Phosphodiesterase 3 inhibitor cilostazol induces migraine-like attacks via cyclic AMP increase

PACAP38-induced migraine attacks are independent of CGRP signaling: a randomized controlled trial

BACKGROUND

Calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide-38 (PACAP38) are key pathogenic drivers of migraine. While CGRP has become the target of several mechanism-based therapies, less is known about PACAP38 signaling in migraine pathogenesis. Previous studies suggest that PACAP38 can modulate CGRP release, but it might also induce migraine attacks via CGRP-independent mechanisms. Whether PACAP38 signaling is independent of and parallel to CGRP signaling has implications for future therapeutic strategies. Here, we aimed to ascertain whether PACAP-38 can mediate migraine attacks independently of CGRP signaling by assessing the ability of eptinezumab to prevent PACAP38-induced migraine attacks.

METHODS

In a double-blind, placebo-controlled, parallel-group study, we randomly allocated adults with migraine without aura to receive either an intravenous infusion of 300-mg eptinezumab or matching placebo (isotonic saline) over 30 min. Two hours post-infusion, all participants were administered PACAP38 intravenously at 10 pmol/kg/min for 20 min. The primary endpoint was the incidence of migraine attacks during the 24-hour observational period post-infusion of eptinezumab or placebo. Key secondary endpoints included between-group differences in incidence of headache, and area under the curve (AUC) for headache intensity scores, diameter of the superficial temporal artery (STA) and facial skin blood flow.

RESULTS

A total of 38 participants were enrolled and completed the study. No difference was observed in the incidence of PACAP38-induced migraine attacks between the eptinezumab (10 [53%] of 19) and placebo (12 [63%] of 19) groups (Fisher's exact test: P = 0.74). Headache of any intensity was reported by 15 (79%) participants in the eptinezumab group, compared with 16 (84%) participants in the placebo group (Fisher's exact test: P > 0.99). The AUC for headache intensity scores did not differ between the two groups during the first 12 h post-infusion of PACAP38 (Mann-Whitney U-test: P = 0.96). No differences were observed in AUC between the eptinezumab and placebo groups with respect to changes in STA diameter and facial skin blood flow (P > 0.05). No serious adverse events occurred.

CONCLUSIONS

Our results suggest that PACAP38 may mediate its signaling independently of CGRP in migraine pathogenesis. Therapies targeting PACAP signaling are thus a promising new avenue for treating migraine.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT05635604. Registered on November 15 2022.

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.

Molecular nociceptive mechanisms in migraine: The migraine cascade

OBJECTIVE

This review will explore the categorization of migraine-provoking molecules, their cellular actions, site of action and potential drug targets based on the migraine cascade model.

METHODS

Personal experience and literature.

RESULTS

Migraine impacts over 1 billion people worldwide but is underfunded in research. Recent progress, particularly through the human and animal provocation model, has deepened our understanding of its mechanisms. This model have identified endogenous neuropeptides such as calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP) that induces controlled migraine-like attacks leading to significant discoveries of their role in migraine. This knowledge led to the development of CGRP-inhibiting drugs; a groundbreaking migraine treatment now accessible globally. Also a PACAP-inhibiting drug was effective in a recent phase II trial. Notably, rodent studies have shed light on pain pathways and the mechanisms of various migraine-inducing substances identifying novel drug targets. This is primarily done by using selective inhibitors that target specific signaling pathways of the known migraine triggers leading to the hypothesized cellular cascade model of migraine.

CONCLUSION

The model of migraine presents numerous opportunities for innovative drug development. The future of new migraine treatments is limited only by the investment from pharmaceutical companies.

Provocation of attacks to discover migraine signaling mechanisms and new drug targets: early history and future perspectives - a narrative review

INTRODUCTION

The development of several experimental migraine provocation models has significantly contributed to an understanding of the signaling mechanisms of migraine. The early history of this development and a view to the future are presented as viewed by the inventor of the models.

METHODS

Extensive knowledge of the literature was supplemented by scrutiny of reference lists.

RESULTS

Early studies used methodologies that were not blinded. They suggested that histamine and nitroglycerin (Glyceryl trinitrate, GTN) could induce headache and perhaps migraine. The development of a double blind, placebo-controlled model, and the use of explicit diagnostic criteria for induced migraine was a major step forward. GTN, donor of nitric oxide (NO), induced headache in people with- and without migraine as well as delayed migraine attacks in those with migraine. Calcitonin gene-related peptide (CGRP) did the same, supporting the development of CGRP antagonists now widely used in patients. Likewise, pituitary adenylate cyclase activating peptide (PACAP) provoked headache and migraine. Recently a PACAP antibody has shown anti migraine activity in a phase 2 trial. Increase of second messengers activated by NO, CGRP and PACAP effectively induced migraine. The experimental models have also been used in other types of headaches and have been combined with imaging and biochemical studies. They have also been used for drug testing and in genetic studies.

CONCLUSION

Conclusion. Human migraine provocation models have informed about signaling mechanisms of migraine leading to new drugs and drug targets. Future use of these models in imaging-, biochemistry- and genetic studies as well as in the further study of animal models is promising.

Emerging Role of Extracellular Vesicles in Intercellular Communication in the Brain: Implications for Neurodegenerative Diseases and Therapeutics

Extracellular vesicles (EVs) are minute lipid-bilayer sacs discharged by cells, encompassing a diverse array of proteins, nucleic acids, and lipids. The identification of EVs as pivotal agents in intercellular communication has sparked compelling research pathways in the realms of cell biology and neurodegenerative diseases. Utilizing EVs for medicinal reasons has garnered interest due to the adaptability of EV-mediated communication. EVs can be classified based on their physical characteristics, biochemical composition, or cell of origin following purification. This review delves into the primary sub-types of EVs, providing an overview of the biogenesis of each type. Additionally, it explores the diverse environmental conditions triggering EV release and the originating cells, including stem cells and those from the Central Nervous System. Within the brain, EVs play a pivotal role as essential mediators of intercellular communication, significantly impacting synaptic plasticity, brain development, and the etiology of neurological diseases. Their potential diagnostic and therapeutic applications in various brain-related conditions are underscored, given their ability to carry specific cargo. Specially engineered EVs hold promise for treating diverse diseases, including neurodegenerative disorders. This study primarily emphasizes the diagnostic and potential therapeutic uses of EVs in neurological disorders such as Alzheimer's Disease, Huntington's Disease, Parkinson's Disease, Amyotrophic Lateral Sclerosis, and Prions disease. It also summarizes innovative techniques for detecting EVs in the brain, suggesting that EVs could serve as non-invasive biomarkers for early detection, disease monitoring, and prognosis in neurological disorders.

Effects of PDE-3 inhibition in persistent post-traumatic headache: evidence of cAMP-dependent signaling

BACKGROUND

Phosphodiesterase 3 (PDE-3) inhibition have been implicated in the neurobiologic underpinnings of migraine. Considering the clinical similarities between migraine and persistent post-traumatic headache (PPTH), we aimed to ascertain whether PDE-3 inhibition can elicit migraine-like headache in persons with PPTH.

METHODS

We tested cilostazol, which inhibits PDE-3, in a randomized, double-blind, placebo-controlled, two-way crossover study involving persons with PPTH attributed to mild traumatic brain injury. The randomized participants were allocated to receive oral administration of either 200-mg cilostazol or placebo (calcium tablet) on two separate experiment days. The primary end point was the incidence of migraine-like headache during a 12-hour observation window post-ingestion. The secondary endpoint was the area under the curve (AUC) for reported headache intensity scores during the same observation window.

RESULTS

Twenty-one persons underwent randomization and completed both experiment days. The mean participants' age was 41.4 years, and most (n = 17) were females. During the 12-hour observation window, 14 (67%) of 21 participants developed migraine-like headache post-cilostazol, in contrast to three (14%) participants after placebo (P =.003). The headache intensity scores were higher post-cilostazol than after placebo (P <.001).

CONCLUSIONS

Our results provide novel evidence showing that PDE-3 inhibition can elicit migraine-like headache in persons with PPTH. Given that PDE-3 inhibition increases intracellular cAMP levels, our findings allude to the potential therapeutic value of targeting cAMP-dependent signaling pathways in the management of PPTH. Further investigations are imperative to substantiate these insights and delineate the importance of cAMP-dependent signaling pathways in the neurobiologic mechanisms underlying PPTH.

CLINICALTRIALS

GOV IDENTIFIER

NCT05595993.

Reconceptualizing autonomic function testing in migraine: a systematic review and meta-analysis

BACKGROUND

Autonomic nervous system (ANS) testing has aided in our ability to evaluate autonomic dysfunction in migraine patients. We reviewed the literature in multiple databases which investigate ANS function in migraine patients and healthy subjects.

METHODS

This systematic review and meta-analysis examined the respective deep breathing, Valsalva manoeuvre, orthostatic and isometric challenge results, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analyses of Observational Studies in Epidemiology (MOOSE) statements.

RESULTS

Seven articles met all inclusion criteria. Fixed-effects meta-analysis showed migraine patients (n = 424), collectively, had lower interictal autonomic test results compared with healthy controls (n = 268). In detail, this was true for the standardized mean difference (g) of deep breathing (g= -0.32; 95% confidence interval (CI) -0.48, -0.16), orthostatic challenge (g= -0.28; 95% CI -0.44, -0.13) and isometric challenge (g= -0.55; 95% CI -0.71, -0.39) and for the difference of means (MD) of the Valsalva ratio (MD = -0.17; 95% CI -0.23, -0.10).

CONCLUSIONS

Interictal ANS dysfunction can be identified in migraine patients when compared to healthy controls. These findings indicate the importance to evaluate ANS function in migraine patients - especially, as migraine-specific prophylactic therapies (such as anti-calcitonin gene-related peptide (CGRP) antibodies) may affect the function of the ANS.

Assessing the association between age at first sexual intercourse and migraine: a Mendelian randomization study

Background and objectives

As indicated by observational and genetic variation studies, age at first sexual intercourse (AFS) may be associated with migraine attack, but there is a lack of evidence from real-world studies due to ethical concerns. Therefore, we conducted a Mendelian randomization study to determine the causal relationship between AFS and migraine.

Methods

We extracted instrumental variables from summary data of a genome-wide association study (GWAS) on AFS and migraine and then conducted two-sample Mendelian randomization analyses. GWAS data for AFS and migraine were obtained from 397,338 unrelated individuals (214,547 females and 182,791 males) and 306,314 individuals (18,477 patients and 287,837 control individuals), respectively.

Results

There was a causal relationship between AFS and risk for migraine (odds ratio (OR) = 0.73, 95% confidence interval (CI) [0.61 to 0.86]), both for migraine with aura (MWA; OR = 0.72, 95% CI [0.58 to 0.89]) and migraine without aura (MOA; OR = 0.66, 95% CI [0.51 to 0.86]). Stratified analyses provided suggestive evidence of the causal relationship between delayed AFS and a decreased risk of migraine for both males (OR = 0.71, 95% CI [0.59 to 0.84]) and females (OR = 0.73, 95% CI [0.61 to 0.89]). Reverse Mendelian randomization did not reveal any effect of migraine on AFS (p > 0.05). No pleiotropy was detected.

Discussion

A delayed AFS is a protective factor against migraine (for both MWA and MOA) in both males and females. This causal relationship indicates the presence of extracranial regulatory pathways of migraine.

Migraine signaling pathways: purine metabolites that regulate migraine and predispose migraineurs to headache

Migraine is a debilitating disorder that afflicts over 1 billion people worldwide, involving attacks that result in a throbbing and pulsating headache. Migraine is thought to be a neurovascular event associated with vasoconstriction, vasodilation, and neuronal activation. Understanding signaling in migraine pathology is central to the development of therapeutics for migraine prophylaxis and for mitigation of migraine in the prodrome phase before pain sets in. The fact that both vasoactivity and neural sensitization are involved in migraine indicates that agonists which promote these phenomena may very well be involved in migraine pathology. One such group of agonists is the purines, in particular, adenosine phosphates and their metabolites. This manuscript explores what is known about the relationship between these metabolites and migraine pathology and explores the potential for such relationships through their known signaling pathways. Reported receptor involvement in vasoaction and nociception.

Second messenger signalling bypasses CGRP receptor blockade to provoke migraine attacks in humans

There are several endogenous molecules that can trigger migraine attacks when administered to humans. Notably, calcitonin gene-related peptide (CGRP) has been identified as a key player in a signalling cascade involved in migraine attacks, acting through the second messenger cyclic adenosine monophosphate (cAMP) in various cells, including intracranial vascular smooth muscle cells. However, it remains unclear whether intracellular cAMP signalling requires CGRP receptor activation during a migraine attack in humans. To address this question, we conducted a randomized, double-blind, placebo-controlled, parallel trial using a human provocation model involving the administration of CGRP and cilostazol in individuals with migraine pretreated with erenumab or placebo. Our study revealed that migraine attacks can be provoked in patients by cAMP-mediated mechanisms using cilostazol, even when the CGRP receptor is blocked by erenumab. Furthermore, the dilation of cranial arteries induced by cilostazol was not influenced by the CGRP receptor blockade. These findings provide clinical evidence that cAMP-evoked migraine attacks do not require CGRP receptor activation. This discovery opens up new possibilities for the development of mechanism-based drugs for the treatment of migraine.

Real-World Safety and Effectiveness of Controlled-Release Cilostazol in Patients with Symptomatic Peripheral Artery Disease

BACKGROUND

Cilostazol is the only first-line medication for treating intermittent claudication, and the controlled-release (CR) formulation is associated with a lower prevalence of adverse events (AEs).

OBJECTIVE

The objective of the study was to assess the safety and effectiveness of cilostazol CR in patients with symptomatic peripheral artery disease (PAD).

METHODS

In this multicentre (113 sites), open-label, prospective observational study, we evaluated the real-world safety and effectiveness of cilostazol CR 200 mg once daily in patients with symptomatic PAD treated in routine clinical settings. The primary endpoint was the incidence and severity of AEs, and their causal relationship with cilostazol CR. The secondary endpoint was the effectiveness of the drug, as assessed by each patient's physician, for improving intermittent claudication.

RESULTS

Among 2063 participants who received cilostazol CR for a mean duration of 88.6 days, 99 (4.80 %) experienced adverse drug reactions (ADRs), although no unexpected adverse reactions were observed. There was no significant difference in the incidence of ADRs according to patient demographics and comorbidities (all p > 0.05). The treatment was 'effective' in 1600 patients (78.93 %), although effectiveness significantly differed according to the patients' sex and the presence of comorbidities, including diabetes mellitus, hypertension, and coronary artery disease (all p < 0.01).

CONCLUSIONS

This study demonstrated the tolerability and effectiveness of cilostazol CR treatment in patients with symptomatic PAD.

Multi-omic analyses of triptan-treated migraine attacks gives insight into molecular mechanisms

Migraine is a common, polygenic disorder that is characterized by moderate to severe headache attacks. Migraine attacks are commonly treated with triptans, i.e. serotonin receptor agonists. However, triptans are effective in ~ 60% of the population, and the mechanisms of triptans are debated. Here, we aim to expose the mechanisms of triptan using metabolomics and transcriptomics in spontaneous migraine attacks. We collected temporal multi-omics profiles on 24 migraine patients, using samples collected at a migraine attack, 2 h after treatment with a triptan, when headache-free, and after a cold-pressor test. Differential metabolomic analysis was performed to find metabolites associated with treatment. Their effect was further investigated using correlation analysis and a machine learning approach. We found three differential metabolites: cortisol, sumatriptan and glutamine. The change in sumatriptan levels correlated with a change in GNAI1 and VIPR2 gene expression, both known to regulate cAMP levels. Furthermore, we found fatty acid oxidation to be affected, a mechanism known to be involved in migraine but not previously found in relation to triptans. In conclusion, using an integrative approach we find evidence for a role of glutamine, cAMP regulation, and fatty acid oxidation in the molecular mechanisms of migraine and/or the effect of triptans.

Migrainous infarction: A serious complication of a common condition

ABSTRACT

Migrainous infarction is a rare neurologic condition that stems from an ordinary migraine with aura, and can cause ischemic stroke in young women. The pathophysiology of migrainous infarction is not entirely understood. An aura that is similar to previous auras but lasts longer than 60 minutes, along with evidence of acute ischemia on MRI, are diagnostic of migrainous infarction. Treatment aimed at minimizing migraine with aura is the most important preventive measure clinicians can take to help patients avoid this complication of migraine.

Future targets for migraine treatment beyond CGRP

BACKGROUND

Migraine is a disabling and chronic neurovascular headache disorder. Trigeminal vascular activation and release of calcitonin gene-related peptide (CGRP) play a pivotal role in the pathogenesis of migraine. This knowledge has led to the development of CGRP(-receptor) therapies. Yet, a substantial proportion of patients do not respond to these treatments. Therefore, alternative targets for future therapies are warranted. The current narrative review provides a comprehensive overview of the pathophysiological role of these possible non-CGRP targets in migraine.

FINDINGS

We covered targets of the metabotropic receptors (pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP), amylin, and adrenomedullin), intracellular targets (nitric oxide (NO), phosphodiesterase-3 (PDE3) and -5 (PDE5)), and ion channels (potassium, calcium, transient receptor potential (TRP), and acid-sensing ion channels (ASIC)). The majority of non-CGRP targets were able to induce migraine-like attacks, except for (i) calcium channels, as it is not yet possible to directly target channels to elucidate their precise involvement in migraine; (ii) TRP channels, activation of which can induce non-migraine headache; and (iii) ASICs, as their potential in inducing migraine attacks has not been investigated thus far. Drugs that target its receptors exist for PACAP, NO, and the potassium, TRP, and ASIC channels. No selective drugs exist for the other targets, however, some existing (migraine) treatments appear to indirectly antagonize responses to amylin, adrenomedullin, and calcium channels. Drugs against PACAP, NO, potassium channels, TRP channels, and only a PAC₁ antibody have been tested for migraine treatment, albeit with ambiguous results.

CONCLUSION

While current research on these non-CGRP drug targets has not yet led to the development of efficacious therapies, human provocation studies using these targets have provided valuable insight into underlying mechanisms of migraine headaches and auras. Further studies are needed on these alternative therapies in non-responders of CGRP(-receptor) targeted therapies with the ultimate aim to pave the way towards a headache-free future for all migraine patients.

Inhibiting neuronal AC1 for treating anxiety and headache in the animal model of migraine

Migraines are a common medical condition. From a basic science point of view, the central mechanism for migraine and headache is largely unknown. In the present study, we demonstrate that cortical excitatory transmission is significantly enhanced in the anterior cingulate cortex (ACC)-a brain region which is critical for pain perception. Biochemical studies found that the phosphorylation levels of both the NMDA receptor GluN2B and AMPA receptor GluA1 were enhanced in ACC of migraine rats. Both the presynaptic release of glutamate and postsynaptic responses of AMPA receptors and NMDA receptors were enhanced. Synaptic long-term potentiation (LTP) was occluded. Furthermore, behavioral anxiety and nociceptive responses were increased, which were reversed by application of AC1 inhibitor NB001 within ACC. Our results provide strong evidence that cortical LTPs contribute to migraine-related pain and anxiety. Drugs that inhibit cortical excitation such as NB001 may serve as potential medicines for treating migraine in the future.

Shared and independent roles of CGRP and PACAP in migraine pathophysiology

The neuropeptides calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating polypeptide (PACAP) have emerged as mediators of migraine pathogenesis. Both are vasodilatory peptides that can cause migraine-like attacks when infused into people and migraine-like symptoms when injected into rodents. In this narrative review, we compare the similarities and differences between the peptides in both their clinical and preclinical migraine actions. A notable clinical difference is that PACAP, but not CGRP, causes premonitory-like symptoms in patients. Both peptides are found in distinct, but overlapping areas relevant to migraine, most notably with the prevalence of CGRP in trigeminal ganglia and PACAP in sphenopalatine ganglia. In rodents, the two peptides share activities, including vasodilation, neurogenic inflammation, and nociception. Most strikingly, CGRP and PACAP cause similar migraine-like symptoms in rodents that are manifested as light aversion and tactile allodynia. Yet, the peptides appear to act by independent mechanisms possibly by distinct intracellular signaling pathways. The complexity of these signaling pathways is magnified by the existence of multiple CGRP and PACAP receptors that may contribute to migraine pathogenesis. Based on these differences, we suggest PACAP and its receptors provide a rich set of targets to complement and augment the current CGRP-based migraine therapeutics.

Role of PACAP in migraine: An alternative to CGRP?

Migraine is a widespread and debilitating neurological condition affecting more than a billion people worldwide. Thus, more effective migraine therapies are highly needed. In the last decade, two endogenous neuropeptides, calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide (PACAP), were identified to be implicated in migraine. Recently, introduction of monoclonal antibodies (mAbs) blocking the CGRP is the most important advance in migraine therapy for decades. However, 40% of patients are unresponsive to these new drugs. We believe that PACAP may be involved in these patients. Like CGRP, PACAP is located to sensory nerve fibers, it dilates cranial arteries, it causes migraine when infused into patients and it is a peptide that lends itself to antibody therapy. Also, recent studies suggest that the PACAP pathway is independent of the CGRP pathway. Understanding the signaling pathways of PACAP may therefore lead to identification of novel therapeutic targets of particular interest in patients unresponsive to anti-CGRP therapy. Accordingly, neutralizing mAb to PACAP is currently in clinical phase II development. The aim of the present review is, therefore, to give a thorough account of the existing data on PACAP, its receptors and its relation to migraine.

Migraine headache pathophysiology

In both episodic and chronic migraine, headache is the most disabling symptom that requires medical care. The migraine headache is the most well-studied symptom of migraine pathophysiology. The trigeminal system and the central processing of sensory information transmitted by the trigeminal system are of considerable importance in the pathophysiology of migraine headache. Glutamate is the main neurotransmitter that drives activation of the ascending trigeminal and trigeminothalamic pathways. The neuropeptide, calcitonin gene-related peptide (CGRP) that is released by the trigeminal system, plays a crucial role in the neurobiology of headache. Peripheral and central sensitizations associated with trigeminal sensory processing are neurobiologic states that contribute to both the development of headache during a migraine attack and the maintenance of chronic migraine.

The role of high-conductance calcium-activated potassium channel in headache and migraine pathophysiology

Migraine is a common, neurovascular headache disorder with a complex molecular interplay. The involvement of ion channels in the pathogenesis of migraine gathered considerable attention with the findings that different ion channels subfamilies are expressed in trigeminovascular system, the physiological substrate of migraine pain, and several ion channel openers investigated in clinical trials with diverse primary endpoints caused headache as a frequent side effect. High-conductance (big) calcium-activated potassium (BK_Ca ) channel is expressed in the cranial arteries and the trigeminal pain pathway. Recent clinical research revealed that infusion of BK_Ca channel opener MaxiPost caused vasodilation, headache and migraine attack. Thus, BK_Ca channel is involved in pathophysiological mechanisms underlying headache and migraine, and targeting BK_Ca channel presents a new potential strategy for migraine treatment.

CGRP-induced migraine-like headache in persistent post-traumatic headache attributed to mild traumatic brain injury

OBJECTIVE

To ascertain whether intravenous infusion of calcitonin gene-related peptide (CGRP) can induce migraine-like headache in people with persistent post-traumatic headache attributed to mild traumatic brain injury (TBI) and no pre-existing migraine.

METHODS

A non-randomized, single-arm, open-label study at a single site in Denmark. Eligible participants were aged 18 to 65 years and had a known history of persistent post-traumatic headache attributed to mild TBI for ≥ 12 months. All participants received continuous intravenous infusion of CGRP (1.5 µg/min) over 20 min. A headache diary was used to collect outcome data until 12 h after the start of CGRP infusion. The primary end point was the incidence of migraine-like headache during 12-hour observational period.

RESULTS

A total of 60 participants completed the study protocol and provided data for the analysis of the primary end point. The median age was 32.5 (IQR, 25.5-43.0) years; 43 participants (72%) were female. Following CGRP infusion, 43 (72%) of 60 participants developed migraine-like headache during the 12-hour observational period. The median time to peak headache intensity was 40 min (IQR, 20-60), and the median peak headache intensity was 6 (IQR, 5-8) on the 11-point numeric rating scale.

CONCLUSION

Intravenous infusion of CGRP is a potent inducer of migraine-like headache in people with persistent post-traumatic headache attributed to mild TBI. This observation underscores the importance of CGRP in the genesis of migraine-like headache that is often experienced by individuals who are afflicted by persistent post-traumatic headache. Further research is warranted to ascertain whether other signaling molecules also contribute to the disease mechanisms underlying post-traumatic headache.

ATP-Sensitive Potassium Channels in Migraine: Translational Findings and Therapeutic Potential

Globally, migraine is a leading cause of disability with a huge impact on both the work and private life of affected persons. To overcome the societal migraine burden, better treatment options are needed. Increasing evidence suggests that ATP-sensitive potassium (KATP) channels are involved in migraine pathophysiology. These channels are essential both in blood glucose regulation and cardiovascular homeostasis. Experimental infusion of the KATP channel opener levcromakalim to healthy volunteers and migraine patients induced headache and migraine attacks in 82-100% of participants. Thus, this is the most potent trigger of headache and migraine identified to date. Levcromakalim likely induces migraine via dilation of cranial arteries. However, other neuronal mechanisms are also proposed. Here, basic KATP channel distribution, physiology, and pharmacology are reviewed followed by thorough review of clinical and preclinical research on KATP channel involvement in migraine. KATP channel opening and blocking have been studied in a range of preclinical migraine models and, within recent years, strong evidence on the importance of their opening in migraine has been provided from human studies. Despite major advances, translational difficulties exist regarding the possible anti-migraine efficacy of KATP channel blockage. These are due to significant species differences in the potency and specificity of pharmacological tools targeting the various KATP channel subtypes.

Personal view: Modelling pain mechanisms of migraine without aura

INTRODUCTION

This review aims to model migraine nociception.

METHODS

Personal experience and litterature.

RESULTS

Genetic and environmental factors in combination decide whether a person suffers from migraine. Endogenous and/or exogenous factors precipitate the individual attacks. Nociception takes place around blood vessels. There is a growing understanding of the molecular pathophysiological mechanisms of migraine from human provocation studies. Rodent models of migraine are necessary to understand the complex interrelation between the many putatively involved molecules and tissues but their relevance for human migraine is uncertain. The crucial element in migraine nociception is a unit consisting of endothelial cells, vascular smooth muscle cells, perivascular nerve fibers (trigeminal, parasympathetic and sympathetic) and mast cells. Attacks may start outside the brain by humoral or neurogenic activity releasing nociceptive substances around blood vessels. They may also (perhaps more often) start by the brain generating efferent activity in autonomic and somatic nerves.

CONCLUSION

Human and rodent studies can quickly uncover the "mystery of migraine".

The headache and aura-inducing effects of sildenafil in patients with migraine with aura

INTRODUCTION

It has not been established if migraine headache and migraine aura share common pathophysiological mechanisms. Sildenafil, a phosphodiesterase-5 inhibitor, causes cGMP accumulation and provokes migraine-like headache in patients with migraine without aura. We investigated if sildenafil induced aura and migraine-like headache in patients with migraine with aura.

METHODS

In a randomized, double-blinded, placebo-controlled crossover study, 16 patients with migraine with aura (of whom 11 patients exclusively had attacks of migraine with aura) received 100 mg sildenafil or placebo on two separate days. The development, duration, and characteristics of aura and headache were recorded using a questionnaire. The primary outcome was the incidence of migraine aura.

RESULTS

Aura symptoms were induced in three patients (19%) after sildenafil and none after placebo (P < 0.001). After administration of sildenafil, 12 patients (75%) developed headache compared with two patients (12.5%) after placebo (Fisher's exact test, P < 0.001). The headache in nine patients (56%) after sildenafil and one patient (6%) after placebo fulfilled the criteria for migraine-like attacks (Fisher's exact test, P = 0.002). All patients, who fulfilled the criteria for migraine-like attacks, reported that the attack mimicked the headache phase during their usual migraine attacks.

DISCUSSION

Sildenafil have a moderate migraine headache-inducing and a modest aura-inducing effect in patients with migraine with aura, even in those who exclusively experienced attacks of migraine with aura in their spontaneous attacks. These findings suggest that accumulation of cGMP by PDE5-inhibition do not play any significant role in the initiation of migraine aura and refute the hypothesis of sildenafil being a tool for pharmacological provocation of this phenomenon. These findings further support dissociation between the aura and the headache phase.Trial registration: ClinicalTrials.gov - NCT02795351.

Wen Dan Tang: A Potential Jing Fang Decoction for Headache Disorders?

BACKGROUND

Chinese herbal medicine is considered relatively safe, inexpensive, and easily accessible. Wen Dan Tang (WDT), a Jing Fang ancient classical Chinese herbal formula with a broad indication profile has been used for several centuries in China to treat various illnesses.

QUESTION

Are there evidence-based clinical trials that show that WDT has a significant impact on the treatment of various diseases, especially in patients with migraine and tension-type headaches (TTH)?

METHODS

This study is based on an online database search using PubMed, Medline, Cochrane Library, AcuTrials, Embase, Semantic Scholar, Jstor, internet research, and review of ancient and modern Chinese medical textbooks regarding WDT and its compounds.

RESULTS

There were no studies on WDT in migraine and TTH; therefore, this work gathers and describes data for every single compound in the formula.

CONCLUSION

This study suggests that the bioactive compounds found in WDT composition show potential in treating patients with neurological, psychiatric disorders, cardiovascular diseases, metabolic syndrome, and digestive disorders. Some coherence between WDT in headache reduction and improvements in the quality of life in patients with migraines and TTH could be evaluated, showing positive results of WDT in these patients.

Smooth muscle ATP-sensitive potassium channels mediate migraine-relevant hypersensitivity in mouse models

BACKGROUND

Opening of KATP channels by systemic levcromakalim treatment triggers attacks in migraine patients and hypersensitivity to von Frey stimulation in a mouse model. Blocking of these channels is effective in several preclinical migraine models. It is unknown in what tissue and cell type KATP-induced migraine attacks are initiated and which KATP channel subtype is targeted.

METHODS

In mouse models, we administered levcromakalim intracerebroventricularly, intraperitoneally and intraplantarily and compared the nociceptive responses by von Frey and hotplate tests. Mice with a conditional loss-of-function mutation in the smooth muscle KATP channel subunit Kir6.1 were given levcromakalim and GTN and examined with von Frey filaments. Arteries were tested for their ability to dilate ex vivo. mRNA expression, western blotting and immunohistochemical stainings were made to identify relevant target tissue for migraine induced by KATP channel opening.

RESULTS

Systemic administration of levcromakalim induced hypersensitivity but central and local administration provided antinociception respectively no effect. The Kir6.1 smooth muscle knockout mouse was protected from both GTN and levcromakalim induced hypersensitivity, and their arteries had impaired dilatory response to the latter. mRNA and protein expression studies showed that trigeminal ganglia did not have significant KATP channel expression of any subtype, whereas brain arteries and dura mater primarily expressed the Kir6.1 + SUR2B subtype.

CONCLUSION

Hypersensitivity provoked by GTN and levcromakalim in mice is dependent on functional smooth muscle KATP channels of extracerebral origin. These results suggest a vascular contribution to hypersensitivity induced by migraine triggers.

Brain barriers and their potential role in migraine pathophysiology

Migraine is a ubiquitous neurologic disease that afflicts people of all ages. Its molecular pathogenesis involves peptides that promote intracranial vasodilation and modulate nociceptive transmission upon release from sensory afferents of cells in the trigeminal ganglion and parasympathetic efferents of cells in the sphenopalatine ganglion. Experimental data have confirmed that intravenous infusion of these vasoactive peptides induce migraine attacks in people with migraine, but it remains a point of scientific contention whether their site of action lies outside or within the central nervous system. In this context, it has been hypothesized that transient dysfunction of brain barriers before or during migraine attacks might facilitate the passage of migraine-inducing peptides into the central nervous system. Here, we review evidence suggestive of brain barrier dysfunction in migraine pathogenesis and conclude with lessons learned in order to provide directions for future research efforts.

Migraine

Migraine is a common, chronic, disorder that is typically characterized by recurrent disabling attacks of headache and accompanying symptoms, including aura. The aetiology is multifactorial with rare monogenic variants. Depression, epilepsy, stroke and myocardial infarction are comorbid diseases. Spreading depolarization probably causes aura and possibly also triggers trigeminal sensory activation, the underlying mechanism for the headache. Despite earlier beliefs, vasodilation is only a secondary phenomenon and vasoconstriction is not essential for antimigraine efficacy. Management includes analgesics or NSAIDs for mild attacks, and, for moderate or severe attacks, triptans or 5HT_1B/1D receptor agonists. Because of cardiovascular safety concerns, unreliable efficacy and tolerability issues, use of ergots to abort attacks has nearly vanished in most countries. CGRP receptor antagonists (gepants) and lasmiditan, a selective 5HT1_F receptor agonist, have emerged as effective acute treatments. Intramuscular onabotulinumtoxinA may be helpful in chronic migraine (migraine on ≥15 days per month) and monoclonal antibodies targeting CGRP or its receptor, as well as two gepants, have proven effective and well tolerated for the preventive treatment of migraine. Several neuromodulation modalities have been approved for acute and/or preventive migraine treatment. The emergence of new treatment targets and therapies illustrates the bright future for migraine management.

Headache provocation by nitric oxide in men who have never experienced a headache

Introduction

In the general population 4% have never experienced a headache. Freedom from headache could be due to distinctive protective mechanisms or a lack of environmental risk factors for headache. Isosorbide-5-mononitrate is an organic nitrate which in the body is metabolised to nitric oxide. The nitric oxide pathway plays a crucial role in the primary headaches. We hypothesized that people who are free from headache are protected by distinctive mechanisms in the nitric oxide pathway.

Methods

We performed an observer blinded case-control study using nitric oxide to provoke a headache. 32 headache free male participants and 26 randomly selected male controls received 60 mg Isosorbide-5-mononitrate orally on the study day. Participants fill out a headache diary with headache intensity and characteristics until 12 hours after administration of Isosorbide-5-mononitrate. Primary endpoint were areas under the curve of headache intensity score.

Results

All 58 participants completed the study. There was no significant difference in headache incidence, headache intensity score or migraine-like attack between headache free participants and controls.

Conclusion

We show that men who have never experienced a headache develop a headache when provoked with Isosorbide-5-mononitrate. This indicates that freedom from headache in men is not related to the nitric oxide pathway which is involved in the primary headache disorders.

Update on Cilostazol: A Critical Review of Its Antithrombotic and Cardiovascular Actions and Its Clinical Applications

Cilostazol, a phosphodiesterase III inhibitor, has vasodilating and antiplatelet properties with a low rate of bleeding complications. It has been used over the past 25 years for improving intermittent claudication in patients with peripheral artery disease (PAD). Cilostazol also has demonstrated efficacy in patients undergoing percutaneous revascularization procedures for both PAD and coronary artery disease. In addition to its antithrombotic and vasodilating actions, cilostazol also inhibits vascular smooth muscle cell proliferation via phosphodiesterase III inhibition, thus mitigating restenosis. Accumulated evidence has shown that cilostazol, due to its "pleiotropic" effects, is a useful, albeit underutilized, agent for both coronary artery disease and PAD. It is also potentially useful after ischemic stroke and is an alternative in those who are allergic or intolerant to classical antithrombotic agents (eg, aspirin or clopidogrel). These issues are herein reviewed together with the pharmacology and pharmacodynamics of cilostazol. Large studies and meta-analyses are presented and evaluated. Current guidelines are also discussed, and the spectrum of cilostazol's actions and therapeutic applications are illustrated.

Opening of BKCa channels causes migraine attacks: a new downstream target for the treatment of migraine

ABSTRACT

Migraine is a common and frequently disabling neurological disorder, but the initiating migraine mechanisms are still poorly understood. Potassium channel opening may cause migraine, and we therefore examined the migraine-inducing effect of MaxiPost, a large (big)-conductance calcium-activated potassium (BKCa) channel opener, on migraine induction and cephalic vasodilation in individuals with migraine. Twenty-six patients with migraine without aura were randomly allocated to receive an infusion of MaxiPost or placebo on 2 study days separated by at least 1 week. The primary endpoint was the difference in incidence of migraine attacks after MaxiPost compared with placebo. The secondary endpoints were the difference in incidence of headaches and the difference in area under the curve for headache intensity scores (0-12 hours), for middle cerebral artery blood flow velocity (VMCA) (0-2 hours), and for superficial temporal artery and radial artery diameter. Twenty-two patients completed the study. Twenty-one of 22 (95%) developed migraine attacks after MaxiPost compared with none after placebo (P < 0.0001); the difference of incidence is 95% (95% confidence interval 86%-100%). The incidence of headache over the 12-hour observation period was higher after MaxiPost day (n = 22) than after placebo (n = 7) (P < 0.0001). We found a significant increase of VMCA and superficial temporal and radial arteries' diameter. Because BKCa channel opening initiates migraine attacks, we suggest that BKCa channel blockers could be potential candidates for novel antimigraine drugs.

CGRP-dependent signalling pathways involved in mouse models of GTN- cilostazol- and levcromakalim-induced migraine

BACKGROUND

Knowledge of exact signalling events during migraine attacks is lacking. Various substances are known to trigger migraine attacks in patients and calcitonin gene-related peptide antagonising drugs are effective against migraine pain. Here, we investigated the signalling pathways involved in three different mouse models of provoked migraine and relate them to calcitonin gene-related peptide and other migraine-relevant targets.

METHODS

In vivo mouse models of glyceryl trinitrate-, cilostazol- and levcromakalim-induced migraine were applied utilising tactile sensitivity to von Frey filaments as measuring readout. Signalling pathways involved in the three models were dissected by use of specific knockout mice and chemical inhibitors. In vivo results were supported by ex vivo wire myograph experiments measuring arterial dilatory responses and ex vivo calcitonin gene-related peptide release from trigeminal ganglion and trigeminal nucleus caudalis from mice.

RESULTS

Glyceryl trinitrate-induced hypersensitivity was dependent on both prostaglandins and transient receptor potential cation channel, subfamily A, member 1, whereas cilostazol- and levcromakalim-induced hypersensitivity were independent of both. All three migraine triggers activated calcitonin gene-related peptide signalling, as both receptor antagonism and antibody neutralisation of calcitonin gene-related peptide were effective inhibitors of hypersensitivity in all three models. Stimulation of trigeminal ganglia and brain stem tissue samples with cilostazol and levcromakalim did not result in release of calcitonin gene-related peptide, and vasodilation following levcromakalim stimulation was independent of CGRP receptor antagonism.

CONCLUSION

The mouse models of glyceryl trinitrate-, cilostazol- and levcromakalim- induced migraine all involve calcitonin gene-related peptide signalling in a complex interplay between different cell/tissue types. These models are useful in the study of migraine mechanisms.

Selective targeting of peripheral cannabinoid receptors prevents behavioral symptoms and sensitization of trigeminal neurons in mouse models of migraine and medication overuse headache

ABSTRACT

Migraine affects ∼15% of the world's population greatly diminishing their quality of life. Current preventative treatments are effective in only a subset of migraine patients, and although cannabinoids seem beneficial in alleviating migraine symptoms, central nervous system side effects limit their widespread use. We developed peripherally restricted cannabinoids (PRCBs) that relieve chronic pain symptoms of cancer and neuropathies, without appreciable central nervous system side effects or tolerance development. Here, we determined PRCB effectiveness in alleviating hypersensitivity symptoms in mouse models of migraine and medication overuse headache. Long-term glyceryl trinitrate (GTN, 10 mg/kg) administration led to increased sensitivity to mechanical stimuli and increased expression of phosphorylated protein kinase A, neuronal nitric oxide synthase, and transient receptor potential ankyrin 1 proteins in trigeminal ganglia. Peripherally restricted cannabinoid pretreatment, but not posttreatment, prevented behavioral and biochemical correlates of GTN-induced sensitization. Low pH-activated and allyl isothiocyanate-activated currents in acutely isolated trigeminal neurons were reversibly attenuated by PRCB application. Long-term GTN treatment significantly enhanced these currents. Long-term sumatriptan treatment also led to the development of allodynia to mechanical and cold stimuli that was slowly reversible after sumatriptan discontinuation. Subsequent challenge with a previously ineffective low-dose GTN (0.1-0.3 mg/kg) revealed latent behavioral sensitization and increased expression of phosphorylated protein kinase A, neuronal nitric oxide synthase, and transient receptor potential ankyrin 1 proteins in trigeminal ganglia. Peripherally restricted cannabinoid pretreatment prevented all behavioral and biochemical correlates of allodynia and latent sensitization. Importantly, long-term PRCB treatment alone did not produce any behavioral or biochemical signs of sensitization. These data validate peripheral cannabinoid receptors as potential therapeutic targets in migraine and medication overuse headache.

Future prophylactic treatments in migraine: Beyond anti-CGRP monoclonal antibodies and gepants

Migraine is ranked as a leading cause of years lived with disability among all neurological disorders. Therapies targeting the calcitonin gene-related peptide (CGRP) signaling pathway, including monoclonal antibodies against the receptor or ligand and small molecule CGRP receptor antagonists (gepants), are today approved for migraine prophylaxis with additional compounds expected to be introduced to the market soon. In this review, we consider other putative prophylactic migraine drugs in development, including compounds targeting G-protein coupled receptors, glutamate, ion channels, and neuromodulatory devices. Emergence of these new interventions could complement our current treatment armamentarium for migraine management.

Intradural artery dilation during experimentally induced migraine attacks

The middle meningeal artery is a proposed surrogate marker for activation of trigeminal nociceptors during migraine. Previous studies focused on the extracranial part of the artery; hence, vasoreactivity in the intradural arteries during migraine is unknown. Thirty-four patients with migraine without aura were given sildenafil on one day and calcitonin gene-related peptide on another in double-blind crossover fashion. Patients were scanned with 3.0 T MR angiography before drug administration and again 6 hours later during induced attacks of migraine. We measured circumference of the intradural segment of the middle meningeal artery before and during induced migraine attacks. The middle cerebral and superficial temporal arteries were also examined. Fourteen patients had attacks during the second scan after both study drugs and 11 had a migraine after either one or the other, resulting in a total of 39 attacks included in the final analysis. Mean circumference of the intradural middle meningeal artery at baseline was 3.18 mm with an increase of 0.11 mm during attacks (P = 0.005), corresponding to a relative dilation of 3.6% [95% CI: 1.4%-5.7%]. Middle cerebral artery dilated by 9.4% [95% CI: 7.1%-11.7%] and superficial temporal artery by 2.3% [95% CI: 0.2%-4.4%]. Our study shows that the intradural middle meningeal artery and the middle cerebral artery are dilated during migraine induced by calcitonin gene-related peptide as well as sildenafil. We propose that intradural vasculature is affected by migraine-driven activation of trigeminal afferents during migraine attacks.

Migraine: disease characterisation, biomarkers, and precision medicine

Migraine is a disabling neurological disorder, diagnosis of which is based on clinical criteria. A shortcoming of these criteria is that they do not fully capture the heterogeneity of migraine, including the underlying genetic and neurobiological factors. This complexity has generated momentum for biomarker research to improve disease characterisation and identify novel drug targets. In this Series paper, we present the progress that has been made in the search for biomarkers of migraine within genetics, provocation modelling, biochemistry, and neuroimaging research. Additionally, we outline challenges and future directions for each biomarker modality. We also discuss the advances made in combining and integrating data from multiple biomarker modalities. These efforts contribute to developing precision medicine that can be applied to future patients with migraine.

Effect of Adrenomedullin on Migraine-Like Attacks in Patients With Migraine: A Randomized Crossover Study

OBJECTIVE

To determine whether the IV infusion of adrenomedullin, a potent vasodilator belonging to calcitonin family of peptides, provokes attacks of migraine in patients.

METHODS

Twenty patients with migraine without aura participated in a placebo-controlled and double-blind clinical study. In a randomized crossover design, the patients received an IV infusion of human adrenomedullin (19.9 pmol/kg/min) or placebo (saline) administrated via an automated IV pump (20 minutes). The patients participated in 2 study days with a washout period of minimum of 7 days. The primary outcome of the study was predefined as a difference in migraine incidence (0-12 hours), and the secondary outcomes were the area under curve (AUC_0-12 hours) for the headache intensity score and AUC_{0-90 minutes} for mean arterial blood pressure (MAP), flushing, and heart rate (HR).

RESULTS

Eleven patients with migraine without aura (55%) fulfilled migraine attacks criteria after adrenomedullin infusion compared to only 3 patients who reported attack (15%) after placebo (p = 0.039). We found that patients reported in a period of 0 to 12 hours stronger headache intensity after adrenomedullin compared to placebo infusion (p = 0.035). AUC_{0-90 minutes} value for HR and flushing (p < 0.05) was significant and for MAP (p = 0.502) remained unchanged. Common reported adverse events were facial flushing, heat sensation, and palpitation (p < 0.001).

CONCLUSION

Our data implicate adrenomedullin in migraine pathogenesis. This suggests that adrenomedullin or its receptors are novel therapeutic targets for the treatment of migraine. However, we cannot discount the possibility that adrenomedullin may be acting through the canonical calcitonin gene-related peptide receptor.

TRIAL REGISTRATION INFORMATION

ClinicalTrials.gov Identifier: NCT04111484.

Opening of ATP sensitive potassium channels causes migraine attacks with aura

Migraine afflicts more than one billion individuals worldwide and is a leading cause of years lived with disability. In about a third of individuals with migraine aura occur in relation to migraine headache. The common pathophysiological mechanisms underlying migraine headache and migraine aura are yet to be identified. Based on recent data, we hypothesized that levcromakalim, an ATP-sensitive potassium channel opener, would trigger migraine attacks with aura in migraine with aura patients.

Early treatment with sumatriptan prevents PACAP38-induced migraine: A randomised clinical trial

OBJECTIVE

To determine whether early treatment with sumatriptan can prevent PACAP38-induced migraine attacks.

METHODS

A total of 37 patients with migraine without aura were enrolled between July 2018 to December 2019. All patients received an intravenous infusion of 10 picomole/kg/min of PACAP38 over 20 min followed by an intravenous infusion of 4 mg sumatriptan or placebo over 10 min on two study days in a randomised, double-blind, placebo-controlled, crossover study.

RESULTS

Of 37 patients enrolled, 26 (70.3%) completed the study and were included in analyses. Of the 26 patients, four (15%) developed a PACAP38-induced migraine attack on sumatriptan and 11 patients (42%) on placebo (p = 0.016). There were no differences in area under the curve for headache intensity between sumatriptan (mean AUC 532) and placebo (mean AUC 779) (p = 0.35). Sumatriptan significantly constricted the PACAP38-dilated superficial temporal artery immediately after infusion (T30) compared with infusion of placebo (p < 0.001).Conclusions and relevance: Early treatment with intravenously administered sumatriptan prevented PACAP38-induced migraine. Prevention of migraine attacks was associated with vasoconstriction by sumatriptan in the earliest phases of PACAP provocation. These results suggest that sumatriptan prevents PACAP38-induced migraine by modulation of nociceptive transmission within the trigeminovascular system.Trial Registration: ClinicalTrials.gov (NCT03881644).

Hypersensitivity to calcitonin gene-related peptide in chronic migraine

OBJECTIVE

To investigate if calcitonin gene-related peptide infusion induces migraine-like attacks in chronic migraine patients.

METHODS

Fifty-eight patients with chronic migraine, either with or without headache on the experimental day, were assessed for the incidence of migraine-like attacks after an intravenous infusion with calcitonin gene-related peptide 1.5 µg/min over 20 min. The primary endpoint was the incidence of migraine-like attacks after calcitonin gene-related peptide. Exploratory endpoints were the association between the incidence of migraine-like attacks and presence of headache on the experimental day, and headache frequency in the past month. Migraine-like attack data was compared to a historic cohort of 91 episodic migraine patients without headache on the experimental day. Total tenderness score, pressure-pain threshold and supra-threshold pressure pain at baseline were investigated in relation to incidence of migraine-like attacks and presence of headache on the experimental day.

RESULTS

In total, 83% of the 58 chronic migraine patients developed migraine-like attacks after calcitonin gene-related peptide infusion. Migraine-like attacks were found in 92% of chronic migraine patients with headache on the experimental day compared to 65% of chronic migraine patients without headache on the experimental day (p = 0.035). No differences were observed in total tenderness score and pressure-pain threshold between chronic migraine patients with and without headache on the experimental day. The incidence of migraine-like attacks following calcitonin gene-related peptide in chronic migraine patients without headache (65%) was equal to the historic cohort of 91 episodic migraine patients without headache (67%) on the experimental day.

CONCLUSIONS

Chronic migraine patients are hypersensitive to calcitonin gene-related peptide. The potency of calcitonin gene-related peptide as a migraine inductor is increased in chronic migraine patients with ongoing headache. We suggest that calcitonin gene-related peptide, besides being a migraine trigger also acts as a modulator of nociceptive transmission in the trigeminal system.

Premonitory symptoms in glyceryl trinitrate triggered migraine attacks: a case-control study

ABSTRACT

Spontaneous and pharmacologically provoked migraine attacks are frequently preceded by nonheadache symptoms called premonitory symptoms. Here, we systematically evaluated premonitory symptoms in migraine patients and healthy controls after glyceryl trinitrate (GTN) infusion. In women with migraine without aura (n = 34) and age-matched female controls (n = 24), we conducted systematically a semistructured interview assessing 21 possible premonitory symptoms every 15 minutes in the 5 hours after GTN infusion (0.5 µg/kg/min over 20 minutes). Migraine-like headaches occurred in 28/34 (82.4%) migraineurs (GTN responders). After GTN, 26/28 (92.9%) responders, 6/6 (100%) nonresponders, and 13/24 (54.2%) controls reported at least one possible premonitory symptom. Concentration difficulties (P = 0.011), yawning (P = 0.009), nausea (P = 0.028), and photophobia (P = 0.001) were more frequently reported by those migraineurs who developed a migraine-like attack vs healthy controls. Importantly, concentration difficulties were exclusively reported by those who developed a migraine-like attack. Thus, our findings support the view that GTN is able to provoke the naturally occurring premonitory symptoms and show that yawning, nausea, photophobia, and concentration difficulties are most specific for an impending GTN-induced migraine-like headache. We suggest that these symptoms may also be helpful as early warning signals in clinical practice with concentration difficulties exclusively reported by those who develop a migraine-like attack.

Opening of BKCa channels alters cerebral hemodynamic and causes headache in healthy volunteers

Introduction

Preclinical data implicate large conductance calcium-activated potassium (BKCa) channels in the pathogenesis of headache and migraine, but the exact role of these channels is still unknown. Here, we investigated whether opening of BKCa channels would cause headache and vascular effects in healthy volunteers.

Methods

In a randomized, double-blind, placebo-controlled, cross-over study, 21 healthy volunteers aged 18–39 years were randomly allocated to receive an intravenous infusion of 0.05 mg/min BKCa channel opener MaxiPost and placebo on two different days. The primary endpoints were the difference in incidence of headache and the difference in area under the curve (AUC) for headache intensity scores (0–12 hours) and for middle cerebral artery blood flow velocity (VMCA) (0–2 hours) between MaxiPost and placebo. The secondary endpoints were the differences in area under the curve for superficial temporal artery and radial artery diameter (0–2 hours) between MaxiPost and placebo.

Results

Twenty participants completed the study. Eighteen participants (90%) developed headache after MaxiPost compared with six (30%) after placebo ( p = 0.0005); the difference of incidence is 60% (95% confidence interval 36–84%). The area under the curve for headache intensity (AUC0–12 hours, p = 0.0003), for mean VMCA (AUC0–2 hours, p = 0.0001), for superficial temporal artery diameter (AUC0–2 hours, p = 0.003), and for radial artery diameter (AUC0–2 hours, p = 0.03) were significantly larger after MaxiPost compared to placebo.

Conclusion

MaxiPost caused headache and dilation in extra- and intracerebral arteries. Our findings suggest a possible role of BKCa channels in headache pathophysiology in humans. ClinicalTrials.gov, ID: NCT03887325.

Low frequency activation of the sphenopalatine ganglion does not induce migraine-like attacks in migraine patients

Introduction

Cephalic autonomic symptoms occur in 27‒73% of migraine patients during attacks. The role of parasympathetic activation in migraine attack initiation remains elusive. Low frequency stimulation of the sphenopalatine ganglion increases parasympathetic outflow. In this study, we hypothesized that low frequency stimulation of the sphenopalatine ganglion would provoke migraine-like attacks in migraine patients.

Methods

In a double-blind randomized sham-controlled crossover study, 12 migraine patients with a sphenopalatine ganglion neurostimulator received low frequency or sham stimulation for 30 min on two separate days. We recorded headache characteristics, cephalic autonomic symptoms, ipsilateral mechanical perception and pain thresholds, mean blood flow velocity in the middle cerebral artery (VMCA) and diameter of the superficial temporal artery during and after stimulation.

Results

Five patients (42%) reported a migraine-like attack after low frequency stimulation compared to six patients (50%) after sham ( p = 1.000). We found a significant increase in mechanical detection thresholds during low frequency stimulation compared to baseline ( p = 0.007). Occurrence of cephalic autonomic symptoms and changes in mechanical perception thresholds, VMCA and diameter of the superficial temporal artery showed no difference between low frequency stimulation compared to sham ( p = 0.533).

Conclusion

Low frequency stimulation of the sphenopalatine ganglion did not induce migraine-like attacks or autonomic symptoms in migraine patients. These data suggest that increased parasympathetic outflow by the sphenopalatine ganglion neurostimulator does not initiate migraine-like attacks. Study protocol: ClinicalTrials.gov registration number NCT02510742

Association Between Sumatriptan Treatment During a Migraine Attack and Central 5-HT1B Receptor Binding

Importance

Triptans, the most efficient acute treatment for migraine attacks, are 5-HT1B/1D receptor agonists, but their precise mechanism of action is not completely understood. The extent to which triptans enter the central nervous system and bind to 5-HT1B receptors in the brain is unknown.

Objectives

To determine the occupancy of sumatriptan to central 5-HT1B receptors, and to investigate changes in brain serotonin levels during migraine attacks.

Design, Setting, and Participants

This study of 8 patients in Denmark used a within-participant design and was conducted from April 20, 2015, to December 5, 2016. Participants were otherwise healthy patients with untreated episodic migraine without aura, aged between 18 and 65 years, and recruited from the general community. Data analysis was performed from January 2017 to April 2018.

Interventions

All participants underwent positron emission tomographic scans after injection of [11C]AZ10419369, a specific 5-HT1B receptor radiotracer. All participants were scanned 3 times: (1) during an experimentally induced migraine attack, (2) after a subcutaneous injection of 6-mg subcutaneous sumatriptan, and (3) on a migraine attack-free day. Scans 1 and 2 were conducted on the same study day. Each scan lasted for 90 minutes.

Main Outcome and Measure

The primary outcome was the nondisplaceable binding potential of [11C]AZ10419369 across 7 brain regions involved in pain modulation. The binding potential reflects receptor density, and changes in binding potential reflects displacement of the radiotracer. The occupancy of sumatriptan was estimated from the 2 scans before and after sumatriptan administration.

Results

Eight patients with migraine were included in the study; of these participants, 7 (87%) were women. The mean (SD) age of participants on study day 1 was 29.5 (9.2) years and on study day 2 was 30.0 (8.9) years. Sumatriptan was associated with statistically significantly reduced 5-HT1B receptor binding across pain-modulating regions (mean [SD] binding potential, 1.20 [0.20] vs 1.02 [0.22]; P = .001), corresponding to a mean (SD) drug occupancy rate of 16.0% (5.3%). Furthermore, during migraine attacks, as compared with outside of attacks, 5-HT1B receptor binding was statistically significantly associated with reduced in pain-modulating regions (mean [SD] binding potential, 1.36 [0.22] vs 1.20 [0.20]; P = .02).

Conclusions and Relevance

Treatment with sumatriptan during migraine attacks appeared to be associated with a decrease in 5-HT1B receptor binding, a finding that is most likely associated with the binding of sumatriptan to central 5-HT1B receptors, but the contribution of ongoing cerebral serotonin release to the lower binding cannot be excluded; the migraine attack-associated decrease in binding could indicate that migraine attacks are associated with increases in endogenous serotonin.

The role of erenumab in the treatment of migraine

Calcitonin gene related peptide (CGRP) monoclonal antibodies (mAbs) have been the first class of specifically developed preventive treatments for migraine. Clinical trials data suggest superiority of the CGRP mAbs to placebo in terms of prevention of migraine symptoms, migraine-specific quality of life and headache related disability. Treatment-related side effects overall did not differ significantly from placebo and discontinuation rate due to side effects has been low across the clinical trials, perhaps in view of their peripheral mode of action. Along with their route and frequency of administration, these novel class of drugs may constitute an improvement compared with the established arsenal of migraine treatments. Erenumab is a fully human antibody and the only mAb acting on the CGRP pathway by blocking its receptor. It is the first of the CGRP mAb class approved by the US Food and Drug Administration (May 2018) and the European Medicines Agency (July 2018). Erenumab exists in two different doses (70 mg and 140 mg) and it is administered with monthly subcutaneous injections. This review summarises erenumab pharmacological characteristics, clinical trials data, focusing on the potential role of this treatment in clinical practice.

Targeting BKCa Channels in Migraine: Rationale and Perspectives

Large (big)-conductance calcium-activated potassium (BK_Ca) channels are expressed in migraine-related structures such as the cranial arteries, trigeminal ganglion and trigeminal spinal nucleus, and they play a substantial role in vascular tonus and neuronal excitability. Using synthetic BK_Ca channels openers was associated with headache as a frequent adverse effect in healthy volunteers. Additionally, BK_Ca channels are downstream molecules in migraine signalling pathways that are activated by several compounds known to provoke migraine, including calcitonin gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP) and glyceryl trinitrate (GTN). Also, there is a high affinity and a close coupling between BK_Ca channels and ATP-sensitive potassium (K_ATP) channels, the role of which has recently been established in migraine pathophysiology. These observations raise the question as to whether direct BK_Ca channel activation can provoke migraine in migraine patients, and whether the BK_Ca channel could be a potential novel anti-migraine target. Hence, randomized and placebo-controlled clinical studies on BK_Ca channel openers or blockers in migraine patients are needed.

Subcutaneous sumatriptan reduces cilostazol induced headache in migraine patients

OBJECTIVES

The authors have previously tried to develop a model for the testing of novel drug candidates for migraine, using the headache and migraine provoking agent cilostazol. Previous studies have used sumatriptan tablets as the validating drug, but they were not sufficiently effective. In this study we test the effect of subcutaneous sumatriptan on cilostazol induced headache in patients with migraine without aura.

METHOD

Thirty patients with migraine without aura received 200 mg cilostazol on two different study days. The induced headache was treated with subcutaneous sumatriptan in a randomized, double-blind cross-over design. The patients filled out a self-reported headache questionnaire until 12 h after cilostazol.

RESULTS

All 30 patients experienced headache (range 3-10) on both study days and the headache fulfilled the criteria for a migraine-like attack in 73% on the sumatriptan day and in 77% on the placebo day. Sumatriptan injection reduced the headache score 2 h after treatment (p = 0.003). The difference between headache intensity on the sumatriptan day and the placebo day was significant at both 2 h (p = 0.01) and 4 h (p = 0.0007) after treatment.

CONCLUSION

Subcutaneous sumatriptan reduces cilostazol induced headache in migraine patients. The cilostazol model may be useful as a tool to test the potential of new anti-migraine drugs.Trial registration: The study is registered on clinicaltrials.gov (NCT03422796).