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Previous studies of herpes zoster (HZ) have focused on acute patient manifestations and the most common sequela, postherpetic neuralgia (PHN), both serving to disrupt brain dynamics. Although the majority of such patients gradually recover, without lingering severe pain, little is known about life situations of those who recuperate or the brain dynamics. Our goal was to determine whether default mode network (DMN) dynamics of the recuperative population normalize to the level of healthy individuals.
Learn More >The delta opioid receptor (DOR) has been identified as a therapeutic target for migraine, with DOR agonists exhibiting low abuse potential compared with conventional µ-opioid agonists. TRV250 is a novel small molecule agonist of the DOR that is preferentially selective for G-protein signaling, with relatively little activation of the β-arrestin2 post-receptor signaling pathway. This selectivity provides reduced susceptibility to proconvulsant activity seen with non-selective DOR agonists. TRV250 significantly reduced nitroglycerin-evoked hyperalgesia in rodents, indicating a potential utility in acute migraine without the risk of seizure activity or abuse potential.
Learn More >The aim of this scoping review was to identify initiatives focused on the secondary prevention and management of chronic pain in Australian primary care to understand options available to Primary Health Networks and to identify evidence gaps. The Medline, EMBASE, Cumulative Index to Nursing and Allied Health Literature and Cochrane databases, as well as relevant websites, were searched for eligible records published from 2007 to 2018. Initiative characteristics and outcomes evaluated were extracted and synthesised. In all, 84 initiatives from 167 published and grey literature records were identified, including: (1) consumer initiatives that aimed to improve access to multidisciplinary care, health literacy and care navigation (n=56); (2) health professional capacity building initiatives that aimed to ensure health professionals are skilled and provide best-practice evidence-based care (n=21); and (3) quality improvement and health system support initiatives (n=7). Evidence gaps were found relating to initiatives addressing the secondary prevention of chronic pain, those targeting vulnerable and regional populations, health professional capacity building initiatives for all primary health care providers and quality improvement and system support initiatives. Addressing evidence gaps related to effectiveness, cost-effectiveness and implementation should be the focus for future chronic pain initiatives in primary care settings.
Learn More >CGRP Antibodies are high-cost newly licensed migraine preventatives.
Learn More >Cortical spreading depression (CSD) is the propagation of a relatively slow wave in cortical brain tissue that is linked to a number of pathological conditions such as stroke and migraine. Most of the existing literature investigates the dynamics of short term phenomena such as the depolarization and repolarization of membrane potentials or large ion shifts. Here, we focus on the clinically-relevant hour-long state of neurovascular malfunction in the wake of CSDs. This dysfunctional state involves widespread vasoconstriction and a general disruption of neurovascular coupling. We demonstrate, using a mathematical model, that dissolution of calcium that has aggregated within the mitochondria of vascular smooth muscle cells can drive an hour-long disruption. We model the rate of calcium clearance as well as the dynamical implications on overall blood flow. Based on reaction stoichiometry, we quantify a possible impact of calcium phosphate dissolution on the maintenance of F0F1-ATP synthase activity.
Learn More >Background and aims Pain is a disabling symptom in knee osteoarthritis (KOA) and its underlying mechanism remains poorly understood. Dysfunction of descending pain modulatory pathways and reduced pain inhibition enhance pain facilitation in many chronic pain syndromes but do not fully explain pain levels in chronic musculoskeletal conditions. The objective of this study is to explore the association of clinical variables with pain intensity perception in KOA individuals with varying levels of Conditioned Pain Modulation (CPM) response. Methods This is a cross-sectional, exploratory analysis using baseline data of a randomized clinical trial investigating the effects of a non-invasive brain stimulation treatment on the perception of pain and functional limitations due to KOA. Sixty-three subjects with KOA were included in this study. Data on pain perception, mood perception, self-reported depression, physical function, quality of life, and quantitative sensory testing was collected. Multiple linear regression analysis was performed to explore the association between the clinical variables with pain perception for individuals with different levels of CPM response. Results For KOA patients with limited CPM response, perception of limitations at work/other activities due to emotional problems and stress scores were statistically significantly associated with pain scores, F(2, 37) = 7.02, p < 0.01. R-squared = 0.275. For KOA patients with normal CPM response, general health perception scores were statistically significantly associated with pain scores, F(1, 21) = 5.60, p < 0.05. R-squared = 0.2104. Limitations of this study include methodology details, small sample size and study design characteristics. Conclusions Pain intensity perception is associated differently with clinical variables according to the individual CPM response. Mechanistic models to explain pain perception in these two subgroups of KOA subjects are discussed.
Learn More >Morphine is a key drug for the treatment of pain but its side effects limit its clinical application. MEL-0614, an endomorphin-1 analog, has fewer side effects than morphine in addition to its powerful analgesic effect. In this study, we measured the effect of morphine and MEL-0614 on hyperalgesia (7 days) and neuropathic allodynia (14 days) after thermal, mechanical, and cold stimulation. We found that after 4 and 8 consecutive days of intrathecal administration (1, 3, and 10 nmol), morphine induced severe hyperalgesia and neuropathic allodynia, respectively. MEL-0614 did not induce hyperalgesia at low doses (1 and 3 nmol) and had a mitigating effect on morphine-induced neuropathic exacerbations in spared nerve injury mice. Hyperalgesia was blocked by Dynorphin A (1-17) antibody but not by an opioid receptor antagonist. To explore the reasons for the different results of morphine and MEL-0614, we used quantitative PCR and immunofluorescence to explore the effects of both on NMDA receptor subtype 2B (NR2B), microglia marker iba-1, and inflammatory mediators. After 8 days of consecutive administration, morphine (10 nmol) promoted an increase in the number of NR2B, iba-1, and inflammatory mediators in the spinal cord of mice. MEL-0614 (10 nmol) had no significant effect on these factors, and after co-administration with morphine, the expression of NR2B, iba-1, and inflammatory mediators was lower than that with morphine injection alone. Our research showed the advantage of MEL-0614 in terms of hyperalgesia and neuropathic allodynia, which may provide clinical relief of hyperalgesia and neuropathic allodynia caused by morphine.
Learn More >Hitherto only studies with selected populations have found an increased all-cause mortality of some selected opioids compared to selected non-opioids for chronic non-cancer pain (CNCP). We have examined the all-cause mortality for CNCP associated with all established opioids compared to non-opioid analgesic therapy (anticonvulsants, antidepressants, dipyrone, non-steroidal agents).
Learn More >Monoacylglycerol lipase (MAGL) is the enzyme that is primarily responsible for hydrolyzing the endocannabinoid 2-arachidononylglycerol (2-AG) to arachidonic acid (AA). It has emerged in recent years as a potential drug target for a number of diseases. Herein, we report the discovery of compound 6g from a series of azetidine-piperazine di-amide compounds as a potent, selective, and reversible inhibitor of MAGL. Oral administration of compound 6g increased 2-AG levels in rat brain and produced full efficacy in the rat complete Freund's adjuvant (CFA) model of inflammatory pain.
Learn More >Osteoarthritis (OA) causes chronic joint pain and significantly impacts daily activities. Hence, developing novel treatment options for OA has become an increasingly important area of research. Recently, studies have reported that exogenous, as well as endogenous, hypothalamic-neurohypophysial hormones, oxytocin (OXT) and arginine-vasopressin (AVP), significantly contribute to nociception modulation. Moreover, the parvocellular OXT neurone (parvOXT) extends its projection to the superficial spinal dorsal horn, where it controls the transmission of nociceptive signals. Meanwhile, AVP produced in the magnocellular AVP neurone (magnAVP) is released into the systemic circulation where it contributes to pain management at peripheral sites. The parvocellular AVP neurone (parvAVP), as well as corticotrophin-releasing hormone (CRH), suppresses inflammation via activation of the hypothalamic-pituitary adrenal (HPA) axis. Previously, we confirmed that the OXT/AVP system is activated in rat models of pain. However, the roles of endogenous hypothalamic-neurohypophysial hormones in OA have not yet been characterised. In the present study, we investigated whether the OXT/AVP system is activated in a knee OA rat model. Our results show that putative parvOXT is activated and the amount of OXT-monomeric red fluorescent protein 1 positive granules in the ipsilateral superficial spinal dorsal horn increases in the knee OA rat. Furthermore, both magnAVP and parvAVP are activated, concurrent with HPA axis activation, predominantly modulated by AVP, and not CRH. The OXT/AVP system in OA rats was similar to that in systemic inflammation models, including adjuvant arthritis; however, magnocellular OXT neurones (magnOXT) were not activated in OA. Hence, localised chronic pain conditions, such as knee OA, activate the OXT/AVP system without impacting magnOXT.
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