CGRP and migraine: could PACAP play a role too?

Exploring the Role of Neuropeptide PACAP in Cytoskeletal Function Using Spectroscopic Methods

The behavior and presence of actin-regulating proteins are characteristic of various clinical diseases. Changes in these proteins significantly impact the cytoskeletal and regenerative processes underlying pathological changes. Pituitary adenylate cyclase-activating polypeptide (PACAP), a cytoprotective neuropeptide abundant in the nervous system and endocrine organs, plays a key role in neuron differentiation and migration by influencing actin. This study aims to elucidate the role of PACAP as an actin-regulating polypeptide, its effect on actin filament formation, and the underlying regulatory mechanisms. We examined PACAP27, PACAP38, and PACAP6-38, measuring their binding to actin monomers via fluorescence spectroscopy and steady-state anisotropy. Functional polymerization tests were used to track changes in fluorescent intensity over time. Unlike PACAP27, PACAP38 and PACAP6-38 significantly reduced the fluorescence emission of Alexa488-labeled actin monomers and increased their anisotropy, showing nearly identical dissociation equilibrium constants. PACAP27 showed weak binding to globular actin (G-actin), while PACAP38 and PACAP6-38 exhibited robust interactions. PACAP27 did not affect actin polymerization, but PACAP38 and PACAP6-38 accelerated actin incorporation kinetics. Fluorescence quenching experiments confirmed structural changes upon PACAP binding; however, all studied PACAP fragments exhibited the same effect. Our findings indicate that PACAP38 and PACAP6-38 strongly bind to G-actin and significantly influence actin polymerization. Further studies are needed to fully understand the biological significance of these interactions.

Reporting Quality and Risk of Bias Analysis of Published RCTs Assessing Anti-CGRP Monoclonal Antibodies in Migraine Prophylaxis: A Systematic Review

Objective: Phase II/III randomized clinical trials (RCTs) are vulnerable to many types of bias beyond randomization. Insights into the reporting quality of RCTs involving migraine patients treated with monoclonal antibodies targeting the calcitonin gene-related peptide system (anti-CGRP MAbs) are currently lacking. Our aim was to analyze the reporting quality of phase II/III RCTs involving migraine patients treated with anti-CGRP MAbs. Methods: A systematic search was performed on the PubMed and EMBASE databases, according to PRISMA guidelines, for relevant RCTs in either episodic or chronic migraine prevention. Additionally, an adapted version of the 2010 CONSORT statement checklist was utilized. The ROBvis online tool was used to document the risk of bias. Results: From the initially identified 179 articles, we finally found 31 RCTs that were eligible for evaluation. The average CONSORT compliance was 88.7% (69.7-100%), while 93.5% (N = 29) of the articles had a compliance greater than 75%. Twenty-eight CONSORT items were reported in more than 75% of the articles. The average compliance of the analyzed RCTs was 93.9% for Galcanezumab, 91.3% for Fremanezumab, followed by 85.4% for Erenumab and Eptinezumab studies. Implementation of the ROB2 tool showed some concerning "missing information" arising from the inadequate reporting. Specifically, 50% of the studies (N = 16) were categorized as having inadequate information regarding the randomization process. Conclusions: Adequate reporting quality was disclosed in the evaluated RCTs with anti-CGRP MAbs in migraine prevention. However, some methodological issues need to be highlighted to be addressed in future studies assessing the efficacy of new molecules targeting CGRP or other candidate pathways implicated in migraine pathophysiology.

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

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

From CGRP to PACAP, VIP, and Beyond: Unraveling the Next Chapters in Migraine Treatment

Migraine is a neurovascular disorder that can be debilitating for individuals and society. Current research focuses on finding effective analgesics and management strategies for migraines by targeting specific receptors and neuropeptides. Nonetheless, newly approved calcitonin gene-related peptide (CGRP) monoclonal antibodies (mAbs) have a 50% responder rate ranging from 27 to 71.0%, whereas CGRP receptor inhibitors have a 50% responder rate ranging from 56 to 71%. To address the need for novel therapeutic targets, researchers are exploring the potential of another secretin family peptide, pituitary adenylate cyclase-activating polypeptide (PACAP), as a ground-breaking treatment avenue for migraine. Preclinical models have revealed how PACAP affects the trigeminal system, which is implicated in headache disorders. Clinical studies have demonstrated the significance of PACAP in migraine pathophysiology; however, a few clinical trials remain inconclusive: the pituitary adenylate cyclase-activating peptide 1 receptor mAb, AMG 301 showed no benefit for migraine prevention, while the PACAP ligand mAb, Lu AG09222 significantly reduced the number of monthly migraine days over placebo in a phase 2 clinical trial. Meanwhile, another secretin family peptide vasoactive intestinal peptide (VIP) is gaining interest as a potential new target. In light of recent advances in PACAP research, we emphasize the potential of PACAP as a promising target for migraine treatment, highlighting the significance of exploring PACAP as a member of the antimigraine armamentarium, especially for patients who do not respond to or contraindicated to anti-CGRP therapies. By updating our knowledge of PACAP and its unique contribution to migraine pathophysiology, we can pave the way for reinforcing PACAP and other secretin peptides, including VIP, as a novel treatment option for migraines.

Age-dependent down-regulation of orexin receptors in trigeminal nucleus caudalis correlated with attenuation of orexinergic analgesia in rats

Aging is related to a variety of physiological organ changes, including central and peripheral nervous systems. It has been reported that the orexin signaling has a potential analgesic effect in different models of pain, especially inflammatory pulpal pain. However, the age-induced alteration in dental pain perception and orexin analgesia has not yet been fully elucidated. Here, we tested that how aging may change the effect of orexin-A on nociceptive behaviors in a rat dental pulp pain model. The expression levels of orexin receptors and the nociceptive neuropeptides substance P (SP) and calcitonin-related gene peptide (CGRP) were also assessed in the trigeminal nucleus caudalis (TNC) of young and aged rats. Dental pulp pain was induced by intradental application of capsaicin (100 μg). The immunofluorescence technique was used to evaluate the expression levels. The results show less efficiency of orexin-A to ameliorate pain perception in aged rats as compared to young rats. In addition, a significant decrease in the number of orexin 1 and 2 receptors was observed in the TNC of aged as compared to young rats. Dental pain-induced SP and CGRP overexpression was also significantly inhibited by orexin-A injection into the TNC of young animals. In contrast, orexin-A could not produce such effects in the aged animals. In conclusion, the older age-related reduction of the antinociceptive effect of orexin may be due to the downregulation of its receptors and inability of orexin signaling to inhibit the expression of nociceptive neuropeptides such as SP and CGRP in aged rats.

Effects of Vitamin D on Migraine: A Meta-Analysis

Objective

The aim of this study was to evaluate the difference in mean serum 25-hydroxy vitamin D level between migraineurs and nonmigraineurs, the association between hypovitaminosis D and migraine, and the effects of oral vitamin D supplementation on migraine-related symptoms as compared to placebo.

Methods

Relevant databases were searched for observational studies and randomized-controlled trials (RCTs) which evaluated the difference in mean serum 25-hydroxy vitamin D level between migraineurs and nonmigraineurs; the association between hypovitaminosis D and migraine; and the effects of vitamin D supplementation on migraine-frequency, duration, and severity. Pooled mean difference and odds ratio were calculated (random-effects model, RevMan version 5.3).

Results

Ten observational studies and two RCTs were included. The serum 25-hydroxy vitamin D level in the migraineurs was significantly lower than that in the nonmigraineurs [mean difference - 4.44 ng/mL (95% CI: -6.11, -2.77)] (low-GRADE evidence). Hypovitaminosis D was found to be significantly associated with migraine [OR: 1.95 (95% CI: 1.07, 3.58)] (low-GRADE evidence). As compared to placebo, oral vitamin D supplementation significantly reduced the monthly migraine-frequency [mean difference: -2.20 (95% CI: -3.04, -1.36)].

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although it did not reduce the migraine-duration [mean difference: -16.00 hours per month (95% CI: -42.77, 10.76)] and migraine-severity score [standardized mean difference: -0.23 (95% CI: -0.79, 0.32)] (moderate-GRADE evidence).

Conclusion

Serum 25-hydroxy vitamin D level was significantly lower in the migraineurs than that in the nonmigraineurs, and hypovitaminosis D was significantly associated with migraine. Oral vitamin D supplementation significantly reduced migraine-frequency, but not its duration and severity.

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.

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

Predictors of response to galcanezumab in patients with chronic migraine: a real-world prospective observational study

BACKGROUND

Despite high efficacy and tolerability, not all patients with chronic migraine benefit from anti-CGRP monoclonal antibodies. We aimed to identify the clinical predictors of the response to galcanezumab treatment in patients with chronic migraine from real-world data.

METHODS

We prospectively recruited patients with CM who underwent galcanezumab injections between December 2019 and February 2022. Treatment response was determined after three months of follow-up and was defined as ≥ 50% reduction in monthly headache days. The migraine characteristics, comorbidities, and other treatment responses were compared between the responder and non-responder groups.

RESULTS

Of 238 patients with CM, 153 (64.3%) showed treatment response. The responder group was younger, had lower frequency of baseline headache days, and had more accompanying symptoms such as nausea, vomiting, and photophobia. Better triptan response and less depression were also observed in the responder group. Multivariable regression analysis revealed that the everyday headache (OR = 0.351, 95% CI = 0.133-0.874, p = 0.017), depression (OR = 0.439, 95% CI = 0.216-0.896, p = 0.024) and absence of accompanying symptoms (OR = 0.314, 95% CI = 0.118-0.834, p = 0.020) were significantly associated with response to galcanezumab treatment.

CONCLUSIONS

Our real-world data showed the efficacy of galcanezumab in patients with CM, regardless of medication overuse. Everyday headache, presence of depression, and absence of accompanying symptoms of migraine were significant predictors of a poor response.

Exploration of phytochemicals and probing potential effects of Priva cordifolia active extract on PACAP 38 and its nociceptor in the human trigeminovascular system

Several tribal medicinal systems assert anti-migraine and common headache-remedying properties in all parts of Priva cordifolia (L.f.) Druce. Therefore, there are no clear scientific references to the validated traditional use of this plant. The present study provides a scientific basis for the ethnobotanical utility of P. cordifolia whose whole-plant extracts were evaluated against target proteins (PACAP 38 and PAC1-R) that cause migraine. Understanding the polarity-based distribution and oxidative stress scavenging ability was reported higher in ethyl acetate extracts due to the moderate distribution of secondary metabolites. Based on the preliminary analysis anti-migraine activity in the wet and dry lab experiments was compared with a commercial drug Sumatriptan. The GC-MS analysis revealed that two lead volatile compounds Bicyclo(3.2.1)oct-3-en-2-one,3,8-Dihydroxy-1-methoxy-7-(7-methoxy-1,3- and -Hexyl-2-nitrocyclohexane, present in the ethyl acetate extract showed favourable in silico anti-migraine efficiency. Notably, the ex-vivo results also showed considerable downregulation of the extract-induced mRNA expression of PACAP38. The conclusion of our study justifies that P. cordifolia has valuable plant metabolites that portray it as an efficient anti-oxidant and anti-migraine source.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03462-w.

Nutrition and Calcitonin Gene Related Peptide (CGRP) in Migraine

Targeting calcitonin gene-related peptide (CGRP) and its receptor by antibodies and antagonists was a breakthrough in migraine prevention and treatment. However, not all migraine patients respond to CGRP-based therapy and a fraction of those who respond complain of aliments mainly in the gastrointestinal tract. In addition, CGRP and migraine are associated with obesity and metabolic diseases, including diabetes. Therefore, CGRP may play an important role in the functioning of the gut-brain-microflora axis. CGRP secretion may be modulated by dietary compounds associated with the disruption of calcium signaling and upregulation of mitogen-activated kinase phosphatases 1 and 3. CGRP may display anorexigenic properties through induction of anorexigenic neuropeptides, such as cholecystokinin and/or inhibit orexigenic neuropeptides, such as neuropeptide Y and melanin-concentrating hormone CH, resulting in the suppression of food intake, functionally coupled to the activation of the hypothalamic 3',5'-cyclic adenosine monophosphate. The anorexigenic action of CGRP observed in animal studies may reflect its general potential to control appetite/satiety or general food intake. Therefore, dietary nutrients may modulate CGRP, and CGRP may modulate their intake. Therefore, anti-CGRP therapy should consider this mutual dependence to increase the efficacy of the therapy and reduce its unwanted side effects. This narrative review presents information on molecular aspects of the interaction between dietary nutrients and CGRP and their reported and prospective use to improve anti-CGRP therapy in migraine.

Therapeutic applications and potential mechanisms of acupuncture in migraine: A literature review and perspectives

Acupuncture is commonly used as a treatment for migraines. Animal studies have suggested that acupuncture can decrease neuropeptides, immune cells, and proinflammatory and excitatory neurotransmitters, which are associated with the pathogenesis of neuroinflammation. In addition, acupuncture participates in the development of peripheral and central sensitization through modulation of the release of neuronal-sensitization-related mediators (brain-derived neurotrophic factor, glutamate), endocannabinoid system, and serotonin system activation. Clinical studies have demonstrated that acupuncture may be a beneficial migraine treatment, particularly in decreasing pain intensity, duration, emotional comorbidity, and days of acute medication intake. However, specific clinical effectiveness has not been substantiated, and the mechanisms underlying its efficacy remain obscure. With the development of biomedical and neuroimaging techniques, the neural mechanism of acupuncture in migraine has gained increasing attention. Neuroimaging studies have indicated that acupuncture may alter the abnormal functional activity and connectivity of the descending pain modulatory system, default mode network, thalamus, frontal-parietal network, occipital-temporal network, and cerebellum. Acupuncture may reduce neuroinflammation, regulate peripheral and central sensitization, and normalize abnormal brain activity, thereby preventing pain signal transmission. To summarize the effects and neural mechanisms of acupuncture in migraine, we performed a systematic review of literature about migraine and acupuncture. We summarized the characteristics of current clinical studies, including the types of participants, study designs, and clinical outcomes. The published findings from basic neuroimaging studies support the hypothesis that acupuncture alters abnormal neuroplasticity and brain activity. The benefits of acupuncture require further investigation through basic and clinical studies.

CGRP and PACAP-38 play an important role in diagnosing pediatric migraine

Background

An increasing number of studies have suggested that the important role of vasoactive peptides, such as pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) and calcitonin gene-related peptide (CGRP), in the pathophysiology of migraine seems undeniable in adults, but studies in pediatric migraine patients remain scarce. We prospectively investigated CGRP and PACAP-38 plasma levels in children with migraine during ictal and interictal periods and compared the results between migraine patients with aura and without aura. We were the first to explore the diagnostic value of a combination of CGRP and PACAP-38.

Methods

Seventy-six migraine patients aged 4–18 years and seventy-seven age-matched healthy children were included in the study. Plasma vasoactive peptides were measured using the enzyme-linked immunosorbent assay (ELISA). Differences and correlations of groups were analyzed using the independent samples t-test, analysis of variance (ANOVA), Mann-Whitney U test, and multiple linear regression. We also performed logistic regression and receiver operating characteristic curve (ROC) analyses to evaluate the diagnostic value of CGRP and PACAP-38 in pediatric migraine.

Results

PACAP-38 and CGRP levels in migraine patients during the ictal and interictal periods were higher than those in controls (p < 0.001). PACAP-38 and CGRP levels in migraine patients with aura and without aura were higher than those in controls (p < 0.001). PACAP-38 and CGRP were independent risk factors in diagnosing pediatric migraine (adjusted OR (PACAP-38) =1.331, 95% CI: 1.177–1.506, p < 0.001; adjusted OR (CGRP) = 1.113, 95% CI: 1.064–1.165, p < 0.001). Area Under Curve (AUC) comparison: Combination (0.926) > CGRP (0.869) > PACAP-38 (0.867).

Conclusions

Our study found almost the same changes in CGRP and PACAP levels in pediatric migraine, suggesting that CGRP and PACAP-38 may work together to play an integral role in pediatric migraine. Higher CGRP levels were found in the ictal phase than in the interictal phase and with aura group than without aura group, indicating that CGRP may take part in the formation of pain and aura. Moreover, ROC and logistic regression analyses suggested that CGRP and PACAP-38 are good indicators to diagnose pediatric migraine, and the combination of CGRP and PACAP-38 was valuable in diagnosing pediatric migraine and differentiating pediatric migraine from non-migraine headaches.

Trial registration

The study has been registered at the Chinese Clinical Trial Registry (ChiCTR2100043157).

Neurogenic Inflammation: The Participant in Migraine and Recent Advancements in Translational Research

Migraine is a primary headache disorder characterized by a unilateral, throbbing, pulsing headache, which lasts for hours to days, and the pain can interfere with daily activities. It exhibits various symptoms, such as nausea, vomiting, sensitivity to light, sound, and odors, and physical activity consistently contributes to worsening pain. Despite the intensive research, little is still known about the pathomechanism of migraine. It is widely accepted that migraine involves activation and sensitization of the trigeminovascular system. It leads to the release of several pro-inflammatory neuropeptides and neurotransmitters and causes a cascade of inflammatory tissue responses, including vasodilation, plasma extravasation secondary to capillary leakage, edema, and mast cell degranulation. Convincing evidence obtained in rodent models suggests that neurogenic inflammation is assumed to contribute to the development of a migraine attack. Chemical stimulation of the dura mater triggers activation and sensitization of the trigeminal system and causes numerous molecular and behavioral changes; therefore, this is a relevant animal model of acute migraine. This narrative review discusses the emerging evidence supporting the involvement of neurogenic inflammation and neuropeptides in the pathophysiology of migraine, presenting the most recent advances in preclinical research and the novel therapeutic approaches to the disease.

Macrophage Polarization and Alveolar Bone Healing Outcome: Despite a Significant M2 Polarizing Effect, VIP and PACAP Treatments Present a Minor Impact in Alveolar Bone Healing in Homeostatic Conditions

Host inflammatory immune response comprises an essential element of the bone healing process, where M2 polarization allegedly contributes to a favorable healing outcome. In this context, immunoregulatory molecules that modulate host response, including macrophage polarization, are considered potential targets for improving bone healing. This study aims to evaluate the role of the immunoregulatory molecules VIP (Vasoactive intestinal peptide) and PACAP (Pituitary adenylate cyclase activating polypeptide), which was previously described to favor the development of the M2 phenotype, in the process of alveolar bone healing in C57Bl/6 (WT) mice. Experimental groups were submitted to tooth extraction and maintained under control conditions or treated with VIP or PACAP were evaluated by microtomographic (µCT), histomorphometric, immunohistochemical, and molecular analysis at 0, 3, 7, and 14 days to quantify tissue healing and host response indicators at the healing site. Gene expression analysis demonstrates the effectiveness of VIP or PACAP in modulating host response, evidenced by the early dominance of an M2-type response, which was paralleled by a significant increase in M2 (CD206+) in treated groups. However, despite the marked effect of M1/M2 balance in the healing sites, the histomorphometric analysis does not reveal an equivalent/corresponding modulation of the healing process. µCT reveals a slight increase in bone matrix volume and the trabecular thickness number in the PACAP group, while histomorphometric analyzes reveal a slight increase in the VIP group, both at a 14-d time-point; despite the increased expression of osteogenic factors, osteoblastic differentiation, activity, and maturation markers in both VIP and PACAP groups. Interestingly, a lower number of VIP and PACAP immunolabeled cells were observed in the treated groups, suggesting a reduction in endogenous production. In conclusion, while both VIP and PACAP treatments presented a significant immunomodulatory effect with potential for increased healing, no major changes were observed in bone healing outcome, suggesting that the signals required for bone healing under homeostatic conditions are already optimal, and additional signals do not improve an already optimal process. Further studies are required to elucidate the role of macrophage polarization in the bone healing process.

Vitamin B12 and folic acid levels in pediatric migraine patients

Migraine is a recurrent, primary cause of headache. Although prophylactic vitamin B12 therapy is used on migraine patients, there is a limited number of studies examining the levels of B12 vitamin and folic acid in pediatric patients diagnosed with migraine. The study group (Group 1) included 65 pediatric patients diagnosed with migraine in the Pediatric neurology outpatient clinic, and 87 healthy cases admitted to the general pediatric clinic were included in the control group (Group 2). Complete blood count parameters, vitamin B12, folic acid, ferritin, and 25 OH D vitamin levels of the study and control groups were compared. The mean vitamin B12 level was 196.42 ± 95.54 pg/mL (59-499) in Group 1 and 240 ± 105.24 pg/mL (74-619) in Group 2. The mean folic acid level was 8.85 ± 3.49 pg/mL (3.68-23.70) in Group 1 and 7.24 ± 7.17 pg/mL (1.11-35.50) in Group 2. There was a statistically significant difference between Group 1 and 2 in terms of vitamin B12 and folic acid levels (p = 0.008, p = 0.00). The results of this study indicate the requirement for routine evaluation of vitamin B12 and folic acid levels in pediatric patients diagnosed with migraine.

Pituitary adenylate cyclase-activating polypeptide attenuates mitochondria-mediated oxidative stress and neuronal apoptosis after subarachnoid hemorrhage in rats

Mitochondria-mediated oxidative stress and neuronal apoptosis play an important role in early brain injury following subarachnoid hemorrhage (SAH). Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to reduce oxidative stress and cellular apoptosis by maintaining mitochondrial function under stress. The objective of this study is to investigate the effects of PACAP on mitochondria dysfunction - induced oxidative stress and neuronal apoptosis in both vivo and vitro models of SAH. PACAP Knockout CRISPR and exogenous PACAP38 were used to verify the neuroprotective effects of PACAP in rats after endovascular perforation - induced SAH as well as in primary neuron culture after hemoglobin stimulation. The results showed that endogenous PACAP knockout aggravated mitochondria dysfunction - mediated ATP reduction, reactive oxygen species accumulation and neuronal apoptosis in ipsilateral hemisphere at 24 h after SAH in rats. The exogenous PACAP38 treatment provided both short- and long-term neurological benefits by attenuating mitochondria - mediated oxidative stress and neuronal apoptosis after SAH in rats. Consistently, the exogenous PACAP38 treatment presented similar neuroprotection in the primary neuron culture after hemoglobin stimulation. Pharmacological inhibition of adenylyl cyclase (AC) or extracellular signal-regulated kinase (ERK) partly abolished the anti-oxidative stress and anti-apoptotic effects provided by PACAP38 treatment after the experimental SAH both in vivo and in vitro, suggesting the involvement of the AC-cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) and ERK pathway. Collectively, PACAP38 may serve as a promising treatment strategy for alleviating early brain injury after SAH.

Fifteen-Years Follow-Up in a Cohort of Children with Functional Gastrointestinal Disorders: Prevalence and Risk Factors to Develop Neuropsychiatric Disorders and Other Comorbidities

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are chronic and recurrent disorders, which affect up to 23% of children and adolescents and represent 50% of gastroenterological accesses. The association between FGIDs diagnosed at paediatric age and the onset of migraine or headache and neuropsychiatric diseases in adolescence and adulthood is widely reported in the literature. However, there is still limited knowledge about the long-term prognosis and risk factors for neuropsychiatric pathologies and other comorbidities.

AIM

The aim is to assess the prevalence and persistence of FGIDs as well as the occurrence of migraine or headache and neuropsychiatric disorders in a cohort of patients diagnosed with FGIDs 15 years ago compared with a control group of peers.

MATERIALS AND METHODS

We enrolled a group of patients diagnosed with FGIDs at paediatric age, at least 10 years ago (FGIDs group, n = 79; median age 23), and control subjects (control group, n = 201; median age 23). In both groups, an online questionnaire created explicitly for the study was submitted in order to investigate the presence of chronic intestinal diseases, migraine, headache or neuropsychiatric disorders.

RESULTS

45.6% (36 out of 79) of patients previously diagnosed with FGIDs still suffer from FGIDs versus 12% (24 out of 201) of healthy controls (p < 0.0001). The prevalence of chronic organic gastrointestinal disorders was comparable in the two groups (2.5% in FGIDs group versus 1% in healthy group, p = 0.3). Thirty-three percent (26 out of 79) of FGIDs patients reported headache or migraine versus 13% (26 out of 201) of healthy peers (p < 0.001). No differences were found regarding the prevalence of anxiety and depression.

CONCLUSION

The outcome at 15 years of FGIDs was characterized by a high prevalence of persisting functional symptoms along with a significant incidence of headaches and migraines. Abbreviation: FGIDs: Functional gastrointestinal disorders; IBS: Inflammatory Bowel Syndrome.

Transient receptor potential canonical 5 mediates inflammatory mechanical and spontaneous pain in mice

Tactile and spontaneous pains are poorly managed symptoms of inflammatory and neuropathic injury. Here, we found that transient receptor potential canonical 5 (TRPC5) is a chief contributor to both of these sensations in multiple rodent pain models. Use of TRPC5 knockout mice and inhibitors revealed that TRPC5 selectively contributes to the mechanical hypersensitivity associated with CFA injection, skin incision, chemotherapy induced peripheral neuropathy, sickle cell disease, and migraine, all of which were characterized by elevated concentrations of lysophosphatidylcholine (LPC). Accordingly, exogenous application of LPC induced TRPC5-dependent behavioral mechanical allodynia, neuronal mechanical hypersensitivity, and spontaneous pain in naïve mice. Lastly, we found that 75% of human sensory neurons express TRPC5, the activity of which is directly modulated by LPC. On the basis of these results, TRPC5 inhibitors might effectively treat spontaneous and tactile pain in conditions characterized by elevated LPC.

Biomarkers in Migraine

Background

Disability from migraine has a profound impact on the world's economy. Research has been ongoing to identify biomarkers to aid in diagnosis and treatment.

Objective

The aim of this study was to highlight the purported diagnostic and therapeutic migraine biomarkers and their role in precision medicine.

Methods

A comprehensive literature search was conducted using PubMed, Google Scholar, and clinicaltrials.gov using keywords: "migraine" OR "headache" combined with "biomarkers" OR "marker." Other keywords included "serum," "cerebral spinal fluid," "inflammatory," and "neuroimaging."

Results

After a review of 88 papers, we find the literature supports numerous biomarkers in the diagnosis of migraine. Therapeutic biomarkers, while not as extensively published, highlight calcitonin gene-related peptide (CGRP) and pituitary adenylate cyclase-activating peptide-38 (PACAP-38) as biomarkers with the most substantiated clinical relevance. Genetic markers mainly focusing on gene mutations with resultant biochemical alterations continue to be studied and show promise.

Conclusion

Although there are several proposed biomarkers for migraine, continued research is needed to substantiate their role in clinical practice.

PACAP Induces Light Aversion in Mice by an Inheritable Mechanism Independent of CGRP

The neuropeptides CGRP (calcitonin gene-related peptide) and PACAP (pituitary adenylate cyclase-activating polypeptide) have emerged as mediators of migraine, yet the potential overlap of their mechanisms remains unknown. Infusion of PACAP, like CGRP, can cause migraine in people, and both peptides share similar vasodilatory and nociceptive functions. In this study, we have used light aversion in mice as a surrogate for migraine-like photophobia to compare CGRP and PACAP and ask whether CGRP or PACAP actions were dependent on each other. Similar to CGRP, PACAP induced light aversion in outbred CD-1 mice. The light aversion was accompanied by increased resting in the dark, but not anxiety in a light-independent open field assay. Unexpectedly, about one-third of the CD-1 mice did not respond to PACAP, which was not seen with CGRP. The responder and nonresponder phenotypes were stable, inheritable, and not sex linked, although there was a trend for greater responses among male mice. RNA-sequencing analysis of trigeminal ganglia yielded hierarchical clustering of responder and nonresponder mice and revealed a number of candidate genes, including greater expression of the Trpc5 and Kcnk12 ion channels and glycoprotein hormones and receptors in a subset of male responder mice. Importantly, an anti-PACAP monoclonal antibody could block PACAP-induced light aversion but not CGRP-induced light aversion. Conversely, an anti-CGRP antibody could not block PACAP-induced light aversion. Thus, we propose that CGRP and PACAP act by independent convergent pathways that cause a migraine-like symptom in mice.SIGNIFICANCE STATEMENT The relationship between the neuropeptides CGRP (calcitonin gene-related peptide) and PACAP (pituitary adenylate cyclase-activating polypeptide) in migraine is relevant given that both peptides can induce migraine in people, yet to date only drugs that target CGRP are available. Using an outbred strain of mice, we were able to show that most, but not all, mice respond to PACAP in a preclinical photophobia assay. Our finding that CGRP and PACAP monoclonal antibodies do not cross-inhibit the other peptide indicates that CGRP and PACAP actions are independent and suggests that PACAP-targeted drugs may be effective in patients who do not respond to CGRP-based therapeutics.

Discovery of Selective Pituitary Adenylate Cyclase 1 Receptor (PAC1R) Antagonist Peptides Potent in a Maxadilan/PACAP38-Induced Increase in Blood Flow Pharmacodynamic Model

Inhibition of the pituitary adenylate cyclase 1 receptor (PAC1R) is a novel mechanism that could be used for abortive treatment of acute migraine. Our research began with comparative analysis of known PAC1R ligand scaffolds, PACAP38 and Maxadilan, which resulted in the selection of des(24-42) Maxadilan, 6, as a starting point. C-terminal modifications of 6 improved the peptide metabolic stability in vitro and in vivo. SAR investigations identified synergistic combinations of amino acid replacements that significantly increased the in vitro PAC1R inhibitory activity of the analogs to the pM IC₉₀ range. Our modifications further enabled deletion of up to six residues without impacting potency, thus improving peptide ligand binding efficiency. Analogs 17 and 18 exhibited robust in vivo efficacy in the rat Maxadilan-induced increase in blood flow (MIIBF) pharmacodynamic model at 0.3 mg/kg subcutaneous dosing. The first cocrystal structure of a PAC1R antagonist peptide (18) with PAC1R extracellular domain is reported.

Real-world efficacy, tolerability, and safety of ubrogepant

OBJECTIVE

To assess the real-world efficacy, tolerability, and safety of ubrogepant in a tertiary headache center.

BACKGROUND

The efficacy and safety of ubrogepant for the acute treatment of migraine were established in phase 3 randomized controlled trials. However, there is no real-world data of patient experience with ubrogepant in a population in which the majority of patients have chronic migraine, multiple prior unsuccessful treatments, complex medical comorbidities, and concurrent use of other migraine-specific medications.

METHOD

This was a post-market cohort study conducted at Mayo Clinic Arizona. All patients prescribed ubrogepant were tracked and contacted 1-3 months after the prescription to answer a list of standardized questions. Demographic information and additional headache history were obtained from chart review.

RESULTS

We obtained eligible questionnaire responses from 106 patients. Chronic migraine accounted for 92/106 (86.8%) of the population. Complete headache freedom (from mild/moderate/severe to no pain) and headache relief (from moderate/severe to mild/no pain or mild to no pain) for ≥75% of all treated attacks at 2 hours after taking ubrogepant were achieved in 20/105 (19.0%) and 50/105 (47.6%) patients, respectively. A total of 33/106 (31.1%) patients reported being "very satisfied" with ubrogepant. Adverse events were reported in 42/106 (39.6%) patients, including fatigue in 29/106 (27.4%), dry mouth in 8/106 (7.5%), nausea/vomiting in 7/106 (6.6%), constipation in 5/106 (4.7%), dizziness in 3/106 (2.8%), and other adverse events in 7/106 (6.6%). Predictive factors for being a "good responder" to ubrogepant, defined as headache relief for ≥75% of all treated attacks at 2 hours after taking ubrogepant, included migraine with aura, episodic migraine, <5 prior unsuccessful preventive or acute treatment trials. Additionally, prior treatment responses to a CGRP monoclonal antibody and onabotulinumtoxinA injections are predictive of treatment responses and patient satisfaction to ubrogepant. For the 62/106 (58.5%) patients concurrently using a CGRP monoclonal antibody, there was no difference in the "good responder" rate or adverse event rate compared to those who were not on a CGRP monoclonal antibody, though the rate of moderate, as opposed to mild adverse events was higher, 11/62 (47.8%) versus 3/44 (17.6%), p = 0.048. Additionally, 16 patients had a history of significant cardiovascular or cerebrovascular diseases. No severe adverse events were reported in any patient.

CONCLUSION

Our study confirms and extends the efficacy profile and tolerability of ubrogepant in a real-world tertiary headache clinic and identifies factors that may predict efficacy. Adverse event rates were higher than reported in clinical trials. Further studies are needed to confirm these findings and to evaluate the long-term efficacy and safety of ubrogepant.

Pituitary Adenylate Cyclase-Activating Polypeptide: A Promising Neuroprotective Peptide in Stroke

The search for viable, effective treatments for acute stroke continues to be a global priority due to the high mortality and morbidity. Current therapeutic treatments have limited effects, making the search for new treatments imperative. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a well-established cytoprotective neuropeptide that participates in diverse neural physiological and pathological activities, such as neuronal proliferation, differentiation, and migration, as well as neuroprotection. It is considered a promising treatment in numerous neurological diseases. Thus, PACAP bears potential as a new therapeutic strategy for stroke treatment. Herein, we provide an overview pertaining to the current knowledge of PACAP, its receptors, and its potential neuroprotective role in the setting of stroke, as well as various mechanisms of neuroprotection involving ionic homeostasis, excitotoxicity, cell edema, oxidative stress, inflammation, and cell death, as well as the route of PACAP administration.

Non-invasive vagus nerve stimulation for primary headache: A clinical update

Background

Non-invasive vagus nerve stimulation (nVNS) is a proven treatment for cluster headache and migraine. Several possible mechanisms of action by which nVNS mitigates headache have been identified.

Methods

We conducted a narrative review of recent scientific and clinical research into nVNS for headache, including findings from mechanistic studies and their possible relationships to the clinical effects of nVNS.

Results

Findings from animal and human studies have provided possible mechanistic explanations for nVNS efficacy in headache involving four core areas: Autonomic nervous system functions; cortical spreading depression inhibition; neurotransmitter regulation; and nociceptive modulation. We discuss how overlap and interplay among these areas may underlie the utility of nVNS in the context of clinical evidence supporting its safety and efficacy as acute and preventive therapy for both cluster headache and migraine. Possible future nVNS applications are also discussed.

Conclusion

Significant progress over the past several years has yielded valuable mechanistic and clinical evidence that, combined with the excellent safety and tolerability profile of nVNS, suggests that it should be considered a first-line treatment for both acute and preventive treatment of cluster headache, an effective option for acute treatment of migraine, and a highly relevant, practical option for migraine prevention.

Calcitonin gene-related peptide (CGRP)-targeted therapies as preventive and acute treatments for migraine-The monoclonal antibodies and gepants

Calcitonin Gene-Related Peptide (CGRP) plays a pivotal role in migraine pathophysiology. Two types of CGRP function-blocking modalities, monoclonal antibodies, and small molecules (gepants), have been developed to target the CGRP ligands and CGRP receptors. Four CGRP monoclonal antibodies have received FDA approval for the prevention of migraine: erenumab, fremanezumab, galcanezumab, and eptinezumab. Two gepants have been approved by the FDA for the acute treatment of migraine: ubrogepant and rimegepant. Multiple clinical trials of the CGRP monoclonal antibodies and gepants, and now some open-label long-term extension data, established their efficacy, safety, and tolerability. In this chapter, we summarize the major clinical trials, pharmacokinetic insights, safety and tolerability profiles, and real-world data (if available) of the CGRP monoclonal antibodies and gepants.

Selective amplification of ipRGC signals accounts for interictal photophobia in migraine

Second only to headache, photophobia is the most debilitating symptom reported by people with migraine. While the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are thought to play a role, how cone and melanopsin signals are integrated in this pathway to produce visual discomfort is poorly understood. We studied 60 people: 20 without headache and 20 each with interictal photophobia from migraine with or without visual aura. Participants viewed pulses of spectral change that selectively targeted melanopsin, the cones, or both and rated the degree of visual discomfort produced by these stimuli while we recorded pupil responses. We examined the data within a model that describes how cone and melanopsin signals are weighted and combined at the level of the retina and how this combined signal is transformed into a rating of discomfort or pupil response. Our results indicate that people with migraine do not differ from headache-free controls in the manner in which melanopsin and cone signals are combined. Instead, people with migraine demonstrate an enhanced response to integrated ipRGC signals for discomfort. This effect of migraine is selective for ratings of visual discomfort, in that an enhancement of pupil responses was not seen in the migraine group, nor were group differences found in surveys of other behaviors putatively linked to ipRGC function (chronotype, seasonal sensitivity, presence of a photic sneeze reflex). By revealing a dissociation in the amplification of discomfort vs. pupil response, our findings suggest a postretinal alteration in processing of ipRGC signals for photophobia in migraine.

Mechanism of Action of OnabotulinumtoxinA in Chronic Migraine: A Narrative Review

Objective

To review the literature on the mechanism of action of onabotulinumtoxinA in chronic migraine.

Background

OnabotulinumtoxinA is a chronic migraine preventive treatment that significantly reduces headache frequency. The traditional mechanism described for onabotulinumtoxinA – reducing muscle contractions – is insufficient to explain its efficacy in migraine, which is primarily a sensory neurological disease.

Methods

A narrative literature review on the mechanism of action of onabotulinumtoxinA in chronic migraine.

Results

Following injection into tissues, onabotulinumtoxinA inhibits soluble N‐ethylmaleimide‐sensitive fusion attachment protein receptor (SNARE)‐mediated vesicle trafficking by cleaving one of its essential proteins, soluble N‐ethylmaleimide‐sensitive fusion attachment protein (SNAP‐25), which occurs in both motor and sensory nerves. OnabotulinumtoxinA inhibits regulated exocytosis of motor and sensory neurochemicals and proteins, as well as membrane insertion of peripheral receptors that convey pain from the periphery to the brain, because both processes are SNARE dependent. OnabotulinumtoxinA can decrease exocytosis of pro‐inflammatory and excitatory neurotransmitters and neuropeptides such as substance P, calcitonin gene‐related peptide, and glutamate from primary afferent fibers that transmit nociceptive pain and participate in the development of peripheral and central sensitization. OnabotulinumtoxinA also decreases the insertion of pain‐sensitive ion channels such as transient receptor potential cation channel subfamily V member 1 (TRPV1) into the membranes of nociceptive neurons; this is likely enhanced in the sensitized neuron. For chronic migraine prevention, onabotulinumtoxinA is injected into 31‐39 sites in 7 muscles of the head and neck. Sensory nerve endings of neurons whose cell bodies are located in trigeminal and cervical ganglia are distributed throughout the injected muscles, and are overactive in people with migraine. Through inhibition of these sensory nerve endings, onabotulinumtoxinA reduces the number of pain signals that reach the brain and consequently prevents activation and sensitization of central neurons postulated to be involved in migraine chronification.

Conclusion

OnabotulinumtoxinA likely acts via sensory mechanisms to treat chronic migraine.

No central action of CGRP antagonising drugs in the GTN mouse model of migraine

Introduction

Clinically, calcitonin gene-related peptide antagonising drugs are recognized as effective in migraine treatment, but their site of action is debated. Only a small fraction of these compounds pass the blood-brain barrier and accesses the central nervous system. Regardless, it has been argued that the central nervous system is the site of action. Here, we test this hypothesis by bypassing the blood-brain barrier through intracerebroventricular injection of calcitonin gene-related peptide antagonising drugs.

Methods

We used the glyceryl trinitrate (GTN) mouse model, which is well validated by its response to specific migraine drugs. The calcitonin gene-related peptide receptor antagonist olcegepant and the calcitonin gene-related peptide monoclonal antibody ALD405 were administered either intraperitoneally or intracerebroventricularly. The outcome measure was cutaneous mechanical allodynia.

Results

Mice given olcegepant intraperitoneally + GTN on day 1 had a mean 50% withdrawal threshold of 1.2 g in contrast to mice receiving placebo + GTN, which had a threshold of 0.3 g ( p < 0.001). Similarly, in the ALD405 + GTN group, mice had thresholds of 1.2 g versus 0.2 g in the placebo + GTN group ( p < 0.001). However, both drugs were ineffective when delivered intracerebroventricularly, as control and active groups had identical mechanical sensitivity thresholds, 0.2 g versus 0.1 g and 0.1 g versus 0.1 g for olcegepant and ALD405, respectively ( p > 0.99 in both cases).

Discussion

The site of action of olcegepant and of the monoclonal antibody ALD405 is outside the blood-brain barrier in this mouse model of migraine. It is likely that these results can be generalised to all gepants and all antibodies and that the results are relevant for human migraine.

Cortical potentiation induced by calcitonin gene-related peptide (CGRP) in the insular cortex of adult mice

Recent studies demonstrate that calcitonin gene-related peptide (CGRP) plays critical roles in migraine. Immunohistochemistry and in situ hybridization studies have shown that CGRP and its receptors are expressed in cortical areas that are critical for pain perception including the anterior cingulate cortex (ACC) and insular cortex (IC). Recent studies reported that CGRP enhanced excitatory transmission in the ACC. However, little is known about the possible effect of CGRP on excitatory transmission in the IC. In the present study, we investigated the role of CGRP on synaptic transmission in the IC slices of adult male mice. Bath application of CGRP produced dose-dependent potentiation of evoked excitatory postsynaptic currents (eEPSCs). This potentiation was NMDA receptor (NMDAR) independent. After application of CGRP1 receptor antagonist CGRP_8–37 or BIBN 4096, CGRP produced potentiation was significantly reduced. Paired-pulse facilitation was significantly decreased by CGRP, suggesting possible presynaptic mechanisms. Consistently, bath application of CGRP significantly increased the frequency of spontaneous and miniature excitatory postsynaptic currents (sEPSCs and mEPSCs). By contrast, amplitudes of sEPSCs and mEPSCs were not significantly affected. Finally, adenylyl cyclase subtype 1 (AC1) and protein kinase A (PKA) are critical for CGRP-produced potentiation, since both selective AC1 inhibitor NB001 and the PKA inhibitor KT5720 completely blocked the potentiation. Our results provide direct evidence that CGRP contributes to synaptic potentiation in the IC, and the AC1 inhibitor NB001 may be beneficial for the treatment of migraine in the future.

Calcitonin gene-related peptide (CGRP): role in migraine pathophysiology and therapeutic targeting

Introduction: The neuropeptide calcitonin gene-related peptide (CGRP) is recognized as a critical player in migraine pathophysiology. Excitement has grown regarding CGRP because of the development and clinical testing of drugs targeting CGRP or its receptor. While these drugs alleviate migraine symptoms in half of the patients, the remaining unresponsive half of this population creates an impetus to address unanswered questions that exist in this field.Areas covered: We describe the role of CGRP in migraine pathophysiology and CGRP-targeted therapeutics currently under development and in use. We also discuss how a second CGRP receptor may provide a new therapeutic target.Expert opinion: CGRP-targeting drugs have shown a remarkable safety profile. We speculate that this may reflect the redundancy of peptides within the CGRP family and a second CGRP receptor that may compensate for reduced CGRP activity. Furthermore, we propose that an inherent safety feature of peptide-blocking antibodies is attributed to the fundamental nature of peptide release, which occurs as a large bolus in short bursts of volume transmission. These facts support the development of more refined CGRP therapeutic drugs, as well as drugs that target other neuropeptides. We believe that the future of migraine research is bright with exciting advances on the horizon.

[Recent advances in the elucidation of migraine pathophysiology]

Three hypotheses have been proposed so far regarding the pathophysiology of migraine: one is the "vascular theory", which posits cerebral vascular dysfunction as the etiological factor. The second is the "neuronal theory", which suggests that migraine is triggered by cortical spreading depression. The third is the "trigemino-vascular theory", which postulates that migraine is triggered by inflammation of trigeminal nerves and vessels around trigeminal ganglion cells. Nowadays, the "trigemino-vascular theory" is widely accepted. However, recent advances in imaging analysis indicate that the origin of migraine lies in a premonitory phase which precedes the aura phase. Modern imaging techniques such as functional MRI and PET reveal high activity of the hypothalamic area during the premonitory phase of migraine. These findings suggest that hypothalamic activation might be a generator of a migraine attack. On the other hand, current analyses show that the photosensitivity of migraine (photophobia) could be caused by dysfunction of the newly discovered intrinsically photosensitive retinal ganglion cells (ipRGCs). In the absence of visual signaling from rods and cones, light activation of ipRGCs expressing melanopsin photopigment is sufficient to produce photophobia during migraine. The ipRGCs project to the hypothalamus; their activation might be the trigger for migraine attacks. Significant advances in molecular biology and imaging in recent years have clarified the previous hypotheses of migraine pathophysiology.

Ischemic Stroke Associated With Calcitonin Gene-Related Peptide Inhibitor Therapy for Migraine: A Case Report

Calcitonin gene-related peptide (CGRP) is involved in nociception and neurogenic inflammation in migraine, but also serves as a potent vasodilator acting on intracranial arteries. This latter effect raises concern about the possibility of drugs inhibiting CGRP precipitating cerebral ischemia. We describe a 41-year-old woman with migraine without aura who developed a right thalamic infarction following a first dose of erenumab, a CGRP-receptor blocker. Stroke onset occurred during a typical migraine. Imaging demonsrated right posterior cerebral artery near-occlusion initially with normalization of the vessel at follow-up imaging 2 months later, suggesting vasospasm as a possible mechanism. Extensive evaluation revealed no other specific cause of stroke or vascular risk factors aside from long-term use of oral contraceptive pills. CGRP inhibitors might be associated with ischemic stroke due to blockade of normal cerebral vasodilatory regulatory function.

The association between dietary tryptophan intake and migraine

Migraineurs have been identified to have chronically decreased serotonin levels while its concentrations markedly increase during ictal periods. Regarding the importance of adequate tryptophan intake in regulating serotonin homeostasis and subsequent effect on migraine attacks, we designed the current study. The migraine group (n = 514, diagnosed according to the ICHDIII criteria) was recruited from a tertiary headache clinic. The controls consisted of 582 sex-matched healthy volunteers who were randomly selected from general population. After collecting demographic and anthropometric data, a validated 168-item semi-quantitative food frequency questionnaire (FFQ) was used for dietary intake assessments. Multiple regression models were applied to explore the relationship between migraine and tryptophan intake. The mean (SD) of the age of participants in the controls and migraine group was 44.85 (13.84) and 36.20 (9.78) years, respectively. The multiple regression models were adjusted for age (year), sex, body mass index (BMI) (kg/m²), total daily energy intake (kcal/day), dietary intakes of total carbohydrates (g/day), animal-based protein (g/day), plant-based protein (g/day), total fat (g/day), saturated fat (g/day), and cholesterol (mg/day). It was shown that there is a negative association between tryptophan intake and migraine risk ((OR in the 3rd quartile = 0.46; 95% CI = 0.25-0.85) (OR in the 4th quartile = 0.40; 95% CI = 0.16-0.98) compared with the first quartile; P for trend = 0.045). Therefore, our results showed that subjects who had a median intake of 0.84-1.06 g of tryptophan per day had reduced odds of developing migraine by approximately 54-60%, relative to those consumed ≤ 0.56 g/day.

Dynamic changes in CGRP, PACAP, and PACAP receptors in the trigeminovascular system of a novel repetitive electrical stimulation rat model: Relevant to migraine

Migraine is the seventh most disabling disorder globally, with prevalence of 11.7% worldwide. One of the prevailing mechanisms is the activation of the trigeminovascular system, and calcitonin gene-related peptide (CGRP) is an important therapeutic target for migraine in this system. Recent studies suggested an emerging role of pituitary adenylate cyclase-activating peptide (PACAP) in migraine. However, the relation between CGRP and PACAP and the role of PACAP in migraine remain undefined. In this study, we established a novel repetitive (one, three, and seven days) electrical stimulation model by stimulating dura mater in conscious rats. Then, we determined expression patterns in the trigeminal ganglion and the trigeminal nucleus caudalis of the trigeminovascular system. Electrical stimulation decreased facial mechanical thresholds, and the order of sensitivity was as follows: vibrissal pad >inner canthus >outer canthus (P < 0.001). The electrical stimulation group exhibited head-turning and head-flicks (P < 0.05) nociceptive behaviors. Importantly, electrical stimulation increased the expressions of CGRP, PACAP, and the PACAP-preferring type 1 (PAC1) receptor in both trigeminal ganglion and trigeminal nucleus caudalis (P < 0.05). The expressions of two vasoactive intestinal peptide (VIP)-shared type 2 (VPAC1 and VPAC2) receptors were increased in the trigeminal ganglion, whereas in the trigeminal nucleus caudalis, their increases were peaked on Day 3 and then decreased by Day 7. PACAP was colocalized with NEUronal Nuclei (NeuN), PAC1, and CGRP in both trigeminal ganglion and the trigeminal nucleus caudalis. Our results demonstrate that the repetitive electrical stimulation model can simulate the allodynia during the migraine chronification, and PACAP plays a role in the pathogenesis of migraine potentially via PAC1 receptor.

Cerebral hemodynamics in the different phases of migraine and cluster headache

Headache is one of the most common ailments; migraine is one of the most prevalent and disabling neurological disorders and cluster headache presents as one of the most excruciating pain disorders. Both are complex disorder characterized by recurrent episodes of headache. A key feature is that various triggers can set off an attack providing the opportunity to explore disease mechanisms by experimentally inducing attacks. This review summarizes neuroimaging and hemodynamic studies in human in provoked and spontaneous attacks of migraine and cluster headache. Cerebral hemodynamics during different phases of the migraine attack demonstrate alterations in cerebral blood flow and perfusion, vessel caliber, cortical and sub-cortical function, underscoring that migraine pathophysiology is highly complex. Migraine attacks might begin in diencephalic and brainstem areas, whereas migraine aura is a cortical phenomenon. In cluster headache pathophysiology, the hypothalamus might also play a pivotal role, whereas the pattern of cerebral blood flood differs from migraine. For both disorders, alterations of arterial blood vessel diameter might be more an epiphenomenon of the attack than a causative trigger. Studying cerebral hemodynamics in provocation models are important in the search for specific biomarkers in the hope to discover future targets for more specific and effective mechanism-based anti-headache treatment.

A prospective study of headache and neuropeptides in patients with pituitary adenomas

OBJECTIVE

To evaluate clinical criteria for headache associated with pituitary adenoma (HaPA) in the International Classification of Headache Disorders (ICHD) 3rd edition version criteria and further determine whether elevations of plasma calcitonin gene-related peptide and pituitary adenylate cyclase-activating peptide 1-38 (PACAP1-38) concentration contribute to HaPA.

METHODS

Demographic and clinical features of consecutive patients with pituitary adenoma were recorded. Plasma calcitonin gene-related peptide and PACAP1-38 concentrations in pituitary adenoma patients within 72 h pre- and post-operation were measured. Primary outcome for HaPA patients were 50% reduction of moderate-to-severe headache days at 3 months after discharge.

RESULTS

Sixty-three patients with pituitary adenoma were recruited, 33 (52.4%) of whom had headache. The patients who had HaPA presented with migraine-like (32.9%), tension-type-like (12.1%), and stabbing headache (9.1%). Non-functional adenoma was present in the majority of cases (82.5%). Surgical resection improved headache in 83.3% of cases at 3 month follow-up. Pre- and post-operative calcitonin gene-related peptide and PACAP1-38 levels were significantly higher in patients with headache than in those without headache (p < 0.05). Plasma calcitonin gene-related peptide and PACAP1-38 levels at 72 h post-operation were lower at 72 h after operation in patients who had greater improvement in headache compared with those who had little improvement, while plasma calcitonin gene-related peptide and PACAP1-38 levels were similar between these two groups preoperatively.

CONCLUSIONS

Most pituitary adenoma patients have non-functional adenoma, and half of this group have HaPA, indicating that the ICHD-3 criteria for HaPA with the emphasis on secretion status need further modifications. Lower plasma calcitonin gene-related peptide and PACAP1-38 concentrations at 72 h after operation may predict a better outcome in patients with HaPA.

CGRP-based Migraine Therapeutics: How Might They Work, Why So Safe, and What Next?

Migraine is a debilitating neurological condition that involves the neuropeptide calcitonin gene-related peptide (CGRP). An exciting development is the recent FDA approval of the first in an emerging class of CGRP-targeted drugs designed to prevent migraine. Yet despite this efficacy, there are some fundamental unanswered questions, such as where and how CGRP works in migraine. Preclinical data suggest that CGRP acts via both peripheral and central mechanisms. The relevance of peripheral sites is highlighted by the clinical efficacy of CGRP-blocking antibodies, even though they do not appreciably cross the blood-brain barrier. The most likely sites of action are within the dura and trigeminal ganglia. Furthermore, it would be foolish to ignore perivascular actions in the dura since CGRP is the most potent vasodilatory peptide. Ultimately, the consequence of blocking CGRP or its receptor is reduced peripheral neural sensitization. Underlying their efficacy is the question of why the antibodies have such an excellent safety profile so far. This may be due to the presence of a second CGRP receptor and vesicular release of a large bolus of peptides. Finally, despite the promise of these drugs, there are unmet gaps because they do not work for all patients; so what next? We can expect advances on several fronts, including CGRP receptor structures that may help development of centrally-acting antagonists, combinatorial treatments that integrate other therapies, and development of drugs that target other neuropeptides. This is truly an exciting time for CGRP and the migraine field with many more discoveries on the horizon.

Pharmacologic Characterization of ALD1910, a Potent Humanized Monoclonal Antibody against the Pituitary Adenylate Cyclase-Activating Peptide

Migraine is a debilitating disease that affects almost 15% of the population worldwide and is the first cause of disability in people under 50 years of age, yet its etiology and pathophysiology remain incompletely understood. Recently, small molecules and therapeutic antibodies that block the calcitonin gene-related peptide (CGRP) signaling pathway have reduced migraine occurrence and aborted acute attacks of migraine in clinical trials and provided prevention in patients with episodic and chronic migraine. Heterogeneity is present within each diagnosis and patient's response to treatment, suggesting migraine as a final common pathway potentially activated by multiple mechanisms, e.g., not all migraine attacks respond to or are prevented by anti-CGRP pharmacological interventions. Consequently, other unique mechanisms central to migraine pathogenesis may present new targets for drug development. Pituitary adenylate cyclase-activating peptide (PACAP) is an attractive novel target for treatment of migraines. We generated a specific, high-affinity, neutralizing monoclonal antibody (ALD1910) with reactivity to both PACAP38 and PACAP27. In vitro, ALD1910 effectively antagonizes PACAP38 signaling through the pituitary adenylate cyclase-activating peptide type I receptor, vasoactive intestinal peptide receptor 1, and vasoactive intestinal peptide receptor 2. ALD1910 recognizes a nonlinear epitope within PACAP and blocks its binding to the cell surface. To test ALD1910 antagonistic properties directed against endogenous PACAP, we developed an umbellulone-induced rat model of neurogenic vasodilation and parasympathetic lacrimation. In vivo, this model demonstrates that the antagonistic activity of ALD1910 is dose-dependent, retaining efficacy at doses as low as 0.3 mg/kg. These results indicate that ALD1910 represents a potential therapeutic antibody to address PACAP-mediated migraine.

Antagonism of Cannabinoid Receptor 1 Attenuates the Anti-Inflammatory Effects of Electroacupuncture in a Rodent Model of Migraine

Background

The anti-nociceptive effects of electroacupuncture (EA) in migraine have been documented in multiple randomised controlled trials. Neurogenic inflammation plays a key role in migraine attacks, and the anti-inflammatory effects of acupuncture have been associated with the type 1 cannabinoid (CB1) receptor.

Objective

To investigate whether CB1 receptors mediate the anti-inflammatory effects of EA on migraine attacks.

Methods

A migraine model was produced in Sprague-Dawley rats by unilateral electrical stimulation of the trigeminal ganglion (TGES). Rats received EA daily on the 5 days preceding TGES with (TGES+EA+SR141716 group) or without (TGES+EA group) intraperitoneal injections of the CB1 receptor antagonist SR141716. Another group of TGES rats (TGES+MA group) and a non-TGES sham-operated group of rats (Sham+MA group) received minimal acupuncture (MA). Calcitonin gene-related peptide (CGRP) and prostaglandin E2 (PGE2) concentrations were determined in serum obtained from the ipsilateral jugular vein at initiation of TGES and 5 min after. Postmortem interleukin (IL)-1β and cyclooxygenase (COX)2 protein levels in the trigeminal ganglion (TG) and plasma protein extravasation (PPE) in the dura mater were assessed.

Results

TGES induced increases in serum CGRP and PGE2 levels (TGES+MA vs baseline and vs Sham: all p<0.001), as well as IL-1β and COX2 protein expression in the TG, and neurogenic PPE levels (TGES+MA vs Sham+MA: all p<0.001). EA attenuated TGES-induced increases in the levels of these proteins (TGES+EA vs TGES+MA: all p<0.001). CB1 receptor antagonism reversed the effects of EA (TGES+EA+SR141716 vs TGES+EA: all p<0.05).

Conclusions

CB1 receptors appear to mediate anti-inflammatory effects of EA in a rat model of migraine.

An Intraperitoneal Treatment with Calcitonin Gene-Related Peptide (CGRP) Regulates Appetite, Energy Intake/Expenditure, and Metabolism

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide expressed both centrally and peripherally. CGRP has been shown to be involved in arteriolar dilation, cardiovascular regulation, pain transmission, migraine, and gastrointestinal physiology. Our current research is aimed at analyzing CGRP's impact on appetite/satiety, body metabolism, and energy homeostasis. Our study investigated the effects of a single-dose intraperitoneal (IP) treatment with CGRP on food and water consumption, energy expenditure, physical activity, respirometry, and a panel of plasma metabolic hormones in C57Bl/6 wild-type (WT) mice. After a CGRP IP injection at a dose of 2 nmol (10 μM CGRP in 200 μl of saline), a significant reduction in food intake and metabolic parameters as RQ, VCO₂, and VO₂ was observed. CGRP-injected mice had also significantly lower total energy expenditure (TEE) with no changes in activity levels compared to vehicle-injected controls. CGRP treatment in mice induced significantly lower plasma levels of glucagon and leptin but higher levels of amylin. Our data show that a single dose of CGRP peptide significantly decreased food consumption and altered calorimetric parameters and plasma metabolic hormone levels, thus confirming that CGRP plays a pivotal role in the regulation of appetite and metabolism. Future studies are necessary to analyze CGRP's long-term impact on body metabolism and its potential effects on appetite, obesity, and metabolic disorders.

Serum Vitamin D Status in a Group of Migraine Patients Compared With Healthy Controls: A Case-Control Study

OBJECTIVE

The association between serum vitamin D and migraine is investigated in this research.s BACKGROUND: Although the pathogenesis of migraine headache is not fully understood, the possible role of inflammation and disturbed immune system has been proposed; thus, higher levels of vitamin D might reduce the risk of migraine. However, the results of related studies have been inconclusive.

METHODS

Seventy healthy individuals and 70 age- and sex-matched migraineurs (34 chronic and 36 episodic migraineurs), diagnosed according to the International Headache Society criteria (ICHD-IIIβ), were recruited. After obtaining baseline data and assessing migraine disability, a 30-day headache diary was given to the participants. Blood samples were obtained and 25(OH)D serum concentrations were determined using ELISA techniques. Serum 25(OH)D under 20, 20-29, and 30-100 ng/mL were considered deficient, insufficient, and sufficient, respectively. The applied statistical tests for between-group comparisons include independent-sample t-test, chi-square, and analysis of variance. Multiple regression analysis was also performed to identify the possible risk factors of migraine headache.

RESULTS

Migraine patients had significantly lower mean (SD) of serum VitD (30 (16) ng/mL) than healthy subjects (43 (19) ng/mL) (P < .001). The number (%) of subjects with VitD deficiency and insufficiency was significantly higher among the migraineurs (36 (53.7%)) than the controls (18 (26.1%)) (P < .0001). A significant negative association between migraine headache and serum VitD was detected in the fully adjusted multiple regression models when comparing the third and the highest serum 25(OH)D quartiles with the lowest (OR = 0.20; 95% CI = 0.05-0.77; OR = 0.17; 95% CI = 0.04-0.64, respectively, P for trend = .009). For each 5 ng/mL increase in serum 25(OH)D, there was a 22% odds decrease in the odds of migraine (OR = 0.78; 95% CI = 0.68-0.90; P = .001).

CONCLUSION

We have found that a higher level of serum VitD (between 50 to less than 100 ng/mL) among a sample of the Iranian population is associated with 80-83% lower odds of migraine headache than those with serum 25(OH)D levels below 20 ng/mL. However, there is a need for well-designed clinical trials to investigate beneficial effects of increased serum 25(OH)D on lower risk of migraine.

Comorbidity of Migraine and Epilepsy in Pediatrics: A Review

Migraine and epilepsy are classified as chronic paroxysmal neurologic disorders sharing many clinical features, as well as possible treatment options. This review highlights the similarities between migraine and epilepsy in pediatrics, focusing on epidemiologic, pathophysiological, genetic, clinical, and pharmacologic aspects. Despite the fact that several syndromes share symptoms of both migraine and epilepsy, further research is needed to clarify the pathophysiological and genetic basis of their comorbidity. Drugs used for prophylactic therapy of migraine and epilepsy have similar pharmacologic properties. The role of epileptic pharmacotherapy in the prophylaxis of migraine is assessed, including the use of conventional antiepileptic drugs, calcium channel blockers, and nonpharmacologic methods such as dietary therapy, supplements, and vagal nerve stimulation. Further randomized, controlled clinical trials assessing pharmacologic and nonpharmacologic methods for the treatment of both disorders are essential, in order to initiate new therapeutic approaches.

The efficacy and safety of calcitonin gene-related peptide monoclonal antibody for episodic migraine: a meta-analysis

OBJECTIVE

This meta-analysis was performed to evaluate the efficacy and safety of monoclonal antibodies against calcitonin gene-related peptide (CGRP) for episodic migraine prevention.

METHODS

MEDLINE, EMBASE, Web of Science, and the Cochrane Library were searched from inception to April 2018. Studies considered to be eligible were randomized controlled trials about efficacy and safety of calcitonin gene-related peptide monoclonal antibody for episodic migraine prevention.

RESULTS

Eight randomized controlled trials involving 2292 patients were included. The outcomes of this meta-analysis presented that CGRP monoclonal antibodies for preventive treatment of episodic migraine significantly reduced the monthly migraine days from baseline [weighted mean difference (WMD) = - 1.52; 95%CI, - 1.92 to - 1.11; Z = 7.40; P < 0.001] and monthly acute migraine-specific medication consumption from baseline [WMD = - 1.45; 95%CI, - 2.17 to - 0.72; Z = 3.93; P < 0.001], as compared with placebo group. CGRP monoclonal antibodies for preventive treatment of episodic migraine significantly increased the ≥ 50% reduction from baseline in migraine days per month [RR = 1.54; 95%CI, 1.38 to1.71; Z = 7.88; P < 0.001]. The adverse events were similar between the CGRP monoclonal antibody group and placebo group (P = 0.998). The outcomes of subgroup analysis showed that erenumab, galcanezumab, and fremanezumab significantly reduced the monthly migraine days from baseline and increased the ≥ 50% reduction from baseline in migraine days per month. Both erenumab and fremanezumab significantly reduced from baseline.

CONCLUSIONS

Based on the results of this meta-analysis, CGRP monoclonal antibodies significantly reduced the monthly migraine days and acute migraine-specific medication. CGRP monoclonal antibodies were effective and safe for preventive treatment of episodic migraine.

Endothelial nitric oxide synthase (-786T>C) polymorphism and migraine susceptibility: A meta-analysis

BACKGROUND

The aim of this study was to evaluate the correlation between endothelial nitric oxide synthase (eNOS) polymorphism (-786T>C) and migraine susceptibility in a meta-analysis.

METHODS

A literature search was performed for case-control studies from inception to July 30, 2018 focusing on eNOS polymorphism (-786T>C) and risk of migraine. From 454 full-text articles, 6 were included in this study. Heterogeneity was assessed with the I index and quality assessment was performed using the Newcastle-Ottawa scale.

RESULTS

CC genotype was not related to higher susceptibility of migraine compared with TT+ TC genotypes with significant difference (fixed effects model; OR = 1.27; 95% CI = 0.90-1.80; P = .17; I = 18%). However, subgroup analysis showed CC variant increase the risk for migraine compared with TT+ TC genotypes in Caucasian populations (fixed effects model; OR = 1.62; 95% CI = 1.03-2.56; P = .04; I = 18%), which could not be observed in non-Caucasian populations (fixed effects model; OR = 0.88; 95% CI = 0.51-1.53; P = .66; I = 0%). There was no significant difference for other genotypes and alleles between patients with migraine and healthy controls (all P > .05).

CONCLUSION

This meta-analysis indicated that CC variant increases the risk for migraine compared with TT + TC genotypes in Caucasian populations.

Vascular Contributions to Migraine: Time to Revisit?

Migraine is one of the most prevalent and disabling neurovascular disorders worldwide. However, despite the increase in awareness and research, the understanding of migraine pathophysiology and treatment options remain limited. For centuries, migraine was considered to be a vascular disorder. In fact, the throbbing, pulsating quality of the headache is thought to be caused by mechanical changes in vessels. Moreover, the most successful migraine treatments act on the vasculature and induction of migraine can be accomplished with vasoactive agents. However, over the past 20 years, the emphasis has shifted to the neural imbalances associated with migraine, and vascular changes have generally been viewed as an epiphenomenon that is neither sufficient nor necessary to induce migraine. With the clinical success of peripherally-acting antibodies that target calcitonin gene-related peptide (CGRP) and its receptor for preventing migraine, this neurocentric view warrants a critical re-evaluation. This review will highlight the likely importance of the vasculature in migraine.

Drosophila CaV2 channels harboring human migraine mutations cause synapse hyperexcitability that can be suppressed by inhibition of a Ca2+ store release pathway

Gain-of-function mutations in the human CaV2.1 gene CACNA1A cause familial hemiplegic migraine type 1 (FHM1). To characterize cellular problems potentially triggered by CaV2.1 gains of function, we engineered mutations encoding FHM1 amino-acid substitutions S218L (SL) and R192Q (RQ) into transgenes of Drosophila melanogaster CaV2/cacophony. We expressed the transgenes pan-neuronally. Phenotypes were mild for RQ-expressing animals. By contrast, single mutant SL- and complex allele RQ,SL-expressing animals showed overt phenotypes, including sharply decreased viability. By electrophysiology, SL- and RQ,SL-expressing neuromuscular junctions (NMJs) exhibited enhanced evoked discharges, supernumerary discharges, and an increase in the amplitudes and frequencies of spontaneous events. Some spontaneous events were gigantic (10-40 mV), multi-quantal events. Gigantic spontaneous events were eliminated by application of TTX-or by lowered or chelated Ca2+-suggesting that gigantic events were elicited by spontaneous nerve firing. A follow-up genetic approach revealed that some neuronal hyperexcitability phenotypes were reversed after knockdown or mutation of Drosophila homologs of phospholipase Cβ (PLCβ), IP3 receptor, or ryanodine receptor (RyR)-all factors known to mediate Ca2+ release from intracellular stores. Pharmacological inhibitors of intracellular Ca2+ store release produced similar effects. Interestingly, however, the decreased viability phenotype was not reversed by genetic impairment of intracellular Ca2+ release factors. On a cellular level, our data suggest inhibition of signaling that triggers intracellular Ca2+ release could counteract hyperexcitability induced by gains of CaV2.1 function.

Calcitonin-gene related peptide is a potent inducer of oedema in rat orofacial tissue

BACKGROUND AND AIMS

This study aimed to assess the potential of calcitonin-gene related peptide (CGRP), a neuropeptide released from sensory nerves, to induce oedema in orofacial tissue.

EXPERIMENTAL APPROACH

Wistar rats (150-200 g) anesthetized with isoflurane were injected intraorally with CGRP (100 μl; 8-33 pmol) in the right side of the mouth. The contralateral side was injected with the same volume of physiological saline. Increased cheek thickness (in mm), as a measure of oedema formation, was assayed bilaterally with a digital caliper before (T = 0) and up to 24 h following injection of CGRP. Pretreatment with antagonists (CGRP_8-37, 10 nmol; pizotifen, 2 mg/kg) was given by intra-oral or subcutaneous injection, 10 or 30 min, respectively, before the inflammatory stimulus. CGRP and CGRP_8-37 were also injected into the rat hind paw to induce oedema. Data are presented as the mean (±SEM) difference in thickness between the right and the left sides at each time.

RESULTS

Following intra-oral injection, CGRP induced a rapidly developing (5-15 min) and long-lasting (6 h), dose-dependent oedema in the rat cheek, blocked by pre-treatment with CGRP_8-37 or pizotifen. CGRP induced a smaller oedematogenic effect in the rat hind paw also blocked by the CGRP antagonist. CGRP (16 pmol) potentiated the oedema induced by co-injected substance P (3.7 nmol) and contributed to the oedema following intraoral injection of carrageenan (100 μg). Injection of CGRP_8-37 alone induced an early but short-lasting oedema.

CONCLUSION

Local injection of CGRP potently induced oedema in the orofacial tissue of rats which was blocked by a CGRP receptor antagonist. The overall inhibition of carrageenan-induced oedema by CGRP_8-37 suggests that endogenous CGRP contributes to an oedematogenic response in orofacial tissues.