Migraine susceptibility is modulated by food triggers and analgesic overuse via sulfotransferase inhibition

Extrasynaptic δGABAA receptors mediate resistance to migraine-like phenotype in rats

BACKGROUND

GABA, a key inhibitory neurotransmitter, has synaptic and extrasynaptic receptors on the postsynaptic neuron. Background GABA, which spills over from the synaptic cleft, acts on extrasynaptic delta subunit containing GABAA receptors. The role of extrasynaptic GABAergic input in migraine is unknown. We investigated the susceptibility to valid migraine-provoking substances with clinically relevant behavioral readouts in Genetic Absence Epilepsy of Rats Strasbourg (GAERS), in which the GABAergic tonus was altered. Subsequently, we screened relevant GABAergic mechanisms in Wistar rats by pharmacological means to identify the mechanisms.

METHODS

Wistar and GAERS rats were administered nitroglycerin (10 mg/kg) or levcromakalim (1 mg/kg). Mechanical allodynia and photophobia were assessed using von Frey monofilaments and a dark-light box. Effects of GAT-1 blocker tiagabine (5 mg/kg), GABAB receptor agonist baclofen (2 mg/kg), synaptic GABAA receptor agonist diazepam (1 mg/kg), extrasynaptic GABAA receptor agonists gaboxadol (4 mg/kg), and muscimol (0.75 mg/kg), T-type calcium channel blocker ethosuximide (100 mg/kg) or synaptic GABAA receptor antagonist flumazenil (15 mg/kg) on levcromakalim-induced migraine phenotype were screened.

RESULTS

Unlike Wistar rats, GAERS exhibited no reduction in mechanical pain thresholds or light aversion following nitroglycerin or levcromakalim injection. Ethosuximide did not reverse the resistant phenotype in GAERS, excluding the role of T-type calcium channel dysfunction in this phenomenon. Tiagabine prevented levcromakalim-induced mechanical allodynia in Wistar rats, suggesting a key role in enhanced GABA spillover. Baclofen did not alleviate mechanical allodynia. Diazepam failed to mitigate levcromakalim-induced migraine phenotype. Additionally, the resistant phenotype in GAERS was not affected by flumazenil. Extrasynaptic GABAA receptor agonists gaboxadol and muscimol inhibited periorbital allodynia in Wistar rats.

CONCLUSION

Our study introduced a rat strain resistant to migraine-provoking agents and signified a critical involvement of extrasynaptic δGABAergic receptors. Extrasynaptic δ GABAA receptors, by mediating constant background inhibition on the excitability of neurons, stand as a novel drug target with a therapeutic potential in migraine.

Medication overuse headache is associated with elevated lipopolysaccharide binding protein and pro-inflammatory molecules in the bloodstream

OBJECTIVE

Medication overuse headache (MOH) is a secondary headache that accompanies chronic migraine. Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most frequently used analgesics worldwide and they are known to induce leaky gut. In this study, we aimed to investigate whether NSAID induced MOH is associated with altered circulating lipopolysaccharide binding protein (LBP) levels and inflammatory molecules.

MATERIALS AND METHODS

Piroxicam (10 mg/kg/day, po) for 5 weeks was used to induce MOH in female Sprague Dawley rats. Pain behavior was evaluated by periorbital withdrawal thresholds, head-face grooming, freezing, and head shake behavior. Serum samples and brain tissues were collected to measure circulating LBP, tight junction protein occludin, adherens junction protein vascular endothelial (VE)-cadherin, calcitonin gene-related peptide (CGRP), IL-6 levels and brain high mobility group box-1 (HMGB1) and IL-17 levels.

RESULTS

Chronic piroxicam exposure resulted in decreased periorbital mechanical withdrawal thresholds, increased head-face grooming, freezing, and head shake behavior compared to vehicle administration. Serum LBP, CGRP, IL-6, IL-17, occludin, VE-cadherin levels and brain IL-17 and HMGB1 levels were significantly higher in piroxicam group compared to controls. Serum LBP was positively correlated with occludin (r = 0.611), VE-cadherin (r = 0.588), CGRP (r = 0.706), HMGB1 (r = 0.618) and head shakes (r = 0.921), and negatively correlated with periorbital mechanical withdrawal thresholds (r = -0.740).

CONCLUSION

Elevated serum LBP, VE-cadherin and occludin levels indicating disrupted intestinal barrier function and leakage of LPS into the systemic circulation were shown in female rats with MOH. LPS induced low-grade inflammation and elevated nociceptive and/or pro-inflammatory molecules such as HMGB1, IL-6, IL-17 and CGRP may play a role in the development and maintenance of MOH. Interference with leaky gut and pro-inflammatory nociceptive molecules could also be a target for sustained management of MOH.

Leaky gut and inflammatory biomarkers in a medication overuse headache model in male rats

Background/aim

Medication overuse is common among chronic migraine patients and nonsteroidal antiinflammatory drugs (NSAIDs) are the most frequently overused drugs. The pathophysiological mechanisms underlying medication overuse headache (MOH) are not completely understood. Intestinal hyperpermeability and leaky gut are reported in patients using NSAIDs. The aim of the study is to investigate the role of leaky gut and inflammation in an MOH model MOH model in male rats.

Methods

The study was conducted in male Sprague Dawley rats. There were two experimental groups. The first group was the chronic NSAID group in which the rats received mefenamic acid (n = 8) for four weeks intraperitoneally (ip) and the second group was the vehicle group (n = 8) that received 5% dimethyl sulfoxide+sesame oil (ip) for 4 weeks. We assessed spontaneous pain-like behavior, periorbital mechanical withdrawal thresholds, and anxiety-like behavior using an elevated plus maze test. After behavioral testing, serum levels of occludin and lipopolysaccharide-binding protein (LBP) and brain levels of IL-17, IL-6, and high mobility group box 1 protein (HMGB1) were evaluated with ELISA.Results: Serum LBP and occludin levels and brain IL-17 and HMGB1 levels were significantly elevated in the chronic NSAID group compared to its vehicle (p = 0.006, p = 0.016, p = 0.016 and p = 0.016 respectively) while brain IL-6 levels were comparable (p = 0.67) between the groups. The chronic NSAID group showed pain-like and anxiety-like behavior in behavioral tests. Brain IL-17 level was positively correlated with number of head shakes (r = 0.64, p = 0.045), brain IL-6 level was negatively correlated with periorbital mechanical withdrawal thresholds (r = -0.71, p = 0.049), and serum occludin level was positively correlated with grooming duration (r = 0.73, p = 0.032) in chronic NSAID group.

Conclusion

Elevated serum occludin and LBP levels and brain IL-17 and HMGB1 levels indicate a possible role of leaky gut and inflammation in an MOH model in male rats. Additionally, a significant correlation between pain behavior and markers of inflammation and intestinal hyperpermeability, supports the role of inflammation and leaky gut in MOH pathophysiology.

Distinct Food Triggers for Migraine, Medication Overuse Headache and Irritable Bowel Syndrome

BACKGROUND

Irritable bowel syndrome (IBS) is an under-diagnosed common health problem that impairs quality of life. Migraine and IBS are comorbid disorders that are triggered by foods. We aim to investigate IBS frequency in medication overuse headache (MOH) patients and identify food triggers and food avoidance behavior.

METHODS

Participants who completed the cross-sectional, observational and online survey were included (n = 1118). Demographic data, comorbid disorders, medications used, presence of headache, the diagnostic features of headache and IBS, migraine related subjective cognitive symptoms scale (MigSCog), consumption behavior of patients regarding 125 food/food additives and food triggers were asked about in the questionnaire.

RESULTS

Migraine and MOH diagnoses were made in 88% and 30.7% of the participants, respectively. Non-steroidal anti-inflammatory drugs (NSAIDs) were the main overused drug (89%) in MOH patients. IBS symptoms were present in 35.8% of non-headache sufferers, 52% of migraine patients and 65% of MOH patients. Specific food triggers for MOH patients were dopaminergic and frequently consumed as healthy foods such as banana, apple, cherry, apricot, watermelon, olive, ice cream and yogurt. MigSCog scores were significantly higher in episodic migraine and MOH patients when IBS symptoms coexisted.

CONCLUSIONS

The frequency of IBS was higher in MOH patients compared to migraine patients. Coexistence of IBS seems to be a confounding factor for cognitive functions. MOH specific triggers were mostly dopaminergic foods, whereas migraine specific food triggers were mostly histaminergic and processed foods. Personalized diets focusing on food triggers and interference with leaky gut must be integrated to MOH and migraine treatment to achieve sustainable management of these disorders.

Topographic localization of migraine triggers and its association with headache frequency and severity

OBJECTIVE

Internal biological rhythm with or without external trigger may precipitate migraine. Classifying exogenous and endogenous triggers to a topographic localization may help in understanding the migraine. We report topographic localization of migraine triggers and its influence on headache frequency and severity.

METHODS

588 migraineurs, aged 16-69 years were included. Various endogenous and exogenous triggers were categorized to topographic localization- hypothalamic, pituitary, auditory, visual, somato-sensory, olfactory and gustatory. The relationship of topographic localization of triggers with episodic versus chronic migraine, and moderate versus severe headache were analyzed using univariate followed by multivariate analysis.

RESULTS

All migraineurs had triggers 584(99.9%) except 4(0.1%) patients. Presence of multiple triggers (99.4%), and combination of both endogenous and exogenous triggers (97.7%) was the rule. On topographic localization, hypothalamic trigger was the commonest (98.1%) followed by visual (84.1%), auditory (82.1%), somatosensory (76.1%), olfactory (26.2%), pituitary (24.1%), and gustatory (6.6%). 98.6% patients had combination of hypothalamic with pituitary triggers. Hypothalamic [Adjusted odds ratio (AOR) 4.50] and auditory triggers (AOR 0.34) independently predicted chronic migraine, and auditory (AOR 0.55) and gustatory (AOR 2.41) triggers predicted severity of headache.

CONCLUSION

Hypothalamic triggers are the commonest suggesting an innate susceptibility of migraine. Auditory trigger may precipitate frequent and severe headache.

A history of International Headache Society grants and their impact on headache careers

Background

The International Headache Society has been offering multiple award opportunities for young researchers and clinicians for many years, with the aim of supporting the development of careers in headache science and medicine.

Methods

In order to assess the outcomes of the International Headache Society award grants, a questionnaire was sent to all previous recipients, investigating a series of aspects related to their work, both during and after award completion.

Results

Of 44 total questionnaires sent, 36 were returned. Eighty-one percent of the recipients reported to have remained in the headache field since the award, half of them held a current academic position and over three-quarters had stayed in contact with the host institution. The totality of questionnaire responders stated that the grant had had a significantly positive impact on their careers.

Conclusions

The International Headache Society grants have assisted many young researchers in building an academic and clinical career in the field of headache, throughout the years.