CGRP and the Trigeminal System in Migraine

Bimodal functions of calcitonin gene-related peptide in the brain

AIMS

Calcitonin gene-related peptide (CGRP) is a pluripotent neuropeptide crucial for maintaining vascular homeostasis, yet its full therapeutic potential remains incompletely exploited. Within the brain, CGRP demonstrates a distinct bimodal effect, contributing to neuroprotection in ischemic conditions while inducing neuronal sensitization and inflammation in non-ischemic settings. Despite extensive research on CGRP, the absence of a definitive determinant for this observed dichotomy has limited its potential for therapeutic applications in the brain. This review examines the effects of CGRP in both physiological and pathological conditions, aiming to identify a unifying factor that could enhance its therapeutic applicability.

MATERIALS AND METHODS

This comprehensive literature review analyzes the molecular pathways associated with CGRP and the specific cellular responses observed in these contexts. Additionally, the review investigates the psychological implications of CGRP in relation to cerebral perfusion levels, aiming to elucidate its underlying factors.

KEY FINDINGS

Reviewing the literature reveals that, elevated levels of CGRP in non-ischemic conditions exert detrimental effects on brain function, while they confer protective effects in the context of ischemia. These encompass anti-oxidative, anti-inflammatory, anti-apoptotic, and angiogenic properties, along with behavioral normalization. Current findings indicate promising therapeutic avenues for CGRP beyond the acute phases of cerebral injury, extending to neurodegenerative and psychological disorders associated with cerebral hypoperfusion, as well as chronic recovery following acute cerebral injuries.

SIGNIFICANCE

Improved understanding of CGRP's bimodal properties, alongside advancements in CGRP delivery methodologies and brain ischemia detection technologies, paves the way for realizing its untapped potential and broad therapeutic benefits in diverse pathological conditions.

Exploring the potential of Fargesin from Chrysanthemum indicum for chronic migraine: in-silico and pharmacokinetic study

INTRODUCTION

Chronic migraine is recognized by the WHO as one of the most debilitating chronic conditions. It is primarily caused by central sensitization of the trigeminal nucleus caudalis. Key biomarkers associated with migraine include NFkB, IL-1β, CGRP, and iNOS. While CGRP antagonists have proven effective in treating migraines, Chrysanthemum indicum L., a traditional herbal remedy, has not been established as a treatment.

METHODS

To address this, we investigated whether Fargesin, a lignan found in CI, could potentially reduce migraines by targeting these biomarkers. We conducted pharmacokinetic, toxicological, and in-silico studies. Molecular docking studies revealed a strong interaction between Fargesin and CGRP/iNOS.

RESULTS

The pharmacokinetic analysis indicated robust intestinal absorption and effective penetration of the blood-brain barrier. In-silico toxicity assessments showed favorable results. Promising interactions with drug targets were observed in bioactivity tests.

CONCLUSION

Fargesin from Chrysanthemum indicum may hold potential as a therapeutic agent for migraines.

Decoding the neuroimmune axis in the atopic march: mechanisms and implications

The immune and nervous systems have co-evolved complex mechanisms to sense environmental dangers and orchestrate a concerted response to safeguard tissue and mobilize host defenses. This sophisticated interplay, marked by a shared repertoire of receptors and ligands, influences disease pathogenesis. Neuro-immune interactions in allergic diseases are pivotal for symptom development, from anaphylaxis to chronic conditions like asthma and atopic dermatitis. This review explores the neuro-immune interplay within the atopic march, emphasizing its role in host defense, inflammation resolution, and tissue repair. We delve into the multifaceted functions of nociceptors in orchestrating type 2 immune responses and the progression of allergic disorders, focusing on key regulators such as CGRP-RAMP1 and SP-MRGPRB2/A2. Additionally, we discuss the potential of nociceptor neuron-blocking drugs to target neuro-immunity, offering the possibility of reversing the progression of the atopic march. Altogether, we underscore the need for targeted interventions to disrupt the pathological processes and enhance therapeutic outcomes at various stages of the atopic march.

Neuroanatomical evidence and a mouse calcitonin gene-related peptide model in line with human functional magnetic resonance imaging data support the involvement of peptidergic Edinger-Westphal nucleus in migraine

ABSTRACT

The urocortin 1 (UCN1)-expressing centrally projecting Edinger-Westphal (EWcp) nucleus is influenced by circadian rhythms, hormones, stress, and pain, all known migraine triggers. Our study investigated EWcp's potential involvement in migraine. Using RNAscope in situ hybridization and immunostaining, we examined the expression of calcitonin gene-related peptide (CGRP) receptor components in both mouse and human EWcp and dorsal raphe nucleus (DRN). Tracing study examined connection between EWcp and the spinal trigeminal nucleus (STN). The intraperitoneal CGRP injection model of migraine was applied and validated by light-dark box, and von Frey assays in mice, in situ hybridization combined with immunostaining, were used to assess the functional-morphological changes. The functional connectivity matrix of EW was examined using functional magnetic resonance imaging in control humans and interictal migraineurs. We proved the expression of CGRP receptor components in both murine and human DRN and EWcp. We identified a direct urocortinergic projection from EWcp to the STN. Photophobic behavior, periorbital hyperalgesia, increased c-fos gene-encoded protein immunoreactivity in the lateral periaqueductal gray matter and trigeminal ganglia, and phosphorylated c-AMP-responsive element binding protein in the STN supported the efficacy of CGRP-induced migraine-like state. Calcitonin gene-related peptide administration also increased c-fos gene-encoded protein expression, Ucn1 mRNA, and peptide content in EWcp/UCN1 neurons while reducing serotonin and tryptophan hydroxylase-2 levels in the DRN. Targeted ablation of EWcp/UCN1 neurons induced hyperalgesia. A positive functional connectivity between EW and STN as well as DRN has been identified by functional magnetic resonance imaging. The presented data strongly suggest the regulatory role of EWcp/UCN1 neurons in migraine through the STN and DRN with high translational value.

The Influence of Neck Pain and Sleep Quantity on Headache Burden in Service Members With and Without Mild Traumatic Brain Injury: An Observational Study

INTRODUCTION

Headache is the most overwhelmingly reported symptom following mild traumatic brain injury (mTBI). The upper cervical spine has been implicated in headache etiology, and cervical dysfunction may result in neck pain that influences the experience of headache. Sleep problem is the second most reported symptom following mTBI. We explored the contribution of neck pain (as a potential proxy for cervical dysfunction) on headache burden along with the contribution of sleep quantity following mTBI.

MATERIALS AND METHODS

Retrospective data from a repository consisting of service members recruited from primary care, with (N = 493) and without a history of mTBI (N = 63), was used for analysis. Portions of the Neurobehavioral Symptom Inventory, Pittsburgh Sleep Quality Index, and Orebro Musculoskeletal Pain Questionnaire were used for headache, sleep, and neck pain measures.

RESULTS

Demographic and military characteristics that differed between groups were treated as covariates in analyses. Group comparisons revealed significant differences in the expected direction on all measures: mTBI > controls on headache and neck pain; controls > mTBI on sleep quantity. Regression revealed that neck pain accounted for the most variance in headache score, followed by group membership and sleep quantity. When analyzing groups separately, no difference in the pattern of results was revealed in the mTBI group. In the control group, variance in headache score was only significantly related to neck pain.

CONCLUSIONS

Amongst service members who sought service from primary care, neck pain explains more variance in headache burden than mTBI history or sleep quantity, supporting that cervical dysfunction may be a salient factor associated with headache. Neck functioning may be a potential area of intervention in the management of headaches.

Increased risk of migraine among patients with hidradenitis suppurativa: A US multi-center cohort study

BACKGROUND

Hidradenitis suppurativa (HS) and migraine share common inflammatory pathways and neuropsychological implications. Both conditions involve proinflammatory cytokines like tumor necrosis factor and are associated with psychological comorbidities. Despite these similarities, the association between HS and migraine remained unclear. This study aimed to evaluate the relation between HS and incident migraine.

MATERIALS AND METHODS

We conducted a multicenter cohort study using the TriNetX Research Network. Patients diagnosed with HS between January 1, 2005 and December 31, 2022 were identified with a control group of non-HS subjects established by propensity score matching at a 1:1 ratio. Our outcome was the hazard ratio (HR) of incident migraine in relation to HS. We also examined the HR for various subtypes of migraine. We conducted stratified analyses based on age, gender, insomnia, depression, and anxiety subgroups. Sensitivity analyses were performed to strengthen the robustness of our analysis.

RESULTS

The HS group exhibited an increased risk of incident migraine compared to controls (HR 1.35, 95% confidence interval (CI) 1.28-1.42). Also, HS patients had increased risk of migraine with aura and migraine without aura than controls, with HR being 1.36 (95% CI 1.21-1.52), 1.36 (95% CI 1.20-1.45), respectively. Female HS patients demonstrated an increased risk of incident migraine compared to their controls (HR 1.38, 95% CI 1.30-1.45). Elevated risk of incident migraine was observed in both younger and older HS patients when compared to their respective controls. The increased risk of incident migraine among HS patients remained consistent across various sensitivity analyses.

CONCLUSIONS

HS patients present with an increased risk of incident migraine. Physicians should be aware of this association and provide timely referral and interventions when appropriate.

IL18 rs360717 and rs187238 genetic variants are associated with migraine diagnosis

BACKGROUND

Migraine is a genetically determined disorder that predisposes to recurrent episodes of headache. Interleukin (IL)-18 is a pro-inflammatory cytokine that seems to play a role in migraine pathophysiology, and its genetic variants could potentially impact susceptibility to migraine.

OBJECTIVE

To investigate the association between IL18 rs360717 and rs187238 genetic variants with migraine diagnosis and its clinical characteristics.

METHODS

A case-control study was conducted with 152 people with migraine and 155 healthy controls, matched by sex, age, ethnicity, and body mass index. Clinical characteristics of migraine, as well as validated questionnaires regarding disability and impact of migraine, presence of allodynia, anxiety, depression, and hyperacusis were collected. Genotyping for IL18 rs360717 and rs187238 variants was performed using real-time polymerase chain reaction (qPCR) and TaqMan™ method.

RESULTS

The IL18 rs360717A and rs187238G alleles were associated with increased chance of being diagnosed with migraine (OR = 1.53, 95%CI 1.05-2.24, p = 0.028 and OR = 1.46, 95%CI 1.00-2.14, p = 0.049, respectively). In the dominant model, the rs360717GA + AA genotypes were also associated with a higher chance of migraine than the GG genotype (OR = 1.69, 95%CI 1.05-2.73, p = 0.030). In women, in addition to the previous associations, there was also an effect of the variants on the chance of migraine in the codominant models and dominant models. Furthermore, among women, there was an influence on the prevalence of postdrome perception with rs360717GA + AA (OR = 3.04, 95%CI 1.10-8.42, p = 0.032) and rs187238CG + GG (OR = 2.97, 95%CI 1.08-8.21, p = 0.035).

CONCLUSION

IL18 rs360717 and rs187238 variants were associated with migraine diagnosis and postdrome symptoms, especially in women.

SIGNIFICANCE

This study has demonstrated that IL18 rs360717 and rs187238 variants play a role in migraine, influencing the chance of being diagnosed with migraine, particularly among women. There are prospects that IL18 variants could be considered potential genetic biomarkers for migraine.

Effects of onabotulinumtoxin A in patients concurrently diagnosed with chronic migraine encephalalgia and temporomandibular disorders: A retrospective case series

OBJECTIVE

Chronic migraine encephalalgia (CME) with concomitant temporomandibular disorder (TMD) is a serious illness with limited effective treatment options. This study explores the effectiveness of onabotulinumtoxinA (BtxA) as an adjunct therapeutic to TMJ arthroscopy in the relief of CME.

METHODS

A retrospective cohort study of patients receiving TMJ arthroscopy, with or without BtxA injections for CME, was conducted. Variables assessed include pain using a visual analog scale (VAS), maximal incisal opening (MIO), muscle soreness, and headache frequency and duration.

RESULTS

Sixty patients (44 BtxA, 16 Control), consisting of 56 (93.3%) females, met inclusion criteria. A significant reduction in pain is reported with patients receiving BtxA (p < 0.0001) on VAS as compared to Control group. BtxA treatment also significantly reduced headache frequency and duration (p < 0.05).

CONCLUSION

These results support the use of adjunctive BtxA treatment with arthroscopy for the treatment of CME in the context of TMD.

Morphological and mechanical properties of cervical muscles in fibromyalgia with migraine: A case-control study

BACKGROUND

The precise manner in which morphological and mechanical properties of cervical muscles in patients with fibromyalgia and migraine are affected remains unclear.

OBJECTIVES

The objective of this study was to compare the morphological and mechanical properties of cervical muscles in individuals diagnosed with fibromyalgia who also experience migraine headaches with those who do not.

METHODS

The study included two groups of fibromyalgia patients: one with migraine (n = 18, age = 44.7 ± 7.5 years, body mass index = 28.7 ± 6.9 kg/m2) and one without migraine (n = 21, age = 42.6 ± 9.5 years, body mass index = 25.1 ± 4.4 kg/m2). Body pain intensity related to fibromyalgia and migraine attack severity were evaluated with a Visual Analog Scale (VAS). The cervical muscle morphological and mechanical properties, including thickness, cross-sectional area (CSA), and stiffness, were measured using ultrasound imaging.

RESULTS

It was found that there was a greater decrease in longus colli muscle CSA scores (p = 0.004) and a greater increase in upper trapezius muscle stiffness scores (p = 0.013) in the fibromyalgia + migraine group compared to the fibromyalgia group. No statistically significant differences were observed in trapezius muscle thickness (p = 0.261), sternocleidomastoid muscle thickness (p = 0.874), multifidus CSA (p = 0.963), or sternocleidomastoid muscle stiffness (p = 0.642) between the two groups.

CONCLUSION

Patients with fibromyalgia and migraine exhibited diminished longus colli muscle CSA and heightened upper trapezius muscle stiffness compared to those with fibromyalgia but no migraine. It should be considered that migraine comorbidity in fibromyalgia may negatively affect cervical muscle morphological and mechanical properties.

Advances and controversies in meningeal biology

The dura, arachnoid and pia mater, as the constituent layers of the meninges, along with cerebrospinal fluid in the subarachnoid space and ventricles, are essential protectors of the brain and spinal cord. Complemented by immune cells, blood vessels, lymphatic vessels and nerves, these connective tissue layers have held many secrets that have only recently begun to be revealed. Each meningeal layer is now known to have molecularly distinct types of fibroblasts. Cerebrospinal fluid clearance through peripheral lymphatics and lymph nodes is well documented, but its routes and flow dynamics are debated. Advances made in meningeal immune functions are also debated. This Review considers the cellular and molecular structure and function of the dura, arachnoid and pia mater in the context of conventional views, recent progress, and what is uncertain or unknown. The hallmarks of meningeal pathophysiology are identified toward developing a more complete understanding of the meninges in health and disease.

Intranasal administration of recombinant human BDNF as a potential therapy for some primary headaches

BACKGROUND

In addition to its critical role in neurogenesis, brain-derived neurotrophic factor (BDNF) modulates pain and depressive behaviors.

METHODS

In a translational perspective, we tested the anti-migraine activity of highly purified and characterized recombinant human BDNF (rhBDNF) in an animal model of cephalic pain based on the chronic and intermittent NTG administration (five total injections over nine days), used to mimic recurrence of attacks over a given period. To achieve this, we assessed the effects of two doses of rhBDNF (40 and 80 µg/kg) administered intranasally to adult male Sprague-Dawley rats, on trigeminal hyperalgesia (by orofacial formalin test), gene expression (by rt-PCR) of neuropeptides and inflammatory cytokines in specific areas of the brain related to migraine pain. Serum levels of CGRP, PACAP, and VIP (by ELISA) were also evaluated. The effects of rhBDNF were compared with those of sumatriptan (5 mg/kg i.p), administered 1 h before the last NTG administration.

RESULTS

Both doses of rhBDNF significantly reduced NTG-induced nocifensive behavior in Phase II of the orofacial formalin test. The anti-hyperalgesic effect of intranasal high-dose rhBDNF administration in the NTG-treated animals was associated with a significant modulation of mRNA levels of neuropeptides (CGRP, PACAP, VIP) and cytokines (IL-1beta, IL-10) in the trigeminal ganglion, medulla-pons, and hypothalamic area. Of note, the effects of rhBNDF treatment were comparable to those induced by the administration of sumatriptan. rhBDNF administration at both doses significantly reduced serum levels of PACAP, while the higher dose also significantly reduced serum levels of VIP.

CONCLUSIONS

The findings suggest that intranasal rhBDNF has the potential to be a safe, non-invasive and effective therapeutic approach for the treatment of primary headache, particularly migraine.

Interplay between cannabinoids and the neuroimmune system in migraine

Migraine is a common and complex neurological disorder that has a high impact on quality of life. Recent advances with drugs that target the neuropeptide calcitonin gene-related peptide (CGRP) have helped, but treatment options remain insufficient. CGRP is released from trigeminal sensory fibers and contributes to peripheral sensitization, perhaps in part due to actions on immune cells in the trigeminovascular system. In this review, we will discuss the potential of cannabinoid targeting of immune cells as an innovative therapeutic target for migraine treatment. We will cover endogenous endocannabinoids, plant-derived phytocannabinoids and synthetically derived cannabinoids. The focus will be on six types of immune cells known to express multiple cannabinoid receptors: macrophages, monocytes, mast cells, dendritic cells, B cells, and T cells. These cells also contain receptors for CGRP and as such, cannabinoids might potentially modulate the efficacy of current CGRP-targeting drugs. Unfortunately, to date most studies on cannabinoids and immune cells have relied on cell cultures and only a single preclinical study has tested cannabinoid actions on immune cells in a migraine model. Encouragingly, in that study a synthetically created stable chiral analog of an endocannabinoid reduced meningeal mast cell degranulation. Likewise, clinical trials evaluating the safety and efficacy of cannabinoid-based therapies for migraine patients have been limited but are encouraging. Thus, the field is at its infancy and there are significant gaps in our understanding of the impact of cannabinoids on immune cells in migraine. Future research exploring the interactions between cannabinoids and immune cells could lead to more targeted and effective migraine treatments.

Association between human herpes simplex virus and severe headache or migraine among aged 20-49 years: a cross-sectional study

Background and purpose

Previous studies have shown that human herpes simplex virus (HSV) infection may be associated with the onset of headache or migraine. We aimed to investigate the association between HSV infection and severe headache or migraine.

Materials and methods

The cross-sectional data on 5,730 participants aged 20-49 years were obtained from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). We used weighted logistic regression analysis to assess the association between HSV infection (HSV-1 gG-1 and HSV-2 gG-2) and severe headache or migraine, and performed subgroup analyses.

Results

Our study found that women, higher education, higher body mass index, better family conditions, smoking and alcohol consumption were all associated with severe headaches or migraines. After adjusting for confounding factors such as sex, age, race, and education, HSV-2 (+) was still significantly associated with severe headache or migraine (OR = 1.22, 95%CI:1.03-1.46, p = 0.0443). In subgroup analyses, we found that participants with HSV-1 (-) and HSV-2 (+) were also significantly associated with severe headache or migraine (OR = 1.41, 95%CI:1.04-1.91, p = 0.0281).

Conclusion

HSV-2 gG-2(+) was significantly associated with severe headache or migraine.

Novel and reappraised wide-band EEG findings in migraineurs: Its correlation with several clinical variables

OBJECTIVE

Cortical spreading depolarization is one possible pathogenesis of migraine, of which slow neurophysiological change is barely recorded in conventional EEG settings. Using wide-band EEG conditions, we reappraised the features of EEG in migraineurs, including subdelta-band EEG changes.

METHODS

This retrospective study included 144 patients with migraine. We delineated EEG of focal delta slow (FDS) (1-4 Hz) by time constant (TC) 0.3 s and focal subdelta slow (FSDS) (< 1 Hz) by TC 2 s. Relationships between clinical variables and EEG findings were evaluated.

RESULTS

Of 144 patients, 39 had aura and 105 did not. FSDS and FDS were observed in 38 and 58 patients, respectively. No EEG was recorded during the aura. In multivariate analysis with the phase of migraine, family history, age, and percentage of sleep during EEG recording, the phase of migraine was related to the occurrence of FSDS (postdrome vs interictal, prodrome, and headache respectively (OR = 49.00 [95% CI = 3.89-616.66], 46.28 [2.99-715.78], 32.79 [2.23-481.96], p = 0.0026, 0.0061, 0.011). FDS was clinically unremarkable for differential evaluation.

CONCLUSIONS

Wide-band EEG abnormality in migraineurs, i.e., FSDS, can be affected by migraine phase.

SIGNIFICANCE

Wide-band EEG finding could be a biomarker related to clinical variables in migraines.

Targeting IGF1/IGF1r signaling relieve pain and autophagic dysfunction in NTG-induced chronic migraine model of mice

BACKGROUND

Chronic migraine is a severe and common neurological disorder, yet its precise physiological mechanisms remain unclear. The IGF1/IGF1r signaling pathway plays a crucial role in pain modulation. Studies have shown that IGF1, by binding to its receptor IGF1r, activates a series of downstream signaling cascades involved in neuronal survival, proliferation, autophagy and functional regulation. The activation of these pathways can influence nociceptive transmission. Furthermore, alterations in IGF1/IGF1r signaling are closely associated with the development of various chronic pain conditions. Therefore, understanding the specific mechanisms by which this pathway contributes to pain is of significant importance for the development of novel pain treatment strategies. In this study, we investigated the role of IGF1/IGF1r and its potential mechanisms in a mouse model of chronic migraine.

METHODS

Chronic migraine was induced in mice by repeated intraperitoneal injections of nitroglycerin. Mechanical and thermal hypersensitivity responses were assessed using Von Frey filaments and radiant heat, respectively. To determine the role of IGF1/IGF1r in chronic migraine (CM), we examined the effects of the IGF1 receptor antagonist ppp (Picropodophyllin) on pain behaviors and the expression of calcitonin gene-related peptide (CGRP) and c-Fos.

RESULT

In the nitroglycerin-induced chronic migraine model in mice, neuronal secretion of IGF1 is elevated within the trigeminal nucleus caudalis (TNC). Increased phosphorylation of the IGF1 receptor occurs, predominantly co-localizing with neurons. Treatment with ppp alleviated basal mechanical hypersensitivity and acute mechanical allodynia. Furthermore, ppp ameliorated autophagic dysfunction and reduced the expression of CGRP and c-Fos.

CONCLUSION

Our findings demonstrate that in the chronic migraine (CM) model in mice, there is a significant increase in IGF1 expression in the TNC region. This upregulation of IGF1 leads to enhanced phosphorylation of IGF1 receptors on neurons. Targeting and inhibiting this signaling pathway may offer potential preventive strategies for mitigating the progression of chronic migraine.

Biological markers of brain network connectivity and pain sensitivity distinguish low coping from high coping Veterans with persistent post-traumatic headache

Headache is the most common type of pain following mild traumatic brain injury. Roughly half of those with persistent post-traumatic headache (PPTH) also report neck pain which is associated with greater severity and functional impact of headache. This observational cohort study aimed to identify biological phenotypes to help inform mechanism-based approaches in the management of PPTH with and without concomitant neck pain. Thirty-three military Veterans (mean (SD) = 37±16 years, 29 males) with PPTH completed a clinical assessment, quantitative sensory testing, and magnetic resonance imaging of the brain and cervical spine. Multidimensional phenotyping was performed using a Random Forest analysis and Partitioning Around Medoids (PAM) clustering of input features from three biologic domains: 1) resting state functional connectivity (rsFC) of the periaqueductal gray (PAG), 2) quality and size of cervical muscles, and 3) mechanical pain sensitivity and central modulation of pain. Two subgroups were distinguished by biological features that included forehead pressure pain threshold and rsFC between the PAG and selected nodes within the default mode, salience, and sensorimotor networks. Compared to the High Pain Coping group, the Low Pain Coping group exhibited higher pain-related anxiety (p=0.009), higher pain catastrophizing (p=0.004), lower pain self-efficacy (p=0.010), and greater headache-related disability (p=0.012). Findings suggest that greater functional connectivity of pain modulation networks involving the PAG combined with impairments in craniofacial pain sensitivity, but not cervical muscle health, distinguish a clinically important subgroup of individuals with PPTH who are less able to cope with pain and more severely impacted by headache.

Mechanism of Traditional Chinese Medicine in Treating Migraine: A Comprehensive Review

Migraine is a common neurological illness that causes a great burden on individuals and society. Many migraine patients seek relief through complementary and alternative therapies, with Traditional Chinese medicine (TCM) often being their preferred choice. Acupuncture, Chinese herbal medicine, and massage are important components of TCM, and are commonly used in clinical treatment of migraine. This review aims to consolidate the current knowledge regarding the mechanisms of the three TCM interventions for migraine: acupuncture, herbs, and massage, and how they relieve pain. However, the mechanisms underlying the effectiveness of TCM therapies in treating migraine remain unclear. Therefore, we reviewed the research progress on acupuncture, herbal medicine, and massage as TCM approaches for the treatment of migraine. We conducted a comprehensive search of CNKI, PubMed, Web of Science, and Cochrane databases using keywords such as migraine, acupuncture, needle, herbs, herbal, prescription, decoction, massage, Tuina, and TCM, covering the period from 2000 to 2023. The literature included in the review was selected based on specified exclusion criteria. We discussed the mechanism of TCM therapies on migraine from the perspective of modern medicine, focusing on changes in inflammatory factors, neurotransmitters, and other relevant biomarkers. TCM can relieve migraine by decreasing neuropeptide levels, inhibiting inflammation, modulating neuronal sensitization, changing brain function and structure, changing blood brain barrier permeability, regulating hormone levels, and relieving muscle tension. The purpose of this paper is to provide a basis for improving the clinical strategies of TCM for the treatment of migraine.

Unravelling Migraine Stigma: A Comprehensive Review of Its Impact and Strategies for Change

Migraine-related stigma is a pervasive issue impacting nearly half of chronic migraine patients, with significant consequences for their quality of life, disability and mental health. Despite its profound effects, migraine stigma remains under-recognised in both clinical practice and research. This narrative review explores the three primary types of stigmas affecting migraine patients: public, structural and internalised. Public stigma involves negative societal attitudes and stereotypes that trivialise the condition. Structural stigma is reflected in policies that restrict access to necessary care and resources. Internalised stigma occurs when patients absorb these negative views, leading to self-blame and diminished self-worth. Addressing these different types of stigmas is crucial for improving the understanding, diagnosis and treatment of migraine. Educational efforts, advocacy and policy reform are essential strategies in this context. A deep understanding of stigma is vital for developing effective interventions that enhance clinical management and patient quality of life. Ultimately, reducing stigma can lead to better health outcomes and a more comprehensive approach to migraine care.

CGRP Modulating Therapies: An Update

INTRODUCTION

Calcitonin-gene related peptide (CGRP) is a vasoactive neuropeptide involved in the pathophysiology ofmigraine. CGRP has been targeted for both preventive and acute treatment of migraine.

OBJECTIVE

Provide a summary of the most clinically relevant literature surrounding CGRP modulating therapies.

METHODS

This update on CGRP modulating therapies includes articles selected as most clinically relevant by theauthors.

CONCLUSION

CGRP modulating therapies are an exciting new addition to migraine treatment given their safety andtolerability. Additionally, compared to traditional migraine preventive medication these treatments are migrainespecific.Further real-world and clinical data is ongoing to better understand these treatments that continue to gainfavor in the management of migraine.

Antimigraine activity of Asarinin by OPRM1 pathway with multifaceted impacts through network analysis

Migraine is a debilitating neurological disorder impacting millions worldwide. Calcitonin Gene-Related Peptide (CGRP) has emerged as a key player in migraine pathophysiology, leading to the development of targeted therapies. This study reviews novel CGRP-targeted treatments, including monoclonal antibodies small molecule inhibitors/nutraceuticals and introduces Asarinin as a potential modulator of the pathway. Asarinin, a natural compound found in various plants, is examined for its pharmacological potential in migraine management. Pharmacokinetic assessments, toxicological modelling, molecular property analysis, and network pharmacology were conducted. Molecular docking and dynamics studies with CGRP reveal potential interactions, providing a foundation for understanding Asarinin's therapeutic effects. Asarinin's favourable pharmacokinetics, safety profile, and bioactivity, supporting its candidacy as a therapeutic agent. In-depth molecular docking studies with the CGRP receptor (PDB: 6ZHO) demonstrate strong binding affinity (- 10.3kcal/mol), while molecular dynamics simulations unveil the dynamic behavior of the Asarinin-CGRP complex, (- 10.53 kcal/mol) for Atogepant-CGRP complex. Network analysis highlights key proteins in migraine pathology, indicating Asarinin's potential efficacy. The groundwork for future investigations, suggests Asarinin as a promising candidate for migraine management by targeting OPRM1 pathway. The integration of diverse assessments provides a comprehensive understanding of Asarinin's potential and paves the way for further preclinical and clinical research.

The role of kynurenines in migraine-related neuroimmune pathways

Migraine, a primary headache disorder whose mechanism remains incompletely understood, appears to involve the activation of the trigeminovascular system (TS) during attacks. Research suggests that inflammatory processes mediated by the immune system may play a role in migraine pathophysiology. Neuroinflammation is often associated with migraine attacks, with cytokines serving as crucial mediators in the process. Elevated levels of pro-inflammatory cytokines, such as interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α), have been observed in the blood and cerebrospinal fluid of individuals experiencing migraine attacks. These cytokines have the capacity to sensitize pain pathways in the brain, thereby increasing sensitivity to pain stimuli. This phenomenon, known as central sensitization, is believed to contribute to the intensity and persistence of migraine pain. Kynurenines, endogenous mediators of glutamatergic mechanisms, can significantly influence the pathophysiology of primary headache disorders. The kynurenine system is collectively known as the kynurenine pathway (KP), which can act on multiple receptors, such as glutamate receptors, aryl hydrocarbon receptors (AhRs), G protein-coupled receptors 35 (GPR35), and α-7 nicotinic acetylcholine (α7 nACh) receptors. These receptors are also found on various cells of the immune system, so the role of the KP in the pathomechanism of primary headaches may also be mediated through them. In this review, our goal is to show a possible link between the receptors of the KP and immune system in the context of inflammation and migraine. Migraine research in recent years has focused on neuropeptides, such as calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) as potential pathogenic factors and possible therapeutic approaches. These peptides share many similarities in their characteristics and roles. For instance, they exhibit potent vasodilation, occur in both the peripheral and central nervous systems, and play a role in transmitting nociception and neurogenic inflammation. The investigation of potential connections between the aforementioned neuropeptides and the kynurenine pathway could play a significant role in uncovering the pathomechanism of migraine and identifying new drug candidates.

Glucagon-like peptide 1 receptor activation: anti-inflammatory effects in the brain

The glucagon-like peptide 1 is a pleiotropic hormone that has potent insulinotropic effects and is key in treating metabolic diseases such as diabetes and obesity. Glucagon-like peptide 1 exerts its effects by activating a membrane receptor identified in many tissues, including different brain regions. Glucagon-like peptide 1 activates several signaling pathways related to neuroprotection, like the support of cell growth/survival, enhancement promotion of synapse formation, autophagy, and inhibition of the secretion of proinflammatory cytokines, microglial activation, and apoptosis during neural morphogenesis. The glial cells, including astrocytes and microglia, maintain metabolic homeostasis and defense against pathogens in the central nervous system. After brain insult, microglia are the first cells to respond, followed by reactive astrocytosis. These activated cells produce proinflammatory mediators like cytokines or chemokines to react to the insult. Furthermore, under these circumstances, microglia can become chronically inflammatory by losing their homeostatic molecular signature and, consequently, their functions during many diseases. Several processes promote the development of neurological disorders and influence their pathological evolution: like the formation of protein aggregates, the accumulation of abnormally modified cellular constituents, the formation and release by injured neurons or synapses of molecules that can dampen neural function, and, of critical importance, the dysregulation of inflammatory control mechanisms. The glucagon-like peptide 1 receptor agonist emerges as a critical tool in treating brain-related inflammatory pathologies, restoring brain cell homeostasis under inflammatory conditions, modulating microglia activity, and decreasing the inflammatory response. This review summarizes recent advances linked to the anti-inflammatory properties of glucagon-like peptide 1 receptor activation in the brain related to multiple sclerosis, Alzheimer's disease, Parkinson's disease, vascular dementia, or chronic migraine.

Profile of Sensory Integration Disorders in Migraine Patients-New Perspectives of Therapy

Background: The involvement of sensory integration disorders in the pathophysiology of migraine has been suggested. This study aims to analyze the relationship between symptoms of sensory integration disorders and migraine in a broad scope, including all sensory domains, and examine its impact on migraine attacks. Methods: The study included 372 people diagnosed with migraine. The Daniel Travis Questionnaire was used to assess symptoms of sensory integration disorders and their severity across six domains. The relationships between the severity of these symptoms and headache features, as well as accompanying headache symptoms, were the subject of statistical analysis. Results: Current impairment in all sensory domains was significantly associated with headaches exacerbated by everyday life activities. A significant inverse relationship was found between the occurrence of throbbing headaches and symptoms of sensory integration disorders in terms of current sensory discrimination, current motor skills, and current emotional/social skills. Past under-responsiveness and past disturbances in emotional/social abilities were significantly associated with migraine aura. Conclusions: The severity of symptoms of sensory integration disorders affects the clinical picture of migraine. The significant association between migraine and emotional/social disorders, as well as under-responsiveness in the past, needs further research to assess whether this is a cause-and-effect relationship. There is a need for in-depth diagnostics of sensory integration disorders in migraine patients, which could be an additional target of their therapy.

A thorough investigation into the correlation between migraines and the gut microbiome: an in-depth analysis using Mendelian randomization studies

Objective

A growing body of evidence underscores a significant association between neurological disorders, particularly migraines, and the gut microbiota. However, a research gap persists in understanding the cause-and-effect dynamics between these elements. Therefore, we employed robust methodologies aimed at thoroughly exploring the causal relationship between the gut microbiome and migraines.

Methods

Employing bidirectional Two Sample Mendelian Randomization (TSMR) analysis, we investigated the causal association between the composition of the gut microbiota and migraines. Data summarizing the relationship between gut microbiota and migraines were extracted from one or more genome-wide association studies. The TSMR analysis employed five methods to assess the correlation between the gut microbiota and migraines, with the inverse variance-weighted method serving as the primary approach for analyzing causal links. Sensitivity analyses were applied to address horizontal pleiotropy and heterogeneity. Simultaneously, a meta-analysis was performed to strengthen the robustness of the findings. Additionally, a reverse TSMR was carried out to explore potential occurrences of reverse causal relationships.

Results

The ongoing TSMR analysis identified a collection of 14 bacterial taxa connected to migraines. Among these, 8 taxa exhibited a protective effect, while 5 taxa had a detrimental impact, and 1 taxon maintained a neutral relationship. The reverse Mendelian randomization analysis highlighted stable outcomes for only one bacterial taxonomic group.

Conclusion

The study confirms a causal relationship between the gut microbiota and migraines, offering a new perspective for migraine research. Strategically targeting specific bacterial taxa with dysregulation may be effective in both preventing and treating migraines, thus opening new avenues for therapeutic strategies.

Mulligan manual therapy added to exercise improves headache frequency, intensity and disability more than exercise alone in people with cervicogenic headache: a randomised trial

QUESTION

What is the effect of a 4-week regimen of Mulligan manual therapy (MMT) plus exercise compared with exercise alone for managing cervicogenic headache? Is MMT plus exercise more effective than sham MMT plus exercise? Are any benefits maintained at 26 weeks of follow-up?

DESIGN

A three-armed, parallel-group, randomised clinical trial with concealed allocation, blinded assessment of some outcomes and intention-to-treat analysis.

PARTICIPANTS

Ninety-nine people with cervicogenic headache as per International Classification of Headache Disorders (ICHD-3).

INTERVENTIONS

Participants were randomly allocated to 4 weeks of: MMT with exercise, sham MMT with exercise or exercise alone.

OUTCOME MEASURES

The primary outcome was headache frequency. Secondary outcomes were headache intensity, headache duration, medication intake, headache-related disability, upper cervical rotation range of motion, pressure pain thresholds and patient satisfaction. Outcome measures were collected at baseline and at 4, 13 and 26 weeks.

RESULTS

MMT plus exercise reduced headache frequency more than exercise alone immediately after the intervention (MD between groups in change from baseline: 2 days/month, 95% CI 2 to 3) and this effect was still evident at 26 weeks (MD 4 days, 95% CI 3 to 4). There were also benefits across all time points in several secondary outcomes: headache intensity, headache duration, headache-related disability, upper cervical rotation and patient satisfaction. Pressure pain thresholds showed benefits at all time points at the zygapophyseal joint and suboccipital areas but not at the upper trapezius. The outcomes in the sham MMT with exercise group were very similar to those of the exercise alone group.

CONCLUSIONS

In people with cervicogenic headache, adding MMT to exercise improved: headache frequency, intensity and duration; headache-related disability; upper cervical rotation; and patient satisfaction. These benefits were not due to placebo effects.

TRIAL REGISTRATION

CTRI/2019/06/019506.

Reduced hepatic impairment study to evaluate pharmacokinetics and safety of zavegepant and to inform dosing recommendation for hepatic impairment

Zavegepant, a high-affinity, selective, small-molecule calcitonin gene-related peptide (CGRP) receptor antagonist, is approved in the United States for acute treatment of migraine in adults. The effects of moderate hepatic impairment (8 participants with Child-Pugh score 7-9 points) on the pharmacokinetics of a single 10-mg intranasal dose of zavegepant versus eight matched participants with normal hepatic function were evaluated in a phase I study. Pharmacokinetic sampling determined total and unbound plasma zavegepant concentrations. Moderate hepatic impairment increased the exposure of total zavegepant (~2-fold increase in AUC0-inf and 16% increase in Cmax) versus normal hepatic function, which is not considered clinically meaningful. The geometric least squares mean ratios (moderate impairment/normal) of plasma zavegepant AUC0-inf and Cmax were 193% (90% confidence interval [CI]: 112, 333; p = 0.051) and 116% (90% CI: 69, 195; p = 0.630), respectively. The geometric mean fraction unbound of zavegepant was similar for participants with moderate hepatic impairment (0.13; coefficient of variation [CV] 13.71%) versus those with normal hepatic function (0.11; CV 21.43%). Similar exposure findings were observed with unbound zavegepant versus normal hepatic function (~2.3-fold increase in AUC0-inf and 39% increase in Cmax). One treatment-emergent adverse event (mild, treatment-related headache) was reported in a participant with normal hepatic function. No dosage adjustment of intranasal zavegepant is required in adults with mild or moderate hepatic impairment.

The Intersection of Migraine and Epistaxis: Clinical Observations and Analysis

Migraine prevalence has risen over the last few decades, which may be attributed to lifestyle changes. Epistaxis is unusual in migraine. Here we present a case series of four patients, who are presented with headaches associated with epistaxis. A detailed history revealed cardinal symptoms of migraine according to the International Headache Society, including hemicranial throbbing headache of moderate to severe intensity lasting for a duration of four to 72 hours, along with associated features of nausea, vomiting, photophobia, and phonophobia. Investigations, including ENT (ear, nose, and throat) examination, nasal endoscopy, gastroscopy, bronchoscopy, hematological, and coagulation parameters, were negative. All patients were started on prophylactic treatment for migraine, and they responded well. Epistaxis occurs at the peak of headache following which symptoms tend to resolve. The pathophysiology behind this is stimulation of the trigeminovascular system leading to dilatation of external and internal carotid arteries.

The preclinical discovery and development of atogepant for migraine prophylaxis

INTRODUCTION

Atogepant is a selective calcitonin gene-related peptide (CGRP) receptor antagonist that is utilized in adults for the prevention of episodic and chronic migraine. Cumulative findings support the involvement of CGRP in migraine pathophysiology, and atogepant functions by competitively antagonizing CGRP receptors, which results in the inhibition of trigeminovascular nociception. The mechanism of action addresses the cause of migraine pain, providing an effective preventive treatment option.

AREAS COVERED

The key milestones in its development, including preclinical achievements, phase I, II, and III clinical trials, and regulatory approvals are reviewed. Additionally, clinical efficacy, safety profile, and tolerability of atogepant are discussed. The literature review is based on a comprehensive search of English peer-reviewed articles from various electronic databases, including PubMed and ClinicalTrials.gov.

EXPERT OPINION

The development of atogepant represents a significant breakthrough in migraine prevention, particularly due to its improved safety profile that reduces the risk of liver injury, which was a major limitation of first-generation gepants. Drug-drug interaction studies with atogepant highlight the necessity for more inclusive study populations. Given that migraine disproportionately affects females, future clinical development programs should include diverse patient demographics to ensure the findings are generalizable to all individuals suffering from migraine.

Effects of Anti-CGRP Monoclonal Antibodies on Neurophysiological and Clinical Outcomes: A Combined Transcranial Magnetic Stimulation and Algometer Study

BACKGROUND

the aim of this study was to investigate the neurophysiological effect of anti-CGRP monoclonal antibodies on central and peripheral levels in migraine patients.

METHODS

An observational cohort study in patients with migraine was performed. All subjects underwent Single-Pulse and Paired-Pulse Transcranial Magnetic Stimulation, as well as a Pressure Pain Threshold assessment. The same protocol was repeated three and four months after the first injection of anti-CGRP monoclonal antibodies.

RESULTS

A total of 11 patients with a diagnosis of migraine and 11 healthy controls were enrolled. The main findings of this study are the significant effects of anti-CGRP mAb treatment on the TMS parameters of intracortical inhibition and the rise in the resting motor threshold in our group of patients affected by resistant migraine. The clinical effect of therapy on migraine is associated with the increase in short-interval intracortical inhibition (SICI), resting motor threshold (RMT), and Pressure Pain Threshold (PPT). In all patients, all clinical headache parameters improved significantly 3 months after the first injection of mAbs and the improvement was maintained at the 1-month follow-up. At baseline, migraineurs and HCs had significant differences in all TMS parameters and in PPT, while at follow-up assessment, no differences were observed on RMT, SICI, and PPT between the two groups. After anti-CGRP monoclonal antibody injection, a significant increase in the intracortical inhibition, in the motor threshold, and in the Pressure Pain Threshold in critical head areas was observed in patients with migraine, which was related to significant clinical benefits.

CONCLUSIONS

Anti-CGRP monoclonal antibodies improved clinical and neurophysiological outcomes, reflecting a normalization of cortical excitability and peripheral and central sensitization. By directly acting on the thalamus or hypothalamus and indirectly on the trigeminocervical complex, treatment with anti-CGRP monoclonal antibodies may modulate central sensorimotor excitability and peripheral sensitization pain.

Association of dietary vitamin C consumption with severe headache or migraine among adults: a cross-sectional study of NHANES 1999-2004

Background

An antioxidant-rich diet has been shown to protect against migraines in previous research. However, little has been discovered regarding the association between migraines and vitamin C (an essential dietary antioxidant). This study assessed the dietary vitamin C intake among adult migraineurs in the United States to determine if there is a correlation between migraine incidence and vitamin C consumption in adults.

Methods

This cross-sectional research encompassed adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2004, providing detailed information on their dietary vitamin C intake as well as their history of severe headaches or migraines. The study used weighted multivariable and logistic regression analyses to find an independent connection between vitamin C consumption and severe headache or migraine. Tests of interactions and subgroup analysis were conducted.

Results

Among the 13,445 individuals in the sample, 20.42% had a severe headache or migraine. In fully adjusted models, dietary vitamin C consumption was substantially linked negatively with severe headache or migraine (odds ratio [OR] = 0.94, 95% confidence interval [CI] = 0.91-0.98, p = 0.0007). Compared to quartile 1, quartile 4 had 22% fewer odds of having a severe headache or migraine (OR = 0.78, 95% CI = 0.69-0.89, p = 0.0002). Subgroup analyses showed a significant difference between vitamin C intake and severe headaches or migraines by gender (p for interaction < 0.01).

Conclusion

Reduced risk of severe headaches or migraines may be associated with increased consumption of vitamin C.

Dopamine D2 Receptor Activation Blocks GluA2/ROS Positive Feedback Loop to Alienate Chronic-Migraine-Associated Pain Sensitization

Chronic migraine is a disabling disorder without effective therapeutic medicine. AMPA receptors have been proven to be essential to pathological pain and headaches, but the related regulatory mechanisms in chronic migraine have not yet been explored. In this study, we found that the level of surface GluA2 was reduced in chronic migraine rats. Tat-GluR23Y (a GluA2 endocytosis inhibitor) reduced calcium inward flow and weakened synaptic structures, thus alleviating migraine-like pain sensitization. In addition, the inhibition of GluA2 endocytosis reduced the calcium influx and alleviated mitochondrial calcium overload and ROS generation in primary neurons. Furthermore, our results showed that ROS can induce allodynia and GluA2 endocytosis in rats, thus promoting migraine-like pain sensitization. In our previous study, the dopamine D2 receptor was identified as a potential target in the treatment of chronic migraine, and here we found that dopamine D2 receptor activation suppressed chronic-migraine-related pain sensitization through blocking the GluA2/ROS positive feedback loop in vivo and in vitro. Additionally, ligustrazine, a core component of ligusticum chuanxiong, was shown to target the dopamine D2 receptor, thereby alleviating ROS production and abnormal nociception in CM rats. This study provides valuable insight into the treatment of chronic migraine.

Cortical Hyperperfusion on MRI Arterial Spin-Labeling during the Interictal Period of Patients with Migraine Headache

BACKGROUND AND PURPOSE

Concentrations of calcitonin gene-related peptide, a neuropeptide and potent endogenous vasodilator, are reportedly higher in patients with migraine than in healthy subjects, both during and between migraine attacks, reflecting ongoing activation of the trigeminal nervous system. In this prospective study, we measured CBF during the interictal period of patients with migraine after considering insomnia and depression and examined the effects of ongoing activation of the trigeminal nervous system, including during the interictal period, on CBF.

MATERIALS AND METHODS

In a total of 242 patient with migraine (age range, 18-75 years), CBF was measured by MR imaging arterial spin-labeling during the interictal period and was compared with results from 26 healthy volunteers younger than 45 years of age as control subjects (age range, 22-45 years). Cortical hyperperfusion was defined as identification of ≥2 cerebral cortical regions with regional CBF values at least 2 SDs above the mean regional CBF in control subjects.

RESULTS

The overall frequency of cortical hyperperfusion was significantly higher in patients with migraine (115 of 242, 48%) than in control subjects (1 of 26, 4%). Multivariable analysis revealed the 18- to 40-year age group and patients with migraine without insomnia as significant positive clinical factors associated with cortical hyperperfusion. Among patients with migraine without insomnia, the frequency of cortical hyperperfusion was >92% (89 of 97). One-way ANOVA showed that in all ROIs of the cortex, regional CBF was significantly higher in patients with migraine without insomnia than in patients with migraine with insomnia or control subjects. In patients with migraine without insomnia, cortical hyperperfusion findings showed a sensitivity of 0.918 and a specificity of 0.962 for migraine in the interictal period, representing excellent accuracy. In contrast, among patients with migraine with insomnia, sensitivity was only 0.179 but specificity was 0.962.

CONCLUSIONS

Patients with migraine without insomnia may have cortical hyperperfusion during the interictal period; however, the findings of the present study need to be prospectively validated on a larger scale before clinical applicability can be considered.

Pharmacokinetics of Ubrogepant in Healthy Japanese and White Adults

Ubrogepant is a calcitonin gene-related peptide receptor antagonist indicated for the acute treatment of migraine with or without aura in adults. The objectives of this study were to evaluate (1) single-dose pharmacokinetics (PK) and dose proportionality of ubrogepant in Japanese participants, (2) the safety and tolerability of ubrogepant in healthy Japanese and White participants, and (3) to compare the PK of ubrogepant in Japanese versus White participants. A total of 48 participants were enrolled into 4 cohorts (N = 12 [9 active + 3 placebo] per cohort). A single dose was administered on Day 1 following an overnight fast to assess the PK of ubrogepant at 3 dose levels and test dose proportionality between 25 and 100 mg in Japanese participants. White participants were randomly assigned to ubrogepant (100 mg) or placebo. Dose proportionality was observed in the dose range of 25-100 mg in Japanese participants. Systemic exposure was 20% lower in Japanese participants as compared with White participants, but this difference is unlikely to be clinically relevant. Single doses of ubrogepant (25-100 mg) had a safety profile similar to placebo, and no differences in the safety profile of ubrogepant 100 mg were observed between Japanese versus White participants.

Can calcitonin gene-related peptide monoclonal antibodies ameliorate writer's cramp and migraine?

Recently, calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs) have become available as a prophylactic treatment for migraine and have shown high efficacy and safety in clinical practice. CGRP mAbs have been reported to be effective not only for migraine but also for other comorbidities, such as psychiatric complications in patients with migraine. However, there are no reports examining the effect of CGRP mAbs on dystonia. We treated a patient with comorbid migraine and focal task-specific dystonia (writer's cramp) with a CGRP mAb (erenumab) because of an increase in monthly migraine days despite the addition of migraine prophylaxis. In this patient, erenumab treatment for 3 months led to improvements in symptoms of both focal dystonia and migraine, suggesting a role for CGRP in the pathophysiology of both conditions.

SIRT1-regulated ROS generation activates NMDAR2B phosphorylation to promote central sensitization and allodynia in a male chronic migraine rat model

Background

Central sensitization is one of the pivotal pathological mechanisms in chronic migraine (CM). Silent information regulator 1 (SIRT1) was shown to be involved in CM, but its specific mechanism is unclear. Reactive oxygen species (ROS) are increasingly regarded as important signaling molecules in several models of pain. However, studies about the role of ROS in the central sensitization of CM model are rare. We thus explored the specific process of SIRT1 involvement in the central sensitization of CM, focusing on the ROS pathway.

Methods

Inflammatory soup was repeatedly administered to male Sprague-Dawley rats to establish a CM model. The SIRT1 expression level in trigeminal nucleus caudalis (TNC) tissues was assessed by qRT-PCR and Western blotting analysis. The levels of ROS were detected by a Tissue Reactive Oxygen Detection Kit, DHE staining, and the fluorescence signal intensity of 8-OHdG. A ROS scavenger (tempol), a SIRT1 activator (SRT1720), a SIRT1 inhibitor (EX527), and a mitochondrial fission inhibitor (Mdivi-1) were used to investigate the specific molecular mechanisms involved. NMDAR2B, CGRP, ERK, and mitochondrial fission-related protein were evaluated by Western blotting, and the CGRP level in frozen sections of the TNC was detected via immunofluorescence staining.

Results

After repeated inflammatory soup infusion and successful establishment of the CM rat model, SIRT1 expression was found to be significantly reduced, accompanied by elevated ROS levels. Treatment with Tempol, SRT1720, or Mdivi-1 alleviated allodynia and reduced the increase in NMDAR2B phosphorylation and CGRP and ERK phosphorylation in the CM rat. In contrast, EX527 had the opposite effect in CM rat. SRT1720 and EX527 decreased and increased ROS levels, respectively, in CM rats, and tempol reversed the aggravating effect of EX527 in CM rats. Furthermore, the regulatory effect of SIRT1 on ROS may include the involvement of the mitochondrial fission protein DRP1.

Conclusion

The results indicate the importance of SIRT1 in CM may be due to its role in regulating the production of ROS, which are involved in modulating central sensitization in CM. These findings could lead to new ideas for CM treatment with the use of SIRT1 agonists and antioxidants.

A role of NLRP3 and MMP9 in migraine progression: a systematic review of translational study

Background

Migraines affect one billion individuals globally, with a higher occurrence among young adults and women. A significant survey in the United States indicated that 17.1% of women and 5.6% of men suffer from migraines. This study seeks to investigate the potential connection between NLRP3 and MMP9 in migraine pathology.

Methods

The research involved searching databases such as PubMed, Scopus, Science Direct, Google Scholar, and Proquest, with the search concluding on March 31, 2024. Following PRISMA guidelines, PICO data were collected, focusing exclusively on animal models induced by Nitroglycerine (10 mg/kg), while excluding clinical studies.

Results

The study, originally registered in Prospero Reg. No. CRD42022355893, conducted bias analysis using SYRCLE's RoB tool and evaluated author consensus using GraphPad v9.5.1. Out of 7,359 search results, 22 papers met the inclusion criteria. Inter-rater reliability among reviewers was assessed using Cohen's kappa statistics.

Conclusion

This review summarizes 22 preclinical studies on Nitroglycerin (NTG), NLRP3, MMP9, and related biomarkers in migraine. They reveal that NTG, especially at 10 mg/kg, consistently induces migraine-like symptoms in rodents by activating NLRP3 inflammasome and stimulating proinflammatory molecule production.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/, CRD42022355893.

Effects of electroacupuncture on treatment-resistant chronic migraine with medication overuse headache: A 12-month follow-up case report

Background

Medication overuse headache (MOH) is a secondary headache disorder that leads to pronounced disability and decreased quality of life. Available therapeutic options for MOH are limited, and many are only effective in a subset of individuals. Although the existing evidence is limited, acupuncture may be an effective treatment option for MOH.

Case presentation

A 45-year-old Chinese woman presented to the Medical Acupuncture Department of Sanming Integrated Traditional Chinese and Western Medicine Hospital on April 11, 2022. Thirty-five years ago, she had episodic migraines. The frequency increased over time, however, and for the past 10 years she has had daily headaches. These headaches were characterized by daily persistent throbbing pain on the left side of the patient's head, accompanied by photophobia, phonophobia, neck stiffness, dizziness, and fatigue. Without painkillers, the patient rated her headache intensity as 9 out of 10 on a visual analog scale (0 = no pain, 10 = intolerable pain), and reported that the headaches lasted for up to 7 days or more. With painkillers, the headaches had a reduced intensity (5 of 10), but persisted. The patient had taken 1-3.5 compound aminopyrine phenacetin tablets daily for more than 5 years. Standard conservative therapy (patient education, medication withdrawal, and behavioral intervention) for MOH had failed to improve her symptoms. Before her visit, the patient had headache and engaged in short-term medication use on 30 days per month. The total monthly headache intensity score was 90. The patient's Migraine-Specific Quality of Life Questionnaire (MSQ) score was 33 points, her Hamilton Depression Scale (HAMD) score was 24 points, and her Hamilton Anxiety Scale (HAMA) score was 20 points.

Results

After 48 acupuncture sessions over 24 weeks, the patient completely discontinued short-term analgesic use and the monthly number of headache days and headache intensity score were both reduced by 96.67 % (from 30 to 1 and 90 to 3, respectively), with no adverse effect. Compared with baseline, the MSQ, HAMD, and HAMA scores improved by 45, 17, and 16 points, respectively. At 12 months, the patient's condition remained stable and her MOH had not relapsed.

Conclusion

In the context of the current literature and the present case, electroacupuncture shows promise for the long-term relief of chronic migraine with MOH when other treatments fail.

Environmental enrichment alleviates hyperalgesia by modulating central sensitization in a nitroglycerin-induced chronic migraine model of mice

BACKGROUND

Chronic migraine (CM) is a debilitating neurofunctional disorder primarily affecting females, characterized by central sensitization. Central sensitization refers to the enhanced response to sensory stimulation, which involves changes in neuronal excitability, synaptic plasticity, and neurotransmitter release. Environmental enrichment (EE) can increase the movement, exploration, socialization and other behaviors of mice. EE has shown promising effects in various neurological disorders, but its impact on CM and the underlying mechanism remains poorly understood. Therefore, the purpose of this study was to determine whether EE has the potential to serve as a cost-effective intervention strategy for CM.

METHODS

A mouse CM model was successfully established by repeated administration of nitroglycerin (NTG). We selected adult female mice around 8 weeks old, exposed them to EE for 2 months, and then induced the CM model. Nociceptive threshold tests were measured using Von Frey filaments and a hot plate. The expression of c-Fos, calcitonin gene-related peptide (CGRP) and inflammatory response were measured using WB and immunofluorescence to evaluate central sensitization. RNA sequencing was used to find differentially expressed genes and signaling pathways. Finally, the expression of the target differential gene was investigated.

RESULTS

Repeated administration of NTG can induce hyperalgesia in female mice and increase the expression of c-Fos and CGRP in the trigeminal nucleus caudalis (TNC). Early exposure of mice to EE reduced NTG-induced hyperalgesia in CM mice. WB and immunofluorescence revealed that EE inhibited the overexpression of c-Fos and CGRP in the TNC of CM mice and alleviated the inflammatory response of microglia activation. RNA sequencing analysis identified that several central sensitization-related signaling pathways were altered by EE. VGluT1, a key gene involved in behavior, internal stimulus response, and ion channel activity, was found to be downregulated in mice exposed to EE.

CONCLUSION

EE can significantly ameliorate hyperalgesia in the NTG-induced CM model. The mechanisms may be to modulate central sensitization by reducing the expression of CGRP, attenuating the inflammatory response, and downregulating the expression of VGluT1, etc., suggesting that EE can serve as an effective preventive strategy for CM.

Meningeal mast cell-mediated mechanisms of cholinergic system modulation in neurogenic inflammation underlying the pathophysiology of migraine

Growing evidence indicates that the parasympathetic system is implicated in migraine headache. However, the cholinergic mechanisms in the pathophysiology of migraine remain unclear. We investigated the effects and mechanisms of cholinergic modulation and a mast cell stabilizer cromolyn in the nitroglycerin-induced in vivo migraine model and in vitro hemiskull preparations in rats. Effects of cholinergic agents (acetylcholinesterase inhibitor neostigmine, or acetylcholine, and muscarinic antagonist atropine) and mast cell stabilizer cromolyn or their combinations were tested in the in vivo and in vitro experiments. The mechanical hyperalgesia was assessed by von Frey hairs. Calcitonin gene-related peptide (CGRP) and C-fos levels were measured by enzyme-linked immunosorbent assay. Degranulation and count of meningeal mast cells were determined by toluidine-blue staining. Neostigmine augmented the nitroglycerin-induced mechanical hyperalgesia, trigeminal ganglion CGRP levels, brainstem CGRP, and C-fos levels, as well as degranulation of mast cells in vivo. Atropine inhibited neostigmine-induced additional increases in CGRP levels in trigeminal ganglion and brainstem while it failed to do this in the mechanical hyperalgesia, C-fos levels, and the mast cell degranulation. However, all systemic effects of neostigmine were abolished by cromolyn. The cholinergic agents or cromolyn did not alter basal release of CGRP, in vitro, but cromolyn alleviated the CGRP-inducing effect of capsaicin while atropine failed to do it. These results ensure for a first time direct evidence that endogenous acetylcholine contributes to migraine pathology mainly by activating meningeal mast cells while muscarinic receptors are involved in CGRP release from trigeminal ganglion and brainstem, without excluding the possible role of nicotinic cholinergic receptors.

Role of neuropeptides in orofacial pain: A literature review

BACKGROUND

Neuropeptides play a critical role in regulating pain and inflammation. Despite accumulating evidence has further uncovered the novel functions and mechanisms of different neuropeptides in orofacial pain sensation and transmission, there is deficient systematic description of neuropeptides' pain modulation in the orofacial region, especially in the trigeminal system.

OBJECTIVES

The present review aims to summarise several key neuropeptides and gain a better understanding of their major regulatory roles in orofacial inflammation and pain.

METHODS

We review and summarise current studies related to calcitonin gene-related peptide (CGRP), substance P (SP), opioid peptide (OP), galanin (GAL) and other neuropeptides' functions and mechanisms as well as promising targets for orofacial pain control.

RESULTS

A number of neuropeptides are clearly expressed in the trigeminal sensory system and have critical functions in the transduction and pathogenesis of orofacial pain. The functions, possible cellular and molecular mechanisms have been introduced and discussed. Neuropeptides and their agonists or antagonists which are widely studied to be potential treatment options of orofacial pain has been evaluated.

CONCLUSIONS

Various neuropeptides play important but distinct (pro-nociceptive or analgesic) roles in orofacial pain with different mechanisms. In summary, CGRP, SP, NPY, NKA, HK-1, VIP mainly play proinflammatory and pro-nociceptive effects while OP, GAL, OXT, OrxA mainly have inhibitory effects on orofacial pain.

Analysis of the ocular surface functional unit in episodic migraine

AIM

Migraine is a chronic neurovascular disease that affects the trigeminovascular system. The purpose of this study was to evaluate corneal subbasal nerve fibers, dendritic cells and to measure tear film parameters in migraine.

PATIENTS AND METHODS

87 eyes of 44 patients suffering from migraine with a mean age of 33.23 ± 11.41 years were included in our study. 25 age-matched controls (mean age of 30.16 ± 12.59 years; P = 0.162) were recruited. The corneal subbasal plexus and the dendritic cells (DC) were analyzed using in vivo confocal microscopy (Heidelberg Retina Tomograph II Rostock Cornea Module; Heidelberg Engineering GmbH), and the tear film was imaged using LacryDiag (Quantel Medical, France).

RESULTS

Regarding the subbasal nerve fibers of the cornea, none of the examined parameters differed significantly in migraine patients from controls. We found a significant increase in the corneal DC density (P < 0.0001) and DC area (P < 0.0001) in migraine patients compared to healthy volunteers. DC density showed a positive correlation with the monthly attack frequency (r = 0.32, P = 0.041) and the DC area a negative correlation with corneal nerve branch density (r = -0.233, P = 0.039), nerve fiber length (r = -0.232, P = 0.04) and total branch density (r = -0.233, P = 0.039). Using LacryDiag a significant loss of Meibomian gland area could be detected on the superior eyelid (P = 0.005) in migraine.

CONCLUSIONS

Our results suggest the presence of neuroinflammation in the cornea of migraine patients affecting the peripheral trigeminal system. Dendritic cells surrounding the subbasal plexus may be involved in the activation and modulation of pain in migraine.

Real-world effectiveness and satisfaction with intravenous eptinezumab treatment in patients with chronic migraine: REVIEW, an observational, multi-site, US-based study

BACKGROUND

Despite recent advancements in migraine treatment, some patients continue to endure significant disease burden. Due to the controlled nature of randomized trials in migraine prevention, many real-world patients with comorbidities or prior exposure to certain therapies are excluded. Capturing evidence of the effectiveness of treatment in real-world clinical settings can further shape treatment paradigms. The objective of this study was to develop a comprehensive understanding of both patients' and physicians' real-world experiences with eptinezumab for chronic migraine (CM).

METHODS

REVIEW (Real-world EVidence and Insights into Experiences With eptinezumab) is an observational, multi-site (n = 4), US-based study designed to evaluate real-world experiences of patients treated with eptinezumab and their treating physicians. Patients were ≥ 18 years of age, with a diagnosis of CM, who had completed ≥ 2 consecutive eptinezumab infusion cycles (≥ 6 months of exposure). The study included a retrospective chart review, a patient survey, and a semi-structured physician interview that assessed patient and/or physician satisfaction with elements of daily living / well-being, migraine symptomology, and perspectives of the eptinezumab infusion experience.

RESULTS

Of the 94 patients enrolled, 83% (78/94) were female, the mean age was 49.2 years, and the mean time since migraine diagnosis was 15.4 years. Before eptinezumab treatment, patients experienced a mean of 8 self-reported "good" days/month, which increased to 18 after treatment. Most patients took, on average, ≥ 10 days/month of prescription and/or over-the-counter medication (81% [75/93] and 66% [61/93], respectively) to treat migraine attacks before eptinezumab treatment, which dropped to 26% (24/93) and 23% (21/93) following eptinezumab treatment. Prior to receiving eptinezumab, 62% (58/93) of patients indicated being at least slightly concerned about infusions; after eptinezumab infusion, this dropped to 14% (13/93). These patient survey findings were consistent with physician responses.

CONCLUSION

This real-world evidence study demonstrated high overall satisfaction with the effectiveness of eptinezumab treatment for CM among most patients and their physicians.

Calcitonin gene-related peptide: a possible biomarker in migraine patients with patent foramen ovale

BACKGROUND

Serum CGRP has been found to increase during migraine attack. However, whether CGRP can identify MA with PFO subtypes in MA remains unknown. This study aimed to investigate the differential expression of calcitonin gene-related peptide (CGRP) between migraine (MA) patients with and without patent foramen ovale (PFO), and to evaluate the predictive value of CGRP for MA with PFO.

METHODS

A total of 153 patients with MA, 51 patients with PFO and 102 patients without. Venous blood was drawn and HIT-6 score was calculated during the onset of MA, and blood routine, inflammatory indexes and serum CGRP were detected. The differences in serum markers and HIT-6 scores were compared between the two groups, and the risk factors of MA with PFO were determined by univariate and multivariate logistics regression. Furthermore, the correlation between CGRP level with right-to-left shunt (RLS) grades and headache impact test-6 (HIT-6) score in MA patients with PFO were assessed. Independent risk factors were screened out by multivariate Logistic regression analysis. We used the receiver operating characteristic (ROC) curve to analyze the diagnostic value of these risk factors in MA complicated with PFO.

RESULTS

The serum CGRP level and HIT-6 scores in the MA with PFO group were significantly higher than those in the MA group (P < 0.001). Multivariate regression analysis showed that CGRP was an independent risk factor for MA with PFO (OR = 1.698, 95% CI = 1.325-2.179, P < 0.001). CGRP values ​​increased with the increase of RLS grade(Spearmen rho = 0.703, P < 0.001). Furthermore, a positive correlation between CGRP and HIT-6 scores was found (Spearmen rho = 0.227; P = 0.016). ROC curve showed that the optimal cut-off value for diagnosing MA with PFO was 79 pg/mL, the area under the curve (AUC) for predicting MA with PFO was 0.845, with 72.55% sensitivity and 78.43% specificity.

CONCLUSIONS

MA patients with PFO have higher serum CGRP level. elevated CGRP concentration was associated with higher RLS grade and increased HIT-6 score. Higher serum CGRP level has certain clinical value in predicting PFO in MA patients.

TRIAL REGISTRATION

This study was approved by the Ethics Committee of Zhuhai Hospital of Integrated Traditional Chinese and Western Medicine (Ethics batch number: 20,201,215,005).

Unveiling the therapeutic potential of Dl-3-n-butylphthalide in NTG-induced migraine mouse: activating the Nrf2 pathway to alleviate oxidative stress and neuroinflammation

BACKGROUND

Migraine stands as a prevalent primary headache disorder, with prior research highlighting the significant involvement of oxidative stress and inflammatory pathways in its pathogenesis and chronicity. Existing evidence indicates the capacity of Dl-3-n-butylphthalide (NBP) to mitigate oxidative stress and inflammation, thereby conferring neuroprotective benefits in many central nervous system diseases. However, the specific therapeutic implications of NBP in the context of migraine remain to be elucidated.

METHODS

We established a C57BL/6 mouse model of chronic migraine (CM) using recurrent intraperitoneal injections of nitroglycerin (NTG, 10 mg/kg), and prophylactic treatment was simulated by administering NBP (30 mg/kg, 60 mg/kg, 120 mg/kg) by gavage prior to each NTG injection. Mechanical threshold was assessed using von Frey fibers, and photophobia and anxious behaviours were assessed using a light/dark box and elevated plus maze. Expression of c-Fos, calcitonin gene-related peptide (CGRP), Nucleus factor erythroid 2-related factor 2 (Nrf2) and related pathway proteins in the spinal trigeminal nucleus caudalis (SP5C) were detected by Western blotting (WB) or immunofluorescence (IF). The expression of IL-1β, IL-6, TNF-α, Superoxide dismutase (SOD) and malondialdehyde (MDA) in SP5C and CGRP in plasma were detected by ELISA. A reactive oxygen species (ROS) probe was used to detect the expression of ROS in the SP5C.

RESULTS

At the end of the modelling period, chronic migraine mice showed significantly reduced mechanical nociceptive thresholds, as well as photophobic and anxious behaviours. Pretreatment with NBP attenuated nociceptive sensitization, photophobia, and anxiety in the model mice, reduced expression levels of c-Fos and CGRP in the SP5C and activated Nrf2 and its downstream proteins HO-1 and NQO-1. By measuring the associated cytokines, we also found that NBP reduced levels of oxidative stress and inflammation. Most importantly, the therapeutic effect of NBP was significantly reduced after the administration of ML385 to inhibit Nrf2.

CONCLUSIONS

Our data suggest that NBP may alleviate migraine by activating the Nrf2 pathway to reduce oxidative stress and inflammation in migraine mouse models, confirming that it may be a potential drug for the treatment of migraine.

Medication "underuse" headache

BACKGROUND

Many risk factors have been associated with migraine progression, including insufficient and ineffective utilization of migraine medications; however, they have been inadequately explored. This has resulted in suboptimal usage of medications without effective altering of prescribing recommendations for patients, posing a risk for migraine chronification.

METHODS

Our aim is to conduct a comprehensive review of the available evidence regarding the underuse of migraine medications, both acute and preventive. The term "underuse" includes, but is not limited to: (1) ineffective use of appropriate and inappropriate medication; (2) underutilization; (3) inappropriate timing of usage; and (4) patient dissatisfaction with medication.

RESULTS

The underuse of both acute and preventive medications has been shown to contribute to the progression of migraine. In terms of acute medication, chronification occurs as a result of insufficient drug use, including failure of the prescriber to select the appropriate type based on pain intensity and disability, patients taking medication too late (more than 60 minutes after the onset or after central sensitization has occurred as evidenced by allodynia), and discontinuation because of lack of effect or intolerable side effects. The underlying cause of inadequate effectiveness of acute medication lies in its inability to halt the propagation of peripheral activation to central sensitization in a timely manner. For oral and injectable preventive migraine medications, insufficient efficacy and intolerable side effects have led to poor adherence and discontinuation with subsequent progression of migraine. The underlying pathophysiology here is rooted in the repetitive stimulation of afferent sensory pain fibers, followed by ascending brainstem pain pathways plus dysfunction of the endogenous descending brainstem pain inhibitory pathway. Although anti-calcitonin gene-related peptide (CGRP) medications partially address pain caused by the above factors, including decreased efficacy and tolerability from conventional therapy, some patients do not respond well to this treatment. Research suggests that initiating preventive anti-CGRP treatment at an early stage (during low frequency episodic migraine attacks) is more beneficial than commencing it during high frequency episodic attacks or when chronic migraine has begun.

CONCLUSIONS

The term "medication underuse" is underrecognized, but it holds significant importance. Optimal usage of acute care and preventive migraine medications could potentially prevent migraine chronification and improve the treatment of migraine attacks.

Migraine and the microbiota. Can probiotics be beneficial in its prevention? - a narrative review

Migraine is a recurrent disease of the central nervous system that affects an increasing number of people worldwide causing a continuous increase in the costs of treatment. The mechanisms underlying migraine are still unclear but recent reports show that people with migraine may have an altered composition of the intestinal microbiota. It is well established that the gut-brain axis is involved in many neurological diseases, and probiotic supplementation may be an interesting treatment option for these conditions. This review collects data on the gastrointestinal and oral microbiota in people suffering from migraine and the use of probiotics as a novel therapeutic approach in its treatment.

Is calcitonin gene-related peptide (CGRP) the missing link in food histamine-induced migraine? A review of functional gut-to-trigeminovascular system connections

Calcitonin gene-related peptide (CGRP) and histamine plasma concentrations increase during migraine attacks. Both mediators are potent vasodilators, and they have been shown to reciprocally contribute to the release of each other in the trigeminovascular system, possibly driving migraine development. A high-histamine-content diet triggers migraine in patients who have histamine degradation deficiency owing to diaminooxidase (DAO) gene mutations. Therefore, studying functional links between exogenous histamine and CGRP seems promising for the understanding of diet-induced migraine generation. Notably, there is a lack of knowledge about the interplay of the enteric nervous system and the spinal/trigeminal somatosensory system with regard to CGRP and histamine. Based on background evidence, we propose that a functional interconnection between exogenous histamine and CGRP contributes to migraine development.

Restoring brain health: Electroacupuncture at GB20 and LR3 for migraine mitigation through mitochondrial restoration

BACKGROUND

Electroacupuncture (EA) is a promising alternative therapy for migraine, with mitochondrial dysfunction hypothesized as a pivotal mechanism in migraine pathophysiology. This research endeavors to investigate the therapeutic potential of EA in addressing migraines and shed light on the associated mechanisms linked to mitochondrial anomalies.

MATERIALS AND METHODS

Migraine in rats was induced by 10 mg/kg nitroglycerin, followed by 2/15 Hz EA treatment at GB20 and LR3. Nociceptive behavior was recorded via a camera and analyzed using EthoVision XT 12.0 software. The hind-paw withdrawal threshold was assessed using the von Frey test. We assessed the levels of calcitonin gene-related peptide (CGRP), nitric oxide (NO), and endothelin (ET) - key parameters in migraine pathophysiology using immunohistochemistry and enzyme-linked immunosorbent assay. Mitochondrial morphology in brain tissues was observed through transmission electron microscopy. Reactive oxygen species (ROS) level in mitochondria was measured by flow cytometry. The levels of PINK1 and Parkin were assessed using Western blot analysis.

RESULTS

EA at GB20 and LR3 decreased nociceptive behaviors (resting and grooming) and increased exploratory and locomotor behaviors in migraine rats. The hind-paw withdrawal threshold in migraine rats was significantly elevated following EA treatment. Post-EA treatment, levels of CGRP and NO decreased, while ET level increased, suggesting an alteration in pain and vascular physiology. Notably, EA treatment mitigated the mitochondrial damage and reduced ROS level in the brain tissues of migraine rats. EA treatment upregulated the expression of PINK1 and Parkin in migraine rats.

CONCLUSION

EA at GB20 and LR3 may treat migraine by alleviating PINK1/Parkin-mediated mitochondrial dysfunction.

Cellular and molecular mechanisms involved in the analgesic effects of botulinum neurotoxin: A literature review

Botulinum neurotoxins (BoNTs), derived from Clostridium botulinum, have been employed to treat a range of central and peripheral neurological disease. Some studies indicate that BoNT may be beneficial for pain conditions as well. It has been hypothesized that BoNTs may exert their analgesic effects by preventing the release of pain-related neurotransmitters and neuroinflammatory agents from sensory nerve endings, suppressing glial activation, and inhibiting the transmission of pain-related receptors to the neuronal cell membrane. In addition, there is evidence to suggest that the central analgesic effects of BoNTs are mediated through their retrograde axonal transport. The purpose of this review is to summarize the experimental evidence of the analgesic functions of BoNTs and discuss the cellular and molecular mechanisms by which they can act on pain conditions. Most of the studies reviewed in this article were conducted using BoNT/A. The PubMed database was searched from 1995 to December 2022 to identify relevant literature.