Migraine pathophysiology: anatomy of the trigeminovascular pathway and associated neurological symptoms, CSD, sensitization and modulation of pain

Mechanistic approach and therapeutic strategies in menstrual and non-menstrual migraine

Migraine is a common condition that can cause intense headaches, often on one side of the head, along with symptoms like nausea and sensitivity to light and sound. These headaches can be triggered by various factors, including stress, changes in hormones, sleep disturbances, diet, and even gut health. Migraines are more frequent in women, particularly those under 45, and this may be linked to hormones. After age 45, this difference between men and women becomes less noticeable. Women tend to experience migraines that are more severe and last longer than men, with menstrual migraines affecting about 22% of women during nearly half of their menstrual cycles, and 7.6% of women with migraines. Treatments for migraines include medications, lifestyle changes, and alternative therapies, all of which aim to address the different ways migraines can affect people. This review explores these aspects in detail.

Association of health-related factors with self-reported sleep and awake bruxism in Northern Finland Birth Cohort 1966 - a cross-sectional study

OBJECTIVE

The study aimed to investigate the association of sleep bruxism (SB) and awake bruxism (AB) with health-related factors.

METHODS

Data on bruxism and diagnosed diseases, use of psychoactive substances and regular identified psychoactive drugs were collected from 1,962 subjects in the Northern Finland Birth Cohort 1966 through a questionnaire. The associations were analyzed using chi-square tests and binary regression models, adjusting for gender and education, and for anxiety/depression symptoms.

RESULTS

Migraine and gastric/duodenal disorders, use of serotonergic antidepressants and a high number of psychoactive drugs associated significantly with AB and SB. Gastrointestinal diseases associated with SB. Poor general health and hand eczema associated with AB. Based on the multivariate model, depression/anxiety symptoms seemed to mediate the associations of bruxism with depression, hand eczema, self-reported gastric/duodenal disorders and the number of identified drugs.

CONCLUSION

Several diseases, depression/anxiety symptoms and psychoactive medications were associated with SB and AB, the associations being stronger with AB than SB.

Identifying signals of disproportionate reporting for calcitonin gene-related peptide inhibitors: real-world evidence from the FDA adverse event reporting system

BACKGROUND

Calcitonin gene-related peptide (CGRP) inhibitors have been FDA-approved for migraine prophylaxis and relief. However, their safety profile remains uncertain. This study analyzes adverse events (AEs) and signals of disproportionate reporting (SDRs) using the FDA Adverse Event Reporting System (FAERS).

RESEARCH DESIGN AND METHODS

We analyzed FAERS reports from approval through Q2 2023, standardizing terms using preferred terminology and system organ class (SOCs) classifications. Disproportionality analyses (ROR, PRR, IC) identified SDRs and inclusion in FDA prescribing information was reviewed. Additional analyses included comparisons with other migraine drugs, indication-based sensitivity analyses and causality assessment using the Bradford Hill framework.

RESULTS

Galcanezumab showed strong signals for underdose (ROR 47.4; 95% CI 43.79-51.3), alopecia (5.72; 5.09-6.43), and constipation (6.01; 5.35-6.75), while fremanezumab exhibited notable associations with alopecia (6.9; 5.72-8.33) and weight increased (6.34; 5.18-7.76). Among gepants, rimegepant was linked to somnolence (4.52; 3.57-5.73) and dizziness (3.73; 3.15-4.42) and atogepant showed a strong signal for therapy interruption (16.58; 12.86-21.38).

CONCLUSIONS

This study highlights CGRP inhibitor-associated AEs, underscoring the need for clinical monitoring and risk identification. Early detection of AEs and SDRs can inform protective measures to enhance patient safety.

Orofacial Migraine and Neurovascular Orofacial Pain: Response to Treatment-A Pilot Study

Introduction: The International Classification of Orofacial Pain (ICOP) recognizes orofacial migraine (OFM) and neurovascular orofacial pain (NVOP) as migraine-related entities affecting the facial and oral regions. The diagnostic features of OFM and NVOP indicate that there are many similarities between the two. However, we recently demonstrated that NVOP and OFM are two distinct diagnostic entities, confirming the ICOP classification. It was the aim of the present study to examine whether OFM and NVOP differ in response to pharmacotherapy. Materials and Methods: The cohort was made up of 40 patients attending a tertiary orofacial pain clinic. When implementing ICOP criteria, an OFM diagnosis was made in 23 and an NVOP diagnosis in 17. Results: No statistically significant differences between NVOP versus OFM were observed in the global response to standard abortive therapy such as triptans, or NSAIDs. Similarly, no statistically significant differences were found following prophylactic therapy that included beta-blockers, anti-epileptic drugs, and tricyclic antidepressants. Up to 80% of patients responded favorably with ≥50% pain reduction. Conclusions: NVOP and OFM differ in diagnostic characteristics, demonstrating unique features, and were confirmed as two diagnostic entities. However, NVOP and OFM did not differ in their response to abortive or prophylactic treatments. Study limitations include the lack of starting data precluding a more precise pharmacological analysis. The small sample size limits any far reaching conclusions. This is particularly true regarding individual drug efficacy. We were unable to analyze drug and dose responses separately due to data constraints.

The effects of concurrent alpha-linolenic acid, L-carnitine supplementation on clinical symptoms, mental health, and quality of life in women with migraine: a randomized, triple-blind, placebo-controlled trial

BACKGROUND

Migraine, as a widespread neurological condition, substantially impacts quality of life, particularly among women. Therefore, this study aimed to explore the potential effects of alpha-linolenic acid (ALA) and L-carnitine co-supplementation on migraine symptoms, mental health, and life quality in women with migraine.

METHODS

In this randomized, triple-blind, placebo-controlled trial, 80 women with migraine were randomly assigned to receive either ALA (1000 mg) plus L-carnitine (500 mg) or matching placebos daily for 12 weeks. Migraine characteristics, mental health parameters, and quality of life measures were assessed at baseline and study end.

RESULTS

The intervention group demonstrated a significant reduction in migraine frequency (-2.96; 95% CI (-3.48, -2.45) vs -0.07; 95% CI (-0.68, 0.53), P < 0.001), severity (-1.6; 95% CI (-2.05, -1.15) vs - 0.44; 95% CI (-0.91, 0.02), P = 0.001), and duration (-4.9; 95% CI (-6.34, -3.45) vs -0.5; 95% CI (-1.06, 0.66) hours, P < 0.001) compared to the placebo group. Mental health improvements were observed in depression (-7.4; 95% CI (-9.24, -5.55) vs 0.05; 95% CI (-1.16, 1.26), P < 0.001), and anxiety scores (-5.7; 95% CI (-7.26, -4.14) vs - 0.65; 95% CI (-2.33, 1.03), P < 0.001). Quality of life measures showed significant enhancement, with increased migraine-specific quality of life (9.75; 95% CI (8.01, 11.49) vs 1.22; 95% CI (-0.66, 3.11), P < 0.001) and decreased headache impact test-6 scores (-8.57; 95% CI (-11.79, -5.36) vs -1.35; 95% CI (-3.41, 0.71), P = 0.005) in the intervention group compared to the controls.

CONCLUSION

Co-supplementation with ALA and L-carnitine may offer a promising adjuvant therapy for managing migraine in women, addressing both physical symptoms and psychological burdens.

TRIAL REGISTRATION

IRCT20121216011763N57.

Characterisation of periorbital mechanical allodynia in the reserpine-induced fibromyalgia model in mice: The role of the Schwann cell TRPA1/NOX1 signalling pathway

Fibromyalgia (FM) is a complex and multifaceted condition characterized by a range of clinical symptoms, including widespread pain and a strong association with migraine headaches. Recent findings have underscored the role of oxidative stress and transient receptor potential ankyrin 1 (TRPA1) channel in migraine and FM. However, the precise mechanisms underlying the comorbidity between migraine and FM are unclear. Periorbital mechanical allodynia (PMA), which recapitulates one of the major symptoms of migraine, and the feed-forward mechanism driven by reactive oxygen species and TRPA1, were investigated in a reserpine-induced FM model in C57BL/6J mice, employing pharmacological interventions and genetic approaches. Reserpine-treated mice developed PMA (which was alleviated by antimigraine drugs) and increased endoneurial macrophages and oxidative stress markers in the trigeminal nerve tissues (neuroinflammation). These responses were absent upon macrophage depletion and by pharmacological inhibition or global genetic deletion of the TRPA1 channel. Furthermore, selective silencing of TRPA1 in Schwann cells attenuated both reserpine-induced PMA and neuroinflammation, while selective silencing of TRPA1 in sensory neurons reduced PMA but not neuroinflammation. In reserpine-treated mice, Schwann cell TRPA1 promoted NADPH oxidase 1-mediated reactive oxygen species generation and macrophage density increase in the mouse trigeminal nerve, which sustains PMA. Targeting TRPA1 channels in Schwann cells could offer a novel therapeutic strategy for FM-related headaches.

Optogenetic cortical spreading depression originating from the primary visual cortex induces migraine-like pain and anxiety behaviors in freely moving C57BL/6 J mice

BACKGROUND

Migraine is the second disabling neurological disorder with a high prevalence. Aura occurs in one-third of migraineurs and visual aura accounts for over 90%. Cortical spreading depression (CSD) underlies aura and might trigger migraine headaches. Compared with CSD induction by invasive electrical, chemical, or mechanical stimulation, optogenetics avoids direct influences on meninges in the stimulation process. However, previous optogenetic CSD models mainly use Thy1-ChR2-YFP or CaMKIIα-cre transgenic mice. They are limited when the pathogenesis study requires transgenic mice to express other specific promotor, such as the dopamine or serotonin transporter promotor. In addition, reported behavioral paradigms were based on CSD induction under anesthesia. This study aimed to establish an optogenetic CSD-induced migraine model originating in the primary visual cortex (VISp) in C57BL/6 J mice and presented the behavioral paradigm when CSD induction was under awake condition.

METHODS

We performed viral transduction for the expression of light-sensitive channelrhodopsin-2 in pyramidal neurons of VISp in C57BL/6 J mice. Regional cerebral blood flow (rCBF) was measured by laser speckle flowmetry to confirm CSD induction. The von Frey, light-dark box, elevated plus maze, and open field test were conducted to verify migraine-related behaviors in freely moving mice.

RESULTS

An optogenetic stimulus induced typical spreading triphasic rCBF change with a reduction of over 20%, confirming CSD induction. A single unilateral CSD in freely moving C57BL/6 J mice triggered bilateral periorbital and hind-paw allodynia lasting for 4-24 h. Notably, the ipsilateral periorbital mechanical threshold was significantly lower than the contralateral at 1 h. It also generated photophobia and anxiety behaviors persisting for 24-48 h. Furthermore, cutaneous allodynia and anxiety behaviors were alleviated by sumatriptan.

CONCLUSIONS

This study proposes an optogenetic CSD-induced migraine model originating from VISp in awake and freely moving C57BL/6 J mice and presents the behavioral paradigm in detail. The CSD model in wild-type mice is promising to be wildly used to study the pathogenesis of MwA.

Sex difference in TRPM3 channel functioning in nociceptive and vascular systems: an emerging target for migraine therapy in females?

Transient Receptor Potential Melastatin 3 (TRPM3) channels are Ca2+ permeable ion channels that act as polymodal sensors of mechanical, thermal, and various chemical stimuli. TRPM3 channels are highly expressed in the trigeminovascular system, including trigeminal neurons and the vasculature. Their presence in dural afferents suggests that they are potential triggers of migraine pain, which is originating from the meningeal area. This area is densely innervated by autonomous and trigeminal nerves that contain the major migraine mediator calcitonin gene-related peptide (CGRP) in peptidergic nerve fibers. Co-expression of TRPM3 channels and CGRP receptors in meningeal nerves suggests a potential interplay between both signalling systems. Compared to other members of the TRP family, TRPM3 channels have a high sensitivity to sex hormones and to the endogenous neurosteroid pregnenolone sulfate (PregS). The predominantly female sex hormones estrogen and progesterone, of which the levels drop during menses, act as natural inhibitors of TRPM3 channels, while PregS is a known endogenous agonist of these channels. A decrease in sex hormone levels has also been suggested as trigger for attacks of menstrually-related migraine. Notably, there is a remarkable sex difference in TRPM3-mediated effects in trigeminal nociceptive signalling and the vasculature. In line with this, the relaxation of human isolated meningeal arteries induced by the activation of TRPM3 channels is greater in females. Additionally, the sex-dependent vasodilatory responses to CGRP in meningeal arteries seem to be influenced by age-related hormonal changes, which could contribute to sex differences in migraine pathology. Consistent with these observations, activation of TRPM3 channels triggers nociceptive sensory firing much more prominently in female than male mouse meninges, suggesting that pain processing in female patients with migraine may differ. Overall, the combined TRPM3-related neuronal and vascular mechanisms could provide a possible explanation for the higher prevalence and even the more severe quality of migraine attacks in females. This narrative review summarizes recent data on the sex-dependent roles of TRPM3 channels in migraine pathophysiology, the potential interplay between TRPM3 and CGRP signalling, and highlights the prospects for translational therapies targeting TRPM3 channels, which may be of particular relevance for women with migraine.

Altered white matter microstructural integrity in patients with postherpetic neuralgia: a combined DTI and DTI-NODDI study

Background

Postherpetic neuralgia (PHN) is a debilitating condition resulting from herpes zoster infection, characterized by persistent pain that significantly impacts quality of life. This study aimed to investigate the white matter microstructural alterations associated with PHN and to assess the relationship between diffusion metrics and clinical symptoms.

Methods

A total of 29 patients with PHN, 28 patients recovering from herpes zoster (RHZ), and 27 healthy controls (HC) were recruited, and clinical assessments were obtained to evaluate pain intensity and psychological distress. Diffusion tensor imaging (DTI) data was collected, followed by analysis of diffusion and neurite orientation dispersion and density imaging (NODDI) metrics. Statistical analyses included ANOVA to compare groups and Pearson correlation coefficients to assess relationships between imaging metrics and clinical outcomes.

Results

PHN patients exhibited significantly altered white matter integrity, specifically in neurite density index (NDI) and orientation dispersion index, compared to both RHZ patients and HC. Significant correlations were also found between altered imaging metrics and clinical assessments of pain and emotional distress, with lower fractional anisotropy (FA) and NDI associated with higher pain scores and psychological symptoms.

Conclusion

Our study highlights significant microstructural changes in white matter tracts in patients with PHN, indicating compromised neural integrity that correlates with increased pain perception and emotional distress. NODDI demonstrated superior sensitivity in detecting these alterations compared to traditional DTI metrics, underscoring its potential for enhancing diagnostic and therapeutic approaches in managing chronic pain conditions like PHN.

The 5-HT1F Receptor Agonist Lasmiditan improves Cognition and Ameliorates Associated Cortico-Hippocampal Pathology in Aging Parkinsonian Mice

While the etiopathology of Parkinson's disease (PD) is complex, mitochondrial dysfunction is established to have a central role. Thus, mitochondria have emerged as targets of therapeutic interventions aiming to slow or modify PD progression. We have previously identified serotonergic 5-HT1F receptors as novel mediators of mitochondrial biogenesis (MB) - the process of producing new mitochondria. Given this, here, we assessed the therapeutic potential of the FDA-approved 5-HT1F receptor agonist, lasmiditan, in a chronic progressive PD model (Thy1-aSyn 'line 61' mice). It was observed that systemic lasmiditan exhibited robust brain penetration and reversed cognitive deficits in young (4-5.5 months old) Thy1-aSyn mice (1mg/kg, every other day). Anxiety-like behavior was also improved while motor function remained unaffected. These behavioral changes were associated with enhanced MB and mitochondrial function, paired with reduced alpha-synuclein aggregation particularly in cortico-hippocampal regions. Furthermore, in older (10-11.5 months old) mice, although the effects were milder, daily lasmiditan administration increased MB and bettered cognitive abilities. In essence, these findings indicate that repurposing lasmiditan could be a potent strategy to address PD-related cognitive decline.

Framing and Management of Migraines in Women: An Expert Opinion on Challenges, Current Approaches, and Future Multidisciplinary Perspectives

Background/Objectives: Migraines are a common neurological disorder that significantly impact women, especially during their reproductive years. Hormonal, neurological, and lifestyle factors shape migraine patterns, with fluctuations during menstruation, pregnancy, perimenopause, and menopause influencing migraine prevalence and severity. This expert opinion explores current challenges, therapeutic strategies, and future directions for personalized care, addressing the limited inclusion of women in clinical research across different life stages. Methods: In order to focus on hormonal influences, pharmacological and non-pharmacological therapies, including CGRP monoclonal antibodies, neuromodulation, and lifestyle interventions, a comprehensive analysis of literature, in particular on clinical trials, real-world studies, and guidelines on migraine management was performed. Emerging digital tools and AI-based approaches were also evaluated to improve personalized care for women with migraine. Results: Hormonal therapies, including contraceptives and HRTs, present both risks and benefits, particularly for women with migraines with aura, highlighting the need for individualized approaches. Advances in CGRP-targeted therapies have shown effectiveness in preventing refractory migraines. Non-pharmacological treatments, such as neuromodulation, acupuncture, and lifestyle adjustments, further expand the treatment landscape. However, research gaps remain, particularly regarding hormonal influences on migraines during pregnancy and menopause. Conclusions: Future research should prioritize female-specific clinical trials to better understand the impact of hormonal changes on migraines. Tailored therapies combining pharmacological, non-pharmacological, and digital solutions are essential for improving care. A multidisciplinary approach integrating personalized medicine, technological advancements, and patient education is crucial to optimizing outcomes and enhancing quality of life for women with migraine.

From the latin "re-cordis, passing through the heart": autonomic modulation differentiates migraineurs from controls when recounting a significant life event

OBJECTIVE

The literature on clinical psychophysiology highlights the possibility of using Heart Rate Variability (HRV) as an index of psychophysical balance and resilience to stress. This study investigates the differences in stress reactivity and subsequent recovery between a group of migraineurs and healthy controls.

METHODS

Socio-demographic (i.e., sex, age, profession, marital status, and level of education) and psychophysiological (HR and HRV) measures of a group of thirty subjects with migraine (26 migraineurs without aura (86.7%), 2 migraineurs with aura (6.7%), and 2 migraineurs with and without aura (6.7%)) and from thirty healthy control subjects were collected. In particular, HRV was analyzed through frequency-domain parameters, including Low-Frequency (LF; 0.04-0.15 Hz) and High-Frequency (HF; 0.15-0.4 Hz) bands as well as LF/HF ratio during a Psychophysiological Stress Profile (PSP) structured in seven phases: (1) Baseline, (2) Objective stressor 1 (Stroop Test), (3) Rest 1, (4) Objective stressor 2 (Mental Arithmetic Task), (5) Rest 2, (6) Subjective stressor (recount a significant life event), and (7) Rest 3. The LF, HF, and LF/HF ratio values were transformed into a logarithmic scale (i.e., log-LF, log-HF, and log LF/HF ratio). Additionally, LF and HF were converted into normalized units (0-100) (i.e., LF% and HF%) which, in turn, were used to obtain reactivity and recovery to stress through delta values (Δ) calculation.

RESULTS

Subjects with migraine reported greater ΔLF% levels of reactivity and recovery to subjective stressor, demonstrating a prevalence of sympathetic activity while recounting a personal life event. At the same time, a lowering of the same values was found in the subjects of the group control.

DISCUSSION

Our results underline the importance of conducting a psychophysiological assessment in patients with headaches because reduced stress management skills could influence the clinical manifestations of the disease, considering stress as one of the most common triggers for migraine patients.

Mitochondrial dysfunction in trigeminal ganglion contributes to nociceptive behavior in a nitroglycerin-induced migraine mouse model

Migraine is a chronic episodic neurological disorder. However, its diagnosis and management remain unclear. The pathogenesis of migraine is intricately linked to the dysfunction of mitochondria and aberrant trigeminal neuronal activity. Here, we established a murine migraine model via intraperitoneal administration of nitroglycerin (NTG) to examine alterations in mitochondria-associated proteins and calcium signaling patterns within trigeminal neurons, while also investigating the underlying mechanisms. NTG-treated mice exhibited marked periorbital allodynia, decreased crossing of the central area, and decreased time spent in the central area in the open field test compared to Veh treated animals. Furthermore, increased calcium signaling in response to adenosine triphosphate (ATP) stimulation was observed in the trigeminal ganglion (TG) of mice with migraine. Meanwhile, mRNA levels of genes including nuclear respiratory factor-1 (Nrf1), nuclear respiratory factor-2 (Nrf2) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1) were decreased in the TG. Pharmacological regulation of the mitochondrial function affected NTG-induced migraine chronic pain symptoms. TG mitochondria dysfunctions is implicated in the regulation of mechanical hyperalgesia through the modulation of calcium signaling in an NTG-induced migraine animal model.

Plasma pQTL and brain eQTL integration identifies PNKP as a therapeutic target and reveals mechanistic insights into migraine pathophysiology

BACKGROUND

Migraine is a prevalent neurological disorder affecting 14.1% of the global population. Despite advances in genetic research, further investigation is needed to identify therapeutic targets and better understand its mechanisms. In this study, we aimed to identify drug targets and explore the relationships between gene expression, protein levels, and migraine pathophysiology.

METHODS

We utilized cis-pQTL data from deCODE Genetics, combined with migraine GWAS data from the GERA + UKB cohort as the discovery cohort and the FinnGen R10 cohort as the replication cohort. SMR and MR analyses identified migraine-associated protein loci. Brain eQTL data from GTEx v8 and BrainMeta v2 were used to explore causal relationships between gene expression, protein levels, and migraine risk. Mediation analysis assessed the role of metabolites, and PheWAS evaluated potential side effects.

RESULTS

Four loci were identified: PNKP, MRVI1, CALCB, and INPP5B. PNKP and MRVI1 showed a high level of evidence and opposing effects at the gene and protein levels. PNKP gene expression in certain brain regions was protective against migraine, while its plasma protein levels were positively associated with migraine risk. MRVI1 showed protective effects at the protein level but had the opposite effect at the gene expression level. Mediation analysis revealed that the glutamate to pyruvate ratio and 3-CMPFP mediated PNKP's effects on migraine. PheWAS indicated associations between PNKP and body composition traits, suggesting drug safety considerations.

CONCLUSION

PNKP and MRVI1 exhibit dual mechanisms of action at the gene and protein levels, potentially involving distinct mechanistic pathways. Among them, PNKP emerges as a promising drug target for migraine treatment, supported by multi-layered validation.

Distinct expression profile reveals glia involvement in the trigeminal system attributing to post-traumatic headache

BACKGROUND

Post-traumatic headache (PTH) is a common comorbid symptom affecting at least one-third of patients with mild traumatic brain injury (mTBI). While neuroinflammation is known to contribute to the development of PTH, the cellular mechanisms in the trigeminal system crucial for understanding the pathogenesis of PTH remain unclear.

METHODS

A non-invasive repetitive mTBI (4 times with a 24-h interval) was induced in male mice and effect of mTBI was tested on either bregma or pre-bregma position on the head. Periorbital allodynia and spontaneous pain behavior were assessed using von Frey test and grimace score, respectively. Quantitative PCR was used to assess extent of mTBI pathology. RNA sequencing was performed to obtain transcriptomic profile of the trigeminal ganglion (TG), trigeminal nucleus caudalis (Sp5C) and periaqueductal gray (PAG) at 7 days post-TBI. Subsequently, quantitative PCR, in situ hybridization and immunohistochemistry were used to examine mRNA and protein expression of glia specific markers and pain associated molecules.

RESULTS

The repetitive impacts at the bregma, but not pre-bregma site led to periorbital hypersensitivity, which was correlated with enhanced inflammatory gene expression in multiple brain regions. RNA sequencing revealed mTBI induced distinct transcriptomic profiles in the peripheral TG and central Sp5C and PAG. Using gene set enrichment analysis, positive enrichment of non-neuronal cells in the TG and neuroinflammation in the Sp5C were identified to be essential in the pathogenesis of PTH. In situ assays also revealed that gliosis of satellite glial cells in the TG and astrocytes in the Sp5C were prominent days after injury. Furthermore, immunohistochemical study revealed a close interaction between activated microglia and reactive astrocytes correlating with increased calretinin interneurons in the Sp5C.

CONCLUSIONS

Transcriptomics analysis indicated that non-neuronal cells in peripheral TG and successive in situ assays revealed that glia in the central Sp5C are crucial in modulating headache-like symptoms. Thus, selective targeting of glia cells can be a therapeutic strategy for PTH attributed to repetitive mTBI.

Assessment of White Matter Alterations in Patients of Migraine Using Diffusion Tensor Imaging

BACKGROUND

Vascular hypotheses was previously considered to play a major role in pathophysiology of migraine. Recently, neurological mechanisms have been proposed with implication of the trigemino-vascular pathway. Deciphering the pathophysiology of this disorder is extremely important for diagnosis, assessment of progression and to explore targeted treatment options.

OBJECTIVES

To assess white matter alterations in patients of migraine by using Diffusion Tensor Imaging.

MATERIALS AND METHODS

We performed Diffusion Tensor Imaging in migraine patients to assess changes in microstructural integrity of white matter tracts involved in pain processing to localize the tracts involved in migraine. This is a cross-sectional observational study involving 50 subjects (30 patients of migraine diagnosed as per ICHD-III and 20 age and sex matched controls). DTI was performed on 3T MRI and the mean diffusivity and fractional anisotropy values of the cases were compared with controls.

RESULTS AND CONSLUSION

Significant changes were noted in the multiple white matter tracts implicated in pain processing compared to the controls. Significant association was also noted between the DTI parameters and the type and frequency of migraine. DTI can thus assist in the diagnosis, assessing the extent of neurological damage in patients of migraine and follow up post treatment.

The neurotrophic factor artemin and its receptor GFRα3 mediate migraine-like pain via the ion channel TRPM8

BACKGROUND

Migraine has a strong genetic foundation, including both monogenic and polygenic types. The former are rare, with most migraine considered polygenic, supported by genome-wide association studies (GWAS) identifying numerous genetic variants linked with migraine risk. Surprisingly, some of the most common mutations are associated with transient receptor potential melastatin 8 (TRPM8), a non-selective cation channel that is the primary sensor of cold temperatures in cutaneous primary afferents of the somatosensory system. However, it is unlikely that the temperature sensitivity of TRPM8 is relevant in migraine-related tissues, such as the meninges, suggesting other activation mechanisms underly its role in migraine pathogenesis. Thus, to define the basis of the channel's involvement, we reasoned that cellular processes that increase cold sensitivity in the skin, such as the neurotrophic factor artemin, via its receptor glial cell-line derived neurotrophic factor family receptor alpha-3 (GFRα3), also mediate TRPM8-associated migraine-like pain in the meninges.

METHODS

To investigate the role of artemin and GFRα3 in preclinical rodent migraine models, we infused nitroglycerin acutely and chronically, and measured changes in periorbital and hind paw mechanical sensitivity in male and female mice lacking GFRα3, after neutralization of free artemin with specific monoclonal antibodies, or by systemic treatment with a TRPM8-specific antagonist. Further, in mice lacking GFRα3 we tested the effects of supradural infusions of a mix of inflammatory mediators, as well as tested if dura stimulation with artemin or a TRPM8-specific agonist induce migraine-related pain in mice.

RESULTS

We find that mechanical allodynia induced by systemic nitroglycerin, or supradural infusion of inflammatory mediators, involves GFRα3. In addition, neutralization of circulating artemin reduces the nitroglycerin phenotype, demonstrating the importance of this neurotrophic pathway in headaches. Further, we show TRPM8 expression in the meninges, and that direct supradural infusion of either a TRPM8-specific agonist or artemin itself produces mechanical allodynia, with the latter dependent on TRPM8 and ameliorated by concurrent treatment with sumatriptan.

CONCLUSIONS

These results indicate that neuroinflammatory events in the meninges can produce migraine-like pain in mice via artemin and GFRα3, likely acting upstream of TRPM8, providing a novel pathway that may contribute to headaches or migraine pathogenesis.

Pituitary adenylate cyclase-activating polypeptide signalling as a therapeutic target in migraine

Migraine is a disabling neurological disorder that affects more than one billion people worldwide. The clinical presentation is characterized by recurrent headache attacks, which are often accompanied by photophobia, phonophobia, nausea and vomiting. Although the pathogenesis of migraine remains incompletely understood, mounting evidence suggests that specific signalling molecules are involved in the initiation and modulation of migraine attacks. These signalling molecules include pituitary adenylate cyclase-activating polypeptide (PACAP), a vasoactive peptide that is known to induce migraine attacks when administered by intravenous infusion to people with migraine. Discoveries linking PACAP to migraine pathogenesis have led to the development of drugs that target PACAP signalling, and a phase II trial has provided evidence that a monoclonal antibody against PACAP is effective for migraine prevention. In this Review, we explore the molecular and cellular mechanisms of PACAP signalling, shedding light on its role in the trigeminovascular system and migraine pathogenesis. We then discuss emerging therapeutic strategies that target PACAP signalling for the treatment of migraine and consider the research needed to translate the current knowledge into a treatment for migraine in the clinic.

Hallmarks of primary headache: part 1 - migraine

BACKGROUND AND AIM

Migraine is a common disabling conditions which, globally, affects 15.2% of the population. It is the second cause of health loss in terms of years lived with disability, the first among women. Despite being so common, it is poorly recognised and too often undertreated. Specialty centres and neurologists with specific expertise on headache disorders have the knowledge to provide specific care: however, those who do not regularly treat patients with migraine will benefit from a synopsis on the most relevant and updated information about this condition. This paper presents a comprehensive view on the hallmarks of migraine, from genetics and diagnostic markers, up to treatments and societal impact, and reports the elements that identify migraine specific features.

MAIN RESULTS

The most relevant hallmark of migraine is that it has common and individual features together. Besides the known clinical manifestations, migraine presentation is heterogeneous with regard to frequency of attacks, presence of aura, response to therapy, associated comorbidities or other symptoms, which likely reflect migraine heterogeneous genetic and molecular basis. The amount of therapies for acute and for prophylactic treatment is really wide, and one of the difficulties is with finding the best treatment for the single patient. In addition to this, patients carry out different daily life activities, and might show lifestyle habits which are not entirely adequate to manage migraine day by day. Education will be more and more important as a strategy of brain health promotion, because this will enable reducing the amount of subjects needing specialty care, thus leaving it to those who require it in reason of refractory condition or presence of comorbidities.

CONCLUSIONS

Recognizing the hallmarks of migraine and the features of single patients enables prescribing specific pharmacological and non-pharmacological treatments. Medical research on headaches today particularly suffers from the syndrome of single-disease approach, but it is important to have a cross-sectional and joint vision with other close specialties, in order to treat our patients with a comprehensive approach that a heterogeneous condition like migraine requires.

Anti-Calcitonin Gene-Related Peptide Monoclonal Antibody Is Effective for Preventing Migraine Aura Without Headache

BACKGROUND

Anti-calcitonin gene-related peptide monoclonal antibodies (CGRP mAbs) are clinically effective in preventing the migraine attacks, photophobia, and migraine auras associated with headaches. However, no study has yet investigated the effectiveness of CGRP mAbs in preventing migraine aura without headache.

CASE REPORT

A female patient of 49 years old presented with a long history (since age 10) of photosensitivity and typical migraine auras without a headache. The symptoms slightly responded to oral medication, lomerizine chloride, but did not completely resolve. Just one day after the administration of galcanezumab, her photo-hypersensitivity and migraine aura had completely resolved. Consequently, the administration of the oral migraine preventive medication was discontinued. Monthly galcanezumab at a dose of 120 mg was continuously given and she did not re-experience any auras or headaches.

CONCLUSIONS

The use of CGRP mAbs can be considered as a potential treatment in preventing migraine aura without headache. Currently, CGRP mAb is indicated only for migraines with and without auras. Given our findings and the promising effects of this medication for this migraine subtype, a large clinical trial is required to better assess the effects and potential adverse events of CGRP mAb in patients with migraine aura without headache.

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.

The Trigeminal Sensory System and Orofacial Pain

The trigeminal sensory system consists of the trigeminal nerve, the trigeminal ganglion, and the trigeminal sensory nuclei (the mesencephalic nucleus, the principal nucleus, the spinal trigeminal nucleus, and several smaller nuclei). Various sensory signals carried by the trigeminal nerve from the orofacial area travel into the trigeminal sensory system, where they are processed into integrated sensory information that is relayed to higher sensory brain areas. Thus, knowledge of the trigeminal sensory system is essential for comprehending orofacial pain. This review elucidates the individual nuclei that comprise the trigeminal sensory system and their synaptic transmission. Additionally, it discusses four types of orofacial pain and their relationship to the system. Consequently, this review aims to enhance the understanding of the mechanisms underlying orofacial pain.

Metabolic Pathophysiology of Cortical Spreading Depression: A Review

Cortical spreading depression (CSD) is an electrophysiologic pathological state in which a wave of depolarization in the cerebral cortex is followed by the suppression of spontaneous neuronal activity. This transient spread of neuronal depolarization on the surface of the cortex is the hallmark of CSD. Numerous investigations have demonstrated that transmembrane ion transport, astrocytic ion clearing and fatigue, glucose metabolism, the presence of certain genetic markers, point mutations, and the expression of the enzyme responsible for the production of various arachidonic acid derivatives that participate in the inflammatory response, namely, cyclooxygenase (COX), all influence CSD. Here, we explore the associations between CSD occurrence in the cortex and various factors, including how CSD is related to migraines, how the glucose state affects CSD, the effect of TBI and its relationship with CSD and glucose metabolism, how different markers can be measured to determine the severity of CSD, and possible connections to oligemia, orexin, and leptin.

Reduced neurovascular coupling of the visual network in migraine patients with aura as revealed with arterial spin labeling MRI: is there a demand-supply mismatch behind the scenes?

BACKGROUND

Although neuroimaging investigations have consistently demonstrated that "hyperresponsive" and "hyperconnected" visual cortices may represent the functional substrate of cortical spreading depolarization in patients with migraine with aura, the mechanisms which underpin the brain "tendency" to ignite the cortical spreading depolarization and, consequently, aura phenomenon are still matter of debate. Considering that triggers able to induce aura phenomenon constrain brain to increase global (such as physical activity, stressors and sleep abnormalities) or local (such as bright light visual stimulations) energy demand, a vascular supply unable to satisfy the increased energy requirement could be hypothesized in these patients.

METHODS

Twenty-three patients with migraine with aura, 25 patients with migraine without aura and 20 healthy controls underwent a 3-Tesla MRI study. Cerebral blood flow and local functional connectivity (regional homogeneity) maps were obtained and registered to the MNI space where 100 cortical regions were derived using a functional local-global normative parcellation. A surrogate estimate of the regional neurovascular coupling for each subject was obtained at each parcel from the correlation coefficient between the z-scored ReHo map and the z-scored cerebral blood flow maps.

RESULTS

A significantly higher regional cerebral blood flow across the visual cortex of both hemispheres (i.e. fusiform and lingual gyri) was detected in migraine with aura patients when compared to patients with migraine without aura (p < 0.05, corrected for multiple comparisons). Concomitantly, a significantly reduced neurovascular coupling (p < 0.05, false discovery rate corrected) in the primary visual cortex parcel (VIS-4) of the large-scale visual network was observed in the left hemisphere of patients with migraine with aura (0.23±0.03), compared to both patients with migraine without aura (0.32±0.05) and healthy controls (0.29±0.05).

CONCLUSIONS

Visual cortex neurovascular "decoupling" might represent the "link" between the exposure to trigger factors and aura phenomenon ignition. While physiological vascular oversupply may compensate neurovascular demand-supply at rest, it becomes inadequate in case of increased energy demand (e.g. when patients face with trigger factors) paving the way to the aura phenomenon ignition in patients with migraine with aura. Whether preventive treatments may exert their therapeutic activity on migraine with aura restoring the energy demands and cerebral blood flow trade-off within the visual network should be further investigated.

Pediatric migraine is characterized by traits of ecological and metabolic dysbiosis and inflammation

BACKGROUND

Recently, there has been increasing interest in the possible role of the gut microbiota (GM) in the onset of migraine. Our aim was to verify whether bacterial populations associated with intestinal dysbiosis are found in pediatric patients with migraine. We looked for which metabolic pathways, these bacteria were involved and whether they might be associated with gut inflammation and increased intestinal permeability.

METHODS

Patients aged between 6 and 17 years were recruited. The GM profiling was performed by the 16S rRNA metataxonomics of faecal samples from 98 patients with migraine and 98 healthy subjects. Alpha and beta diversity analyses and multivariate and univariate analyses were applied to compare the gut microbiota profiles between the two group. To predict functional metabolic pathways, we used phylogenetic analysis of communities. The level of indican in urine was analyzed to investigate the presence of metabolic dysbiosis. To assess gut inflammation, increased intestinal permeability and the mucosal immune activation, we measured the plasmatic levels of lipopolysaccharide, occludin and IgA, respectively.

RESULTS

The α-diversity analysis revealed a significant increase of bacterial richness in the migraine group. The β-diversity analysis showed significant differences between the two groups indicating gut dysbiosis in patients with migraine. Thirty-seven metabolic pathways were increased in the migraine group, which includes changes in tryptophan and phenylalanine metabolism. The presence of metabolic dysbiosis was confirmed by the increased level of indican in urine. Increased levels of plasmatic occludin and IgA indicated the presence of intestinal permeability and mucosal immune activation. The plasmatic LPS levels showed a low intestinal inflammation in patients with migraine.

CONCLUSIONS

Pediatric patients with migraine present GM profiles different from healthy subjects, associated with metabolic pathways important in migraine.

Serum melatonin levels and in a sample of Iranian patients with migraine

Migraine, a complex disorder, is characterized by recurrent headache episodes. The production of melatonin in the pineal gland, which is crucial for controlling circadian rhythms and sleep-wake cycles, is altered in various conditions, including neurological disorders such as migraine. Recent studies underscore the significance of serum melatonin levels in patients with chronic and episodic migraine, the focus of this study. This case‒control study, conducted from September 2017 to June 2020 in Tehran, Iran, selected potential participants aged 18-65 years from a headache clinic at Sina Hospital (affiliated with Tehran University of Medical Sciences). Both episodic migraine and chronic migraine were diagnosed following the diagnostic criteria in the International Classification of Headache Disorders' third edition. Melatonin levels were measured according to the instructions of the ELISA kits. There were significant differences in the frequency of headache days and the duration of abortive medication usage between the two groups (P value < 0.001). Besides, analysis revealed significantly lower serum melatonin levels in patients with episodic ((80.45-45.06) 72.83) and chronic migraine ((154.34-63.34) 70.38, P value < 0.001) than in healthy controls (281.25-160.86) 280). Although no considerable differences were found between episodic and chronic migraine patients, the current study demonstrated that serum melatonin levels were substantially greater in healthy controls than in patients with migraine.

Orofacial Migraine-A Narrative Review

The diagnosis of migraine is based on clear criteria outlined in the International Classification of Headache Disorders version 3 (ICHD-3). Notably, the criteria in ICHD-3 omit the location of the migraine. There are increasing reports of migraine in the facial region. Facial presentations of migraine are not easy to diagnose as they appear in the lower two-thirds of the face, often in the maxillary sinus region, around the ear, the upper/lower jaws, and the teeth. Additionally, a similar but distinct entity, neurovascular orofacial pain, has been established. The symptomatology of facial presentations of these headaches often resembles sinusitis and dental pathology. We will review these presentations, their diagnosis, and possible pathophysiology.

Migraine and Risk of Parkinson Disease in Women: A Cohort Study

BACKGROUND AND OBJECTIVES

Migraine and Parkinson disease (PD) are common neurologic disorders, which are hypothesized to share some pathophysiologic mechanisms. However, data on the association between migraine and risk of developing PD are sparse. We estimate the effect of migraine, migraine subtypes, and migraine episode frequency on the risk of developing PD in middle-aged and older women.

METHODS

We used data from the Women's Health Study, a United States-based cohort of women in health professions aged 45 years and older at baseline (1992-1995). Only women with complete self-reported information on migraine and headache and no history of PD were included. Participants were followed up for self-reported physician-diagnosed PD through December 31, 2021. We used multivariable Cox proportional hazards models to estimate hazard ratios (HRs) and corresponding 95% CIs of the association between migraine, migraine subtypes, and migraine episode frequency and the risk of developing PD.

RESULTS

A total of 39,312 women were included in the analyses. Among those, 7,321 women (18.6%) reported any migraine at baseline, of whom 2,153 (5.5%) reported a history of migraine, 2,057 (5.2%) reported migraine with aura, and 3,111 (7.9%) reported migraine without aura. During a mean follow-up of 22.0 years, 685 PD cases were reported. Of those, 128 (18.7%) were reported by women who also reported any migraine and 557 (81.3%) by women without any migraine. After adjusting for confounding, the HR for the association of any migraine on the risk of PD was 1.07 (0.88-1.29). Compared with women without migraine, the HRs (95% CI) for PD were 0.87 (0.59-1.27) for migraine with aura, 1.21 (0.93-1.58) for migraine without aura, and 1.05 (0.76-1.45) for history of migraine. Compared with those with a migraine frequency of less than monthly, the HRs were 1.09 (0.64-1.87) for a monthly frequency and 1.10 (0.44-2.75) for a weekly or greater frequency.

DISCUSSION

In this large cohort of women, the risk of developing PD was not elevated among those experiencing migraine, irrespective of migraine subtypes or the frequency of migraine. The generalizability of our findings to other populations, such as men, should be further investigated.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT00000479.

The neurotrophic factor artemin and its receptor GFRα3 mediate migraine-like pain via the ion channel TRPM8

Background

Migraine has a strong genetic foundation, including both monogenic and polygenic types. The former are rare, with most migraine considered polygenic, supported by genome-wide association studies (GWAS) identifying numerous genetic variants associated with migraine risk. Surprisingly, some of the most common mutations are associated with TRPM8, a non-selective cation channel that is the primary sensor of cold temperatures in primary afferent neurons of the somatosensory system. However, it is unlikely that the temperature sensitivity of TRPM8 underlies its role in migraine pathogenesis. To define the basis of the channel's involvement, we reasoned that cellular processes that increase cold sensitivity in the skin, such as the neurotrophic factor artemin, via its receptor GFRα3, also mediate TRPM8-associated migraine-like pain in the meninges.

Methods

To investigate the role of artemin and GFRα3 in preclinical rodent migraine models, we infused nitroglycerin acutely and chronically, and measured changes in periorbital and hind paw mechanical sensitivity in male and female mice lacking GFRα3, after neutralization of free artemin with specific monoclonal antibodies, or by systemic treatment with a TRPM8-specific antagonist. Further, in wildtypes and mice lacking either GFRα3 or TRPM8, we tested the effects of supradural infusions of a mix of inflammatory mediators, artemin, and a TRPM8-specific agonist on migraine-related pain in mice.

Results

We find that mechanical allodynia induced by systemic nitroglycerin, or supradural infusion of inflammatory mediators, involves GFRα3. In addition, neutralization of circulating artemin reduces the nitroglycerin phenotype, demonstrating the importance of this neurotrophic pathway. Further, we show TRPM8 expression in the meninges and that direct supradural infusion of either a TRPM8-specific agonist or artemin itself produces mechanical allodynia, the latter dependent on TRPM8 and ameliorated by concurrent treatment with sumatriptan.

Conclusions

These results indicate that neuroinflammatory events in the meninges can produce migraine-like pain in mice via artemin and GFRα3, likely acting upstream of TRPM8, providing a novel pathway that may contribute to migraine pathogenesis.

Genetic variants associated with response to anti-CGRP monoclonal antibody therapy in a chronic migraine Han Chinese population

BACKGROUND

Anti-calcitonin gene-related peptide (CGRP) monoclonal antibodies have emerged as promising therapeutic options for the treatment of chronic migraine. However, treatment response varies considerably among individuals, suggesting a potential role for genetic factors. This study aimed to identify genetic variants affecting the efficacy of anti-CGRP monoclonal antibody therapy in chronic migraine among the Han Chinese population in Taiwan to enhance treatment precision and to understand the genetic architecture of migraine.

METHODS

We conducted a quantitative trait locus (QTL) association study in patients with chronic migraines from a tertiary medical center in Taiwan using the Taiwan Precision Medicine Array Chip. The patients received fremanezumab or galcanezumab for at least 12 weeks. Treatment efficacy was assessed based on the improvement rate in monthly migraine days. Genetic variants were identified, and their associations with treatment efficacy were examined through quantitative trait loci analysis, linkage disequilibrium studies, and functional annotations using the Gene Ontology database.

RESULTS

Six single nucleotide polymorphisms (SNPs) relative variants were significantly associated with anti-CGRP therapy response (p < 1 × 10- 7): rs116870564, rs75244870, rs56216870, rs12938101, rs74655790, and rs149540851. These variants are located in or near genes, including LRRC4C, ATAD2B, and OXR1, which are involved in neuronal development, DNA-dependent ATPase activity, and oxidation-reduction processes, respectively. The rs116870564 variant in LRRC4C showed the strongest association (β = -0.551, p = 6.65 × 10- 9). The functional impact of these variants is attributed to their regulatory effects on gene expression, which are influenced by intron splicing regulation, transcription factors, and changes in chromatin structure.

CONCLUSION

The identification of key genetic markers associated with response to anti-CGRP therapy emphasizes the importance of genetic variability in treatment efficacy. This could lead to more personalized chronic migraine management strategies and tailored therapeutic approaches based on individual genetic profiles. Further research in larger, diverse populations is warranted to validate these findings and refine our understanding of the role of CGRP in chronic migraine pathophysiology.

TRIAL REGISTRATION

Not applicable.

The association between dietary antioxidant quality score and intensity and frequency of migraine headaches among women: a cross-sectional study

BACKGROUND

Migraine is an episodic disorder and a frequent form of headache. An impaired balance between free radical production and an impaired antioxidant defense system leading to oxidative damage may play a major role in migraine etiology. We sought to investigate whether dietary antioxidant quality score (DAQS) is associated with migraine intensity and frequency among women suffering from migraine.

METHODS

This cross-sectional study was conducted on 265 women. The data related to anthropometric measures and dietary intake were collected. DAQS score was calculated based on FFQ (food frequency questionnaire) vs. the reference daily intake (RDI) quantity. To measure migraine intensity, the migraine disability assessment questionnaire (MIDAS) and visual analog scale (VAS) were used. The frequency of headaches was defined as the days the participants had headaches in the last month and a 30-day headache diary was used.

RESULTS

The results of the study demonstrated that VAS, MIDAS, and frequency of headaches were reduced significantly from the low DAQS (poor quality of antioxidants) to high DAQS (high quality of antioxidants) after adjusting covariates. Also, multinomial regression showed there was an inverse association between higher DAQS and the frequency of headaches. In the adjusted model, subjects with the higher DAQS were 69% less likely to have moderate migraine disability, compared with those with the lower DAQS. Linear regression showed, there was an inverse association between vitamin C intake and the grades of pain severity.َAlso in a crude model, a negative association was found between vitamin E and the frequency of headaches.

CONCLUSION

In conclusion, Participants with higher DAQS had lower migraine intensity and headache frequency. In addition, the consumption of vitamin C may potentially associate with decreasing the severity of headaches. Dietary antioxidants should be monitored closely in individuals suffering from migraine.

Insights from 25 years of onabotulinumtoxinA in migraine - mechanisms and management

OnabotulinumtoxinA (BTX-A) was first linked to beneficial effects in migraine 25 years ago and was approved by the FDA for preventive treatment of chronic migraine in 2010. The treatment has since had a major impact on the well-being of people with chronic migraine. The clinical development programme for BTX-A and research since its approval have provided insights into the neuromodulatory sensory effect of BTX-A, how it can control chronic migraine despite its peripheral action, and the underlying biology of migraine as a disease. In this Review, we consider the impact that BTX-A has had on the management of chronic migraine and on the research field. We discuss the insights provided by clinical research, encompassing the clinical trials and subsequent real-world evidence, and the mechanistic insights provided by preclinical and translational research. We also provide an overview of future directions of research in the field BTX-A in migraine and the clinical translation of this research.

Efficacy of Desvenlafaxine in Reducing Migraine Frequency and Severity: A Retrospective Study

Background: Migraine is characterized by sudden acute episodes of pain, with a global prevalence of 18% among all age groups. It is the second leading cause of years lived with disability worldwide. Prophylactic treatment is important in managing migraine; however, its efficacy and safety are debated. This study aimed to evaluate the efficacy of desvenlafaxine in female patients with migraine. Methods: We conducted a retrospective observational case study involving 10 women diagnosed with migraine who were treated with desvenlafaxine. We measured the number of migraine days per month, average headache duration in minutes, headache severity using a visual analog scale, use of acute medications, and frequency of acute medication use per week. Results: Desvenlafaxine significantly reduced the number of migraine days from 14.70 ± 3.68 at baseline to 2.50 ± 2.50 at follow-up (p < 0.05). The average headache duration dropped from 131.25 ± 32.81 min to 52.50 ± 44.64 min. Headache severity scores improved from 6.80 ± 1.49 at baseline to 0.80 ± 0.92 at follow up, the frequency of acute medication use per week reduced from 3.30 ± 1.49 at baseline to 0.80 ± 0.92, and the frequency of acute medication use decreased from 3.30 ± 1.49 times per week to 0.80 ± 0.92. Conclusions: Desvenlafaxine shows potential as an effective prophylactic therapy for migraine. Larger-scale studies are necessary to further explore its benefits.

Intracellular pathways of calcitonin gene-related peptide-induced relaxation of human coronary arteries: A key role for Gβγ subunit instead of cAMP

BACKGROUND AND PURPOSE

Calcitonin gene-related peptide (CGRP) is a potent vasodilator. While its signalling is assumed to be mediated via increases in cAMP, this study focused on elucidating the actual intracellular signalling pathways involved in CGRP-induced relaxation of human isolated coronary arteries (HCA).

EXPERIMENTAL APPROACH

HCA were obtained from heart valve donors (27 M, 25 F, age 54 ± 2 years). Concentration-response curves to human α-CGRP or forskolin were constructed in HCA segments, incubated with different inhibitors of intracellular signalling pathways, and intracellular cAMP levels were measured with and without stimulation.

RESULTS

Adenylyl cyclase (AC) inhibitors SQ22536 + DDA and MDL-12330A, and PKA inhibitors Rp-8-Br-cAMPs and H89, did not inhibit CGRP-induced relaxation of HCA, nor did the guanylyl cyclase inhibitor ODQ, PKG inhibitor KT5823, EPAC1/2 inhibitor ESI09, potassium channel blockers TRAM-34 + apamin, iberiotoxin or glibenclamide, or the Gαq inhibitor YM-254890. Phosphodiesterase inhibitors induced a concentration-dependent decrease in the response to KCl but did not potentiate relaxation to CGRP. Relaxation to forskolin was not blocked by PKA or AC inhibitors, although AC inhibitors significantly inhibited the increase in cAMP. Inhibition of Gβγ subunits using gallein significantly inhibited the relaxation to CGRP in human coronary arteries.

CONCLUSION

While CGRP signalling is generally assumed to act via cAMP, the CGRP-induced vasodilation in HCA was not inhibited by targeting this intracellular signalling pathway at different levels. Instead, inhibition of Gβγ subunits did inhibit the relaxation to CGRP, suggesting a different mechanism of CGRP-induced relaxation than generally believed.

The Brain, the Eating Plate, and the Gut Microbiome: Partners in Migraine Pathogenesis

This review summarizes the relationship between diet, the gut microbiome, and migraine. Key findings reveal that certain dietary factors, such as caffeine and alcohol, can trigger migraine, while nutrients like magnesium and riboflavin may help alleviate migraine symptoms. The gut microbiome, through its influence on neuroinflammation (e.g., vagus nerve and cytokines), gut-brain signaling (e.g., gamma-aminobutyric acid), and metabolic function (e.g., short-chain fatty acids), plays a crucial role in migraine susceptibility. Migraine can also alter eating behaviors, leading to poor nutritional choices and further exacerbating the condition. Individual variability in diet and microbiome composition highlights the need for personalized dietary and prebiotic interventions. Epidemiological and clinical data support the effectiveness of tailored nutritional approaches, such as elimination diets and the inclusion of beneficial nutrients, in managing migraine. More work is needed to confirm the role of prebiotics, probiotics, and potentially fecal microbiome translation in the management of migraine. Future research should focus on large-scale studies to elucidate the underlying mechanisms of bidirectional interaction between diet and migraine and develop evidence-based clinical guidelines. Integrating dietary management, gut health optimization, and lifestyle modifications can potentially offer a holistic approach to reducing migraine frequency and severity, ultimately improving patient outcomes and quality of life.

Computerized Axiographic Findings in a Cohort of Migraine Patients: A Cross-Sectional Study

BACKGROUND

The objective of this work was to investigate the association between the function of the stomatognathic system and migraine presence through an instrumental functional analysis in a group of diagnosed migraine patients and a control group.

METHODS

This study included 50 individuals in each group. A jaw-tracking analysis was performed using Cadiax 4. Tracings of the following movements were recorded: open/close, protrusion/retrusion, mediotrusion, speech, bruxing, and mastication. The tracings were evaluated for their quantity, quality, transversal characteristics, speed, curvature pattern, and condylar stability.

RESULTS

Statistically significant differences between the groups were established for several aspects of the evaluation. Migraineurs presented with (a) higher values of mandibular lateral translation in protrusion/retrusion (p = 0.001), open/close (p = 0.031), and mastication (p = 0.016); (b) transient velocity losses in open/close (p = 0.001) and protrusive movements (p = 0.018); (c) a compromised condylar stability for protrusion/retrusion (p = 0.001) and mediotrusion (p = 0.003); (d) a compromised quality for protrusion/retrusion (p < 0.001) and mediotrusion (p = 0.003); and (e) a more frequent "figure-eight" curvature in open/close (p = 0.012).

CONCLUSIONS

The importance of the stomatognathic function in migraine pathogenesis and treatment should be considered by using a patient-centered and interdisciplinary approach.

Hyperacusis questionnaire and event-related potential correlation in migraine patients

This study aims to investigate auditory hypersensitivity and cortical function in migraine patients using the Hyperacusis Questionnaire and the Event-Related Potential (ERP) technique. The study analyzes alterations in the latency and amplitude of the event-related potentials MMN and P300 components. The findings contribute to a better understanding of the physiological relationship between migraine and auditory hypersensitivity. Seventeen migraine patients were admitted to the outpatient clinic of the Department of Otorhinolaryngology-Head and Neck Surgery at Peking University People's Hospital from June 2023 to September 2023. Nineteen matched healthy subjects were also selected. All participants underwent the pure tone audiometry and the auditory brainstem response test to determine hearing thresholds, the Hyperacusis Questionnaire, the Tinnitus Handicap Inventory, and an ERP examination. The Oddball classical paradigm was used as the stimulation task, and electroencephalography signals were recorded synchronously. The scores of the Hyperacusis Questionnaire, latency and amplitude of MMN and P300 component were compared between the migraine group and the control group, and their correlation was analyzed. The latency of MMN at the Fz and Cz sites in migraine patients was significantly shorter than that in the control group (P < 0.05), and the amplitudes were significantly higher than those in the control group (P < 0.05). The variances in latency and amplitude of P300 at Cz and Pz sites in migraine patients were not statistically significant when compared with the control group. (P > 0.05). The Hyperacusis Questionnaire was negatively correlated with MMN latency, with a correlation coefficient of - 0.374 (P = 0.025), and positively correlated with MMN amplitude, with a correlation coefficient of 0.378 (P = 0.023). There was no significant similarity between the Hyperacusis Questionnaire and P300 latency and amplitude (P > 0.05). Overall, auditory hypersensitivity was enhanced in individuals with migraines compared to healthy individuals, leading to faster information processing, while there may be less impairment in cognitive function.

Investigating the causal association between systemic lupus erythematosus and migraine using Mendelian randomization analysis

OBJECTIVE

To assess whether systemic lupus erythematosus (SLE) may be genetically causally associated with migraine, including the two primary subtypes: migraine with aura (MWA) and migraine without aura (MWoA).

BACKGROUND

The association between SLE and migraine has been investigated extensively. Previous studies have shown a higher prevalence of migraine in patients with SLE, although the exact relationship remains unclear. This study investigated the potential causal association between SLE and migraine using the powerful analytical tool of Mendelian randomization (MR).

METHODS

We performed two-sample MR analysis of publicly available summary statistic datasets using inverse variance-weighted (IVW), weighted median, and MR-Egger methods based on an SLE genome-wide association study (GWAS; 5201 cases; 9066 controls; the exposure frequency is 36.5%) as an exposure and migraine GWAS (15,905 cases; 264,662 controls) in individuals with European ancestry as outcomes, focusing on the two migraine subtypes MWA (6780 cases; 264,662 controls) and MWoA (5787 cases; 264,662 controls). Thepleiotropy and heterogeneity were performed.

RESULTS

We selected 42 single-nucleotide polymorphisms from SLE GWAS as instrumental variables (IVs) for SLE on migraine, and 41 SNP IVs for SLE on MWA or MWoA. The IVW (odds ratio [OR] = 1.01, 95% confidence interval [CI] = [0.99, 1.03], p = 0.271), weighted median (OR = 1.00, 95% CI = [0.97, 1.03], p = 0.914), and MR-Egger (OR = 1.04, 95% CI = [0.99, 1.09], p = 0.153) methods showed no causal effect of SLE on migraine. A causal effect of SLE was observed on MWA (IVW: OR = 1.05, 95% CI = [1.02, 1.08], p = 0.001; weighted median: OR = 1.05, 95% CI = [1.01, 1.10], p = 0.018; MR-Egger: OR = 1.07, 95% CI = [1.01, 1.14], p = 0.035 and pIVW < 0.017 [Bonferroni correction]) but not MWoA (IVW: OR = 0.99, 95% CI = [0.96, 1.02], p = 0.331; weighted median: OR = 0.98, 95% CI = [0.94, 1.03], p = 0.496; MR-Egger: OR = 1.02, 95% CI = [0.95, 1.09], p = 0.652). The results showed no significant pleiotropy or heterogeneity.

CONCLUSION

Our MR analysis demonstrated the complex relationship between SLE and migraine, suggesting a potential effect of SLE on the risk of MWA but not MWoA. These findings can aid in the development of improved subtype-specific management of migraine in patients with SLE.

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.

Aberrant concordance among dynamics of spontaneous brain activity in patients with migraine without aura: A multivariate pattern analysis study

Background

Alterations in the static and dynamic characteristics of spontaneous brain activity have been extensively studied to investigate functional brain changes in migraine without aura (MwoA). However, alterations in concordance among the dynamics of spontaneous brain activity in MwoA remain largely unknown. This study aimed to determine the possibilities of diagnosis based on the concordance indices.

Methods

Resting-state functional MRI scans were performed on 32 patients with MwoA and 33 matched healthy controls (HCs) in the first cohort, as well as 36 patients with MwoA and 32 HCs in the validation cohort. The dynamic indices including fractional amplitude of low-frequency fluctuation, regional homogeneity, voxel-mirrored homotopic connectivity, degree centrality and global signal connectivity were analyzed. We calculated the concordance of grey matter volume-wise (across voxels) and voxel-wise (across time windows) to quantify the degree of integration among different functional levels represented by these dynamic indices. Subsequently, the voxel-wise concordance alterations were analyzed as features for multi-voxel pattern analysis (MVPA) utilizing the support vector machine.

Results

Compared with that of HCs, patients with MwoA had lower whole-grey matter volume-wise concordance, and the mean value of volume-wise concordance was negatively correlated with the frequency of migraine attacks. The MVPA results revealed that the most discriminative brain regions were the right thalamus, right cerebellar Crus II, left insula, left precentral gyrus, right cuneus, and left inferior occipital gyrus.

Conclusions

Concordance alterations in the dynamics of spontaneous brain activity in brain regions could be an important feature in the identification of patients with MwoA.

Rare GPR37L1 Variants Reveal Potential Association between GPR37L1 and Disorders of Anxiety and Migraine

GPR37L1 is an orphan receptor that couples through heterotrimeric G-proteins to regulate physiological functions. Since its role in humans is not fully defined, we used an unbiased computational approach to assess the clinical significance of rare G-protein-coupled receptor 37-like 1 (GPR37L1) genetic variants found among 51,289 whole-exome sequences from the DiscovEHR cohort. Rare GPR37L1 coding variants were binned according to predicted pathogenicity and analyzed by sequence kernel association testing to reveal significant associations with disease diagnostic codes for epilepsy and migraine, among others. Since associations do not prove causality, rare GPR37L1 variants were functionally analyzed in SK-N-MC cells to evaluate potential signaling differences and pathogenicity. Notably, receptor variants exhibited varying abilities to reduce cAMP levels, activate mitogen-activated protein kinase (MAPK) signaling, and/or upregulate receptor expression in response to the agonist prosaptide (TX14(A)), as compared with the wild-type receptor. In addition to signaling changes, knock-out (KO) of GPR37L1 or expression of certain rare variants altered cellular cholesterol levels, which were also acutely regulated by administration of the agonist TX14(A) via activation of the MAPK pathway. Finally, to simulate the impact of rare nonsense variants found in the large patient cohort, a KO mouse line lacking Gpr37l1 was generated. Although KO animals did not recapitulate an acute migraine phenotype, the loss of this receptor produced sex-specific changes in anxiety-related disorders often seen in chronic migraineurs. Collectively, these observations define the existence of rare GPR37L1 variants associated with neuropsychiatric conditions in the human population and identify the signaling changes contributing to pathological processes.

High-definition tDCS over primary motor cortex modulates brain signal variability and functional connectivity in episodic migraine

OBJECTIVE

This study investigated how high-definition transcranial direct current stimulation (HD-tDCS) over the primary motor cortex (M1) affects brain signal variability and functional connectivity in the trigeminal pain pathway, and their association with changes in migraine attacks.

METHODS

Twenty-five episodic migraine patients were randomized for ten daily sessions of active or sham M1 HD-tDCS. Resting-state blood-oxygenation-level-dependent (BOLD) signal variability and seed-based functional connectivity were assessed pre- and post-treatment. A mediation analysis was performed to test whether BOLD signal variability mediates the relationship between treatment group and moderate-to-severe headache days.

RESULTS

The active M1 HD-tDCS group showed reduced BOLD variability in the spinal trigeminal nucleus (SpV) and thalamus, but increased variability in the rostral anterior cingulate cortex (rACC) compared to the sham group. Connectivity decreased between medial pulvinar-temporal pole, medial dorsal-precuneus, and the ventral posterior medial nucleus-SpV, but increased between the rACC-amygdala, and the periaqueductal gray-parahippocampal gyrus. Changes in medial pulvinar variability mediated the reduction in moderate-to-severe headache days at one-month post-treatment.

CONCLUSIONS

M1 HD-tDCS alters BOLD signal variability and connectivity in the trigeminal somatosensory and modulatory pain system, potentially alleviating migraine headache attacks.

SIGNIFICANCE

M1 HD-tDCS realigns brain signal variability and connectivity in migraineurs closer to healthy control levels.

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.

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.

Potential mechanisms for osteopathic manipulative treatment to alleviate migraine-like pain in female rats

Introduction

Migraines are the leading cause of disability in the United States, and the use of non-pharmaceutical treatments like osteopathic manipulative treatment (OMT) has shown promise. Despite its potential, the lack of mechanistic understanding has hindered widespread adoption. This study aims to investigate the efficacy of OMT in treating acute migraines and unravel its underlying mechanisms of action.

Methods

Female rats were subjected to a "two-hit" approach to induce migraine-like pain. This involved bilateral injections of Complete Freund's Adjuvant (CFA) into the trapezius muscle (1st hit) followed by exposure to Umbellulone, a human migraine trigger, on Day 6 post-CFA (2nd hit). Soft tissue and articulatory techniques were applied to the cervical region for acute abortive or repeated prophylactic treatment. Cutaneous allodynia and trigeminal system activation were assessed through behavioral tests and immunohistochemical staining.

Results

Following Umbellulone inhalation, CFA-primed rats exhibited periorbital and hind paw allodynia. Immediate application of OMT after Umbellulone inhalation as an abortive treatment partially alleviated cutaneous allodynia. With OMT applied thrice as a prophylactic measure, complete suppression of tactile hypersensitivity was observed. Prophylactic OMT also prevented the increase of c-fos signals in the trigeminal nucleus caudalis and the elevation of calcitonin gene-related peptide expression in trigeminal ganglia induced by CFA and Umbellulone exposure at 2 h post-inhalation.

Discussion

These findings provide mechanistic insights into OMT's migraine-relief potential and underscore its viability as a non-pharmacological avenue for managing migraines.

Cellular and Molecular Roles of Immune Cells in the Gut-Brain Axis in Migraine

Migraine is a complex and multi-system dysfunction. The realization of its pathophysiology and diagnosis is developing rapidly. Migraine has been linked to gastrointestinal disorders such as irritable bowel syndrome and celiac disease. There is also direct and indirect evidence for a relationship between migraine and the gut-brain axis, but the exact mechanism is not yet explained. Studies have shown that this interaction appears to be influenced by a variety of factors, such as inflammatory mediators, gut microbiota, neuropeptides, and serotonin pathways. Recent studies suggest that immune cells can be the potential tertiary structure between migraine and gut-brain axis. As the hot interdisciplinary subject, the relationship between immunology and gastrointestinal tract is now gradually clear. Inflammatory signals are involved in cellular and molecular responses that link central and peripheral systems. The gastrointestinal symptoms associated with migraine and experiments associated with antibiotics have shown that the intestinal microbiota is abnormal during the attacks. In this review, we focus on the mechanism of migraine and gut-brain axis, and summarize the tertiary structure between immune cells, neural network, and gastrointestinal tract.

PACAP-38 related modulation of the cranial parasympathetic projection: A novel mechanism and therapeutic target in severe primary headache

BACKGROUND AND PURPOSE

Little is known of how cranial autonomic symptoms (CAS) in cluster headache and migraine may contribute to their severe headache phenotype. This strong association suggests the involvement of the cranial parasympathetic efferent pathway. To investigate its contribution, we studied the role of pituitary adenylate cyclase activating polypeptide-38 (PACAP-38), a potent sensory and parasympathetic neuropeptide, in modulating pre- and post-ganglionic cranial parasympathetic projection neurons, and their influence on headache-related trigeminal-autonomic responses.

EXPERIMENTAL APPROACH

Using PACAP-38 and PACAP-38 responsive receptor antagonists, electrophysiological, behavioural and facial neurovascular-blood flow was measured in rats to probe trigeminal- and parasympathetic-neuronal, periorbital thresholds and cranial-autonomic outcomes, as they relate to primary headaches.

KEY RESULTS

Sumatriptan attenuated the development of PACAP-38 mediated activation and sensitization of trigeminocervical neurons and related periorbital allodynia. PACAP-38 also caused activation and enhanced responses of dural-responsive pre-ganglionic pontine-superior salivatory parasympathetic neurons. Further, the PACAP-38 responsive receptor antagonists dissected a role of VPAC1 and PAC1 receptors in attenuating cranial-autonomic and trigeminal-neuronal responses to activation of the cranial parasympathetic projection, which requires post-ganglionic parasympathetic neurotransmission.

CONCLUSION AND IMPLICATIONS

Given the prevailing view that sumatriptan acts to some degree via a peripheral mechanism, our data support that PACAP-38 mediated receptor activation modulates headache-related cranial-autonomic and trigeminovascular responses via peripheral and central components of the cranial parasympathetic projection. This provides a mechanistic rationale for the association of CAS with more severe headache phenotypes in cluster headache and migraine, and supports the cranial parasympathetic projection as a potential novel locus for treatment by selectively targeting PACAP-38 or PACAP-38 responsive VPAC1 /PAC1 receptors.

Understanding the Biological Relationship between Migraine and Depression

Migraine is a highly prevalent neurological disorder. Among the risk factors identified, psychiatric comorbidities, such as depression, seem to play an important role in its onset and clinical course. Patients with migraine are 2.5 times more likely to develop a depressive disorder; this risk becomes even higher in patients suffering from chronic migraine or migraine with aura. This relationship is bidirectional, since depression also predicts an earlier/worse onset of migraine, increasing the risk of migraine chronicity and, consequently, requiring a higher healthcare expenditure compared to migraine alone. All these data suggest that migraine and depression may share overlapping biological mechanisms. Herein, this review explores this topic in further detail: firstly, by introducing the common epidemiological and risk factors for this comorbidity; secondly, by focusing on providing the cumulative evidence of common biological aspects, with a particular emphasis on the serotoninergic system, neuropeptides such as calcitonin-gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), substance P, neuropeptide Y and orexins, sexual hormones, and the immune system; lastly, by remarking on the future challenges required to elucidate the etiopathological mechanisms of migraine and depression and providing updated information regarding new key targets for the pharmacological treatment of these clinical entities.

Anti-CGRP antibody galcanezumab modifies the function of the trigeminovascular nocisensor complex in the rat

BACKGROUND

Monoclonal antibodies directed against the neuropeptide calcitonin gene-related peptide (CGRP) are effective in the prevention of chronic and frequent episodic migraine. Since the antibodies do not cross the blood brain barrier, their antinociceptive effect is attributed to effects in meningeal tissues. We aimed to probe if such an antibody can be visualized within the dura mater and the trigeminal ganglia following its administration to rats and to examine if the activity of the trigeminovascular nocisensor complex is influenced by this treatment.

METHODS

Effects of the anti-CGRP antibody galcanezumab on the trigeminovascular nocisensor complex was examined by measuring release of sensory neuropeptides and histamine from the rat dura mater. Deposits of galcanezumab were visualized by fluorescence microscopy in the trigeminal ganglion and the dura mater.

RESULTS

Fluorophore-labelled galcanezumab was detected in the dura mater and the trigeminal ganglion up to 30 days after treatment affirming the long-lasting modulatory effect of this antibody. In female rats, seven days after systemic treatment with galcanezumab the capsaicin-induced release of CGRP was decreased, while that of substance P (SP) was increased in the dura mater. In control rats, release of the inhibitory neuropeptide somatostatin (SOM) was higher in females than in males. Stimulation with high concentration of KCl did not significantly change the release of SOM in control animals, while in rats treated with galcanezumab SOM release was slightly reduced. Galcanezumab treatment also reduced the amount of histamine released from dural mast cells upon stimulation with CGRP, while the effect of compound 48/80 on histamine release was not changed.

CONCLUSIONS

Galcanezumab treatment is followed by multiple changes in the release of neuropeptides and histamine in the trigeminal nocisensor complex, which may contribute to the migraine preventing effect of anti-CGRP antibodies. These changes affecting the communication between the components of the trigeminal nocisensor complex may reduce pain susceptibility in migraine patients treated with CGRP targeting monoclonal antibodies.