on children, nociception, electrophysiological alteration, mRNA expression of opioid receptors, and expression of certain intracellular proteins in offspring of morphine-abstinent rats were studied. Adult male and female animals received water soluble morphine for 21 days. Ten days after the last morphine administration, animals were placed for mating in four groups as follows: healthy (drug naïve) female and male, morphine-abstinent female and healthy male, morphine-abstinent male and healthy female, morphine-abstinent male and morphine-abstinent female...
January 18, 2018: Journal of Pain: Official Journal of the American Pain Society
Louise S C Nicol, Peter Thornton, Jon P Hatcher, Colin P Glover, Carl I Webster, Matthew Burrell, Kessia Hammett, Clare A Jones, Matthew A Sleeman, Andrew Billinton, Iain Chessell
With less than 50% of patients responding to the current standard of care and poor efficacy and selectivity of current treatments, neuropathic pain continues to be an area of considerable unmet medical need. Biological therapeutics such as monoclonal antibodies (mAbs) provide better intrinsic selectivity; however, delivery to the central nervous system (CNS) remains a challenge. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is well described in inflammation-induced pain, and early-phase clinical trials evaluating its antagonism have exemplified its importance as a peripheral pain target...
January 16, 2018: Pain
Wei-Hsin Chen, Ya-Ting Chang, Yong-Cyuan Chen, Sin-Jhong Cheng, Chien-Chang Chen
Chronic pain can be initiated by one or more acute stimulations to sensitize neurons into the primed state. In the primed state, the basal nociceptive thresholds of the animal are normal, but in response to another hyperalgesic stimulus, the animal develops enhanced and prolonged hyperalgesia. The exact mechanism of how primed state is formed is not completely understood. Here we showed that spinal PKC/ERK signal pathway is required for neuronal plasticity change, hyperalgesic priming formation and the development of chronic hyperalgesia using acid-induced muscle pain (AIMP) model in mice...
January 18, 2018: Pain
Amanda H Klein, Husam K Mohammad, Rabiah Ali, Brad Peper, Steven P Wilson, Srinivasa N Raja, Matthias Ringkamp, Sarah Sweitzer
BACKGROUND: The current study used recombinant herpes simplex virus type I to increase expression of µ-opiate receptors and the opioid ligand preproenkephalin in peripheral nerve fibers in a mouse model of neuropathic pain. It was predicted that viral vector delivery of a combination of genes encoding the µ-opioid receptor and preproenkephalin would attenuate neuropathic pain and enhance opioid analgesia. The behavioral effects would be paralleled by changes in response properties of primary afferent neurons...
January 15, 2018: Anesthesiology
Jeremy M Thompson, Volker Neugebauer
The amygdala is a limbic brain region that plays a key role in emotional processing, neuropsychiatric disorders, and the emotional-affective dimension of pain. Preclinical and clinical studies have identified amygdala hyperactivity as well as impairment of cortical control mechanisms in pain states. Hyperactivity of basolateral amygdala (BLA) neurons generates enhanced feedforward inhibition and deactivation of the medial prefrontal cortex (mPFC), resulting in pain-related cognitive deficits. The mPFC sends excitatory projections to GABAergic neurons in the intercalated cell mass (ITC) in the amygdala, which project to the laterocapsular division of the central nucleus of the amygdala (CeLC; output nucleus) and serve gating functions for amygdala output...
2017: Pain Research & Management: the Journal of the Canadian Pain Society
Kimbria J Blake, Pankaj Baral, Tiphaine Voisin, Ashira Lubkin, Felipe Almeida Pinho-Ribeiro, Kelsey L Adams, David P Roberson, Yuxin C Ma, Michael Otto, Clifford J Woolf, Victor J Torres, Isaac M Chiu
The hallmark of many bacterial infections is pain. The underlying mechanisms of pain during live pathogen invasion are not well understood. Here, we elucidate key molecular mechanisms of pain produced during live methicillin-resistant Staphylococcus aureus (MRSA) infection. We show that spontaneous pain is dependent on the virulence determinant agr and bacterial pore-forming toxins (PFTs). The cation channel, TRPV1, mediated heat hyperalgesia as a distinct pain modality. Three classes of PFTs-alpha-hemolysin (Hla), phenol-soluble modulins (PSMs), and the leukocidin HlgAB-directly induced neuronal firing and produced spontaneous pain...
January 2, 2018: Nature Communications
Wan-Hung Lee, Li-Li Li, Aarti Chawla, Andy Hudmon, Yvonne Y Lai, Michael J Courtney, Andrea G Hohmann
Elevated N-methyl-D-aspartate receptor (NMDAR) activity is linked to central sensitization and chronic pain. However, NMDAR antagonists display limited therapeutic potential due to their adverse side effects. Novel approaches targeting the NR2B-PSD95-nNOS complex to disrupt signaling pathways downstream of NMDARs show efficacy in preclinical pain models. Here, we evaluated the involvement of interactions between neuronal nitric oxide synthase (nNOS) and the nitric oxide synthase 1 adaptor protein (NOS1AP) in pronociceptive signaling and neuropathic pain...
January 9, 2018: Pain
Jairo Alberto Dussán-Sarria, Nadia Regina Jardim da Silva, Alicia Deitos, Luciana Cadore Stefani, Gabriela Laste, Andressa de Souza, Iraci L S Torres, Felipe Fregni, Wolnei Caumo
Background: Although the brain-derived neurotrophic factor (BDNF) has been intensively investigated in animal models of chronic pain, its role in human pain processing is less understood. Objective: To study the neurophysiology of BDNF modulation on acute experimental pain, we performed a cross-sectional study. Methods: We recruited 20 healthy male volunteers (19-40 years old) and assessed their serum BDNF levels, quantitative sensory testing, and cortical excitability parameters using transcranial magnetic stimulation...
December 27, 2017: Pain Medicine: the Official Journal of the American Academy of Pain Medicine
Dominik Mischkowski, Esther E Palacios-Barrios, Lauren Banker, Troy C Dildine, Lauren Y Atlas
Nociception reliably elicits an autonomic nervous system (ANS) response. Because pain and ANS circuitry interact on multiple spinal, subcortical, and cortical levels, it remains unclear whether autonomic responses are simply a reflexive product of noxious stimulation regardless of how stimulation is consciously perceived or whether the experience of pain mediates ANS responses to noxious stimulation. To test these alternative predictions, we examined the relative contribution of noxious stimulation and individual pain experience to ANS responses in healthy volunteers who underwent one or two pain assessment tasks...
December 13, 2017: Pain
P G Wittkopf, D M Lloyd, M I Johnson
The aim of this systematic review was to evaluate the effect of visual feedback techniques on pain perception by analysing the effect of normal-sized, magnified or minified visual feedback of body parts on clinical and experimentally-induced pain. Databases searched: Medline, Embase, PsychInfo, PEDro, CINAHL, CENTRAL and OpenSIGLE. Studies investigating pain patients and pain-free participants exposed to experimentally-induced pain were analysed separately. Risk of bias was assessed and data were meta-analysed...
December 22, 2017: European Journal of Pain: EJP
Stephen J Raithel, Matthew R Sapio, Danielle M LaPaglia, Michael J Iadarola, Andrew J Mannes
BACKGROUND: Peripheral nociceptors expressing the ion channel transient receptor potential cation channel, subfamily V, member 1, play an important role in mediating postoperative pain. Signaling from these nociceptors in the peri- and postoperative period can lead to plastic changes in the spinal cord and, when controlled, can yield analgesia. The transcriptomic changes in the dorsal spinal cord after surgery, and potential coupling to transient receptor potential cation channel, subfamily V, member 1-positive nociceptor signaling, remain poorly studied...
December 22, 2017: Anesthesiology
Ana Bagues, María Isabel Martín, Alejandro Higuera-Matas, Jesús Esteban-Hernández, Emilio Ambrosio, Eva María Sánchez-Robles
BACKGROUND: Previous studies have demonstrated the participation of peripheral μ-opioid receptors (MOR) in the antinociceptive effect of systemically administered morphine and loperamide in an orofacial muscle pain model, induced by hypertonic saline, but not in a spinally innervated one, in rats. In this study, we determine whether this peripheral antinociceptive effect is due to the activation of MOR localized in the muscle, ganglia, or both. METHODS: To determine the local antinociceptive effect of morphine and loperamide, 2 models of acute muscle pain (trigeminal and spinal) were used...
December 19, 2017: Anesthesia and Analgesia
Tal Hoffmann, Ohad Sharon, Jürgen Wittmann, Richard W Carr, Alina Vyshnevska, Roberto De Col, Mohammed A Nassar, Peter W Reeh, Christian Weidner
The sodium channel NaV1.7 contributes to action potential (AP) generation and propagation. Loss-of-function mutations in patients lead to congenital indifference to pain, though it remains unclear where on the way from sensory terminals to central nervous system the signalling is disrupted. We confirm that conditional deletion of NaV1.7 in advillin-expressing sensory neurons leads to impaired heat and mechanical nociception in behavioural tests. With single-fiber recordings from isolated skin, we found (1) a significantly lower prevalence of heat responsiveness to normally mechanosensitive C-fibers, although (2) the rare heat responses seemed quite vigorous, and (3) heat-induced calcitonin gene-related peptide release was normal...
March 2018: Pain
Wei-Ju Chang, Neil E O'Connell, Paula R Beckenkamp, Ghufran Alhassani, Matthew B Liston, Siobhan M Schabrun
Chronic pain can be associated with movement abnormalities. The primary motor cortex (M1) has an essential role in the formulation and execution of movement. A number of changes in M1 function have been reported in studies of people with chronic pain. This review systematically evaluated the evidence for altered M1 structure, organization, and function in people with chronic pain of neuropathic and non-neuropathic origin. Database searches were conducted and a modified STrengthening the Reporting of OBservational studies in Epidemiology checklist was used to assess the methodological quality of included studies...
January 12, 2018: Journal of Pain: Official Journal of the American Pain Society
Suzanne Doolen, Tommaso Iannitti, Benjamin C Shaw, Carolyn M Grachen, Renee R Donahue, Bradley K Taylor
Multiple sclerosis (MS) is an autoimmune-inflammatory neurodegenerative disease that is often accompanied by a debilitating neuropathic pain. Disease-modifying agents slow the progression of MS and prevent relapses, yet it remains unclear if they yield analgesia. We explored the analgesic potential of fingolimod (FTY720), an agonist/functional antagonist at the sphingosine-1-phosphate receptor 1 (S1PR1), because it reduces hyperalgesia in models of peripheral inflammatory and neuropathic pain. We used a myelin oligodendrocyte glycoprotein 35-55 (MOG35-55) mouse model of experimental autoimmune encephalomyelitis (EAE), modified to avoid frank paralysis and thus allow for assessment of withdrawal behaviors to somatosensory stimuli...
November 13, 2017: Pain
2017-11-17 19:40:21
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