Calcitonin gene-related peptide and its role in migraine pathophysiology

Assessment of pharmacokinetic and pharmacodynamic interactions between zavegepant and sumatriptan: A phase 1, randomized, placebo-controlled study in healthy adults

OBJECTIVE

To evaluate the pharmacodynamic (PD) and pharmacokinetic (PK) interactions between zavegepant and sumatriptan in healthy adults.

BACKGROUND

Zavegepant is a high-affinity, selective, small-molecule calcitonin gene-related peptide receptor antagonist administered as a nasal spray approved in the United States for the acute treatment of migraine. Triptans, including sumatriptan, are a different class of drugs for acute migraine treatment and are associated with a risk of increased blood pressure (BP). Hence, it is important to study the drug-drug interactions between zavegepant and sumatriptan due to potential coadministration in clinical settings.

METHODS

This was a Phase 1, single-center, partially blind, randomized, placebo-controlled, single-arm study. Eligible participants were males aged ≥ 18 and ≤ 40 years or females aged ≥ 18 and ≤ 50 years. On Day 1, participants received sumatriptan 2 × 6 mg subcutaneous injections (1 h apart) and were then randomized (6:1 ratio) to receive zavegepant 2 × 10 mg nasal spray (1 in each nostril) or placebo on Days 2 and 3. On Day 4, zavegepant or placebo was coadministered with sumatriptan after the second sumatriptan injection. BP, PK, and safety were evaluated at pre-specified time points.

RESULTS

Forty-two participants enrolled in the study received at least one dose of any treatment and were included in the safety analyses. Forty-one participants who completed the study were included in the BP and PK analyses. The mean (standard deviation) time-weighted average (TWA) of mean arterial pressure (MAP [sumatriptan + zavegepant 87.2 (6.8) vs. sumatriptan 86.9 (6.0)]), diastolic BP (DBP [sumatriptan + zavegepant 72.3 (6.8) vs. sumatriptan 72.1 (6.2)]), and systolic BP (SBP [sumatriptan + zavegepant 116.8 (10.2) vs. sumatriptan 116.2 (8.6)]) did not change following zavegepant and sumatriptan coadministration on Day 4 compared to sumatriptan alone on Day 1. Statistical comparisons of the TWA of MAP, DBP, and SBP between sumatriptan and zavegepant coadministration and sumatriptan alone were similar; the differences observed were 0.04 mmHg for MAP (90% confidence interval [CI]: -0.69, 0.77 mmHg), 0.00 mmHg for DBP (90% CI: -0.76, 0.76 mmHg), and 0.33 mmHg for SBP (90% CI: -0.97, 1.63 mmHg). Sumatriptan PK after sumatriptan and zavegepant coadministration versus sumatriptan alone was similar; the comparison ratios were 102.5% (90% CI: 100.7%, 104.2%) for AUC0-inf and 104.1% (90% CI: 98.0%, 110.6%) for Cmax. A small difference in zavegepant PK exposure after sumatriptan and zavegepant coadministration versus zavegepant alone was not considered clinically relevant: the comparison ratios were 112.4% (90% CI: 103.4%, 122.3%) for AUC0-24 and 96.7% (90% CI: 88.9%, 105.2%) for Cmax. Overall, 90% (38/42) of participants experienced ≥ 1 treatment-emergent adverse event that was mild or moderate in severity. All treatments were generally safe and well tolerated.

CONCLUSION

Coadministration of zavegepant with sumatriptan was safe and without PD or PK interactions in healthy adults.

Real-World Evidence of the Safety and Effectiveness of Atogepant Added to OnabotulinumtoxinA for the Preventive Treatment of Chronic Migraine: A Retrospective Chart Review

INTRODUCTION

Combination use of atogepant and onabotulinumtoxinA has the potential to be more effective than either alone for the preventive treatment of chronic migraine (CM) due to their complementary mechanisms of action. This analysis collected real-world data to evaluate the safety, tolerability, and effectiveness of adding atogepant to onabotulinumtoxinA as a combination preventive treatment for CM.

METHODS

This retrospective, longitudinal, multicenter chart review included adults with CM who received ≥ 2 consecutive cycles of onabotulinumtoxinA before ≥ 1 month of onabotulinumtoxinA and atogepant combination treatment. Charts at atogepant prescription (index date) and two subsequent onabotulinumtoxinA treatment visits (~ 3 and ~ 6 months post-index) were reviewed for change from baseline in monthly headache days (MHDs), ≥ 50% reduction in MHDs, discontinuation rates, and adverse events (AEs).

RESULTS

Of the 55 charts that met safety analysis criteria, 31 had data on headache days at index and first post-index visit and were eligible for effectiveness analysis (mean age 46.7 years, 94.5% female). For those with data available prior to onabotulinumtoxinA treatment (n = 25), the mean MHD was 24.0 days, reduced by 8.15 days after onabotulinumtoxinA treatment. After atogepant was added, MHD was incrementally reduced by 4.53 days and 8.75 days from index date to the first (N = 31) and second (N = 23) post-index onabotulinumtoxinA treatment visit, respectively. A ≥ 50% reduction in MHDs was achieved by 45.2% of patients ~ 3 months post-index. Atogepant and onabotulinumtoxinA were discontinued by 16.1% and 6.5% of patients, respectively. In the safety population, 32.7% of patients experienced ≥ 1 AE. No serious AEs were reported.

CONCLUSIONS

This real-world study of patients with CM demonstrated that adding atogepant to onabotulinumtoxinA as a combination preventive treatment for CM was effective by providing an additional reduction in MHDs over ~ 3 and ~ 6 months of combination treatment. Safety results were consistent with the known safety profiles of onabotulinumtoxinA and atogepant, with no new safety signals identified.

The evolving landscape and research trend of calcitonin gene-related peptide in migraine: A bibliometric analysis and visualization

Background

Migraine is a global public health concern, affecting both social and individual well-being. Calcitonin gene-related peptide (CGRP), a crucial neuropeptide, holds important research value in understanding migraine pathogenesis. CGRP receptor antagonists and monoclonal antibodies that target CGRP or its receptors have shown efficacy in reducing migraine frequency and severity, presenting a promising therapeutic approach. This study aimed to conduct a comprehensive bibliometric analysis to analyze the current state, research trends, and future directions of CGRP in migraine.

Methods

Bibliometric tools including CiteSpace, VOSviewer, etc., were utilized to extract and summarize publications related to CGRP in migraine from the Web of Science Core Collection Database (WOSCC) between 2004 and 2023, as of December 31, 2023. The analysis focused on trends in annual publications, leading countries/regions and institutions, prominent journals and references, influential authors, and high-frequency keywords in the field.

Results

A total of 1,821 articles and reviews involving 5,180 authors from 1,315 organizations across 64 countries were included in the study. These publications were distributed across 362 journals and accumulated 56,999 citations by December 31, 2023. An increasing trend was observed in annual publications on CGRP in migraine. The United States emerged as the leading nation in both publications and citations, with academic Peter Goadsby contributing the highest number of publications. The University of Copenhagen stood out as the institution with the most publications, and Cephalalgia emerged as the most influential journal. The most cited paper identified was "Calcitonin gene-related peptide receptor antagonist BIBN4096BS for the acute treatment of migraine" by Jes Olesen, published in the New Engl Med. Keyword frequency analysis revealed prevalent terms such as "migraine," "CGRP," and "episodic migraine," along with emerging topics represented by keywords including "trial," "monoclonal antibodies," "preventive treatment," and "safety."

Conclusion

CGRP is pivotal in migraine pathogenesis, and there is a robust research foundation exploring its role. The US leads in research output on CGRP in migraine. Investigating the mechanism of CGRP and its receptor in migraine remains a key area of interest, particularly focusing on signaling pathways. Future research should target identifying critical therapeutic targets in CGRP antagonist pathways for migraine treatment.

A Drug-Drug Interaction Study to Evaluate the Impact of Rimegepant on OCT2- and MATE1-Mediated Transport of Metformin in Healthy Participants

Rimegepant is a calcitonin gene-related peptide receptor antagonist approved for migraine treatment. This phase 1, open-label, single-center, fixed-sequence study evaluated the effect of rimegepant on the pharmacokinetics (PK) of metformin. Twenty-eight healthy participants received metformin 500 mg twice daily from Days 1 to 4 and Days 7 to 10, and once daily on Days 5 and 11. Rimegepant, 75 mg tablet, was administered once daily from Days 9 to 12. At pre-specified time points, plasma metformin concentration, serum glucose levels, and safety and tolerability were evaluated. A 16% increase in the area under the plasma metformin concentration-time curve (AUC) for 1 dosing interval (AUC0-τ,ss), a statistically insignificant increase in maximum and minimum steady-state metformin concentration (Cmax,ss and Cmin,ss), and a decrease in metformin renal clearance were observed on Day 11 following metformin-rimegepant coadministration compared with metformin alone; however, the changes were not clinically relevant. Additionally, coadministration of rimegepant with metformin did not induce clinically meaningful change in the maximum observed glucose concentration (Gmax) or AUCgluc compared with metformin alone. Overall, rimegepant and metformin coadministration did not result in clinically relevant changes in metformin PK, renal clearance, or the antihyperglycemic effects of metformin. Rimegepant is considered safe for use with metformin.

The Anti-Calcitonin Gene-Related Peptide (Anti-CGRP) Antibody Fremanezumab Reduces Trigeminal Neurons Immunoreactive to CGRP and CGRP Receptor Components in Rats

Treatment with the anti-CGRP antibody fremanezumab is successful in the prevention of chronic and frequent episodic migraine. In preclinical rat experiments, fremanezumab has been shown to reduce calcitonin gene-related peptide (CGRP) release from trigeminal tissues and aversive behaviour to noxious facial stimuli, which are characteristic pathophysiological changes accompanying severe primary headaches. To further decipher the effects of fremanezumab that underlie these antinociceptive effects in rats, immunohistochemistry and ELISA techniques were used to analyse the content and concentration of CGRP in the trigeminal ganglion, as well as the ratio of trigeminal ganglion neurons which are immunoreactive to CGRP and CGRP receptor components, 1-10 days after subcutaneous injection of fremanezumab (30 mg/kg) compared to an isotype control antibody. After fremanezumab treatment, the fraction of trigeminal ganglion neurons which were immunoreactive to CGRP and the CGRP receptor components calcitonin receptor-like receptor (CLR) and receptor activity modifying protein 1 (RAMP1) was significantly lowered compared to the control. The content and concentration of CGRP in trigeminal ganglia were not significantly changed. A long-lasting reduction in CGRP receptors expressed in trigeminal afferents may contribute to the attenuation of CGRP signalling and antinociceptive effects of monoclonal anti-CGRP antibodies in rats.

Migraine drugs

According to recent studies, migraine affects more than 1 billion people worldwide, making it one of the world’s most prevalent diseases. Although this highly debilitating illness has been known since ancient times, the first therapeutic drugs to treat migraine, ergotamine (Gynergen) and dihydroergotamine (Dihydergot), did not appear on the market until 1921 and 1946, respectively. Both drugs originated from Sandoz, the world’s leading pharmaceutical company in ergot alkaloid research at the time. Historically, ergot alkaloids had been primarily used in obstetrics, but with methysergide (1-methyl-lysergic acid 1′-hydroxy-butyl-(2S)-amide), it became apparent that they also held some potential in migraine treatment. Methysergide was the first effective prophylactic drug developed specifically to prevent migraine attacks in 1959. On the basis of significantly improved knowledge of migraine pathophysiology and the discovery of serotonin and its receptors, Glaxo was able to launch sumatriptan in 1992. It was the first member from the class of triptans, which are selective 5-HT1B/1D receptor agonists. Recent innovations in acute and preventive migraine therapy include lasmiditan, a selective 5-HT1F receptor agonist from Eli Lilly, the gepants, which are calcitonin gene-related peptide (CGRP) receptor antagonists discovered at Merck & Co and BMS, and anti-CGRP/receptor monoclonal antibodies from Amgen, Pfizer, Eli Lilly, and others.

Graphical abstract

Pooled Analysis of Real-World Evidence Supports Anti-CGRP mAbs and OnabotulinumtoxinA Combined Trial in Chronic Migraine

OnabotulinumtoxinA, targeting the CGRP machinery, has been approved for the last two decades for chronic migraine prevention. The recently approved monoclonal antibodies (mAbs) directed towards the calcitonin gene-related peptide (CGRP) pathway open a new age for chronic migraine control. However, some 40% patients suffering from chronic migraine is still resistant to treatment. The aim of this work is to answer the following PICOS (participants intervention comparator outcome study design) question: Is there evidence of efficacy and safety of the combined administration of anti-CGRP mAbs and onabotulinumtoxinA in chronic migraine? A systematic review and meta-analysis [Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 recommendations] was made up to 19 April 2022. The results are encouraging: the combined treatment proved to afford ≥50% monthly headache days (MHDs)/frequency reduction respect to baseline in up to 58.8% of patients; in comparison, anti-CGRP mAbs reduce MHDs of 1.94 days from baseline and botulinum toxin of 1.86 days. Our study demonstrates for the first time that the combination therapy of onabotulinumtoxinA with anti-CGRP mAbs affords a reduction of 2.67 MHDs with respect to onabotulinumtoxinA alone, with moderate certainty of evidence. Adequately powered, good-quality studies are needed to confirm the response to combination therapy in terms of efficacy and safety. PROSPERO registration: CRD42022313640.

Synthesis of pyrimidine-containing alkaloids

This review deals with the synthesis of naturally occurring alkaloids containing partially or completely saturated pyrimidine nuclei. The interest in these compounds is associated with their structural diversity, high biological activity and toxicity. The review is divided into four parts, each of which describes a number of synthetic methodologies toward structurally different naturally occurring alkaloids containing saturated cyclic six-membered amidine, guanidine, aminal and urea (thiourea) moieties, respectively. The development of various synthetic strategies for the preparation of these compounds has remarkably increased during the past few decades. This is primarily due to the fact that some of these compounds are isolated only in limited quantities, which makes it practically impossible to study their full structural characteristics and biological activity.

[CGRP antibodies in migraine prophylaxis : The new standard in migraine treatment?]

Migraine is associated with a high individual level of suffering. Therefore, an effective preventive treatment is highly important. The spectrum of classical prophylactic drugs has now been expanded to include monoclonal antibodies against calcitonin gene-related peptide (CGRP) and its receptor. These antibodies have shown reliable efficacy compared to placebo and a rapid onset of action with a low rate of side effects and negligible interactions in pivotal studies. Recently, the efficacy of the antibody was shown in many studies even on drug-refractory migraine and migraine associated with medication overuse. Comprehensive head to head comparisons with previously established drugs and among the antibodies are not yet available; however, initial studies suggest better tolerability and efficacy compared to conventional drugs and other antibodies. The role of antibodies in established treatment cascades still needs to be clarified.

α-CGRP disrupts amylin fibrillization and regulates insulin secretion: implications on diabetes and migraine

Despite being relatively benign and not an indicative signature of toxicity, fibril formation and fibrillar structures continue to be key factors in assessing the structure-function relationship in protein aggregation diseases. The inability to capture molecular cross-talk among key players at the tissue level before fibril formation greatly accounts for the missing link toward the development of an efficacious therapeutic intervention for Type II diabetes mellitus (T2DM). We show that human α-calcitonin gene-related peptide (α-CGRP) remodeled amylin fibrillization. Furthermore, while CGRP and/or amylin monomers reduce the secretion of both mouse Ins1 and Ins2 proteins, CGRP oligomers have a reverse effect on Ins1. Genetically reduced Ins2, the orthologous version of human insulin, has been shown to enhance insulin sensitivity and extend the life-span in old female mice. Beyond the mechanistic insights, our data suggest that CGRP regulates insulin secretion and lowers the risk of T2DM. Our result rationalizes how migraine might be protective against T2DM. We envision the new paradigm of CGRP : amylin interactions as a pivotal aspect for T2DM diagnostics and therapeutics. Maintaining a low level of amylin while increasing the level of CGRP could become a viable approach toward T2DM prevention and treatment.

Mild systemic inflammation enhances response to OnabotulinumtoxinA in chronic migraineurs

The anti-inflammatory effect of OnabotulinumtoxinA (OnabotA) has been a matter of discussion for many years. In chronic migraine, however, increased pro-inflammatory state is associated with good response to OnabotA. We aimed to investigate whether a mild systemic inflammatory state elicited by a common oral infection (periodontitis) could enhance treatment response to OnabotA. In this study, we included 61 chronic migraineurs otherwise healthy treated with OnabotA of which 7 were poor responders and 54 good responders. Before receiving OnabotA therapy, all participants underwent a full-mouth periodontal examination and blood samples were collected to determine serum levels of calcitonin gene-related peptide (CGRP), interleukin 6 (IL-6), IL-10 and high sensitivity C-reactive protein (hs-CRP). Periodontitis was present in 70.4% of responders and 28.6% of non-responders (P = 0.042). Responders showed greater levels of inflammation than non-responders (IL-6: 15.3 ± 8.7 vs. 9.2 ± 4.7 ng/mL, P = 0.016; CGRP: 18.8 ± 7.6 vs. 13.0 ± 3.1 pg/mL, P = 0.002; and hs-CRP: 3.9 ± 6.6 vs. 0.9 ± 0.8 mg/L, P = 0.003). A linear positive correlation was found between the amount of periodontal tissue inflamed in the oral cavity and markers of inflammation (IL-6: r = 0.270, P = 0.035; CGRP: r = 0.325, P = 0.011; and hs-CRP: r = 0.370, P = 0.003). This report shows that in presence of elevated systemic inflammatory markers related to periodontitis, OnabotA seems to reduce migraine attacks. The changes of scheduled inflammatory parameters after treatment and subsequent assessment during an adequate period still need to be done.

CGRP in rat mesenteric artery and vein - receptor expression, CGRP presence and potential roles

CGRP is a potent dilator of arteries and despite rich perivascular CGRP immunoreactivity in both arteries and veins the role of CGRP in veins remains unknown. The aim of the current study was to compare perivascular CGRP immunoreactivity and expression of CGRP receptor mRNA and CGRP receptor immunoreactivity in rat mesenteric arteries and veins. Furthermore, potential vasomotor effects of CGRP were explored in veins. Immunohistochemical studies reproduced rich perivascular CGRP innervation in arteries and in veins. Further, the presence of mRNA encoding the CGRP receptor subunits, CLR and RAMP1, were demonstrated in both arteries and veins using qPCR. Before comparing the vasoactive effects of CGRP in arteries and veins, we aimed to identify an experimental setting where vasomotor responses could be detected. Therefore, a length-tension study was performed in artery and vein segments. Whereas the arteries showed the characteristic monophasic curve with an IC/IC₁₀₀ value of 0.9, surprisingly the veins showed a biphasic response with two corresponding IC/IC₁₀₀ values of 0.7 and 0.9, respectively. There was no significant difference between fresh and cultured vasculature segments. To investigate whether a potential tension-dependent CGRP-induced dilation of veins caused the decline between the two IC/IC₁₀₀ peaks, a second study was performed, with the CGRP receptor antagonist, BIBN4096BS (olcegepant) and the sensory nerve secretagogue, capsaicin. No significant vascular role of endogenous perivascular CGRP in mesenteric veins could be concluded, and a potential role of the rich perivascular CGRP and CGRP receptor abundancy in veins remains unknown.

Transcriptome analysis of the response provided by Lasiopodomys mandarinus to severe hypoxia includes enhancing DNA repair and damage prevention

Background

Severe hypoxia induces a series of stress responses in mammals; however, subterranean rodents have evolved several adaptation mechanisms of energy metabolisms and O₂ utilization for hypoxia. Mammalian brains show extreme aerobic metabolism. Following hypoxia exposure, mammals usually experience irreversible brain damage and can even develop serious diseases, such as hypoxic ischemic encephalopathy and brain edema. To investigate mechanisms underlying the responses of subterranean rodents to severe hypoxia, we performed a cross-species brain transcriptomic analysis using RNA sequencing and identified differentially expressed genes (DEGs) between the subterranean rodent Lasiopodomys mandarinus and its closely related aboveground species L. brandtii under severe hypoxia (5.0% O₂, 6 h) and normoxia (20.9% O₂, 6 h).

Results

We obtained 361 million clean reads, including 69,611 unigenes in L. mandarinus and 69,360 in L. brandtii. We identified 359 and 515 DEGs by comparing the hypoxic and normoxia groups of L. mandarinus and L. brandtii, respectively. Gene Ontology (GO) analysis showed that upregulated DEGs in both species displayed similar terms in response to severe hypoxia; the main difference is that GO terms of L. brandtii were enriched in the immune system. However, in the downregulated DEGs, GO terms of L. mandarinus were enriched in cell proliferation and protein transport and those of L. brandtii were enriched in nuclease and hydrolase activities, particularly in terms of developmental functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that upregulated DEGs in L. mandarinus were associated with DNA repair and damage prevention as well as angiogenesis and metastasis inhibition, whereas downregulated DEGs were associated with neuronal synaptic transmission and tumor-associated metabolic pathways. In L. brandtii, upregulated KEGG pathways were enriched in the immune, endocrine, and cardiovascular systems and particularly in cancer-related pathways, whereas downregulated DEGs were associated with environmental information processing and misregulation in cancers.

Conclusions

L. mandarinus has evolved hypoxia adaptation by enhancing DNA repair, damage prevention, and augmenting sensing, whereas L. brandtii showed a higher risk of tumorigenesis and promoted innate immunity toward severe hypoxia. These results reveal the hypoxic mechanisms of L. mandarinus to severe hypoxia, which may provide research clues for hypoxic diseases.

Botulinum Toxin a Valuable Prophylactic Agent for Migraines and a Possible Future Option for the Prevention of Hormonal Variations-Triggered Migraines

BACKGROUND

In 1989, Botulinum toxin (BoNT) was accepted by the FDA for the management of some ophthalmic disorders. Although it was initially considered a lethal toxin, in recent times, Botulinum toxin A (BoNT-A), which is the more used serotype, has expanded to cover different clinical conditions, primarily characterized by neuropathic pain, including migraines and headaches. Evidence suggests that migraines are influenced by hormonal factors, particularly by estrogen levels, but very few studies have investigated the prevalence and management strategies for migraines according to the hormonal status. The effects of several therapeutic regimens on migraines have been investigated, but the medications used varied widely in proven efficacies and mechanisms of action. BoNT-A is increasingly used in the management of migraine and several placebo-controlled trials of episodic and chronic migraine are currently underway. This paper is a review of the recently published data concerning the administration of BoNT-A in the prevention of chronic migraines. Considering the lack of population-based studies about the effectiveness of BoNT-A in the alleviation of premenstrual and perimenopausal migraines, this study proposes a new perspective of the therapeutic approach of migraine syndrome associated with menopausal transition and the premenstrual period.

METHODS

We selected the reviewed papers from CrossRef, PubMed, Medline, and GoogleScholar, and a total of 21 studies met our inclusion criteria.

RESULTS

To date, no specific preventive measures have been recommended for menopausal women with migraines. BoNT-A often reduces the frequency and intensity of migraine attacks per month; the treatment is well tolerated and does not exhibit a significantly higher rate of treatment-related side effects. No population-based studies were conducted in order to highlight the role of BoNT-A in menopause-related migraines, neither in menstrual migraines.

CONCLUSION

There is a need for further research in order to quantify the real burden of menstrual and perimenopausal migraines and to clarify if BoNT-A could be used in the treatment of refractory postmenopausal and premenstrual migraines.

The need for new acutely acting antimigraine drugs: moving safely outside acute medication overuse

Background

The treatment of migraine is impeded by several difficulties, among which insufficient headache relief, side effects, and risk for developing medication overuse headache (MOH). Thus, new acutely acting antimigraine drugs are currently being developed, among which the small molecule CGRP receptor antagonists, gepants, and the 5-HT_1F receptor agonist lasmiditan. Whether treatment with these drugs carries the same risk for developing MOH is currently unknown.

Main body

Pathophysiological studies on MOH in animal models have suggested that decreased 5-hydroxytryptamine (5-HT, serotonin) levels, increased calcitonin-gene related peptide (CGRP) expression and changes in 5-HT receptor expression (lower 5-HT_1B/D and higher 5-HT_2A expression) may be involved in MOH. The decreased 5-HT may increase cortical spreading depression frequency and induce central sensitization in the cerebral cortex and caudal nucleus of the trigeminal tract. Additionally, low concentrations of 5-HT, a feature often observed in MOH patients, could increase CGRP expression. This provides a possible link between the pathways of 5-HT and CGRP, targets of lasmiditan and gepants, respectively. Since lasmiditan is a 5-HT_1F receptor agonist and gepants are CGRP receptor antagonists, they could have different risks for developing MOH because of the different (over) compensation mechanisms following prolonged agonist versus antagonist treatment.

Conclusion

The acute treatment of migraine will certainly improve with the advent of two novel classes of drugs, i.e., the 5-HT_1F receptor agonists (lasmiditan) and the small molecule CGRP receptor antagonists (gepants). Data on the effects of 5-HT_1F receptor agonism in relation to MOH, as well as the effects of chronic CGRP receptor blockade, are awaited with interest.

Upregulation of calcitonin gene-related peptide, neuronal nitric oxide synthase, and phosphorylated extracellular signal-regulated kinase 1/2 in the trigeminal ganglion after bright light stimulation of the eye in rats

Bright light stimulation of the eye activates trigeminal subnucleus caudalis (Vc) neurons in rats. Sensory information is conveyed to the Vc via the trigeminal ganglion (TG). Thus, it is likely that TG neurons respond to photic stimulation and are involved in photic hypersensitivity. However, the mechanisms underlying this process are unclear. Therefore, the hypothesis in this study is bright light stimulation enhances the excitability of TG neurons involved in photic hypersensitivity. Expressions of calcitonin gene-related peptide (CGRP) and neuronal nitric oxide synthase (nNOS) were significantly higher in TG neurons from 5 min to 12 h after photic stimulation of the eye. Phosphorylation of extracellular signal-regulated kinase1/2 (pERK1/2) was enhanced in TG neurons within 5 min after photic stimulation, while pERK1/2 immunoreactivity in satellite glial cells (SGCs) persisted for more than 12 h after the stimulus. Activation of SGCs was observed from 5 min to 2 h. Expression of CGRP, nNOS, and pERK1/2 was observed in small and medium TG neurons, and activation of SGCs and pERK1/2-immunoreactive SGCs encircling large TG neurons was accelerated after stimulation. These results suggest that upregulation of CGRP, nNOS, and pERK1/2 within the TG is involved in photic hypersensitivity.

The association between migraine and physical exercise

BACKGROUND

There is an unmet need of pharmacological and non-pharmacological treatment options for migraine patients. Exercise can be used in the treatment of several pain conditions, including. However, what exact role exercise plays in migraine prevention is unclear. Here, we review the associations between physical exercise and migraine from an epidemiological, therapeutical and pathophysiological perspective.

METHODS

The review was based on a primary literature search on the PubMed using the search terms "migraine and exercise".

RESULTS

Low levels of physical exercise and high frequency of migraine has been reported in several large population-based studies. In experimental studies exercise has been reported as a trigger factor for migraine as well as migraine prophylaxis. Possible mechanisms for how exercise may trigger migraine attacks, include acute release of neuropeptides such as calcitonin gene-related peptide or alternation of hypocretin or lactate metabolism. Mechanisms for migraine prevention by exercise may include increased beta-endorphin, endocannabinoid and brain-derived neurotrophic factor levers in plasma after exercise.

CONCLUSION

In conclusion, it seems that although exercise can trigger migraine attacks, regular exercise may have prophylactic effect on migraine frequency. This is most likely due to an altered migraine triggering threshold in persons who exercise regularly. However, the frequency and intensity of exercise that is required is still an open question, which should be addressed in future studies to delineate an evidence-based exercise program to prevent migraine in sufferers.

General Pathways of Pain Sensation and the Major Neurotransmitters Involved in Pain Regulation

Pain has been considered as a concept of sensation that we feel as a reaction to the stimulus of our surrounding, putting us in harm's way and acting as a form of defense mechanism that our body has permanently installed into its system. However, pain leads to a huge chunk of finances within the healthcare system with continuous rehabilitation of patients with adverse pain sensations, which might reduce not only their quality of life but also their productivity at work setting back the pace of our economy. It may not look like a huge deal but factor in pain as an issue for majority of us, it becomes an economical burden. Although pain has been researched into and understood by numerous researches, from its definition, mechanism of action to its inhibition in hopes of finding an absolute solution for victims of pain, the pathways of pain sensation, neurotransmitters involved in producing such a sensation are not comprehensively reviewed. Therefore, this review article aims to put in place a thorough understanding of major pain conditions that we experience-nociceptive, inflammatory and physiologically dysfunction, such as neuropathic pain and its modulation and feedback systems. Moreover, the complete mechanism of conduction is compiled within this article, elucidating understandings from various researches and breakthroughs.

Stimulation of rat cranial dura mater with potassium chloride causes CGRP release into the cerebrospinal fluid and increases medullary blood flow

Primary headaches may be accompanied by increased intracranial blood flow induced by the release of the potent vasodilator calcitonin gene-related peptide (CGRP) from activated meningeal afferents. We aimed to record meningeal and medullary blood flow simultaneously and to localize the sites of CGRP release in rodent preparations in vivo and ex vivo. Blood flow in the exposed rat parietal dura mater and the medulla oblongata was recorded by laser Doppler flowmetry, while the dura was stimulated by topical application of 60mM potassium chloride (KCl). Samples of jugular venous plasma and cerebrospinal fluid (CSF) collected from the cisterna magna were analysed for CGRP concentrations using an enzyme immunoassay. In a hemisected rat skull preparation lined with dura mater the CGRP releasing effect of KCl superfusion was examined. Superfusion of the dura mater with KCl decreased meningeal blood flow unless alpha-adrenoceptors were blocked by phentolamine, whereas the medullary blood flow was increased. The same treatment caused increased CGRP concentrations in jugular plasma and CSF and induced significant CGRP release in the hemisected rat skull preparation. Anaesthesia of the trigeminal ganglion by injection of lidocaine reduced increases in medullary blood flow and CGRP concentration in the CSF upon meningeal KCl application. CGRP release evoked by depolarisation of meningeal afferents is accompanied by increased blood flow in the medulla oblongata but not the dura mater. This discrepancy can be explained by the smooth muscle depolarising effect of KCl and the activation of sympathetic vasoconstrictor mechanisms. The medullary blood flow response is most likely mediated by CGRP released from activated central terminals of trigeminal afferents. Increased blood supply of the medulla oblongata and CGRP release into the CSF may also occur in headaches accompanying vigorous activation of meningeal afferents.

Drosophila DH31 Neuropeptide and PDF Receptor Regulate Night-Onset Temperature Preference

Body temperature exhibits rhythmic fluctuations over a 24 h period (Refinetti and Menaker, 1992) and decreases during the night, which is associated with sleep initiation (Gilbert et al., 2004; Kräuchi, 2007a,b). However, the underlying mechanism of this temperature decrease is largely unknown. We have previously shown that Drosophila exhibit a daily temperature preference rhythm (TPR), in which their preferred temperatures increase during the daytime and then decrease at the transition from day to night (night-onset) (Kaneko et al., 2012). Because Drosophila are small ectotherms, their body temperature is very close to that of the ambient temperature (Stevenson, 1985), suggesting that their TPR generates their body temperature rhythm. Here, we demonstrate that the neuropeptide diuretic hormone 31 (DH31) and pigment-dispersing factor receptor (PDFR) contribute to regulate the preferred temperature decrease at night-onset. We show that PDFR and tethered-DH31 expression in dorsal neurons 2 (DN2s) restore the preferred temperature decrease at night-onset, suggesting that DH31 acts on PDFR in DN2s. Notably, we previously showed that the molecular clock in DN2s is important for TPR. Although PDF (another ligand of PDFR) is a critical factor for locomotor activity rhythms, Pdf mutants exhibit normal preferred temperature decreases at night-onset. This suggests that DH31-PDFR signaling specifically regulates a preferred temperature decrease at night-onset. Thus, we propose that night-onset TPR and locomotor activity rhythms are differentially controlled not only by clock neurons but also by neuropeptide signaling in the brain.

SIGNIFICANCE STATEMENT

Body temperature rhythm (BTR) is fundamental for the maintenance of functions essential for homeostasis, such as generating metabolic energy and sleep. One major unsolved question is how body temperature decreases dramatically during the night. Previously, we demonstrated that a BTR-like mechanism, referred to as temperature preference rhythm (TPR), exists in Drosophila Here, we demonstrate that the diuretic hormone 31 (DH31) neuropeptide and pigment-dispersing factor receptor (PDFR) regulate preferred temperature decreases at night-onset via dorsal neurons 2. This is the first in vivo evidence that DH31 could function as a ligand of PDFR. Although both DH31 and PDF are ligands of PDFR, we show that DH31 regulates night-onset TPR, but PDF does not, suggesting that night-onset TPR and locomotor activity rhythms are controlled by different neuropeptides via different clock cells.

Hyperoxia exposure disrupts adrenomedullin signaling in newborn mice: Implications for lung development in premature infants

Hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD), a chronic lung disease of human infants that is characterized by disrupted lung angiogenesis. Adrenomedullin (AM) is a multifunctional peptide with angiogenic and vasoprotective properties. AM signals via its cognate receptors, calcitonin receptor-like receptor (Calcrl) and receptor activity-modifying protein 2 (RAMP2). Whether hyperoxia affects the pulmonary AM signaling pathway in neonatal mice and whether AM promotes lung angiogenesis in human infants are unknown. Therefore, we tested the following hypotheses: (1) hyperoxia exposure will disrupt AM signaling during the lung development period in neonatal mice; and (2) AM will promote angiogenesis in fetal human pulmonary artery endothelial cells (HPAECs) via extracellular signal-regulated kinases (ERK) 1/2 activation. We initially determined AM, Calcrl, and RAMP2 mRNA levels in mouse lungs on postnatal days (PND) 3, 7, 14, and 28. Next we determined the mRNA expression of these genes in neonatal mice exposed to hyperoxia (70% O₂) for up to 14 d. Finally, using HPAECs, we evaluated if AM activates ERK1/2 and promotes tubule formation and cell migration. Lung AM, Calcrl, and RAMP2 mRNA expression increased from PND 3 and peaked at PND 14, a time period during which lung development occurs in mice. Interestingly, hyperoxia exposure blunted this peak expression in neonatal mice. In HPAECs, AM activated ERK1/2 and promoted tubule formation and cell migration. These findings support our hypotheses, emphasizing that AM signaling axis is a potential therapeutic target for human infants with BPD.

Migraine Modulation and Debut after Percutaneous Atrial Septal Defect Closure: A Review

INTRODUCTION

Change in migraine headache (MH)-preexisting MH change or development of de novo MH-are known potential complications following percutaneous closure of atrial septal defect (ASD), but consensus on a causal trigger remains elusive.

OBJECTIVES

To expose potential MH triggers linked, mainly by timing and occurrence, to the emergence of de novo MH or change in preexisting MH subsequent to percutaneous ASD closure (pASDC).

METHODS

The literature was systematically searched for studies available in English reporting MH status after pASDC published between January 1, 1990 and November 15, 2015. We determined the number and percentage of patients experiencing MH status change within 7 days post procedure and the cumulative total by final follow-up (Mdn = 12 months).

RESULTS

Twenty-five studies met the inclusion criteria, which accounted for a total of 1,646 pASDC patients. Pre-procedure MH prevalence was 8% (126/1,646). Change in preexisting MH occurred in a total of 72% (91/126), 12% (11/91) within 7-days after pASDC; within follow-up MH improved in 14% (18/126), resolved in 37% (47/126), but persisted in 63% (79/126). De novo MH incidence ranged between 10 (153/1,520) and 18.3% (153/836); 34% incipience (52/153) was within 7-days of pASDC; females accounted for 80% (63/79) of gender differentiated cases; of type distinguished cases, 42% (51/122) were MH without aura (MO) and 58% (71/122) were MH with aura (MA); MH improved in 10% (16/153), resolved in 24% (37/153) but persisted beyond final follow-up in 76% (116/153). Antiplatelet agents were effective modulators of MH in 44% (11/25) studies. Possible adverse MH-predisposing traits were scarce: larger ASD size reported in ~2% (39/1,646) of patients experiencing de novo MH or preexisting MH exacerbation; short aortic rim reported in three de novo MH patients; allergic response to occluder nickel alloy in four patients with MH status change from baseline (de novo or preexisting MH change not specified).

INTERPRETATION

Early intensification of MH status change but later amelioration (virtually paralleling stages of endothelialization), relatively high efficacy of antiplatelet agents, and the emergence of MA as the dominant de novo MH type favor proinflammatory triggers of MH status change after pASDC.

Copeptin for risk stratification in non-traumatic headache in the emergency setting: a prospective multicenter observational cohort study

BACKGROUND

In the emergency setting, non-traumatic headache is a benign symptom in 80% of cases, but serious underlying conditions need to be ruled out. Copeptin improves risk stratification in several acute diseases. Herein, we investigated the value of copeptin to discriminate between serious secondary headache and benign headache forms in the emergency setting.

METHODS

Patients presenting with acute non-traumatic headache were prospectively enrolled into an observational cohort study. Copeptin was measured upon presentation to the emergency department. Primary endpoint was serious secondary headache defined by a neurologic cause requiring immediate treatment of the underlying disease. Secondary endpoint was the combination of mortality and hospitalization within 3 months. Two board-certified neurologist blinded to copeptin levels verified the endpoints after a structured 3-month-telephone interview.

RESULTS

Of the 391 patients included, 75 (19%) had a serious secondary headache. Copeptin was associated with serious secondary headache (OR 2.03, 95%CI 1.52-2.70, p < 0.0001). Area under the curve (AUC) for copeptin to identify the primary endpoint was 0.70 (0.63-0.76). After adjusting for age > 50, focal-neurological abnormalities, and thunderclap onset of symptoms, copeptin remained an independent predictive factor for serious secondary headache (OR 1.74, 95%CI 1.26-2.39, p = 0.001). Moreover, copeptin improved the AUC of the multivariate logistic clinical model (p-LR-test < 0.001). Even though copeptin values were higher in patients reaching the secondary endpoint, this association was not significant in multivariate logistic regression.

CONCLUSIONS

Copeptin was independently associated with serious secondary headache as compared to benign headaches forms. Copeptin may be a promising novel blood biomarker that should be further validated to rule out serious secondary headache in the emergency department.

TRIAL REGISTRATION

Study Registration on 08/02/2010 as NCT01174901 at clinicaltrials.gov.

Heteroreceptors Modulating CGRP Release at Neurovascular Junction: Potential Therapeutic Implications on Some Vascular-Related Diseases

Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide belonging to the calcitonin gene peptide superfamily. CGRP is a potent vasodilator with potential therapeutic usefulness for treating vascular-related disease. This peptide is primarily located on C- and Aδ-fibers, which have extensive perivascular presence and a dual sensory-efferent function. Although CGRP has two major isoforms (α-CGRP and β-CGRP), the α-CGRP is the isoform related to vascular actions. Release of CGRP from afferent perivascular nerve terminals has been shown to result in vasodilatation, an effect mediated by at least one receptor (the CGRP receptor). This receptor is an atypical G-protein coupled receptor (GPCR) composed of three functional proteins: (i) the calcitonin receptor-like receptor (CRLR; a seven-transmembrane protein), (ii) the activity-modifying protein type 1 (RAMP1), and (iii) a receptor component protein (RCP). Although under physiological conditions, CGRP seems not to play an important role in vascular tone regulation, this peptide has been strongly related as a key player in migraine and other vascular-related disorders (e.g., hypertension and preeclampsia). The present review aims at providing an overview on the role of sensory fibers and CGRP release on the modulation of vascular tone.

[Pain-relieving effect of CGRP antagonism on inflammatory pain]

The neuropeptide calcitonin gene-related peptide (CGRP) is known to play a major role in the pathogenesis of pain syndromes, in particular migraine pain; however, its implication in inflammatory processes is not well known. The CGRP receptor antagonist BIBN4096BS was shown to reduce migraine pain and trigeminal neuronal activity. An analgesic action of this compound can also be found in rats with induced acute inflammation by injection of complete Freund's adjuvant (CFA) in one hindpaw. In this model the compound reduced inflammatory pain and spinal neuronal activity. Behavioral experiments (Randall-Selitto test) revealed a reversal of the CFA-induced mechanical hyperalgesia in rats after systemic drug administration. In vivo electrophysiological studies performed in rats injected with CFA using recordings of wide dynamic range neurons in deep dorsal horn layers of the lumbar spinal cord, confirmed a reduction of neuronal activity after systemic drug administration. The same considerable amount of reduction occurred after topical administration onto the paw with resulting systemic plasma concentrations in the low nanomolar range. Spinal administration of BIBN4096BS did not modify the neuronal activity in the CFA model which suggests that peripheral blockade of CGRP receptors by BIBN4096BS significantly alleviates inflammatory pain.

Migraine: A disorder of metabolism?

The treatment and prevention of migraine within the last decade has become largely pharmacological. While there is little doubt that the advent of drugs (e.g. triptans) has helped many migraine sufferers to lead a normal life, there is still little knowledge with respect to the factors responsible for precipitating a migraine attack. Evidence from biochemical and behavioural studies from a number of disciplines is integrated to put forward the proposal that migraine is part of a cascade of events, which together act to protect the organism when confronted by a metabolic challenge.

Intravital Microscopy on a Closed Cranial Window in Mice: A Model to Study Trigeminovascular Mechanisms Involved in Migraine

The purpose of the study was to develop a mouse model to study trigeminovascular mechanisms using intravital microscopy on a closed cranial window. In addition, we studied exogenous and endogenous calcitonin gene-related peptide (CGRP)-mediated vasodilation in dural arteries. Arteries in C57BL/6Jico mice were constricted with endothelin-1, which reduced the baseline diameter by 65-75%. Subsequently, vasodilation was induced by α-CGRP, capsaicin or transcranial electrical stimulation of perivascular trigeminal nerves in the absence or presence of different concentrations of BIBN4096BS or sumatriptan. Both α-CGRP and capsaicin induced vasodilation in preconstricted arteries. Transcranial electrical stimulation also induced current-dependent relaxation of dural arteries with 100 μA producing maximal dilation in the control group. BIBN4096BS blocked the responses evoked by ä-CGRP and capsaicin, as well as electrical stimulation, whereas sumatriptan attenuated only vasodilation induced by electrical stimulation. This model is likely to prove useful in dissecting elements of the trigeminovascular system and for exploring pathophysiological aspects of migraine, especially in future studies using transgenic mice with mutations relevant to those observed in patients with migraine.

Calcitonin gene-related peptide contributes to peripheral nerve injury-induced mechanical hypersensitivity through CCL5 and p38 pathways

The role of calcitonin gene related peptide (CGRP) in neuropathic pain was investigated in a mouse model of neuropathic pain, spinal nerve L5 transection (L5Tx). Intrathecal injection (i.t.) of CGRP8-37, a CGRP antagonist, significantly reduced L5Tx-induced mechanical hypersensitivity and lumbar spinal cord CCL5 expression. i.t. injection of a CCL5 neutralizing antibody significantly inhibited L5Tx-induced mechanical hypersensitivity. Further, pre-treatment with a p38-inhibitor, SB203580, was able to reduce CGRP-induced mechanical hypersensitivity, but not CGRP-induced CCL5 production. Our data indicate that CGRP can play its pro-nociceptive role through both a spinal cord CCL5-dependent, p38-independent pathway, and a p38-depenented, CCL5-independent pathway.

5-HT7 Receptors Are Not Involved in Neuropeptide Release in Primary Cultured Rat Trigeminal Ganglion Neurons

Migraine is a common but complex neurological disorder. Its precise mechanisms are not fully understood. Increasing indirect evidence indicates that 5-HT7 receptors may be involved; however, their role remains unknown. Our previous in vivo study showed that selective blockade of 5-HT7 receptors caused decreased serum levels of calcitonin gene-related peptide (CGRP) in the external jugular vein following electrical stimulation of the trigeminal ganglion (TG) in an animal model of migraine. In the present study, we used an in vitro model of cultured TG cells to further investigate whether 5-HT7 receptors are directly responsible for the release of CGRP and substance P from TG neurons. We stimulated rat primary cultured TG neurons with capsaicin or potassium chloride (KCl) to mimic neurogenic inflammation, resulting in release of CGRP and substance P. 5-HT7 receptors were abundantly expressed in TG neurons. Greater than 93 % of 5-HT7 receptor-positive neurons co-expressed CGRP and 56 % co-expressed substance P. Both the capsaicin- and KCl-induced release of CGRP and substance P were unaffected by pretreatment of cultured TG cells with the selective 5-HT7 receptor agonist AS19 and antagonist SB269970. This study demonstrates for the first time that 5-HT7 receptors are abundantly co-expressed with CGRP and substance P in rat primary TG neurons and suggests that they are not responsible for the release of CGRP and substance P from cultured TG neurons evoked by capsaicin or KCl.

Calcitonin Gene-Related Peptide-Exposed Endothelial Cells Bias Antigen Presentation to CD4+ T Cells toward a Th17 Response

Calcitonin gene-related peptide (CGRP) is a neuropeptide with well-established immunomodulatory functions. CGRP-containing nerves innervate dermal blood vessels and lymph nodes. We examined whether CGRP regulates the outcome of Ag presentation by Langerhans cells (LCs) to T cells through actions on microvascular endothelial cells (ECs). Exposure of primary murine dermal microvascular ECs (pDMECs) to CGRP followed by coculture with LCs, responsive CD4(+) T cells and Ag resulted in increased production of IL-6 and IL-17A accompanied by inhibition of IFN-γ, IL-4, and IL-22 compared with wells containing pDMECs treated with medium alone. Physical contact between ECs and LCs or T cells was not required for this effect and, except for IL-4, we demonstrated that IL-6 production by CGRP-treated pDMECs was involved in these effects. CD4(+) cells expressing cytoplasmic IL-17A were increased, whereas cells expressing cytoplasmic IFN-γ or IL-4 were decreased by the presence of CGRP-treated pDMECs. In addition, the level of retinoic acid receptor-related orphan receptor γt mRNA was significantly increased, whereas T-bet and GATA3 expression was inhibited. Immunization at the site of intradermally administered CGRP led to a similar bias in CD4(+) T cells from draining lymph node cells toward IL-17A and away from IFN-γ. Actions of nerve-derived CGRP on ECs may have important regulatory effects on the outcome of Ag presentation with consequences for the expression of inflammatory skin disorders involving Th17 cells.

Calcitonin Gene-Related Peptide Reduces Taste-Evoked ATP Secretion from Mouse Taste Buds

Immunoelectron microscopy revealed that peripheral afferent nerve fibers innervating taste buds contain calcitonin gene-related peptide (CGRP), which may be as an efferent transmitter released from peripheral axon terminals. In this report, we determined the targets of CGRP within taste buds and studied what effect CGRP exerts on taste bud function. We isolated mouse taste buds and taste cells, conducted functional imaging using Fura-2, and used cellular biosensors to monitor taste-evoked transmitter release. The findings showed that a subset of Presynaptic (Type III) taste cells (53%) responded to 0.1 μm CGRP with an increase in intracellular Ca(2+). In contrast, Receptor (Type II) taste cells rarely (4%) responded to 0.1 μm CGRP. Using pharmacological tools, the actions of CGRP were probed and elucidated by the CGRP receptor antagonist CGRP(8-37). We demonstrated that this effect of CGRP was dependent on phospholipase C activation and was prevented by the inhibitor U73122. Moreover, applying CGRP caused taste buds to secrete serotonin (5-HT), a Presynaptic (Type III) cell transmitter, but not ATP, a Receptor (Type II) cell transmitter. Further, our previous studies showed that 5-HT released from Presynaptic (Type III) cells provides negative paracrine feedback onto Receptor (Type II) cells by activating 5-HT1A receptors, and reducing ATP secretion. Our data showed that CGRP-evoked 5-HT release reduced taste-evoked ATP secretion. The findings are consistent with a role for CGRP as an inhibitory transmitter that shapes peripheral taste signals via serotonergic signaling during processing gustatory information in taste buds.

SIGNIFICANCE STATEMENT

The taste sensation is initiated with a highly complex set of interactions between a variety of cells located within the taste buds before signal propagation to the brain. Afferent signals from the oral cavity are carried to the brain in chemosensory fibers that contribute to chemesthesis, the general chemical sensitivity of the mucus membranes in the oronasal cavities and being perceived as pungency, irritation, or heat. This is a study of a fundamental question in neurobiology: how are signals processed in sensory end organs, taste buds? More specifically, taste-modifying interactions, via transmitters, between gustatory and chemosensory afferents inside taste buds will help explain how a coherent output is formed before being transmitted to the brain.

Analysis of Amyloid in Medullary Thyroid Carcinoma by Mass Spectrometry-Based Proteomic Analysis

Amyloid is a characteristic histologic feature in medullary thyroid carcinomas (MTC). We utilized a novel mass spectrometry-based proteomic analysis to determine if we could identify specific proteins associated with amyloid in MTC. We studied 9 MTC (1 multiple endocrine neoplasia type 2A, 1 familial MTC, and 7 sporadic). Laser microdissection was utilized to sample the amyloid which was then trypsin digested and evaluated by liquid chromatography electrospray tandem MS (LC-MS/MS) which identified the presence of amyloidogenic proteins in all cases of MTC. High levels of calcitonin were identified in all 9 cases of MTC. Secretogranin-1 was identified in 6 of 9 MTC. Calcitonin gene-related peptide was identified in 4 of 9 cases of MTC. LC-MS/MS proteomic analysis provides a rapid, highly specific, and sensitive method for identification of the specific type of amyloid in these endocrine tumors. This approach may allow classification of different forms of endocrine amyloid present in neuroendocrine tumors.

Systems pharmacology to decipher the combinational anti-migraine effects of Tianshu formula

Migraine is the most common neurovascular disorder that imparts a considerable burden to health care system around the world. However, currently there are still no effective and widely applicable pharmacotherapies for migraine patients. Herbal formulae, characterized as multiple herbs, constituents and targets, have been acknowledged with clinical effects in treating migraine, which attract more and more researchers' attention although their exact molecular mechanisms are still unclear. In this work, a novel systems pharmacology-based method which integrates pharmacokinetic filtering, target fishing and network analysis was developed and exemplified by a probe, i.e. Tianshu formula, a widely clinically used anti-migraine herbal formula in China which comprises of Rhizoma chuanxiong and Gastrodia elata. The results exhibit that 20 active ingredients of Tianshu formula possess favorable pharmacokinetic profiles, which have interactions with 48 migraine-related targets to provide potential synergistic therapeutic effects. Additionally, from systematic analysis, we speculate that R. chuanxiong as the monarch herb mediates the major targets like PTGS2, ESR1, NOS2, HTR1B and NOS3 to regulate the vascular and nervous systems, as well as the inflammation and pain-related pathways to benefit migraine patients. Meanwhile, as an adjuvant herb, G. elata may not only assist the monarch herb to improve the outcome of migraine patients, but also regulate multiple targets like ABAT, HTR1D, ALOX15 and KCND3 to modify migraine accompanying symptoms like vomiting, vertigo and gastrointestinal disorders.

Taking the headache out of migraine

Migraine is a disease that contributes to major disability. Perhaps because migraine attacks are not immediately life-threatening per se and individuals return to a "normal" state between attacks, it is not taken seriously. However, migraine is associated with a number of comorbidities, including psychiatric disease, stroke, and other chronic pain disorders. Current acute treatments for episodic migraine are relatively effective, but preventive treatments for episodic and chronic migraine are far less so. Recent functional imaging studies have shown that the disease affects brain function and structure (either as a result of its genetic predisposition or as a result of repeated attacks). The current evidence in the pain field is that changes observed in brain function and structure may be reversible, adding credence to the notion that treating the disease aggressively and early may be beneficial to patients. Here we suggest a change in our approach to a disease that is currently not treated with the urgency that it deserves given its global prevalence, disease burden, and effects on brain function.

Up-regulation of calcitonin gene-related peptide in trigeminal ganglion following chronic exposure to paracetamol in a CSD migraine animal model

Previously, our group has demonstrated that chronic paracetamol (APAP) treatment induces alterations to the trigeminovascular nociceptive system in the cortical spreading depression (CSD) migraine animal model. The calcitonin gene related peptide (CGRP) is a key neuropeptide involved in the activation of the trigeminovascular nociceptive system. Therefore, this study examined the expression levels of CGRP in the trigeminal ganglion (TG) after chronic APAP exposure (0, 15, and 30 days) using a CSD model. Rats were divided into control, CSD only, APAP only and APAP treatment with CSD groups. A single injection (i.p.) of APAP (200 mg/kg body weight) was given to the 0-day APAP-treated groups, while the other APAP-treated groups received daily injections for 15 and 30 days. CSD was induced by the topical application of KCl to the parietal cortex. The protein expression of CGRP in the TG was evaluated by immunohistochemistry, and the CGRP mRNA level was investigated by real-time quantitative reverse transcription polymerase chain reaction. The results revealed that the induction of CSD significantly increased the level of CGRP protein but had no effect on CGRP mRNA level. Pretreatment with APAP 1 hour before CSD activation significantly reduced CGRP expression induced by CSD. In contrast, chronic treatment with APAP (15 and 30 days) significantly enhanced CGRP expression in both protein and mRNA levels when compared with the control groups. In combination with CSD, the expression of CGRP further increased in the animal with 30 day treatment. These findings indicate that chronic treatment with APAP induces an increase of CGRP expression in the TG. This alteration may be associated with the increased trigeminovascular nociception observed in our previous studies.

Targeting CGRP: A New Era for Migraine Treatment

Migraine is a highly prevalent headache disease that typically affects patients during their most productive years. Despite significant progress in understanding the underlying pathophysiology of this disorder, its treatment so far continues to depend on drugs that, in their majority, were not specifically designed for this purpose. The neuropeptide calcitonin gene-related peptide (CGRP) has been indicated as playing a critical role in the central and peripheral pathways leading to a migraine attack. It is not surprising that drugs designed to specifically block its action are gaining remarkable attention from researchers in the field with, at least so far, a safe risk profile. In this article, we highlight the evolution from older traditional treatments to the innovative CGRP target drugs that are revolutionizing the way to approach this debilitating neurological disease. We provide a brief introduction on pathophysiology of migraine and details on the characteristic, function, and localization of CGRP to then focus on CGRP receptor antagonists (CGRP-RAs) and CGRP monoclonal antibodies (CGRP mAbs).

Lentivirus mediated over expression of CGRP inhibited oxidative stress in Schwann cell line

CGRP is reported to be implicated in the process of diabetes and neuronal disease. However, the role and underlying mechanism of CGRP involved in diabetic neuropathy is unknown. Schwann cells play a central role in diabetic neuropathy, therefore the protective effect of CGRP on Schwann cells exposed to high glucose is determined. In the present study, full-length CGRP cDNA was isolated and then transferred to gateway adapted lentivirus expression vector by LR recombination reaction. Afterwards, the CGRP bearing recombinant virus was prepared in 293 FT cells and used to infect Schwann cells. The viability and superoxide anions of Schwann cells were evaluated following stimulation with high glucose, and levels of SOD, MDA and NOX1 were assessed. The results suggested that CGRP expression was up-regulated following lentivirus transfection. Lenti-CGRP increased cell viability in high glucose, but the effect was transient. Further lenti-CGRP protected against oxidative stress in Schwann cells triggered by high glucose and lenti-CGRP was effective in increasing SOD and decreasing MDA level. Meanwhile, the increased level of NOX1 caused by high glucose was reversed by lenti-CGRP overexpression. We therefore, suggest that lenti-CGRP may play a role in inhibiting oxidative stress in Schwann cell lines following hyperglycemic stimulation.

Microglial content-dependent inhibitory effects of calcitonin gene-related peptide (CGRP) on murine retroviral infection of glial cells

C57BL/6 (B6) mice develop peripheral neuropathy post-LP-BM5 infection, a murine model of HIV-1 infection, along with the up-regulation of select spinal cord cytokines. We investigated if calcitonin gene-related peptide (CGRP) contributed to the development of peripheral neuropathy by stimulating glial responses. An increased expression of lumbar spinal cord CGRP was observed in vivo, post-LP-BM5 infection. Consequently, in vitro CGRP co-treatments led to a microglial content-dependent attenuation of viral loads in spinal cord mixed glia infected with selected doses of LP-BM5. This inhibition was neither caused by the loss of glia nor induced via the direct inhibition of LP-BM5 by CGRP.

Therapeutic effects and safety of olcegepant and telcagepant for migraine: A meta-analysis

OBJECTIVE:

To evaluate the therapeutic effects and adverse reactions of olcegepant and telcagepant for the treatment of migraine.

DATA RETRIEVAL:

We identified studies using Medline (1966-01/2012-06), PubMed (1966-01/2012-06), Scopus (1980-01/2012-06), Cochrane Central Register of Controlled Trials (1980-01/2012-06) and China National Knowledge Infrastructure (1980-01/2012-06).

SELECTION CRITERIA:

The included studies were double-blind, randomized and placebo-controlled trials of olcegepant or telcagepant for the treatment of single acute migraine in patients with or without aura. Adverse reaction data were also included. Two independent investigators performed quality evaluation and data extraction using Jadad scoring. Meta-analyses were undertaken using RevMan 5.0.25 software.

MAIN OUTCOME MEASURES:

Pain relief rate, pain-free rate, and incidence of adverse reactions were measured in patients 2 and 24 hours after injection of olcegepant and oral telcagepant.

RESULTS:

Six randomized, controlled trials were included. Meta-analysis demonstrated that compared with placebo, the pain relief rate (odds ratio, OR = 5.21, 95% confidence interval, CI: 1.91–14.2, P < 0.01) and pain-free rate (OR = 31.11, 95% CI: 3.80–254.98, P < 0.01) significantly increased 2 hours after 2.5 mg/d olcegepant treatment. Pain relief rate and pain-free rate 2 and 24 hours after treatment with telcagepant 150 mg/d and 300 mg/d were superior to placebo (P < 0.01). Moreover, the remission rate of unrelenting headache was higher after 24 hours of 300 mg/d telcagepant treatment compared with 150 mg/d (OR = 0.78, 95% CI: 0.62–0.97, P < 0.05). The incidence of adverse reactions with olcegepant was not significantly greater than placebo (P = 0.28), but within 48 hours of administration of telcagepant 300 mg/d, the incidence of adverse reactions was higher than placebo (OR = 1.21, 95% CI: 1.04–1.42, P < 0.01). Few studies have compared the therapeutic effects of olcegepant and telcagepant.

CONCLUSION:

The calcitonin-gene-related peptide receptor antagonists olcegepant and telcagepant have shown good therapeutic effects in the treatment of migraine. Moreover, the incidence of adverse reactions compares favorably with placebo, although liver transaminases may become elevated after long-term use.

Evaluation of analgesic, sedative effects and antimigraine mechanism of Qilong Toutong Granule () in rodents

OBJECTIVE

To evaluate the analgesic and sedative effects of Qilong Toutong Granule (, QTG) and explore its possible mechanisms.

METHODS

Kunming mice were randomly divided into 6 groups: normal control group, Zhengtian Pill (, ZTP) group, Western medicine group, and high-dose (5.2 g/kg), medium-dose (2.6 g/kg) and low-dose (1.3 g/kg) of QTG groups. After completing the prophylactic treatment for 3 days, hot-plate test and acetic acid-induced writhing test were used to assess the analgesic effect, and spontaneous locomotor test and sodium pentobarbital-induced hypnosis activity were adopted to estimate the sedative effect. Sprague-Dawley rats were grouped into normal control group, model group, ZTP group, rizatriptan group, and high-dose (3.6 g/kg), medium-dose (1.8 g/kg), and low-dose (0.9 g/kg) of QTG groups. After gavage for continuous 7 days, rats were intraperitoneally injected nitroglycerin, and 4 h later, blood samples were collected from postcava for measuring the levels of plasma calcitonin gene-related peptide (CGRP) and beta-endorphin (β-EP) by radioimmunoassay. Subsequently, rats were perfused transcardially and the brain tissues containing the trigeminal nucleus caudalis (TNC) were achieved for detecting the number of Fos-immunoreactive cells by immunohistochemical method.

RESULTS

In the mice experiments, compared with the normal control group, high- and medium-dose of QTG groups significantly raised the pain threshold (P<0.01), reduced the number of writhing response (P<0.01) and spontaneous activity (P<0.01), but had no influence on the sleeping rate of mice (P>0.05), and low-dose of QTG group also raised the pain threshold at 120 min (P=0.007), as well as lowered locomotor activity of mice at 2 h (P=0.003). On the study of migraine model rats, high- and medium-dose of QTG groups remarkably down-regulated the levels of plasma CGRP (P<0.01), up-regulated the levels of plasma β-EP (P<0.01) and inhibited the expression of Fos protein in TNC (P<0.01), compared with the model group.

CONCLUSIONS

QTG has obvious analgesic and sedative action and its mechanism on relieving migraine may be through regulating the levels of neurotransmitters and/or neuropeptides, and inhibiting the activation of Fos pathway.

Distribution of CGRP in the minipig brainstem

For the first time, an in-depth study has been made of the distribution of fibers and cell bodies containing calcitonin gene-related peptide (CGRP) in the minipig brainstem using an indirect immunoperoxidase technique. The animals studied were not treated with colchicine. Cell bodies containing CGRP were found in 20 nuclei/regions of the brainstem. These perikarya were located in somatomotor, brachiomotor and raphae nuclei, nucleus ambiguus, substantia nigra, nucleus reticularis tegmenti pontis, nucleus prepositus hypoglossi, nuclei olivaris inferior and superior, nuclei pontis, formatio reticularis, nucleus dorsalis tegmenti of Gudden, and in the nucleus reticularis lateralis. Fourteen of the 20 brainstem nuclei showed a high density of immunoreactive cell bodies. In comparison with other species, the minipig, together with the rat, show the most widespread distribution of cell bodies containing CGRP in the mammalian brainstem. Immunoreactive fibers were also observed in the brainstem. However, in the minipig brainstem the density of these fibers is low, as in many brainstem nuclei only single immunoreactive fibers were observed. A high density of immunoreactive fibers was only observed in the pars caudalis of the nucleus tractus spinalis nervi trigemini and in the nucleus ventralis tegmenti of Gudden. According to the observed anatomical distribution of the immunoreactive structures containing CGRP, the peptide could be involved in motor, somatosensory, gustative, and autonomic mechanisms.