Chemical mediators of migraine: preclinical and clinical observations

Understanding the Biological Relationship between Migraine and Depression

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

The Pathophysiological Relationship Between Migraine and SARS-CoV-2 Infection: A Comprehensive Literature Review

People with migraine, and individuals with other neurological conditions, have suffered in multiple aspects during the COVID-19 pandemic. This paper will discuss the factors that impacted the neurology department. The emergence of severe acute respiratory syndrome coronavirus 2 in late 2019 has generated new challenges in healthcare systems across the globe. Similar to the fields of pulmonology and cardiology that saw an increase in research, the neurology department was in search of possible relationships between COVID-19 and other medical conditions. Research on the possible common pathophysiological mechanism between COVID-19 and migraine is currently being studied. The most recent hypothesis suggests the following: migraine is caused by an increased release of calcitonin gene-related peptide from the trigeminal ganglion, which will cause an increase in nitric oxide and IL-1β, resulting in vasodilation and inducing hyperalgesia. COVID-19 causes an increase in nod-like receptor protein 3, which causes the production of IL-1β and again induces an inflammatory response. This review article looks at the mechanisms of migraine and COVID-19, and tries to link a common pathophysiological pathway between the two. This report also serves as a gateway for further research regarding possible management that could potentially target both of these mechanisms.

Estrogen modulation of the pronociceptive effects of serotonin on female rat trigeminal sensory neurons is timing dependent and dosage dependent and requires estrogen receptor alpha

ABSTRACT

The role of the major estrogen estradiol (E2) on orofacial pain conditions remains controversial with studies reporting both a pronociceptive and antinociceptive role of E2. E2 modulation of peripheral serotonergic activity may be one mechanism underlying the female prevalence of orofacial pain disorders. We recently reported that female rats in proestrus and estrus exhibit greater serotonin (5HT)-evoked orofacial nocifensive behaviors compared with diestrus and male rats. Further coexpression of 5HT 2A receptor mRNA in nociceptive trigeminal sensory neurons that express transient receptor potential vanilloid 1 ion channels contributes to pain sensitization. E2 may exacerbate orofacial pain through 5HT-sensitive trigeminal nociceptors, but whether low or high E2 contributes to orofacial pain and by what mechanism remains unclear. We hypothesized that steady-state exposure to a proestrus level of E2 exacerbates 5HT-evoked orofacial nocifensive behaviors in female rats, explored the transcriptome of E2-treated female rats, and determined which E2 receptor contributes to sensitization of female trigeminal sensory neurons. We report that a diestrus level of E2 is protective against 5HT-evoked orofacial pain behaviors, which increase with increasing E2 concentrations, and that E2 differentially alters several pain genes in the trigeminal ganglia. Furthermore, E2 receptors coexpressed with 5HT 2A and transient receptor potential vanilloid 1 and enhanced capsaicin-evoked signaling in the trigeminal ganglia through estrogen receptor α. Overall, our data indicate that low, but not high, physiological levels of E2 protect against orofacial pain, and we provide evidence that estrogen receptor α receptor activation, but not others, contributes to sensitization of nociceptive signaling in trigeminal sensory neurons.

Pharmacokinetics study of chitosan-coated liposomes containing sumatriptan in the treatment of migraine

BACKGROUND

Sumatriptan is a routine medication in the treatment of migraine and cluster headache that is generally given by oral or parental routes. However, a substantial proportion of patients suffer severe side effects. The aim of this study was to investigate the physicochemical characterization and pharmacokinetic parameters of a novel delivery system for sumatriptan succinate (SS) using nanoliposomes (NLs) coated by chitosan (CCLs) to optimize the formulations to enhance its bioavailability.

METHODS

The new formulation was used to minimize drug particle size and extend its release and bioavailability. The mean particle size and entrapment efficiency for NLs and CCls were optimized and the formulations with better characteristics were chosen for in vivo studies. The concentration-time profile of intravenous SS, intranasal SS, SS-NLs, and CCLs were examined in a rabbit model.

RESULTS

The results demonstrated that CCLs were absorbed more rapidly from nasal drops containing chitosan compared to those of SS and SS-NLs as indicated by a shorter tmax, and a higher Cmax in both states. A comparison of the AUC (0-240 min) values revealed that chitosan improved the extent of SS absorption for CCLs formulation. The results of the present study indicated that loading SS into the liposome and coating with chitosan improves drug absorption and a large amount of the drug can be efficiently delivered into the systemic circulation.

CONCLUSION

The liposomal and chitosan formulations of SS had better kinetic behavior than the soluble form in the animal model.

Nitric Oxide as a Target for Phytochemicals in Anti-Neuroinflammatory Prevention Therapy

Nitric oxide (NO) is a neurotransmitter that mediates the activation and inhibition of inflammatory cascades. Even though physiological NO is required for defense against various pathogens, excessive NO can trigger inflammatory signaling and cell death through reactive nitrogen species-induced oxidative stress. Excessive NO production by activated microglial cells is specifically associated with neuroinflammatory and neurodegenerative conditions, such as Alzheimer’s and Parkinson’s disease, amyotrophic lateral sclerosis, ischemia, hypoxia, multiple sclerosis, and other afflictions of the central nervous system (CNS). Therefore, controlling excessive NO production is a desirable therapeutic strategy for managing various neuroinflammatory disorders. Recently, phytochemicals have attracted considerable attention because of their potential to counteract excessive NO production in CNS disorders. Moreover, phytochemicals and nutraceuticals are typically safe and effective. In this review, we discuss the mechanisms of NO production and its involvement in various neurological disorders, and we revisit a number of recently identified phytochemicals which may act as NO inhibitors. This review may help identify novel potent anti-inflammatory agents that can downregulate NO, specifically during neuroinflammation and neurodegeneration.

Prevalence of suicidal ideation and suicide attempt in patients with migraine: A systematic review and meta-analysis

BACKGROUND

Suicidality is common in patients with migraine. Here, we performed a systematic review and estimated the prevalence of suicidal ideation (SI) and suicide attempt (SA) in patients with migraine.

METHODS

We searched Pubmed, Embase, Web of Science, Cochrane database library, CINAHL, and PsycINFO for relevant publications. A random-effects model was used to pool the estimates of the prevalence of SI and SA, which were also stratified by the geographical location of the research institutions from the studies included in this meta-analysis.

RESULTS

Fifteen studies involving 2,247,648 participants with migraine were selected. Pooled prevalence estimates of SI and SA were 15.5% [95% confidence interval (CI) 10.4-21.3%] and 3.9% (95% CI 0.9-8.8%), respectively, and the prevalence of SI was higher in Asian countries (21.5%, 95%CI 16.8-26.6%) compared with non-Asian countries (11.0%, 95%CI 6.1-17.2%). Measures of heterogeneity between studies were high for all outcomes (I² = 89-100%), indicating that the substantial between-study heterogeneity in estimated proportions was not attributed to sampling error. The leave-one-out analysis showed that no single study significantly affected the final pooled results.

CONCLUSIONS

This meta-analysis indicated a high prevalence of SI and SA in migraine patients. Thus, it is necessary to design targeted preventive measures for the management of migraine-related suicide.

Metoclopramide versus sumatriptan in the treatment of migraine in the emergency department: a single-center, open-label, cluster-randomized controlled non-inferiority trial

Migraine is a common disease seen in the emergency department (ED). Triptans, which are recommended in therapeutic guidelines for migraine, have some contraindications and possible severe side effects. Metoclopramide, which is commonly used as an antiemetic, also seems to have pain-relieving effects for migraine. In this article, we will introduce a study in progress, which investigates whether metoclopramide 10 mg intravenously (IV) is non-inferior to sumatriptan 3 mg subcutaneously (SQ) as migraine treatment in the ED. This study is a single-center, open-label, cluster-randomized controlled trial of 80 patients with migraine attacks to investigate the non-inferiority of metoclopramide to sumatriptan. The patients will be cluster-randomized monthly into metoclopramide 10 mg IV and sumatriptan 3 mg SQ arms. The primary outcome will be change in Numerical Rating Scale score for headache at 1 h after baseline. In discussion, if our hypothesis is confirmed, metoclopramide can be considered as first-line medication for migraine attacks in ED settings.

Endothelial and Autonomic Functions in Patients with Migraine

OBJECTIVE

It has been shown that patients with migraine have endothelial dysfunction. Migraine patients with aura, especially, have more clinical manifestations of autonomic nervous system dysfunction. We aimed to evaluate the endothelial and autonomic functions in migraine patients during both migraine headache attack and headache-free periods.

DESIGN

This was a cross-sectional, randomized study.

SUBJECTS AND METHODS

A total of 130 participants (67 male and 63 female patients, minimum age = 19 years, maximum age = 71 years, mean age = 38.8 ± 12.2 years) were enrolled into the study. For the statistical evaluation of data, we classified the participants of the study as follows: group 1: headache (+) aura (+); group 2: headache (+) aura (-); group 3: headache (-) aura (+); group 4: headache (-) aura (-). Noninvasive evaluation of endothelial function was performed by flow-mediated dilation (FMD) and pulse wave analysis methods. Heart rate variability measurements were used for noninvasive evaluation of autonomic functions.

RESULTS

Group 1 had a higher FMD ratio than the control group, group 3, or group 4 (P < 0.001, P < 0.001, and P = 0.003, respectively). Group 4 had lower FMD ratio levels than the other migraine groups and or the control group (P < 0.001). Group 3 had the highest high-frequency (HF) power levels among all migraine groups (P < 0.001). Group 2 had higher low-frequency/HF ratio values than other migraineurs (P < 0.001).

CONCLUSIONS

We concluded that endothelial dysfunction and headache are closely related. Additionally, higher parasympathetic tonus might be associated with the presence of aura.

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.

Association between migraine and suicidal behavior among Ethiopian adults

BACKGROUND

Despite the significant impact of migraine on patients and societies, few studies in low- and middle-income countries (LMICs) have investigated the association between migraine and suicidal behavior. The objective of our study is to examine the extent to which migraines are associated with suicidal behavior (including suicidal ideation, plans, and attempts) in a well-characterized study of urban dwelling Ethiopian adults.

METHODS

We enrolled 1060 outpatient adults attending St. Paul hospital in Addis Ababa, Ethiopia. Standardized questionnaires were used to collect data on socio-demographics, and lifestyle characteristics. Migraine classification was based on the International Classification of Headache Disorders-2 diagnostic criteria. The Composite International Diagnostic Interview (CIDI) was used to assess depression and suicidal behaviors (i.e. ideation, plans and attempts). Multivariable logistic regression models were used to estimate adjusted odds ratio (AOR) and 95% confidence intervals (95% CIs).

RESULTS

The prevalence of suicidal behavior was 15.1%, with a higher suicidal behavior among those who had migraines (61.9%). After adjusting for confounders including substance use and socio-demographic factors, migraine was associated with a 2.7-fold increased odds of suicidal behavior (AOR = 2.7; 95% CI 1.88-3.89). When stratified by their history of depression in the past year, migraine without depression was significantly associated with suicidal behavior (AOR: 2.27, 95% Cl: 1.49-3.46). The odds of suicidal behavior did not reach statistical significance in migraineurs with depression (AOR: 1.64, 95% CI: 0.40-6.69).

CONCLUSION

Our study indicates that migraine is associated with increased odds of suicidal behavior in this population. Given the serious public health implications this has, attention should be given to the treatment and management of migraine at a community level.

Elastomeric sensor surfaces for high-throughput single-cell force cytometry

As cells with aberrant force-generating phenotypes can directly lead to disease, cellular force-generation mechanisms are high-value targets for new therapies. Here, we show that single-cell force sensors embedded in elastomers enable single-cell force measurements with ~100-fold improvement in throughput than was previously possible. The microtechnology is scalable and seamlessly integrates with the multi-well plate format, enabling highly parallelized time-course studies. In this regard, we show that airway smooth muscle cells isolated from fatally asthmatic patients have innately greater and faster force-generation capacity in response to stimulation than healthy control cells. By simultaneously tracing agonist-induced calcium flux and contractility in the same cell, we show that the calcium level is ultimately a poor quantitative predictor of cellular force generation. Finally, by quantifying phagocytic forces in thousands of individual human macrophages, we show that force initiation is a digital response (rather than a proportional one) to the proper immunogen. By combining mechanobiology at the single-cell level with high-throughput capabilities, this microtechnology can support drug-discovery efforts for clinical conditions associated with aberrant cellular force generation.

Recurrent Painful Ophthalmoplegic Neuropathy with Residual Mydriasis in an Adult: Should it Be Classified as Ophthalmoplegic Migraine?

Recurrent painful ophthalmoplegic neuropathy (RPON) is a rare condition that manifests as headache and ophthalmoplegia. It typically occurs in children. Although migraine or neuropathy have been suggested as etiologies, the precise etiology remains unclear. In the International Classification of Headache Disorders 3rd edition-beta version (ICHD3β) (code 13.9), RPON was categorized into painful cranial neuropathies and other facial pains. We encountered a 48-year-old woman who had diplopia and right ptosis. The administration of prednisolone led to the immediate improvement of her oculomotor palsy, but residual mydriasis remained. Based on this case, the pathophysiology of RPON may involve temporary nerve inflammation with migraine. Repeated and severe migraine attacks may cause irreversible nerve damage. Thus, medication for migraine prophylaxis might be needed to prevent RPON.

Metabolomic changes in CSF of migraine patients measured with 1H-NMR spectroscopy

BACKGROUND

Migraine is a common episodic brain disorder. Treatment options and diagnosis are hampered by an incomplete understanding of disease pathophysiology and the lack of objective diagnostic markers. The aim of this study was to identify biochemical differences characteristic for different subtypes of migraine in cerebrospinal fluid (CSF) of migraine patients using an exploratory ¹H-NMR-based metabolomics approach.

METHODS

CSF was obtained, in between migraine attacks, via lumbar puncture from patients with hemiplegic migraine, migraine with aura, migraine without aura, and healthy controls. Metabolite concentrations were measured by quantitative ¹H-NMR spectroscopy. Multivariate data analysis was used to find the optimal set of predictors, generalized linear models (GLM) were used to ascertain the differential significance of individual metabolites.

RESULTS

In CSF samples from 18 patients with hemiplegic migraine, 38 with migraine with aura, 27 migraine without aura, and 43 healthy controls, nineteen metabolites were identified and quantified. Hemiplegic migraine patients could be discriminated from healthy controls using supervised multivariate modelling with 2-hydroxybutyrate and 2-hydroxyisovalerate as the most discriminant metabolites. Univariate GLM analysis showed 2-hydroxybutyrate to be lower in hemiplegic migraine compared with healthy controls; no significant differences were observed for other metabolites. It was not possible to discriminate migraine with and without aura from healthy controls based on their metabolic profile.

CONCLUSIONS

Using an exploratory ¹H-NMR metabolomics analysis we identified metabolites that were able to discriminate hemiplegic migraine patients from healthy controls. The lower levels of 2-hydroxybutyrate found in patients with hemiplegic migraine could indicate a dysregulation of the brain's energy metabolism. An experimental confirmation in vitro or in animal models will be required to confirm or discard this hypothesis. Migraine with and migraine without aura patients did not reveal a metabolic profile different from healthy controls.

Impact of Food Components on in vitro Calcitonin Gene-Related Peptide Secretion-A Potential Mechanism for Dietary Influence on Migraine

Calcitonin gene-related peptide (CGRP) is a pivotal messenger in the inflammatory process in migraine. Limited evidence indicates that diet impacts circulating levels of CGRP, suggesting that certain elements in the diet may influence migraine outcomes. Interruption of calcium signaling, a mechanism which can trigger CGRP release, has been suggested as one potential route by which exogenous food substances may impact CGRP secretion. The objective of this study was to investigate the effects of foods and a dietary supplement on two migraine-related mechanisms in vitro: CGRP secretion from neuroendocrine CA77 cells, and calcium uptake by differentiated PC12 cells. Ginger and grape pomace extracts were selected for their anecdotal connections to reducing or promoting migraine. S-petasin was selected as a suspected active constituent of butterbur extract, the migraine prophylactic dietary supplement. Results showed a statistically significant decrease in stimulated CGRP secretion from CA77 cells following treatment with ginger (0.2 mg dry ginger equivalent/mL) and two doses of grape pomace (0.25 and 1.0 mg dry pomace equivalent/mL) extracts. Relative to vehicle control, CGRP secretion decreased by 22%, 43%, and 87%, respectively. S-petasin at 1.0 μM also decreased CGRP secretion by 24%. Meanwhile, S-petasin and ginger extract showed inhibition of calcium influx, whereas grape pomace had no effect on calcium. These results suggest that grape pomace and ginger extracts, and S-petasin may have anti-inflammatory propensity by preventing CGRP release in migraine, although potentially by different mechanisms, which future studies may elucidate further.

Putative role of 5-HT2B receptors in migraine pathophysiology

Objective

In this review we attempt to characterize the acute and chronic role of 5-HT2B receptors with regard to meningeal nociception in animal experiments and clinical data targeting migraine therapy.

Background

Migraine is a common disabling neurovascular primary headache disease, the pathomechanism of which is still unclear. Serotonin (5-HT) and its receptors might play an important role in some aspects of migraine pathogenesis. The ability of the unselective 5-HT2B receptor agonist m-chlorophenylpiperazine to induce migraine attacks in migraine sufferers, the high affinity of prophylactic antimigraine drugs to this receptor and its expression in migraine-relevant structures like the dura mater argue for a role of 5-HT2B receptors in the pathogenesis of migraine attacks.

Methods

For this review, the relevant databases such as PubMed, MEDLINE®, Cochrane Library and EMBASE, respectively, were searched to December 2015 using the keywords “migraine, 5-HT2, trigeminal, neurogenic inflammation, nitric oxide, nitroxyl, vasodilatation, plasma protein extravasation” and combinations thereof.

Conclusion

Our literature review suggests an important role of 5-HT2B receptor activation in meningeal nociception and the generation of migraine pain.

Mechanisms mediating nitroglycerin-induced delayed-onset hyperalgesia in the rat

Nitroglycerin (glycerol trinitrate, GTN) induces headache in migraineurs, an effect that has been used both diagnostically and in the study of the pathophysiology of this neurovascular pain syndrome. An important feature of this headache is a delay from the administration of GTN to headache onset that, because of GTN's very rapid metabolism, cannot be due to its pharmacokinetic profile. It has recently been suggested that activation of perivascular mast cells, which has been implicated in the pathophysiology of migraine, may contribute to this delay. We reported that hyperalgesia induced by intradermal GTN has a delay to onset of ∼ 30 min in male and ∼ 45 min in female rats. This hyperalgesia was greater in females, was prevented by pretreatment with the anti-migraine drug, sumatriptan, as well as by chronic pretreatment with the mast cell degranulator, compound 48/80. The acute administration of GTN and compound 48/80 both induced hyperalgesia that was prevented by pretreatment with octoxynol-9, which attenuates endothelial function, suggesting that GTN and mast cell-mediated hyperalgesia are endothelial cell-dependent. Furthermore, A-317491, a P2X3 antagonist, which inhibits endothelial cell-dependent hyperalgesia, also prevents GTN and mast cell-mediated hyperalgesia. We conclude that delayed-onset mechanical hyperalgesia induced by GTN is mediated by activation of mast cells, which in turn release mediators that stimulate endothelial cells to release ATP, to act on P2X3, a ligand-gated ion channel, in perivascular nociceptors. A role of the mast and endothelial cell in GTN-induced hyperalgesia suggests potential novel risk factors and targets for the treatment of migraine.

Diphenhydramine as Adjuvant Therapy for Acute Migraine: An Emergency Department-Based Randomized Clinical Trial

STUDY OBJECTIVE

More than 1 million patients present to US emergency departments (EDs) annually seeking care for acute migraine. Parenteral antihistamines have long been used in combination with antidopaminergics such as metoclopramide to treat acute migraine in the ED. High-quality data supporting this practice do not exist. We determine whether administration of diphenhydramine 50 mg intravenously+metoclopramide 10 mg intravenously results in greater rates of sustained headache relief than placebo+metoclopramide 10 mg intravenously.

METHODS

This was a randomized, double-blind, clinical trial comparing 2 active treatments for acute migraine in an ED. Eligible patients were adults younger than 65 years presenting with an acute moderate or severe headache meeting International Classification of Headache Disorders-2 migraine criteria. Patients were stratified according to presence or absence of allergic symptoms. The primary outcome was sustained headache relief, defined as achieving a headache level of mild or none within 2 hours of medication administration and maintaining this level of relief without use of any additional headache medication for 48 hours. Secondary efficacy outcomes included mean improvement on a 0 to 10 verbal scale between baseline and 1 hour, the frequency with which subjects indicated they would want the same medication the next time they present to the ED with migraine, and the ED throughput time. Sample size calculation using a 2-sided α of .05, a β of .20, and a 15% difference between study arms determined the need for 374 patients. An interim analysis was conducted when data were available for 200 subjects.

RESULTS

Four hundred twenty patients were approached for participation. Two hundred eight eligible patients consented to participate and were randomized. At the planned interim analysis, the data and safety monitoring board recommended that the study be halted for futility. Baseline characteristics were comparable between the groups. Fourteen percent (29/208) of the sample reported allergic symptoms. Of patients randomized to diphenhydramine, 40% (40/100) reported sustained relief at 48 hours, as did 37% (38/103) of patients randomized to placebo (95% confidence interval [CI] for difference of 3%: -10% to 16%). One hour after medication administration, patients randomized to diphenhydramine improved by a mean of 5.1 on the 0 to 10 scale versus 4.8 for those randomized to placebo (95% CI for difference of 0.3: -0.6 to 1.1). Eighty-five percent (84/99) of the patients in the diphenhydramine arm reported they would want the same medication combination during a subsequent ED visit, as did 76% (77/102) of those who received placebo (95% CI for difference of 9%: -2% to 20%). Median ED length of stay was 122 minutes (interquartile range 84 to 180 minutes) in the diphenhydramine group and 139 minutes (interquartile range 90 to 235 minutes) in the placebo arm. Rates of adverse effects, including akathisia, were comparable between the groups.

CONCLUSION

Intravenous diphenhydramine, when administered as adjuvant therapy with metoclopramide, does not improve migraine outcomes.

CGRP receptor blockade by MK-8825 alleviates allodynia in infraorbital nerve-ligated rats

BACKGROUND

Previous data showed that, in rats, anti-migraine drugs (triptans, olcegepant) significantly reduced mechanical allodynia induced by infraorbital nerve (ION) ligation but not that evoked by sciatic nerve (SN) ligation. Whether this also occurs with MK-8825, a novel anti-migraine drug also acting through CGRP receptor blockade (but chemically unrelated to olcegepant) was tested in the present study, which also investigated possible anti-neuroinflammatory effects of this drug.

METHODS

Adult male Sprague-Dawley rats underwent unilateral chronic constriction injury (CCI) to either the ION or the SN, and mechanical allodynia was assessed 2 weeks later within the ipsilateral vibrissae territory or hindpaw, respectively. Transcripts of neuroinflammatory markers were quantified by real-time quantitative RT-PCR in ipsilateral trigeminal ganglion and spinal trigeminal nucleus in CCI-ION rats.

RESULTS

Acute as well as repeated (for 4 days) administration of MK-8825 (30-100 mg/kg, i.p.) significantly reduced CCI-ION-induced mechanical allodynia but was ineffective in CCI-SN rats. CCI-ION was associated with marked up-regulation of neuronal and glial inflammatory markers (ATF3, IL6, iNOS, COX2) in ipsilateral trigeminal ganglion but not spinal trigeminal nucleus. MK-8825-induced inhibition of iNOS mRNA up-regulation probably underlay its anti-allodynic effect because pharmacological blockade of iNOS by AMT (6 mg/kg, s.c.) mimicked this effect.

CONCLUSIONS

These data further support the idea that CGRP receptor blockade might be a valuable approach to alleviate trigeminal, but not spinal, neuropathic pain through, at least partly, an inhibitory effect on neuropathic pain-associated increase in NO production in trigeminal ganglion.

Expression and characterization of purinergic receptors in rat middle meningeal artery-potential role in migraine

The dura mater and its vasculature have for decades been central in the hypothesis of migraine and headache pathophysiology. Although recent studies have questioned the role of the vasculature as the primary cause, dural vessel physiology is still relevant in understanding the complex pathophysiology of migraine. The aim of the present study was to isolate the middle meningeal artery (MMA) from rodents and characterize their purinergic receptors using a sensitive wire myograph method and RT-PCR. The data presented herein suggest that blood flow through the MMA is, at least in part, regulated by purinergic receptors. P2X1 and P2Y6 receptors are the strongest contractile receptors and, surprisingly, ADPβS caused contraction most likely via P2Y1 or P2Y13 receptors, which is not observed in other arteries. Adenosine addition, however, caused relaxation of the MMA. The adenosine relaxation could be inhibited by SCH58261 (A2A receptor antagonist) and caffeine (adenosine receptor antagonist). This gives one putative molecular mechanism for the effect of caffeine, often used as an adjuvant remedy of cranial pain. Semi-quantitative RT-PCR expression data for the receptors correlate well with the functional findings. Together these observations could be used as targets for future understanding of the in vivo role of purinergic receptors in the MMA.

Patients profiling for Botox® (onabotulinum toxin A) treatment for migraine: a look at white matter lesions in the MRI as a potential marker

Background

To evaluate if white matter lesions (WML) on MRI can be a potential marker for onabotulinum toxin A (Botox®) treatment success in migraine, given the limited response rate and high costs per treatment.

Methods

Retrospective data base and MRI analysis of 529 migraineurs who received Botox® between 2002 and 2009. Responders were defined as patients who underwent three or more treatments, whereas non-responders had only one or two treatments. MRIs were analysed on axial T2 and coronar FLAIR (fluid attenuated inversion recovery) sequences for the presence of WML. Statistical analysis was done with the Chi-Square-Test and the Mann–Whitney-U-Test.

Results

Of 529 Botox® treated migraineurs, 111 patients had a MRI. Of these 111 patients, 47 were responders, 64 non-responders to Botox®. Response rate to Botox® in migraineurs with WML was 55.3%, in migraineurs without WML 44.7%. In the investigated items “age”, “age at onset”, “gender”, “attack duration”, “frequency”, “aura”, “WML”, “size of WML”, we found no statistical significant difference between the two groups. 55% of the responders and 50% of the non-responders showed WML. All WML were located supratentorially, anteriorly, mostly of small size (3–5 mm).

Conclusion

WML on MRIs cannot serve as a marker to predict a positive response to Botox®.

Characteristics of NO cycle coupling with urea cycle in non-hyperammonemic carriers of ornithine transcarbamylase deficiency

Urea cycle deficient patients with prominent hyperammonemic often exhibit abnormal production of nitric oxide (NO), which reduces vascular tone, along with amino acid abnormalities. However, information related to the metabolic changes in heterozygotes of ornithine transcarbamylase deficiency (OTCD) lacking overt hyperammonemia is quite limited. We examined vascular mediators and amino acids in non-hyperammonemic heterozygotes. Twenty-four heterozygous OTCD adult females without hyperammonemic bouts, defined as non-hyperammonemic carriers, were enrolled. We measured blood amino acids constituting urea cycle and nitric oxide (NO) cycle. Blood concentrations of nitrate/nitrite (NOx) as stable NO-metabolites, asymmetric dimethylarginine (ADMA) inhibiting NO synthesis, and endothelin-1 (ET-1) raising vascular tone were also determined. NOx concentrations were significantly lower in non-hyperammonemic carriers (p < 0.01). However, ADMA and ET-1 levels in this group were comparable to those in the age-matched control group. Arginine and citrulline levels were also significantly lower in non-hyperammonemic carriers than in controls (p < 0.01). Of the 24 non-hyperammonemic carriers, 10 often developed headaches. Their daily NOx and arginine levels were significantly lower than those in headache-free carriers (p < 0.05). In three carriers receiving oral l-arginine, blood NOx concentrations were significantly higher. In two of those three, the occurrence of headaches was decreased. These results suggest that NO cycle coupling with the urea cycle is altered substantially even in non-hyperammonemic OTCD carriers, predisposing them to headaches.

Relationship between headache and mucosal mast cells in pediatric Helicobacter pylori-negative functional dyspepsia

BACKGROUND

Although many patients with functional dyspepsia experience headache concurrently with dyspeptic symptoms, studies suggesting mechanisms underlying this phenomenon are limited. Herein, we explore the relationship between gastrointestinal inflammatory cells and presence of headache associated with dyspeptic symptoms in children with HELICOBACTER PYLORI -negative functional dyspepsia.

METHODS

Fifty-six patients with H. PYLORI -negative functional dyspepsia underwent upper endoscopy with biopsy to investigate recurrent epigastric pain or discomfort. Patients were divided into two groups according to self-reported presence of headache associated with dyspeptic symptoms. Inflammatory cells including mast cells, and enteroendocrine cells in the gastroduodenal mucosa were evaluated. Associations between headache presence and cellular changes in the gastroduodenal mucosa were examined.

RESULTS

Headache was not associated with the grade of lymphocytes, neutrophil infiltration, or enteroendocrine cell density in the gastroduedenal mucosa. However, headache was significantly associated with high mast cell density in the body (27.81 ± 8.71 vs. 20.30 ± 8.16, P  < 0.01) and duodenum (23.16 ± 10.40 vs. 14.84 ± 5.88, P  < 0.01).

CONCLUSIONS

Presence of headache associated with dyspeptic symptoms is strongly related to mucosal mast cell density in pediatric patients with H. PYLORI -negative functional dyspepsia. Thus, our results may help clinicians understand and treat headache during dyspeptic symptoms in such pediatric patients.

What do kinase inhibition profiles tell us about tyrosine kinase inhibitors used for the treatment of CML?

Cancer treatment has long been based upon cytotoxic therapies that affect all rapidly dividing cells, and as such, is necessarily associated with significant toxicity. More recently, drugs targeted toward pathways critical for tumor cell survival have been developed. With limited off-target activity, such therapies are expected to be better tolerated than broad-acting cytotoxic chemotherapies. BCR-ABL inhibitors in chronic myeloid leukemia are reviewed as a model to investigate the concept of targeted cancer therapies and evaluate how the kinase inhibition profiles of these agents may contribute to their toxicity profiles.