Pathophysiology of migraine

Evaluation of the Pharmacokinetic Interaction and Safety of Ubrogepant Coadministered With Esomeprazole Magnesium

Ubrogepant is a calcitonin gene-related peptide receptor antagonist for the acute treatment of migraine. Esomeprazole magnesium increases intragastric pH, which may affect oral ubrogepant absorption. This open-label, nonrandomized, crossover trial evaluated esomeprazole magnesium's impact on the pharmacokinetics and safety of coadministered ubrogepant in healthy adults. Participants received ubrogepant 100 mg on day 1, esomeprazole magnesium 40 mg on days 9 to 13, and ubrogepant 100 mg with esomeprazole magnesium 40 mg on day 14. No effect on ubrogepant pharmacokinetics was concluded if 90% confidence intervals of geometric mean ratios were within 80% to 125% for comparison of pharmacokinetic parameters between ubrogepant + esomeprazole magnesium versus ubrogepant alone. Thirty participants enrolled (mean age, 31.7 years; 53.3% males). Ubrogepant peak plasma concentration (C_max ) decreased 23%, time to C_max increased by 1.5 hours, and area under the plasma concentration-time curve was reduced by ≈10% when coadministered with esomeprazole magnesium versus ubrogepant alone. The 90% confidence interval of the geometric mean ratio for C_max did not fall within the 80% to 125% equivalence range, but the decrease was not considered clinically meaningful. Esomeprazole magnesium coadministered with ubrogepant did not increase the incidence rate of treatment-emergent adverse events, and interactions between the medications are likely to have limited clinical relevance.

Sex differences in the expression of the endocannabinoid system within V1M cortex and PAG of Sprague Dawley rats

BACKGROUND

Several chronic pain disorders, such as migraine and fibromyalgia, have an increased prevalence in the female population. The underlying mechanisms of this sex-biased prevalence have yet to be thoroughly documented, but could be related to endogenous differences in neuromodulators in pain networks, including the endocannabinoid system. The cellular endocannabinoid system comprises the endogenous lipid signals 2-AG (2-arachidonoylglycerol) and AEA (anandamide); the enzymes that synthesize and degrade them; and the cannabinoid receptors. The relative prevalence of different components of the endocannabinoid system in specific brain regions may alter responses to endogenous and exogenous ligands.

METHODS

Brain tissue from naïve male and estrous staged female Sprague Dawley rats was harvested from V1M cortex, periaqueductal gray, trigeminal nerve, and trigeminal nucleus caudalis. Tissue was analyzed for relative levels of endocannabinoid enzymes, ligands, and receptors via mass spectrometry, unlabeled quantitative proteomic analysis, and immunohistochemistry.

RESULTS

Mass spectrometry revealed significant differences in 2-AG and AEA concentrations between males and females, as well as between female estrous cycle stages. Specifically, 2-AG concentration was lower within female PAG as compared to male PAG (*p = 0.0077); female 2-AG concentration within the PAG did not demonstrate estrous stage dependence. Immunohistochemistry followed by proteomics confirmed the prevalence of 2-AG-endocannabinoid system enzymes in the female PAG.

CONCLUSIONS

Our results suggest that sex differences exist in the endocannabinoid system in two CNS regions relevant to cortical spreading depression (V1M cortex) and descending modulatory networks in pain/anxiety (PAG). These basal differences in endogenous endocannabinoid mechanisms may facilitate the development of chronic pain conditions and may also underlie sex differences in response to therapeutic intervention.

Hyperexcitable interneurons trigger cortical spreading depression in an Scn1a migraine model

Cortical spreading depression (CSD), a wave of depolarization followed by depression of cortical activity, is a pathophysiological process implicated in migraine with aura and various other brain pathologies, such as ischemic stroke and traumatic brain injury. To gain insight into the pathophysiology of CSD, we generated a mouse model for a severe monogenic subtype of migraine with aura, familial hemiplegic migraine type 3 (FHM3). FHM3 is caused by mutations in SCN1A, encoding the voltage-gated Na⁺ channel Na_V1.1 predominantly expressed in inhibitory interneurons. Homozygous Scn1a^L1649Q knock-in mice died prematurely, whereas heterozygous mice had a normal lifespan. Heterozygous Scn1a^L1649Q knock-in mice compared with WT mice displayed a significantly enhanced susceptibility to CSD. We found L1649Q to cause a gain-of-function effect with an impaired Na⁺-channel inactivation and increased ramp Na⁺ currents leading to hyperactivity of fast-spiking inhibitory interneurons. Brain slice recordings using K⁺-sensitive electrodes revealed an increase in extracellular K⁺ in the early phase of CSD in heterozygous mice, likely representing the mechanistic link between interneuron hyperactivity and CSD initiation. The neuronal phenotype and premature death of homozygous Scn1a^L1649Q knock-in mice was partially rescued by GS967, a blocker of persistent Na⁺ currents. Collectively, our findings identify interneuron hyperactivity as a mechanism to trigger CSD.

BMI, Alcohol Consumption and Gut Microbiome Species Richness Are Related to Structural and Functional Neurological Abnormalities

Background: The incidence of neurological diseases is increasing throughout the world. The aim of the present study was to identify nutrition and microbiome factors related to structural and functional neurological abnormalities to optimize future preventive strategies. Methods: Two hundred thirty-eight patients suffering from (1) structural (neurodegeneration) or (2) functional (epilepsy) neurological abnormalities or (3) chronic pain (migraine) and 612 healthy control subjects were analyzed by validated 12-month food frequency questionnaire (FFQ) and 16S rRNA microbiome sequencing (from stool samples). A binomial logistic regression model was applied for risk calculation and functional pathway analysis to show which functional pathway could discriminate cases and healthy controls. Results: Detailed analysis of more than 60 macro- and micronutrients revealed no distinct significant difference between cases and controls, whereas BMI, insulin resistance and metabolic inflammation in addition to alcohol consumption were major drivers of an overall neurological disease risk. The gut microbiome analysis showed decreased alpha diversity (Shannon index: p = 9.1× 10⁻⁷) and species richness (p = 1.2 × 10⁻⁸) in the case group as well as significant differences in beta diversity between cases and controls (Bray–Curtis: p = 9.99 × 10⁻⁴; Jaccard: p = 9.99 × 10⁻⁴). The Shannon index showed a beneficial effect (OR = 0.59 (95%-CI (0.40, 0.87); p = 8 × 10⁻³). Cases were clearly discriminated from healthy controls by environmental information processing, signal transduction, two component system and membrane transport as significantly different functional pathways. Conclusions: In conclusion, our data indicate that an overall healthy lifestyle, in contrast to supplementation of single micro- or macronutrients, is most likely to reduce overall neurological abnormality risk and that the gut microbiome is an interesting target to develop novel preventive strategies.

Risk of migraine contributed by genetic polymorphisms of ANKDD1B gene: a case-control study based on Chinese Han population

Early studies have indicated that the risk of migraine is contributed by both genetic and environmental factors. We aimed to evaluate the association between the risk of migraine and genetic polymorphisms in the ANKDD1B gene in a large sample of Chinese Han populations. A total of 882 patients with MO and 1,784 age-matched controls were recruited. A list of 12 tag SNPs located within the ANKDD1B gene region was genotyped. Distributions of SNP genotypes and alleles between patients and controls were examined to investigate the associations between the risk of migraine and genetic polymorphisms. The GTEx database was used to examine the effects of the significant SNPs on gene expressions. A stop-gain SNP, rs34358, was discovered to be significantly related with the risk of migraine (χ² = 25.02, P = 5.66 × 10^-7). The A allele of this SNP was significantly associated with a decreased risk of migraine (OR [95% CI] = 0.73 [0.65-0.83]). A dose-dependent pattern was identified in the genotypic analyses. The OR with 95% confidence interval for genotype AA versus GG was 0.55 [0.42-0.72], while for AG versus GG it was 0.74 [0.62-0.88]. Further bioinformatics analysis showed multiple significant signals (20 out of 47) for the association between SNP rs34358 and gene expression levels of ANKDD1B. In conclusion, we have provided population-based evidence for the association between genetic polymorphisms of the ANKDD1B gene and the risk of migraine. A protein-truncating variant was significantly associated with a decreased risk of migraine in the samples recruited from the Chinese Han population.

CGRP and CGRP-receptor as targets of migraine therapy: Brain Prize-2021

BACKGROUND

Migraine is a highly prevalent primary headache with an unclear pathomechanism. During the last 40 years numerous hypotheses have arisen, among them the theory of the trigeminovascular system is the primary one. It serves as a skeleton in successful preclinical studies and in the development of effective therapeutic options for migraine headache.

OBJECTIVE

The Brain Prize (awarded annually by the Lundbeck Foundation) is the most prestigious tribute in neuroscience. The winners in 2021 were Lars Edvinsson, Peter Goadsby, Michael Moskowitz and Jes Olesen. They are the fathers of the migraine pathomechanism which led to revolutionary new treatments. This review summarizes their landmark findings.

METHODS

Data related to this topic were reviewed from PubMed records published between 1979 and May 2021. Searches were based on preclinical and clinical studies in the covered field. The findings were listed in chronological order. From a therapeutic perspective, only randomized controlled trials and meta-analysis were discussed.

RESULTS

The calcitonin gene-related peptide-related pathogenesis of migraine is based on the activation of the trigeminovascular system. The therapeutic triad for migraine is triptans, gepants and calcitonin gene-related peptide-targeted monoclonal antibodies.

CONCLUSION

In the past 40 years, the systematic work of leading headache scientists has resulted in robust theoretical and therapeutic knowledge in the preclinical and clinical study of migraine.

Hormonal influences in migraine - interactions of oestrogen, oxytocin and CGRP

Migraine is ranked as the second highest cause of disability worldwide and the first among women aged 15-49 years. Overall, the incidence of migraine is threefold higher among women than men, though the frequency and severity of attacks varies during puberty, the menstrual cycle, pregnancy, the postpartum period and menopause. Reproductive hormones are clearly a key influence in the susceptibility of women to migraine. A fall in plasma oestrogen levels can trigger attacks of migraine without aura, whereas higher oestrogen levels seem to be protective. The basis of these effects is unknown. In this Review, we discuss what is known about sex hormones and their receptors in migraine-related areas in the CNS and the peripheral trigeminovascular pathway. We consider the actions of oestrogen via its multiple receptor subtypes and the involvement of oxytocin, which has been shown to prevent migraine attacks. We also discuss possible interactions of these hormones with the calcitonin gene-related peptide (CGRP) system in light of the success of anti-CGRP treatments. We propose a simple model to explain the hormone withdrawal trigger in menstrual migraine, which could provide a foundation for improved management and therapy for hormone-related migraine in women.

PRDM16, LRP1 and TRPM8 genetic polymorphisms are risk factor for Pakistani migraine patients

BACKGROUND

Migraine is a chronic neurovascular condition characterized by recurring attacks of pulsating headaches. Genome-wide association studies (GWAS) identified many potential loci associated with migraine. To check the association of polymorphisms of PRDM16 (rs2651899), LRP1 (rs11172113), and TRPM8 (rs10166942) with migraine, the first time a case-control study was conducted in understudied Pakistani population.

METHODS

The study included 127 migraine patients (21 in migraine with aura and 106 with migraine without aura group) and 120 healthy control subjects from different areas of Punjab, Pakistan. Blood samples were collected from all the participants, and DNA was isolated from the lymphocytes by the modified organic method. Sanger's sequencing was done for PRDM16 (rs2651899), LRP1 (rs11172113), and TRPM8 (rs10166942) in all the samples to check the genotype. Logistic regression analysis was done using SPSS 20.0 to check the association of these SNPs with migraine susceptibility.

RESULTS

We found statistically significant differences between case and control group for PRDM16 (rs2651899) at genotypic level (p < 0.001), allelic level (p < 0.001; OR 3.088; 95% CI 2.082-4.579) and for dominant model (p < 0.001; OR 5.437; 95% CI 3.112-9.498). The major findings of this study suggested that PRDM16 rs2651899 is strongly associated with migraine in overall and subgroup analysis of genotypes. LRP1 (rs11172113) showed significant association with migraine except in subgroup comparison. A similar trend of association was found for TRPM8 (rs10166942) however, significant association was found only at the allelic level but no significant difference was seen at the genotypic level between case and control. One novel mutation c.67 + 4436_67 + 4438delA was also identified in the current study near LRP1 (rs11172113) polymorphic site.

CONCLUSION

In this first-ever replication report from Pakistan, PRDM16 (rs2651899) was found as a potential genetic marker in migraine susceptibility while LRP1 (rs11172113) and TRPM8 (rs10166942) showed partial association in subgroup analysis.

Altered trigeminothalamic spontaneous low-frequency oscillations in migraine without aura: a resting-state fMRI study

Background

Recent resting-state fMRI studies demonstrated functional dysconnectivity within the central pain matrix in migraineurs. This study aimed to investigate the spatial distribution and amplitude of low-frequency oscillations (LFOs) using fractional amplitude of low-frequency fluctuation (fALFF) analysis in migraine patients without aura, and to examine relationships between regional LFOs and clinical variables.

Methods

Resting-state fMRI data were obtained and preprocessed in 44 migraine patients without aura and 31 matched controls. fALFF was computed according to the original method, z-transformed for standardization, and compared between migraineurs and controls. Correlation analysis between regional fALFF and clinical variables was performed in migraineurs as well.

Results

Compared with controls, migraineurs had significant fALFF increases in bilateral ventral posteromedial (VPM) thalamus and brainstem encompassing rostral ventromedial medulla (RVM) and trigeminocervical complex (TCC). Regional fALFF values of bilateral VPM thalamus and brainstem positively correlated with disease duration, but not with migraine attack frequency or Migraine Disability Assessment Scale score.

Conclusions

We have provided evidence for abnormal LFOs in the brainstem including RVM/TCC and thalamic VPM nucleus in migraine without aura, implicating trigeminothalamic network oscillations in migraine pathophysiology. Our results suggest that enhanced LFO activity may underpin the interictal trigeminothalamic dysrhythmia that could contribute to the impairments of pain transmission and modulation in migraine. Given our finding of increasing fALFF in relation to increasing disease duration, the observed trigeminothalamic dysrhythmia may indicate either an inherent pathology leading to migraine headaches or a consequence of repeated attacks on the brain.

Medication Overuse and Headache Burden: Results From the CaMEO Study

Objective

To estimate the relative frequency of acute medication overuse (AMO) among people with episodic migraine and chronic migraine, to characterize the types of acute medications overused for migraine, and to identify factors associated with AMO.

Methods

We analyzed data from the Chronic Migraine Epidemiology and Outcomes (CaMEO) Study (ClinicalTrials.gov, NCT01648530), a cross-sectional and longitudinal internet study that included a systematic sampling of the US population. From September 2012 to November 2013, the CaMEO Study respondents participated in different modules to collect data on the clinical course of migraine, family burden, barriers to care, endophenotypes, and comorbidities. Among people who met the criteria for migraine consistent with the International Classification of Headache Disorders, third edition (ICHD-3), we evaluated types and frequency of medications used for headache/migraine, selected comorbidities, and emergency department (ED) and urgent care (UC) use. AMO was defined by days per month of medication use as specified by ICHD-3 criteria for medication overuse headache (MOH) without the requirement for ≥15 monthly headache days (MHDs). Nested, multivariable binary logistic regression modeling was used to identify factors associated with an increased risk of AMO.

Results

Of 16,789 CaMEO respondents with migraine, 2,975 (17.7%) met the AMO criteria. Approximately 67.9% (2,021/2,975) of AMO respondents reported <15 MHDs. Simple analgesics, combination analgesics, and opioids were the medication classes most commonly overused. Factors associated with AMO in the final multivariable logistic regression model included ≥15 MHDs, moderate to severe disability, severe migraine interictal burden, use of preventive medication, and an ED/UC visit for headache within 6 months.

Conclusions

Approximately two-thirds of respondents with AMO reported <15 MHDs and therefore did not meet the criteria for MOH. Those with AMO had greater disease burden and increased ED/UC utilization relative to people with migraine but not AMO.

Astrocytes mediate migraine-related intracranial meningeal mechanical hypersensitivity

ABSTRACT

The genesis of the headache phase in migraine with aura is thought to be mediated by cortical spreading depression (CSD) and the subsequent activation and sensitization of primary afferent neurons that innervate the intracranial meninges and their related large vessels. Yet, the exact mechanisms underlying this peripheral meningeal nociceptive response remain poorly understood. We investigated the relative contribution of cortical astrocytes to CSD-evoked meningeal nociception using extracellular single-unit recording of meningeal afferent activity and 2-photon imaging of cortical astrocyte calcium activity, in combination with 2 pharmacological approaches to inhibit astrocytic function. We found that fluoroacetate and l-α-aminoadipate, which inhibit astrocytes through distinct mechanisms, suppressed CSD-evoked afferent mechanical sensitization, but did not affect afferent activation. Pharmacological inhibition of astrocytic function, which ameliorated meningeal afferents' sensitization, reduced basal astrocyte calcium activity but had a minimal effect on the astrocytic calcium wave during CSD. We propose that calcium-independent signaling in cortical astrocytes plays an important role in driving the sensitization of meningeal afferents and the ensuing intracranial mechanical hypersensitivity in migraine with aura.

Biological and small molecule strategies in migraine therapy with relation to the calcitonin gene-related peptide family of peptides

Migraine is one of the most common of neurological disorders with a global prevalence of up to 15%. One in five migraineurs have frequent episodic or chronic migraine requiring prophylactic treatment. In recent years, specific pharmacological treatments targeting calcitonin gene-related peptide (CGRP) signalling molecules have provided safe and effective treatments, monoclonal antibodies for prophylaxis and gepants for acute therapy. Albeit beneficial, it is important to understand the molecular mechanisms of these new drugs to better understand migraine pathophysiology and improve therapy. Here, we describe current views on the role of the CGRP family of peptides - CGRP, calcitonin, adrenomedullin, amylin - and their receptors in the trigeminovascular system. All these molecules are present within the trigeminovascular system but differ in expression and localization. It is likely that they have different roles, which can be utilized in providing additional drug targets.

Pharmacological treatment of migraine: Drug classes, mechanisms of action, clinical trials and new treatments

Migraine is the sixth most prevalent disease globally, a major cause of disability, and it imposes an enormous personal and socioeconomic burden. Migraine treatment is often limited by insufficient therapy response, leading to the need for individually adjusted treatment approaches. In this review, we analyse historical and current pharmaceutical development approaches in acute and chronic migraine based on a comprehensive and systematic analysis of Food and Drug Administration (FDA)-approved drugs and those under investigation. The development of migraine therapeutics has significantly intensified during the last 3 years, as shown by our analysis of the trends of drug development between 1970 and 2020. The spectrum of drug targets has expanded considerably, which has been accompanied by an increase in the number of specialised clinical trials. This review highlights the mechanistic implications of FDA-approved and currently investigated drugs and discusses current and future therapeutic options based on identified drug classes of interest.

Intracranial nociception

Understanding intracranial nociceptive innervation is essential to understand the pathophysiology of headaches. Our knowledge about human intracranial nociception comes from sparse observations during neurosurgical procedures performed in awake patients, from human anatomical studies and from experimental studies in animals. In this article we review the anatomical and functional organization underlying nociceptive innervation. Intracranial nociception is mainly mediated by the trigeminal system, except in the posterior cranial fossa that is innervated by the first cervical roots. For decades, the dura mater, its vessels and major cerebral blood vessels were considered as the only intracranial pain-sensitive structures. Recent animal and human studies have suggested that smaller brain arteries and potentially pia mater might also be pain sensitive. Nociceptive neurons innervating intracranial blood vessels project via the ophthalmic division (V1) to the trigeminal ganglion and store several neurotransmitters including glutamate, substance P and calcitonin gene-related peptide (CGRP). The trigeminal ganglion, root and brainstem nuclei have a specific topographic and functional somatotopy. Progressive transition between the trigeminal spinal nucleus and the dorsal horn of the cervical spinal cord, and convergence of nociceptive inputs from the face, intracranial structures and the occipital area on the so-called "trigemino-cervical complex" may explain some headache features, relations between facial and occipital pain, and efficacy of occipital nerve stimulation in headache. The specific anatomic organization of the trigeminal system, from the primary-order neuron in the trigeminal ganglion, to the second-order neuron is the trigeminal nuclei, may explain a part of the various characteristics of headaches.

Migraine with aura

Around 15% to one-third of migraineurs experience aura. Aura is a fully reversible focal neurological phenomenon involving visual, sensory, speech, and/or motor symptoms that develops gradually and usually precedes the headache phase. The pivotal role of cortical spreading depression (CSD) as a mechanism underlying aura has been widely supported by a large body of studies. The diagnosis is based on the International Headache Classification Disorders III edition criteria. Aura is characterized by gradual development, duration of each symptom no longer than one hour, a mix of positive and negative features, and complete reversibility. Visual aura is the most common type of aura, occurring in over 90% of patients. When aura symptoms are multiple, they usually follow one another in succession, beginning with visual, then sensory, then aphasic; but the reverse and other orders have been noted. The accepted duration for most aura symptoms is one hour, but motor symptoms, which are rare, are often longer lasting. When a patient experiences for the first time a possible aura phase it's sometimes difficult to know if there was gradual or brutal onset of the symptoms. If the patient has no visual aura symptoms or simultaneous neurological symptoms, or presents neurological symptoms corresponding to a cerebral vascular territory, emergency exploration of a possible transient ischemic attack is necessary. Long duration (greater than one hour) of what may or may not be an aura phase, late onset of aura, or a dramatic increase in aura attacks should also be explored. The relative risk of ischemic stroke is significantly increased in migraine with aura. Combined hormonal contraception with estrogens significantly increases the risk of stroke in women with migraine with aura. It is recommended to start non-steroidal anti-inflammatory drugs (NSAIDs) or aspirin as soon as possible during the aura phase, not to treat the aura, but to avoid or to diminish the headache phase. In case of failure of NSAIDs or aspirin it is recommended to use a triptan when the headache begins. The prophylactic treatments for migraine with aura are those used in migraine without aura based on very few randomized clinical trials specifically dedicated to migraine with aura.

Effects of CYP3A4 and P-glycoprotein inhibition or induction on the pharmacokinetics of ubrogepant in healthy adults: Two phase 1, open-label, fixed-sequence, single-center, crossover trials

Background:

Ubrogepant is metabolized by cytochrome P450 3A4 (CYP3A4) and is a P-glycoprotein (P-gp) substrate.

Objective:

To assess effects of multiple-dose moderate-strong CYP3A4 and strong P-gp inhibitors and inducers on ubrogepant pharmacokinetic (PK) parameters.

Methods:

Two phase 1, open-label, fixed-sequence, single-center, crossover trials enrolled healthy adults to receive ubrogepant 20 mg with/without verapamil 240 mg (a moderate CYP3A4 inhibitor) or ketoconazole 400 mg (a strong CYP3A4 and P-gp transporter inhibitor) (Study A), or ubrogepant 100 mg with/without rifampin 600 mg (a strong CYP3A4 inducer and P-gp inducer) (Study B). Outcomes included ubrogepant PK parameters (area under plasma concentration-time curve, time 0 through infinity [AUC0-∞], peak plasma concentration [Cmax]), and safety (treatment-emergent adverse events [TEAEs]). PK parameters were compared between ubrogepant with/without coadministered medications using linear mixed-effects models. Cmax and AUC0-∞ least-squares geometric mean ratios (GMR) of ubrogepant with/without coadministration were constructed.

Results:

Twelve participants enrolled in Study A and 30 in Study B. AUC0-∞ and Cmax GMR (90% CI) were 3.53 (3.32–3.75) and 2.80 (2.48–3.15), respectively, for ubrogepant with verapamil; 9.65 (7.27–12.81) and 5.32 (4.19–6.76) with ketoconazole; and 0.22 (0.20–0.24) and 0.31 (0.27–0.36) with rifampin. TEAEs were predominantly mild; no treatment-related serious TEAEs or TEAE-related discontinuations occurred.

Conclusion:

The PK of ubrogepant were significantly affected by the concomitant use of CYP3A4 moderate-strong inhibitors and strong inducers.

Neuroprotective Potential of Limonene and Limonene Containing Natural Products

Limonene is a monoterpene confined to the family of Rutaceae, showing several biological properties such as antioxidant, anti-inflammatory, anticancer, antinociceptive and gastroprotective characteristics. Recently, there is notable interest in investigating the pharmacological effects of limonene in various chronic diseases due to its mitigating effect on oxidative stress and inflammation and regulating apoptotic cell death. There are several available studies demonstrating the neuroprotective role of limonene in neurodegenerative diseases, including Alzheimer's disease, multiple sclerosis, epilepsy, anxiety, and stroke. The high abundance of limonene in nature, its safety profile, and various mechanisms of action make this monoterpene a favorable molecule to be developed as a nutraceutical for preventive purposes and as an alternative agent or adjuvant to modern therapeutic drugs in curbing the onset and progression of neurodegenerative diseases. This manuscript presents a comprehensive review of the available scientific literature discussing the pharmacological activities of limonene or plant products containing limonene which attribute to the protective and therapeutic ability in neurodegenerative disorders. This review has been compiled based on the existing published articles confined to limonene or limonene-containing natural products investigated for their neurotherapeutic or neuroprotective potential. All the articles available in English or the abstract in English were extracted from different databases that offer an access to diverse journals. These databases are PubMed, Scopus, Google Scholar, and Science Direct. Collectively, this review emphasizes the neuroprotective potential of limonene against neurodegenerative and other neuroinflammatory diseases. The available data are indicative of the nutritional use of products containing limonene and the pharmacological actions and mechanisms of limonene and may direct future preclinical and clinical studies for the development of limonene as an alternative or complementary phytomedicine. The pharmacophore can also provide a blueprint for further drug discovery using numerous drug discovery tools.

Vestibular Migraine and Its Comorbidities

Vestibular migraine (VM) is one of the most common neurologic causes of vertigo. Symptoms and International Classification of Headache Disorders criteria are used to diagnose VM because no objective tests, imaging or audiologic, have been shown to reliably diagnose this condition. Central auditory, peripheral, and central vestibular pathway involvement has been associated with VM. Although the interaction between migraine and other vestibular disorders can be a challenging scenario for diagnosis and treatment, there are data to show that vestibular rehabilitation and a variety of pharmacologic agents improve reported symptoms and vertigo frequency.

CGRP and migraine; from bench to bedside

Migraine treatment has reached a new era with the development of drugs that target the trigeminal neuropeptide calcitonin gene-related peptide (CGRP) or its receptor. The CGRP related therapies offer considerable improvements over existing drugs as they are the first to be designed to act on the trigeminal pain system, more specific and with few adverse events. Small molecule CGRP receptor antagonists, such as rimegepant and ubrogepant, are effective for the acute treatment of migraine headache. In contrast, monoclonal antibodies against CGRP or the CGRP receptor are beneficial for the prophylactic treatments in chronic migraine. Here I will provide a historical overview of the long path that led to their successful development. In addition, I will discuss aspects on the biology of CGRP signalling, the role of CGRP in migraine headache, the efficacy of CGRP targeted treatment, and synthesize what currently is known about the role of CGRP in the trigeminovascular system.

Orexin one receptors within the basolateral amygdala are involved in the modulation of cognitive deficits associated with a migraine-like state in rats

OBJECTIVES

This study explored the possible role of orexin one receptors (Orx1R) in the basolateral amygdala (BLA) on the modulation of nitroglycerin (NTG)-induced migraine-like symptoms. In addition, pain-induced subsequent alteration in learning and memory competence was evaluated in the adult male Wistar rats.

METHODS

The rats were given NTG (5 mg/kg, i.p.) every two days (for nine-day) to induce a migraine-like state. The migraine animals were treated with intra-BLA infusion of an Orx1R antagonist SB 334,867 (10, 20, and 40 nM/rat) or its vehicle DMSO. The NTG-induced migraine symptoms were recorded for 90 min. Spatial and passive avoidance performances were assessed by Morris water maze (MWM) and shuttle box tasks, respectively.

RESULTS

In comparison with control, NTG produced significant migraine-like symptoms characterized by a decrease in cage climbing and an increase in head-scratching, freezing, and facial grooming behavior. Intra-BLA infusion of SB 334,867 (40 nM/rat) significantly decreased cage climbing and increased facial grooming responses in NTG-treated rats. Moreover, all administrated doses of SB 334,867 increased NTG-evoked head-scratching and freezing behavior. Besides, NTG impaired learning and memory performances in both tests, which were exaggerated by post-injection of SB 334,867 (40 nM/rat).

CONCLUSIONS

Overall, the data provided an emerging role for the orexin system within BLA in the modulation of cognitive decline comorbid with migraine in rats.

Migraine pharmacology and brain ischemia

Introduction: The aim of this review article was to analyze in details the mechanism of drugs’ effects in the treatment and prevention of a migraine attack, as well as to discuss the hypotheses of migraine pathogenesis.

Migraine attack treatment agents: The main agents for migraine attack treatment have an anti-nociceptive activity.

Agents for migraine preventive treatment: β-blocker propranolol also has anti-serotonin and analgesic activities, and most drugs used for the prophylactic treatment of migraine have a vasodilating activity.

Vascular hypothesis of migraine pathogenesis: Despite numerous studies that have expanded our understanding of migraine pathogenesis, the importance of the vascular component in the pathogenesis of this disease has not questioned yet.

Neurogenic hypotheses of cortical spreading depression: It is necessary to take into account the points of this hypothesis in the context of the pathophysiology of migraine.

Neurochemical serotonin hypotheses of migraine pathogenesis: Serotonin plays an important role in the pathogenesis of migraine.

Trigemino-vascular hypotheses of migraine pathogenesis: The trigemino-vascular hypothesis claims to solve the problem of migraine pain.

Migraine and ischemic brain damage: Migraine is a risk factor for ischemic stroke and cognitive disorders.

Search for the new anti-ischemic anti-migraine preparations: A methodology for the search for new anti-ischemic anti-serotonin drugs for the treatment of migraine is proposed.

Conclusion: Belonging of a drug to one or another pharmacological group does not always correspond to its therapeutic effect on the pathogenetic processes of migraine. Migraine with its variety of forms cannot fit only one of the proposed hypotheses on the pathogenesis of this disease.

Graphical abstract:

Surgical Options for Migraine: An Overview

Objective

The goal of this manuscript was to provide a comprehensive review of the surgical treatment for migraine headaches with a focus on trigger points and their clinical presentations, and to emphasize the importance of appropriate patient selection.

Background

Migraine is a prevalent neurological disease with headache being a disabling component of it. Surgical treatment for migraine headache became available two decades ago, which is based on proper identification and the deactivation of the specific trigger sites in the head and neck area.

Design

This manuscript reviews the discovery and evolution of migraine surgery with changes in patients' selection throughout the years.

Conclusion

Patients with migraine headaches who do not respond or cannot tolerate the medical treatment might benefit from trigger site deactivation surgery. The success of the surgery is closely related to proper identification of trigger point (s) and close collaboration with a neurologist or a headache specialist. This collaboration would enhance patients' positive outcomes and help to rule out other causes of the headache.

A 16S rRNA gene sequencing based study of oral microbiota in migraine patients in China

Migraine is a primary headache characterized by moderate or severe headache attacks, accompanied with reversible neurological and systemic symptoms. There are rare biomarkers for the disease. While emerging evidence has indicated the connection between gut microbiota and migraine, the relation between oral microbiota and migraine is barely known. Thus, the objective of the current study was to explore a possible correlation between oral microbiota and migraine. We compared the oral microbiota communities of migraine patients (26) with healthy subjects (29) via 16S rRNA gene sequencing. Alpha diversity indices were higher in migraine group compared with control group, whereas beta diversity indices also showed significant difference. A total of 23 genera were found differentially abundant between migraine and control groups. To conclude, there was a significant compositional difference in oral microbiota in migraine patients compared with healthy subjects.

Assessment of the choroidal thickness, central macular vascular and optic disk perfusion in migraine patients with optical coherence tomography angiography

BACKGROUND

Comparing the central choroidal thickness (CCT) and the perfusion of the macula and optic disk in patients with migraine and control group participants using optical coherence tomography angiography (OCTA).

METHODS

A total of 38 patients diagnosed with migraine and 32 healthy controls were recruited. OCTA scans were performed on all participants. Optic disk, central macular vascular perfusions, and CCT were measured.

RESULTS

Thirty-eight eyes of 38 participants (34 female and 4 male) in the migraine group and 32 eyes of 32 participants (19 female and 13 male) in the healthy control (HC) group were evaluated. The mean age was 42.74 ± 8.14 and 43.09 ± 14.28 years in the migraine group and HC group, respectively. The mean CCT were 314 ± 103 μm and 301 ± 71 μm in the migraine and HC group, respectively (p = 0.54). The mean optic disk perfusions were 44.77 ± 1.93% and 45.25 ± 1.43% in migraine and HC group, respectively (p = 0.25). The mean central macular vascular perfusions were 20.50 ± 8.20% and 18.65 ± 7.46% in migraine and HC group, respectively (p = 0.32). There was a significant negative correlation between CCT and the duration of migraine history (p = 0.004).

CONCLUSIONS

The macular and peripapillary microvasculature were not significantly different in patients with migraine than in HC. As the duration of migraine prolonged, a significant decrease in choroidal thickness was observed.

Migraine and neuroinflammation: the inflammasome perspective

BACKGROUND

Neuroinflammation has an important role in the pathophysiology of migraine, which is a complex neuro-glio-vascular disorder. The main aim of this review is to highlight findings of cortical spreading depolarization (CSD)-induced neuroinflammatory signaling in brain parenchyma from the inflammasome perspective. In addition, we discuss the limited data of the contribution of inflammasomes to other aspects of migraine pathophysiology, foremost the activation of the trigeminovascular system and thereby the generation of migraine pain.

MAIN BODY

Inflammasomes are signaling multiprotein complexes and key components of the innate immune system. Their activation causes the production of inflammatory cytokines that can stimulate trigeminal neurons and are thus relevant to the generation of migraine pain. The contribution of inflammasome activation to pain signaling has attracted considerable attention in recent years. Nucleotide-binding domain (NOD)-like receptor family pyrin domain containing 3 (NLRP3) is the best characterized inflammasome and there is emerging evidence of its role in a variety of inflammatory pain conditions, including migraine. In this review, we discuss, from an inflammasome point of view, cortical spreading depolarization (CSD)-induced neuroinflammatory signaling in brain parenchyma, the connection with genetic factors that make the brain vulnerable to CSD, and the relation of the inflammasome with diseases that are co-morbid with migraine, including stroke, epilepsy, and the possible links with COVID-19 infection.

CONCLUSION

Neuroinflammatory pathways, specifically those involving inflammasome proteins, seem promising candidates as treatment targets, and perhaps even biomarkers, in migraine.

Specific activation of GluN1-N2B NMDA receptors underlies facilitation of cortical spreading depression in a genetic mouse model of migraine with reduced astrocytic glutamate clearance

Migraine is a common but poorly understood sensory circuit disorder. Mouse models of familial hemiplegic migraine (FHM, a rare monogenic form of migraine with aura) show increased susceptibility to cortical spreading depression (CSD, the phenomenon that underlies migraine aura and can activate migraine headache mechanisms), allowing an opportunity to investigate the mechanisms of CSD and migraine onset. In FHM type 2 (FHM2) knock-in mice with reduced expression of astrocytic Na⁺, K⁺-ATPases, the reduced rate of glutamate uptake into astrocytes can account for the facilitation of CSD initiation. Here, we investigated the underlying mechanisms and show that the reduced rate of glutamate clearance in FHM2 mice results in increased amplitude and slowing of rise time and decay of the NMDA receptor (NMDAR) excitatory postsynaptic current (EPSC) elicited in layer 2/3 pyramidal cells by stimulation of neuronal afferents in somatosensory cortex slices. The relative increase in NMDAR activation in FHM2 mice is activity-dependent, being larger after high-frequency compared to low-frequency afferent activity. Inhibition of GluN1-N2B NMDARs, which hardly affected the NMDAR EPSC in wild-type mice, rescued the increased and prolonged activation of NMDARs as well as the facilitation of CSD induction and propagation in FHM2 mice. Our data suggest that the enhanced susceptibility to CSD in FHM2 is mainly due to specific activation of extrasynaptic GluN1-N2B NMDARs and point to these receptors as possible therapeutic targets for prevention of CSD and migraine.

Identification of a population of peripheral sensory neurons that regulates blood pressure

The vasculature is innervated by a network of peripheral afferents that sense and regulate blood flow. Here, we describe a system of non-peptidergic sensory neurons with cell bodies in the spinal ganglia that regulate vascular tone in the distal arteries. We identify a population of mechanosensitive neurons, marked by tropomyosin receptor kinase C (TrkC) and tyrosine hydroxylase in the dorsal root ganglia, which projects to blood vessels. Local stimulation of TrkC neurons decreases vessel diameter and blood flow, whereas systemic activation increases systolic blood pressure and heart rate variability via the sympathetic nervous system. Ablation of the neurons provokes variability in local blood flow, leading to a reduction in systolic blood pressure, increased heart rate variability, and ultimately lethality within 48 h. Thus, a population of TrkC⁺ sensory neurons forms part of a sensory-feedback mechanism that maintains cardiovascular homeostasis through the autonomic nervous system.

•

TrkC⁺/Th⁺ DRG neurons project to blood vessels

•

Local stimulation of TrkC⁺ DRG neurons decreases vessel diameter and blood flow

•

Systemic activation of TrkC⁺ DRG neurons increases blood pressure and heart rate

•

Ablation of TrkC⁺ neurons dysregulates cardiovascular homeostasis and is lethal

Pathophysiology of Migraine

PURPOSE OF REVIEW

This article summarizes the current understanding of the pathophysiology of migraine, including some controversial aspects of the underlying mechanisms of the disorder.

RECENT FINDINGS

Recent functional neuroimaging studies focusing on the nonpainful symptoms of migraine have identified key areas of the central nervous system implicated in the early phases of a migraine attack. Clinical studies of spontaneous and provoked migraine attacks, together with preclinical studies using translational animal models, have led to a better understanding of the disease and the development of disease-specific and targeted therapies.

SUMMARY

Our knowledge of the pathophysiology of migraine has advanced significantly in the past decades. Current evidence supports our understanding of migraine as a complex cyclical brain disorder that likely results from dysfunctional sensory processing and dysregulation of homeostatic mechanisms. This article reviews the underlying mechanisms of the clinical manifestations of each phase of the migraine cycle.

Eptinezumab for the treatment of migraine

INTRODUCTION

Migraine is one of the most common illnesses in the world, with severe economical and subjective implications. Nowadays specific and nonspecific drugs are used for migraine chronic therapy, but a portion of patients have no benefit from these administrations. CGRP receptor antagonists are a good preventive treatment for episodic and chronic migraine.

AREAS COVERED

This article reviews both preclinical and clinical studies on eptinezumab as a potential preventive therapy for migraine, as well as pharmacokinetic and pharmacodynamic features. Thus, it summarizes safety and tolerability data based on human studies.

EXPERT OPINION

Eptinezumab had good results in several trials, making this molecule a promising migraine preventive drug. Although preclinical and clinical studies showed a significant efficacy, there are no data on the use of Eptinezumab during pregnancy or breastfeeding. There are still some knowledge limits about its pharmacokinetics and metabolism. This is a matter of concern that should be addressed in future studies.

Craniofacial Autonomic Dysfunction in Migraine: Implications for Treatment and Prognosis

BACKGROUND

Craniofacial autonomic signs and symptoms (CASS) are relatively underrecognized in the evaluation of migraine headache. Yet, these features provide insight into diagnostic criterion, therapeutic approaches, and overarching disease burden.

EVIDENCE ACQUISITION

This review aims to summarize relevant literature evaluating autonomic dysfunction, with focus on CASS, in migraine through targeted literature searches in PubMed. Full articles of original data published between 1974 and 2019 were identified using MeSH terms with no search limits.

RESULTS

Although CASS are typically clinically evaluated by subjective patient report, investigational measures of cranial autonomic function have identified marked distinctions between headache attack and attack-free intervals. The presence of CASS during an attack does not differ based on age, sex, or presence of aura. Unilateral CASS may be predictive of longer, more frequent, and/or severe attacks and often co-occur with sensory dysfunction such as allodynia and photophobia. Although limited research has been performed to evaluate targeted therapeutics for migraine with CASS, triptans and onabotulinumtoxinA may demonstrate greater effects in this group.

CONCLUSIONS

Migraine remains a debilitating disorder with significant community-wide impacts, necessitating continued evaluation of contributing features. Consideration of CASS provides important insight into potential treatment approaches and the effectiveness of novel therapeutic interventions aimed at improving overall disease burden. However, further investigation is needed to fully understand primary craniofacial features in migraine, and how these might inform individualized treatment decisions.

Evaluation of the Pharmacokinetic Interaction and Safety of Atogepant Co-Administered with Acetaminophen or Naproxen in Healthy Participants: A Randomized Trial

Background

Atogepant is an oral calcitonin gene-related peptide (CGRP) receptor antagonist in development for preventive treatment of migraine.

Objective

To evaluate potential pharmacokinetic drug–drug interactions (DDIs), safety and tolerability of atogepant co-administered with acetaminophen or naproxen in healthy participants.

Methods

This open-label, randomized, five-way crossover, single-center, phase 1 DDI trial randomized healthy adult participants to one of ten intervention sequences to receive single-dose 60 mg atogepant, 1000 mg acetaminophen, 500 mg naproxen, or co-administrations of atogepant with acetaminophen or naproxen, with 7-day washout periods between interventions. Potential DDIs were assessed using geometric mean ratios and 90% confidence intervals (CIs) calculated from maximum plasma drug concentrations (C_max) and area under the plasma drug concentration-time curves (AUCs) for co-administered medications versus medications administered alone. Secondary pharmacokinetic parameters [time to C_max (t_max), terminal elimination half-life (t_1/2), volume of distribution during terminal phase (V_Z/F), total body clearance (CL/F)], and safety were evaluated.

Results

Forty participants enrolled; 35 (87.5%) completed the trial. Atogepant C_max was unchanged, AUC_0–t and AUC_0–∞ both increased 13%, and t_max and t_1/2 were unchanged when co-administered with acetaminophen; and acetaminophen C_max decreased 11%, AUC_0–t and AUC_0–∞ both decreased 6%, and t_max and t_1/2 were unchanged when co-administered with atogepant. Atogepant mean (SD) V_z/F and CL/F were 369.45 (255.68) L and 18.88 (9.28) L/h, respectively, when administered alone and 297.56 (196.01) L and 16.33 (6.11) L/h when co-administered with acetaminophen. Atogepant C_max was unchanged, AUC_0–t and AUC_0–∞ both decreased 1%, and t_max and t_1/2 were unchanged when co-administered with naproxen; and naproxen C_max decreased 6%, AUC_0–t and AUC_0–∞ both decreased 2%, and t_max and t_1/2 were unchanged when co-administered with atogepant. Atogepant mean (SD) V_z/F and CL/F were 359.61 (247.99) L and 18.80 (7.78) L/h, respectively, when co-administered with naproxen. Treatment-emergent adverse events (TEAEs) occurred at rates of 5.6–21.1% across interventions. The most commonly reported TEAEs were oropharyngeal pain (n = 2, with atogepant; not treatment related) and nausea (n = 2, with atogepant/acetaminophen; treatment related).

Conclusion

Co-administration of 60 mg atogepant with 1000 mg acetaminophen or 500 mg naproxen was safe and well tolerated in healthy participants, and no DDIs were observed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40261-021-01034-5.

A Single Supratherapeutic Dose of Atogepant Does Not Affect Cardiac Repolarization in Healthy Adults: Results From a Randomized, Single-Dose, Phase 1 Crossover Trial

Atogepant is a selective, oral calcitonin gene–related peptide receptor antagonist in development for preventive treatment of migraine. This randomized, double‐blind, phase 1 crossover study evaluated the cardiac repolarization effect of a single supratherapeutic (300 mg) atogepant dose vs placebo in healthy adults. Moxifloxacin 400 mg was the open‐label active control. The primary end point was a change from baseline in Fridericia‐corrected QT intervals (ΔQTcF). Sixty participants were randomized to atogepant 300 mg, placebo, and moxifloxacin; 59 (98.3%) completed all interventions. Assay sensitivity was confirmed: lower 90% confidence interval limit for QTcF interval change from baseline (ΔΔQTcF) for moxifloxacin was >5 millisecond vs placebo at prespecified 2‐, 3‐, and 4‐hour time points. Following single‐dose atogepant 300 mg, mean atogepant ΔΔQTcF and upper 90% confidence interval limits were lower than the 10‐millisecond threshold at all time points. Atogepant mean peak plasma concentration was 3197 ng/mL, area under the concentration‐time curve from time 0 to time t was 16 640 ng • h/mL, area under the concentration‐time curve from time 0 to 24 hours was 16 607 ng • h/mL, and median time to peak plasma concentration was 2.1 hours. The incidence of adverse events was low; no serious adverse events or elevations of liver enzymes were reported. Overall, a single supratherapeutic dose of atogepant was safe and did not impact cardiac repolarization in healthy participants.

Temporal instability of salience network activity in migraine with aura

This study aims to investigate whether intranetwork dynamic functional connectivity and causal interactions of the salience network is altered in the interictal term of migraine. Thirty-two healthy controls, 37 migraineurs without aura, and 20 migraineurs with aura were recruited. Participants underwent a T1-weighted scan and resting-state fMRI protocol inside a 1.5T MR scanner. We obtained average spatial maps of resting-state networks using group independent component analysis, which yielded subject-specific time series through a dual regression approach. Salience network regions of interest (bilateral insulae and prefrontal cortices, dorsal anterior cingulate cortex) were obtained from the group average map through cluster-based thresholding. To describe intranetwork connectivity, average and dynamic conditional correlation was calculated. Causal interactions between the default-mode, dorsal attention, and salience network were characterised by spectral Granger's causality. Time-averaged correlation was lower between the right insula and prefrontal cortex in migraine without aura vs with aura and healthy controls (P < 0.038, P < 0.037). Variance of dynamic conditional correlation was higher in migraine with aura vs healthy controls and migraine with aura vs without aura between the right insula and dorsal anterior cingulate cortex (P < 0.011, P < 0.026), and in migraine with aura vs healthy controls between the dorsal anterior cingulate and left prefrontal cortex (P < 0.021). Causality was weaker in the <0.05 Hz frequency range between the salience and dorsal attention networks in migraine with aura (P < 0.032). Overall, migraineurs with aura exhibit more fluctuating connections in the salience network, which also affect network interactions, and could be connected to altered cortical excitability and increased sensory gain.

Reflexive and Intentional Saccadic Eye Movements in Migraineurs

Background: Migraine has been postulated to lead to structural and functional changes of different cortical and subcortical areas, including the frontal lobe, the brainstem, and cerebellum. The (sub-)clinical impact of these changes is a matter of debate. The spectrum of possible clinical differences include domains such as cognition but also coordination. The present study investigated the oculomotor performance of patients with migraine with and without aura compared to control subjects without migraine in reflexive saccades, but also in intentional saccades, which involve cerebellar as well as cortical networks.

Methods: In 18 patients with migraine with aura and 21 patients with migraine without aura saccadic eye movements were recorded in two reflexive (gap, overlap) and two intentional (anti, memory) paradigms and compared to 25 controls without migraine.

Results: The main finding of the study was an increase of saccade latency in patients with and without aura compared to the control group solely in the anti-task. No deficits were found in the execution of reflexive saccades.

Conclusions: Our results suggest a specific deficit in the generation of correct anti-saccades, such as vector inversion. Such processes are considered to need cortical networks to be executed correctly. The parietal cortex has been suggested to be involved in vector inversion processes but is not commonly described to be altered in migraine patients. It could be discussed that the cerebellum, which is recently thought to be involved in the pathophysiology of migraine, might be involved in distinct processes such as spatial re-mapping through known interconnections with parietal and frontal cortical areas.

Pharmacokinetics and safety of ubrogepant when coadministered with calcitonin gene-related peptide-targeted monoclonal antibody migraine preventives in participants with migraine: A randomized phase 1b drug-drug interaction study

Objective

To evaluate the impact of two calcitonin gene–related peptide (CGRP)‐targeted monoclonal antibodies (mAbs), erenumab and galcanezumab, on the pharmacokinetic (PK) profile, safety, and tolerability of ubrogepant.

Background

People taking CGRP‐targeted mAbs for migraine prevention sometimes take ubrogepant, an oral small‐molecule CGRP receptor antagonist, for acute treatment of breakthrough migraine attacks.

Design

In this two‐arm, multicenter, open‐label, phase 1b trial, adults with migraine were randomized to arm 1 (ubrogepant ± erenumab) or arm 2 (ubrogepant ± galcanezumab). The PK profile of ubrogepant was characterized for administration before and 4 days after CGRP‐targeted mAb injection. Participants received single‐dose ubrogepant 100 mg on day 1, subcutaneous erenumab 140 mg (arm 1) or galcanezumab 240 mg (arm 2) on day 8, and ubrogepant 100 mg once daily on days 12–15. In each study arm, serial blood samples were drawn on days 1 and 12 for measurement of plasma ubrogepant concentrations. The primary outcomes were area under the plasma ubrogepant concentration–time curve (AUC) from time 0 to t post‐dose (AUC_0–t) and from time 0 to infinity (AUC_0–inf), and maximum plasma concentration (C_max) of ubrogepant when ubrogepant was administered before or after a single dose of erenumab or galcanezumab. Vital signs and laboratory parameters were monitored.

Results

Forty participants enrolled (20 per arm; mean [standard deviation] ages, 32.2 [8.9] and 38.4 [8.8] years; 50% [10/20] and 60% [12/20] female in arms 1 and 2, respectively). There were no significant differences in ubrogepant C_max after versus before erenumab administration (geometric least‐squares mean [LSM] ratio, 1.04 [90% CI, 0.93–1.16]), and no significant differences in AUC_0–t (1.06 [0.96–1.16]) or AUC_0–inf (1.05 [0.96–1.15]). Similarly, ubrogepant C_max (1.00 [90% CI, 0.82–1.20]), AUC_0–t (1.05 [0.90–1.23]), and AUC_0–inf (1.05 [0.90–1.22]) geometric LSM ratios were statistically equivalent after galcanezumab versus ubrogepant alone. Treatment‐emergent adverse events (TEAEs) were similar to those reported with each treatment alone. No serious TEAEs, TEAEs leading to discontinuation, or clinically relevant changes in laboratory parameters or vital signs were reported.

Conclusions

The PK profile of ubrogepant was not significantly changed and no safety concerns were identified when ubrogepant was coadministered with erenumab or galcanezumab.

Sodium channelopathies of skeletal muscle and brain

Voltage-gated sodium channels initiate action potentials in nerve, skeletal muscle, and other electrically excitable cells. Mutations in them cause a wide range of diseases. These channelopathy mutations affect every aspect of sodium channel function, including voltage sensing, voltage-dependent activation, ion conductance, fast and slow inactivation, and both biosynthesis and assembly. Mutations that cause different forms of periodic paralysis in skeletal muscle were discovered first and have provided a template for understanding structure, function, and pathophysiology at the molecular level. More recent work has revealed multiple sodium channelopathies in the brain. Here we review the well-characterized genetics and pathophysiology of the periodic paralyses of skeletal muscle and then use this information as a foundation for advancing our understanding of mutations in the structurally homologous α-subunits of brain sodium channels that cause epilepsy, migraine, autism, and related comorbidities. We include studies based on molecular and structural biology, cell biology and physiology, pharmacology, and mouse genetics. Our review reveals unexpected connections among these different types of sodium channelopathies.

An underrepresented majority: A systematic review utilizing allodynic criteria to examine the present scarcity of discrete animal models for episodic migraine

BACKGROUND

Despite increasing evidence differentiating episodic and chronic migraine, little work has determined how currently utilized animal models of migraine best represent each distinct disease state.

AIM

In this review, we seek to characterize accepted preclinical models of migraine-like headache by their ability to recapitulate the clinical allodynic features of either episodic or chronic migraine.

METHODS

From a search of the Pu bMed database for "animal models of migraine", "headache models" and "preclinical migraine", we identified approximately 80 recent (within the past 20 years) publications that utilized one of 10 different models for migraine research. Models reviewed fit into one of the following categories: Dural KCl application, direct electrical stimulation, nitroglycerin administration, inflammatory soup injection, CGRP injection, medication overuse, monogenic animals, post-traumatic headache, specific channel activation, and hormone manipulation. Recapitulation of clinical features including cephalic and extracephalic hypersensitivity were evaluated for each and compared.

DISCUSSION

Episodic migraineurs comprise over half of the migraine population, yet the vast majority of current animal models of migraine appear to best represent chronic migraine states. While some of these models can be modified to reflect episodic migraine, there remains a need for non-invasive, validated models of episodic migraine to enhance the clinical translation of migraine research.

Altered functional connectivity of the insula in a rat model of recurrent headache

Migraine is a pain disorder accompanied by various symptoms. The insula, a “cortical hub,” is involved in many functions. Few studies have focused on the insula in migraine. We explored the resting-state functional connectivity between the insula and other brain areas in rats subjected to repeated meningeal nociception which was commonly used as animal model of migraine. Inflammatory soup was infused through supradural catheters in conscious rats. The rats were subdivided based on the frequency of the inflammatory soup infusions. Magnetic resonance imaging data were acquired on rats 21 days after inflammatory soup infusion and functional connectivity seeded on the insula was analyzed. In the low-frequency inflammatory soup group, magnetic resonance imaging was performed again 1 h after the glyceryl trinitrate injection following baseline scanning. The cerebellum showed increased functional connectivity with the insula in the inflammatory soup groups. The insula showed increased functional connectivity with the medulla and thalamus in the ictal period in the low-frequency inflammatory soup rats. In the high-frequency inflammatory soup group, several areas showed increased functional connectivity with the insula, including the pons, midbrain, thalamus, temporal association cortex, and retrosplenial, visual, and sensory cortices. Our findings support the hypothesis that the headache phase of migraine depends on the activation and sensitization of the trigeminovascular system, and that the chronification of migraine may be related to higher brain centers and limbic cortices. The insula may be a new target for treatment of migraine.

The trigeminal system: The meningovascular complex- A review

Supratentorial sensory perception, including pain, is subserved by the trigeminal nerve, in particular, by the branches of its ophthalmic division, which provide an extensive innervation of the dura mater and of the major brain blood vessels. In addition, contrary to previous assumptions, studies on awake patients during surgery have demonstrated that the mechanical stimulation of the pia mater and small cerebral vessels can also produce pain. The trigeminovascular system, located at the interface between the nervous and vascular systems, is therefore perfectly positioned to detect sensory inputs and influence blood flow regulation. Despite the fact that it remains only partially understood, the trigeminovascular system is most probably involved in several pathologies, including very frequent ones such as migraine, or other severe conditions, such as subarachnoid haemorrhage. The incomplete knowledge about the exact roles of the trigeminal system in headache, blood flow regulation, blood barrier permeability and trigemino-cardiac reflex warrants for an increased investigation of the anatomy and physiology of the trigeminal system. This translational review aims at presenting comprehensive information about the dural and brain afferents of the trigeminovascular system, in order to improve the understanding of trigeminal cranial sensory perception and to spark a new field of exploration for headache and other brain diseases.

Approximation to pain-signaling network in humans by means of migraine

Nociceptive signals are processed within a pain-related network of the brain. Migraine is a rather specific model to gain insight into this system. Brain networks may be described by white matter tracts interconnecting functionally defined gray matter regions. Here, we present an overview of the migraine-related pain network revealed by this strategy. Based on diffusion tensor imaging data from subjects in the Human Connectome Project (HCP) database, we used a global tractography approach to reconstruct white matter tracts connecting brain regions that are known to be involved in migraine-related pain signaling. This network includes an ascending nociceptive pathway, a descending modulatory pathway, a cortical processing system, and a connection between pain-processing and modulatory areas. The insular cortex emerged as the central interface of this network. Direct connections to visual and auditory cortical association fields suggest a potential neural basis of phono- or photophobia and aura phenomena. The intra-axonal volume (Vintra ) as a measure of fiber integrity based on diffusion microstructure was extracted using an innovative supervised machine learning approach in form of a Bayesian estimator. Self-reported pain levels of HCP subjects were positively correlated with tract integrity in subcortical tracts. No correlation with pain was found for the cortical processing systems.

Pain-Related Brain Connectivity Changes in Migraine: A Narrative Review and Proof of Concept about Possible Novel Treatments Interference

A neuronal dysfunction based on the imbalance between excitatory and inhibitory cortical-subcortical neurotransmission seems at the basis of migraine. Intercritical neuronal abnormal excitability can culminate in the bioelectrical phenomenon of Cortical Spreading Depression (CSD) with secondary involvement of the vascular system and release of inflammatory mediators, modulating in turn neuronal activity. Neuronal dysfunction encompasses the altered connectivity between the brain areas implicated in the genesis, maintenance and chronic evolution of migraine. Advanced neuroimaging techniques allow to identify changes in functional connectivity (FC) between brain areas involved in pain processes. Through a narrative review, we re-searched case-control studies on FC in migraine, between 2015 and 2020, by inserting the words migraine, fMRI, EEG, MEG, connectivity, pain in Pubmed. Studies on FC have shown that cortical processes, in the neurolimbic pain network, are likely to be prevalent for triggering attacks, in response to predisposing factors, and that these lead to a demodulation of the subcortical areas, at the basis of migraine maintenance. The link between brain dysfunction and peripheral interactions through the inhibition of CGRP, the main mediator of sterile migraine inflammation needs to be further investigated. Preliminary evidence could suggest that peripheral nerves inference at somatic and trigeminal levels, appears to change brain FC.

Effect of galcanezumab on severity and symptoms of migraine in phase 3 trials in patients with episodic or chronic migraine

BACKGROUND

Galcanezumab, a humanized monoclonal antibody that binds calcitonin gene-related peptide, has demonstrated a significant reduction in monthly migraine headache days compared with placebo. Here, we analyze data from 3 randomized clinical trials (2 episodic trials [EVOLVE-1, EVOLVE-2] and 1 chronic trial [REGAIN]), to examine if galcanezumab also alleviates the severity and symptoms of migraine.

METHODS

The episodic migraine trials were 6-month, double-blind studies in patients with episodic migraine (4-14 monthly migraine headache days). The chronic migraine trial was a 3-month, double-blind study in patients with chronic migraine (≥ 15 headache days per month, where ≥ 8 met criteria for migraine). Patients (18-65 years) were randomized to placebo or galcanezumab 120 mg with a 240-mg loading dose or 240 mg. Patients recorded headache characteristics, duration, severity, and presence of associated symptoms with each headache. The outcomes analyzed were changes from baseline in number of monthly migraine headache days with nausea and/or vomiting, photophobia and phonophobia, aura, and prodromal symptoms other than aura. Additional outcomes analyzed included the number of moderate-to-severe monthly migraine headache days, number of severe migraine headache days, and mean severity of remaining migraine headache days. Change from baseline in the proportion of days with nausea and/or vomiting and the proportion of days with photophobia and phonophobia among the remaining monthly migraine headache days were also analyzed.

RESULTS

Galcanezumab was superior to placebo in reducing the frequency of migraine headache days with associated symptoms of migraine such as nausea and/or vomiting, photophobia and phonophobia, and prodromal symptoms. Galcanezumab reduced the frequency of migraine headache days with aura in the episodic migraine studies. There was a significant reduction in the proportion of remaining migraine headache days with nausea and/or vomiting for the episodic and chronic migraine studies, and with photophobia and phonophobia for the episodic migraine studies. Galcanezumab was superior to placebo in reducing the number of monthly moderate-to-severe migraine headache days and the overall and monthly severe migraine headache days.

CONCLUSIONS

Galcanezumab reduces the frequency of migraine headache days and can alleviate potentially disabling non-pain symptoms on days when migraine is present in patients with episodic or chronic migraine.

TRIAL REGISTRATION

NCT, NCT02614183 (EVOLVE-1), registered 25 November 2015; NCT, NCT02614196 , (EVOLVE-2), registered 25 November 2015; NCT, NCT02614261 (REGAIN), registered 25 November 2015.

Differential effects of the Piezo1 agonist Yoda1 in the trigeminovascular system: An electrophysiological and intravital microscopy study in rats

Migraine is associated with the activation and sensitisation of the trigeminovascular system and is often accompanied by mechanical hyperalgesia and allodynia. The mechanisms of mechanotransduction during a migraine attack are yet unknown. We have proposed that the ion channel Piezo1 may be involved, since it is expressed in endothelial cells as well as in trigeminal ganglion neurons, and thus, may contribute to the activation of both the vascular and neuronal component of the trigeminovascular system. We took advantage of extracellular recordings from the trigeminocervical complex - a key relay centre in the migraine pain pathway, to directly assess the impact of the differently applied Piezo1 agonist Yoda1 on the sensory processing at the spinal level. At a low dose, Yoda1 slightly facilitated the ongoing firing of central trigeminovascular neurons, however, at a high dose, this substance contributed to the suppression of their activity. Using intravital microscopy, we have revealed that Yoda1 at high dose can also induce the dilation of meningeal arteries innervated by trigeminal afferents. Collectively, here we have identified both neuronal and vascular modulation via selective activation of mechanosensitive Piezo1 channels, which provide new evidence in favour of the Piezo1 role in migraine pathogenesis. We propose several mechanisms that may underlie the revealed effects of Yoda1.

Effect of occipitoatlantal decompression on cerebral blood flow dynamics as evaluated by Doppler ultrasonography

Context

Osteopathic manipulative treatment reduces symptoms in patients with headache disorders, but the underlying mechanisms are unclear.

Objective

To evaluate blood flow in the intracranial and extracranial vasculature before and after occipitoatlantal decompression (OAD) using Doppler ultrasonography.

Methods

Healthy, first-year osteopathic medical students from A.T. Still University's Kirksville College of Osteopathic Medicine participated in a randomized, single-blinded, two-period, two-treatment crossover study. The participants were randomly assigned to 1 of 2 treatment interventions: OAD or sham touch. After one week, participants returned to have the other intervention performed. Blood flow parameters-peak systolic velocity (PSV) and end-diastolic velocity (EDV)-in the middle cerebral artery (MCA), internal carotid artery (ICA), and vertebral artery (VA) were evaluated before, immediately after, 5 minutes after, and 10 minutes after treatment. Differences in PSV, EDV, heart rate (HR), and blood pressure (BP) for both interventions were analyzed for the four time points using mixed-effects models.

Results

Thirty healthy medical students (11 men, 19 women; mean age, 24 years) participated in this study. EDV increased after OAD in the MCA, ICA, and VA (all p<0.001); no change occurred after sham touch (all p>0.05). EDV was greater for all post-treatment timepoints after OAD in the MCA, ICA, and VA than after sham touch (all p<0.001). Although baseline PSV in the MCA measured before treatment was different between treatment interventions (p=0.01), no difference was found between interventions at any post-treatment time point (all p>0.59). Changes in PSV in the ICA and VA and for HR and BP did not depend on treatment intervention (p>0.06).

Conclusion

Increases in EDV occurred in major cranial arteries after OAD but not after sham touch, indicating that OAD improves blood flow to the brain. The exact mechanism of this increase is unknown; however, it can be explained by either parasympathetic stimulation through the secretion of vasodilating neurotransmitters or by a decrease in external tissue pressure on ICA and VA, with the resulting flow causing further dilation in the MCA.

Single-Dose Pharmacokinetics and Safety of Atogepant in Adults With Hepatic Impairment: Results From an Open-Label, Phase 1 Trial

Atogepant is a selective oral calcitonin gene‐related peptide receptor antagonist in development for migraine prevention. Here, we report the pharmacokinetics (PK) and safety of single‐dose 60 mg atogepant in participants with severe, moderate, or mild hepatic impairment and matched participants with normal hepatic function from an open‐label, parallel‐group, single‐dose phase 1 trial. Thirty‐two participants aged 45 to 72 years were enrolled, which included 8 each with severe, moderate, mild, or no hepatic impairment. All participants completed the study. Atogepant was rapidly absorbed (median time to maximum plasma concentration, ∼2 hours) with an apparent terminal elimination half‐life of ∼11 hours. Compared with participants with normal hepatic function, the change in maximum plasma concentrations of atogepant were –4%, –12%, and +9% in participants with severe, moderate, or mild hepatic impairment, respectively. Overall systemic exposures to atogepant were 15% to 38% higher in participants with hepatic impairment compared with those with normal hepatic function, but these differences are not expected to be clinically relevant given the established safety profile of atogepant. Only 1 adverse event was reported: mild rhinorrhea in a participant with moderate hepatic impairment. Overall, atogepant was safe and not associated with any clinically relevant change in PK in participants with severe, moderate, or mild hepatic impairment.

Association between tumor necrosis factor alpha and lymphotoxin alpha gene polymorphisms and migraine occurrence among Jordanians

Inflammatory reactions in the body have been shown to contribute to migraine development. Therefore, genes involved in the inflammatory pathways might play a role in the susceptibility and development of migraine. In this study, polymorphisms in tumor necrosis factor alpha (TNFα) and lymphotoxin alpha (LTA) genes were tested for association with migraine. A total of 398 participants (198 migraine patients and 200 controls) were recruited in the study. Serum TNF level was measured using a sandwich ELISA kit. Lymphocytes' and monocytes' counts were obtained from a differential complete blood count profile. Participants' DNA was extracted and genotyped for rs1800629 and rs1799724 in TNFα, and rs909253 in LTA. Controls had a significantly higher mean lymphocyte count (P = 0.018), while the mean monocyte count and serum TNFα levels did not differ between the two groups (P > 0.05). With respect to gene polymorphisms, the rs1800629 and rs1799724 variants showed significant association with migraine in all subjects, and in males and females when analyzed separately (P < 0.001). The rs909253 did not show any statistical difference in frequencies among the two groups (P > 0.05). Having the A allele in rs1800629 was associated with a higher risk of migraine in both male (OR, 95%; CI, G/A = 3.79 [1.87-7.69]; A/A = 14.22 [1.67-121.14]; P < 0.01) and female (OR, 95%; G/A = 2.54 [1.47-4.38]; A/A = 2.52 [1.12-5.69]; P < 0.001) subjects. In conclusion, rs1800629 and rs1799724 in TNFα showed significant association with migraine among the Jordanian population.

Neuropeptide changes in an improved migraine model with repeat stimulations

Migraine is a medical condition with a severe recursive headache. The activation of the trigeminovascular system is an important mechanism. The neuropeptide calcitonin gene-related peptide (CGRP) plays a crucial role in the pathogenesis of migraine. Several other neuropeptides are also involved; however, their roles in migraine remain unclear. In this study, using a rat model of migraine induced by electrical stimulation of the trigeminal ganglia (TG) and an improved version induced with repeated stimulation, we observed the dynamic changes of these peptides in TG and blood. We demonstrated that the expression of CGRP, pituitary adenylate cyclase activating polypeptide (PACAP), neuropeptide Y (NPY), vasoactive intestinal peptide, and nociceptin in TG was significantly elevated and peaked at different time points after a single stimulation. Their levels in the blood plasma were significantly increased at 12 h after stimulation. The peptides were further elevated with repeated stimulation. The improved rat model of migraine with repeated stimulation of TG resulted in a more pronounced elevation of CGRP, PACAP, and NPY. Thus, the dynamic changes in neuropeptides after stimulation suggest that these neuropeptides may play an important role in the pathogenesis of migraine. Additionally, the migraine model with repetitive stimulation would be a novel model for future research.

Novel synthetic treatment options for migraine

Introduction: Migraine is one of the most common neurological disorders. Nowadays, the 5-HT_1B/1D receptor agonists, namely triptans, are considered as the standard of care for migraine acute treatment. However, triptans have limitations in some patients, such as incomplete pain relief, headache recurrence, and cardiovascular contraindications. New 5-HT_1F receptor agonists, namely ditans, and calcitonin gene-related peptide receptor antagonists, namely gepants, have been developed as migraine-specific treatments.Areas covered: This paper reviews the available data from RCTs to assess the clinical efficacy, safety, and tolerability profile of lasmiditan, rimegepant, and ubrogepant for the acute treatment of migraine and atogepant for the prevention of migraine.Expert opinion: Available data suggest that lasmiditan, rimegepant, and ubrogepant might not have a clinical efficacy similar to triptans. Lasmiditan did not cause the typical triptan side effects but was associated with central nervous system side effects, causing temporary driving impairment. On the contrary, the new generation of gepants showed a placebo-like tolerability profile and the absence of a specific pattern of side effects. Future studies on lasmiditan and gepants with respect to established effective comparators are mandatory to support phase III results and to help clinicians to balance the benefit/risk profiles of the various acute and preventive medications.

Downregulation of metabotropic glutamate receptor 5 alleviates central sensitization by activating autophagy via inhibiting mTOR pathway in a rat model of chronic migraine

Central sensitization is one of the important pathological mechanisms of chronic migraine (CM). Metabolic glutamate receptor 5 (mGluR5) mediates pain by activating various intracellular pathways. However, whether mGluR5 contributes to central sensitization in CM and the exact mechanism remains unclear. Male rats were used to establish a CM model by repeated infusions of inflammatory soup (IS) for 7 days to stimulate the activation of the dural nociceptor. The mechanical and thermal thresholds were used to evaluate allodynia, and central sensitization was assessed by measuring calcitonin gene-related peptide (CGRP) and substance P (SP). Microtubule associated protein 1 light chain 3 (LC3) and p62/SQSTM1 were used to assess autophagy. We found that the expression of mGluR5 in the trigeminal nucleus caudalis (TNC) of CM rats was significantly increased. In addition, the downregulation of mGluR5 activated autophagy by inhibiting the mTOR pathway. Moreover, the activation of autophagy alleviated allodynia and central sensitization in CM rats. This study identified a novel strategy for the treatment of CM; the downregulation of mGluR5 in a rat model of CM decreased the expression of the inflammatory factor interleukin-1 beta (IL-1β) and the central sensitization-associated proteins CGRP and SP by activating autophagy via inhibiting the mTOR pathway.

Atogepant Is Not Associated With Clinically Meaningful Alanine Aminotransferase Elevations in Healthy Adults

Atogepant is a potent, selective, oral calcitonin gene–related peptide (CGRP) receptor antagonist in development for migraine prevention. The chemical structure of atogepant is distinct from previous CGRP receptor antagonists, which were associated with elevated serum alanine aminotransferase (ALT) in clinical trials. Here, we report the safety, tolerability, and pharmacokinetics (PKs) of a once‐daily supratherapeutic dose (170 mg) of atogepant for 28 days from a randomized, double‐blind, placebo‐controlled phase I trial in healthy participants. Overall safety, hepatic safety, and plasma PK parameters were evaluated. Thirty‐four participants aged 23–55 years enrolled; 28 (82.4%) completed the study in accordance with the protocol. Multiple doses of 170 mg atogepant for 28 consecutive days were generally well‐tolerated. All adverse events (AEs; reported in 87.0% of the atogepant group; 72.7%, placebo) were mild in severity except one serious AE of subarachnoid hemorrhage due to a bicycle accident and not considered related to treatment. There were two discontinuations due to AEs, both with atogepant, one considered possibly related to treatment. Over 28 days of treatment, no participant receiving atogepant had an ALT elevation above 1.5 × upper limit of normal. Change from baseline in serum ALT levels was not different between atogepant and placebo. Atogepant is rapidly absorbed (median time to maximum plasma concentration, ~ 2 hours) with an apparent terminal half‐life of ~ 11 hours, and no evidence of accumulation after once‐daily dosing. Overall, atogepant at a high oral dose is safe and well‐tolerated in healthy participants with no clinically meaningful elevations in ALT.