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In 2018, three calcitonin gene-related peptide (CGRP) pathway monoclonal antibodies, erenumab, fremanezumab and galcanezumab, were approved in various parts of the world, including Europe and the US, and another, eptinezumab, is pending, for the prevention of migraine. In this article, episodic migraine treatment is reviewed, although these medicines are approved and are just as effective for chronic migraine. These new medicines usher a new phase in the preventive management of migraine with migraine-specific treatments. Data from phase III trials of CGRP pathway monoclonal antibodies have shown they are efficacious, with adverse effect rates comparable to placebo. The combination of clear efficacy and excellent tolerability will be welcome in an area where poor adherence to current preventives is common. Rimegepant, ubrogepant and lasmiditan are migraine-specific acute therapies yet to be approved by regulators. Phase III data for the respective CGRP receptor antagonists, the gepants, and the serotonin 5-HT receptor agonist, the ditan, have been positive and free of cardiovascular adverse effects. These medicines are not vasoconstrictors. When approved, they could meet the acute therapy demand of patients with cardiovascular risk factors where triptans are contraindicated. Beyond this, gepants will see the most disruptive development in migraine management in generations with medicines that can have both acute and preventive effects, the latter evidenced by data from the discontinued drug telcagepant and the early-phase drug atogepant. Moreover, one can expect no risk of medication overuse syndromes with gepants since the more patients take, the less migraines they have. During the next years, as experience with monoclonal antibodies grows in clinical practice, we can expect an evolution in migraine management to take shape. Clinicians will be able to offer treatment patients want rather than trying to fit migraineurs into therapeutic boxes for their management. Despite pessimistic susurrations of a largely addlepated form, many patients, and physicians, will welcome new options, and the challenges of new treatment paradigms, with optimism.
Gene transcription regulation is critical for the development of spinal microgliosis and neuropathic pain after peripheral nerve injury. Using a model of chronic constriction injury (CCI) of the sciatic nerve, this study characterized the role of SET domain containing lysine methyltransferase 7 (SETD7) which monomethylates histone H3 lysine 4 (H3K4me1), a marker for active gene transcription. SETD7 protein expression in the spinal dorsal horn ipsilateral to nerve lesion was increased from one day to 14 days after CCI, concomitantly with the expression of inflammatory genes, Ccl2, Il-6 and Il-1β. The CCI-induced SETD7 expression was predominantly localized to microglia, as demonstrated by immunohistochemistry and western blot from magnetic activated cell sorted spinal microglia. SETD7 knockdown by intrathecal lentivirus shRNA delivery prior to CCI prevented spinal microgliosis and neuropathic pain, whereas lentiviral SETD7 transduction exacerbated these symptoms. In addition, SETD7 regulated H3K4me1 level and expression of inflammatory mediators both in CCI rats and in the HAPI rat microglia cell line. Accordingly, PFI-2, a specific inhibitor of SETD7 monomethylation activity, suppressed the lipopolysaccharides-induced amoeboid morphology of primary microglia and the expression of inflammatory genes, Ccl2, Il-6 and Il-1β. Moreover, intrathecal administration of PFI-2 alleviated CCI-induced neuropathic pain. However, this effect was observed in male but not in female rats. These results demonstrate a critical role of SETD7 in the development of spinal microgliosis and neuropathic pain subsequently to peripheral nerve injury. The pharmacological approach further suggests that SETD7 is a new target for the treatment of neuropathic pain. The underlying mechanisms may involve H3K4me1-dependent regulation of inflammatory gene expression in microglia.
Individuals with migraine exhibit heightened sensitivity to visual input that continues beyond their migraine episodes. However, the contribution of color to visual sensitivity, and how it relates to neural activity, has largely been unexplored in these individuals.
Children of parents with chronic pain have higher rates of pain and internalizing (e.g., anxiety, depressive) symptoms than children of parents without chronic pain. Parental modeling of pain behaviour and reinforcement of child pain have been hypothesized to underlie these relationships. These mechanisms were tested in a sample of 72 parents with chronic pain and their children (ages 8-15). Standardized measures were completed by parents (pain characteristics, pain interference, child internalizing) and children (pain catastrophizing, pain over previous three months, and internalizing). In a laboratory session, children completed the cold pressor task (CPT) in the presence of their parent, and parent-child verbalizations were coded. Significant indirect effects of parental pain interference on child self-reported (B = 0.12, 95% CI: 0.01, 0.29) and parent-reported (B = 0.16, 95% CI: 0.03, 0.40) internalizing symptoms through child pain catastrophizing were found (parental modeling mechanism), and were not moderated by child chronic pain status. Significant indirect effects were found between parent pain-attending verbalizations and child self-reported (B = 2.58, 95% CI: 1.03, 5.31) and parent-reported (B = 2.18, 95% CI: 0.93, 4.27) CPT pain intensity and tolerance (B = -1.02, 95% CI: -1.92, -0.42) through child pain-attending verbalizations (parental reinforcement mechanism). While further understanding of the temporal relationships between these variables is needed, the current study identifies constructs (e.g., parent pain interference, child pain catastrophizing, parent reinforcement of child pain) which should be further examined as potential targets for prevention and intervention of pain and internalizing symptoms in children of parents with chronic pain.
Fibromyalgia syndrome (FM) represents a great challenge for clinicians and researchers because the efficacy of currently available treatments is limited. The present study examined the efficacy of Mindfulness-Based Stress Reduction (MBSR) for reducing functional impairment as well as the role of mindfulness-related constructs as mediators of treatment outcomes for people with FM. 225 participants with FM were randomized into three study arms: MBSR plus treatment-as-usual (TAU), FibroQoL (multicomponent intervention for FM) plus TAU, and TAU alone. The primary endpoint was functional impact (measured with the Fibromyalgia Impact Questionnaire Revised), and secondary outcomes included "fibromyalginess", anxiety and depression, pain catastrophising, perceived stress and cognitive dysfunction. The differences in outcomes between groups at post-treatment assessment (primary endpoint) and 12-month follow-up were analyzed using linear mixed-effects models and mediational models through path analyses. MBSR was superior to TAU both at post-treatment (large effect sizes) and at follow-up (medium to large effect sizes), and MBSR was also superior to FibroQoL post-treatment (medium to large effect sizes), but long-term it was only modestly better (significant differences only in pain catastrophising and fibromyalginess). Immediately post-treatment, the NNT for 20% improvement in MBSR versus TAU and FibroQoL was 4.0 (95%CI= 2.1-6.5) and 5.0 (95%CI= 2.7-37.3). An unreliable NNT value of 9 (not computable 95%CI) was found for FibroQoL vs. TAU. Changes produced by MBSR in functional impact were mediated by psychological inflexibility and the mindfulness facet Acting with awareness. These findings are discussed in relation to previous studies of psychological treatments for FM.
Delayed onset muscle soreness (DOMS) is characterised by mechanical hyperalgesia after lengthening contractions (LC). It is relatively common and causes disturbance for many people who require continuous exercise, yet its molecular and peripheral neural mechanisms are poorly understood.
We present structures of mouse TRPV3 in temperature-dependent open, closed and intermediate states that suggest two-step activation of TRPV3 by heat. During the strongly temperature-dependent first step, sensitization, the channel pore remains closed while S6 helices undergo α-to-π transitions. During the weakly temperature-dependent second step, channel opening, tight association of the S1-S4 and pore domains is stabilized by changes in the carboxy-terminal and linker domains.
A recently defined structure, the rostromedial tegmental nucleus (RMTg; aka tail of the ventral tegmental area), has been proposed as an inhibitory control center for dopaminergic activity of the ventral tegmental area (VTA). This region is composed of GABAergic cells which send afferent projections to the ventral midbrain and synapse onto dopaminergic cells in the VTA and substantia nigra. These cells exhibit µ-opioid receptor immunoreactivity, and in-vivo, ex-vivo, and optogenetic/electrophysiological approaches demonstrate that morphine excites dopamine neurons by targeting receptors on GABAergic neurons localized in the RMTg. This suggests that the RMTg may be a key modulator of opioid effects, and a major brake regulating VTA dopamine systems. However, no study has directly manipulated RMTg GABAergic neurons in-vivo and assessed the effect on nociception or opioid analgesia. In this study, multiplexing of GABAergic neurons in the RMTg was achieved using stimulatory Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) and inhibitory kappa-opioid receptor DREADDs (KORD). Our data show that locally-infused RMTg morphine or selective RMTg GABAergic neuron inhibition produces 87% of the maximal antinociceptive effect of systemic morphine, and RMTg GABAergic neurons modulate dopamine release in the nucleus accumbens. Additionally, chemo-activation of VTA dopamine neurons significantly reduced pain behaviors both in resting and facilitated-pain states and reduced by 75% the dose of systemic morphine required to produce maximal antinociception. These results provide compelling evidence that RMTg GABAergic neurons are involved in processing of nociceptive information and are important mediators of opioid analgesia.
There is an unmet medical need for non-opioid pain therapies in human populations; several pathways are under investigation for possible therapeutic intervention. Tetrahydrobiopterin (BH4) has received attention recently as a mediator of neuropathic pain. Recent reports have implicated sepiapterin reductase (SPR) in this pain pathway as a regulator of BH4 production. To evaluate the role of SPR inhibition on BH4 reduction, we developed analytical methods to monitor the relationship between the plasma concentration of test article and endogenous pterins and applied these in the rat spinal nerve ligation pain model. Sepiapterin is an endogenous substrate, which accumulates upon inhibition of SPR. In response to a potent inhibitor of SPR, plasma concentrations of sepiapterin increased proportionally with exposure. An indirect effect PK/PD model was developed to describe the relationship between the plasma PK of test article and plasma sepiapterin levels in the rat, which was used to determine an in vivo SPR IC value. Evaluation of SPR inhibition and mechanical allodynia was assessed coordinately with pterin biomarkers in plasma and at the site of neuronal injury (i.e., dorsal root ganglion). Upon QD p.o. administration for 3 consecutive days, unbound plasma concentrations of test article exceeded the unbound in vivo rat SPR IC throughout the dose intervals leading to a 60% reduction in BH4 in the dorsal root ganglion. Despite evidence for pharmacological modulation of the BH4 pathway, there was no significant effect on the tactile paw withdrawal threshold relative to vehicle-treated controls. SIGNIFICANCE STATEMENT: N/A.