1 5537 122 ROLE OF CALCITONIN GENE-RELATED PEPTIDE IN LIGHT-AVERSIVE BEHAVIOR: IMPLICATIONS FOR MIGRAINE. MIGRAINE IS A CHRONIC NEUROLOGICAL DISORDER CHARACTERIZED BY RECURRENT EPISODES OF SEVERE UNILATERAL THROBBING HEAD PAIN AND ASSOCIATED SYMPTOMS, SUCH AS PHOTOPHOBIA. OUR CURRENT UNDERSTANDING OF THE MECHANISMS UNDERLYING MIGRAINE HAS BEEN HAMPERED BY LIMITATIONS IN ASCERTAINING MIGRAINE SYMPTOMS IN ANIMAL MODELS. CLINICAL STUDIES HAVE ESTABLISHED THE NEUROPEPTIDE CALCITONIN GENE-RELATED PEPTIDE (CGRP) AS A KEY PLAYER IN MIGRAINE. HERE, WE ESTABLISH A GENETIC MODEL OF PHOTOPHOBIA BY ENGINEERING INCREASED SENSITIVITY TO CGRP IN MICE. THESE TRANSGENIC MICE (NESTIN/HRAMP1) DISPLAY LIGHT-AVERSIVE BEHAVIOR THAT IS GREATLY ENHANCED BY INTRACEREBROVENTRICULAR INJECTION OF CGRP AND BLOCKED BY COADMINISTRATION OF THE CGRP RECEPTOR ANTAGONIST OLCEGEPANT. THIS BEHAVIOR APPEARS TO BE AN INDICATOR OF PHOTOPHOBIA AND CANNOT BE FULLY EXPLAINED BY GROSS ABNORMALITY OF OCULAR ANATOMY OR DIFFERENCES IN GENERAL ANXIETY OR MOTOR ACTIVITY. OUR FINDINGS DEMONSTRATE THAT A SINGLE GENE, RECEPTOR ACTIVITY-MODIFYING PROTEIN 1 (RAMP1), CAN BE A MODIFIER OF PHOTOPHOBIA AND, BY EXTENSION, SUGGEST THAT GENETIC OR EPIGENETIC MODULATION OF RAMP1 LEVELS MAY CONTRIBUTE TO MIGRAINE SUSCEPTIBILITY. MOREOVER, THEY VALIDATE CGRP HYPERSENSITIVE MICE AS A TOOL FOR EXPLORING THE NEUROBIOLOGY AND NOVEL THERAPIES FOR MIGRAINE AND OTHER DISORDERS INVOLVING PHOTOPHOBIA. 2009 2 4139 34 MECHANISMS OF MIGRAINE AS A CHRONIC EVOLUTIVE CONDITION. UNDERSTANDING THE MECHANISMS OF MIGRAINE REMAINS CHALLENGING AS MIGRAINE IS NOT A STATIC DISORDER, AND EVEN IN ITS EPISODIC FORM MIGRAINE REMAINS AN "EVOLUTIVE" CHRONIC CONDITION. CONSIDERABLE PROGRESS HAS BEEN MADE IN ELUCIDATING THE PATHOPHYSIOLOGICAL MECHANISMS OF MIGRAINE, ASSOCIATED GENETIC FACTORS THAT MAY INFLUENCE SUSCEPTIBILITY TO THE DISEASE, AND FUNCTIONAL AND ANATOMICAL CHANGES DURING THE PROGRESSION OF A MIGRAINE ATTACK OR THE TRANSFORMATION OF EPISODIC TO CHRONIC MIGRAINE. MIGRAINE IS A LIFE SPAN NEUROLOGICAL DISORDER THAT FOLLOWS AN EVOLUTIVE AGE-DEPENDENT CHANGE IN ITS PREVALENCE AND EVEN CLINICAL PRESENTATIONS. AS A DISORDER, MIGRAINE INVOLVES RECURRENT INTENSE HEAD PAIN AND ASSOCIATED UNPLEASANT SYMPTOMS. MIGRAINE ATTACKS EVOLVE OVER DIFFERENT PHASES WITH SPECIFIC NEURAL MECHANISMS AND SYMPTOMS BEING INVOLVED DURING EACH PHASE. IN SOME PATIENTS, MIGRAINE CAN BE TRANSFORMED INTO A CHRONIC FORM WITH DAILY OR ALMOST DAILY HEADACHES. THE MECHANISMS BEHIND THIS EVOLUTIVE PROCESS REMAIN UNKNOWN, BUT GENETIC AND EPIGENETIC FACTORS, INFLAMMATORY PROCESSES AND CENTRAL SENSITIZATION MAY PLAY AN IMPORTANT ROLE. 2019 3 6916 29 [WHAT IS MIGRAINE?]. MIGRAINE IS A MULTIFACTORIAL AND HETEROGENEOUS DISORDER. DIAGNOSTIC CRITERIA HAVE BEEN ESTABLISHED BY THE INTERNATIONAL HEADACHE SOCIETY, HOWEVER THESE ARE ONLY SUPPORTIVE IN TERMS OF DEFINITION. THE PATHOPHYSIOLOGY INVOLVES NEURONAL AND VASCULAR PHENOMENA. THE FORMER IS SUPPORTED BY THE CORTICAL SPREADING DEPRESSION BEING THE AURA CORRELATE AND BY BRAINSTEM AND HYPOTHALAMIC ACTIVATION DURING THE PAIN PHASE; THE LATTER IS SUGGESTED BY THE ASSOCIATION BETWEEN MIGRAINE AND CARDIOVASCULAR DISEASE AND FINDINGS OF PATHOLOGICAL VASOREACTIVITY AND ENDOTHELIAL DYSFUNCTION. TRIPTANS AND CALCITONIN GENE-RELATED PEPTIDE RECEPTOR ANTAGONISTS SHOW ONLY A RELATIVE MIGRAINE-SPECIFIC ACTION; UP TO 30% OF PATIENTS ARE NONRESPONDERS. DESPITE A CLEAR GENETIC COMPONENT, THE DISCOVERY OF SPECIFIC GENES FOR COMMON FORMS OF MIGRAINE REMAINS ELUSIVE. ELECTROPHYSIOLOGICAL STUDIES CONSISTENTLY INDICATE A CHARACTERISTIC "DYSHABITUATION" CONCURRING WITH CLINICAL FEATURES OF ALTERED SENSORY PERCEPTION. THE AGE- AND SEX-SPECIFIC PATTERN ALONG WITH THE EFFECT OF EXTERNAL FACTORS ON THE COURSE OF MIGRAINE ARGUE IN FAVOR OF THE INVOLVEMENT OF EPIGENETIC MECHANISMS. KNOWLEDGE ABOUT MIGRAINE IS STILL LIMITED, WHICH HAMPERS A DEFINITION. 2009 4 4339 24 MIGRAINE: A GENETIC DISEASE? MIGRAINES CARRY A SUBSTANTIAL GENETIC LIABILITY, AND IN FAMILIES AFFECTED WITH THE TYPICAL MIGRAINES (MIGRAINE WITH, MA, AND WITHOUT AURA, MO) LINKAGE TO SOME CHROMOSOMAL LOCI HAS BEEN REPORTED. AS YET HOWEVER, NO GENES ARE KNOWN FOR MA/MO, WHILE THE THREE GENES DISCOVERED AS RESPONSIBLE FOR FAMILIAL HEMIPLEGIC MIGRAINE (FHM) ARE NOT INVOLVED IN THE TYPICAL MIGRAINES. ACCORDINGLY, WE PROPOSE TO CONSIDER FHM AS A SYNDROMIC MIGRAINE AND NOT AS A VARIETY OF MA. MOREOVER, WE SUGGEST THAT EPIGENETIC MECHANISMS PLAY A ROLE IN THE DETERMINATION OF THE TYPICAL MIGRAINES, AND THAT THE PRIMARY HEADACHES REPRESENT BEHAVIOURAL RESPONSES (SICKNESS BEHAVIOUR, FIGHT-OR-FLIGHT RESPONSES), HAVING ADAPTIVE ADVANTAGE AND HAVING BEEN EVOLUTIONARY CONSERVED, IN WHICH PAIN REPRESENTS A SIGNAL OF HOMEOSTATIC IMBALANCE. EPIGENETIC MECHANISMS AND THIS PROPOSED GENETIC BEHAVIOURAL MODEL COULD BE USEFULLY INCORPORATED INTO HEADACHE GENETIC RESEARCH. 2008 5 2052 32 EPIGENETIC CONNECTION OF THE CALCITONIN GENE-RELATED PEPTIDE AND ITS POTENTIAL IN MIGRAINE. THE CALCITONIN GENE-RELATED PEPTIDE (CGRP) IS IMPLICATED IN THE PATHOGENESIS OF SEVERAL PAIN-RELATED SYNDROMES, INCLUDING MIGRAINE. TARGETING CGRP AND ITS RECEPTOR BY THEIR ANTAGONISTS AND ANTIBODIES WAS A BREAKTHROUGH IN MIGRAINE THERAPY, BUT THE NEED TO IMPROVE EFFICACY AND LIMIT THE SIDE EFFECTS OF THESE DRUGS JUSTIFY FURTHER STUDIES ON THE REGULATION OF CGRP IN MIGRAINE. THE EXPRESSION OF THE CGRP ENCODING GENE, CALCA, IS MODULATED BY EPIGENETIC MODIFICATIONS, INCLUDING THE DNA METHYLATION, HISTONE MODIFICATION, AND EFFECTS OF MICRO RNAS (MIRNAS), CIRCULAR RNAS, AND LONG-CODING RNAS (LNCRNAS). ON THE OTHER HAND, CGRP CAN CHANGE THE EPIGENETIC PROFILE OF NEURONAL AND GLIAL CELLS. THE PROMOTER OF THE CALCA GENE HAS TWO CPG ISLANDS THAT MAY BE SPECIFICALLY METHYLATED IN MIGRAINE PATIENTS. DNA METHYLATION AND LNCRNAS WERE SHOWN TO PLAY A ROLE IN THE CELL-SPECIFIC ALTERNATIVE SPLICING OF THE CALCA PRIMARY TRANSCRIPT. CGRP MAY BE INVOLVED IN CHANGES IN NEURAL CYTOARCHITECTURE THAT ARE CONTROLLED BY HISTONE DEACETYLASE 6 (HDAC6) AND CAN BE RELATED TO MIGRAINE. INHIBITION OF HDAC6 RESULTS IN REDUCED CORTICAL-SPREADING DEPRESSION AND A BLOCKADE OF THE CGRP RECEPTOR. CGRP LEVELS ARE ASSOCIATED WITH THE EXPRESSION OF SEVERAL MIRNAS IN PLASMA, MAKING THEM USEFUL PERIPHERAL MARKERS OF MIGRAINE. THE FUNDAMENTAL ROLE OF CGRP IN INFLAMMATORY PAIN TRANSMISSION MAY BE EPIGENETICALLY REGULATED. IN CONCLUSION, EPIGENETIC CONNECTIONS OF CGRP SHOULD BE FURTHER EXPLORED FOR EFFICIENT AND SAFE ANTIMIGRAINE THERAPY. 2022 6 5387 35 REDOX MECHANISMS IN MIGRAINE: NOVEL THERAPEUTICS AND DIETARY INTERVENTIONS. SIGNIFICANCE: MIGRAINE REPRESENTS THE THIRD MOST PREVALENT AND THE SEVENTH MOST DISABLING HUMAN DISORDER. APPROXIMATELY 30% OF MIGRAINE PATIENTS EXPERIENCE TRANSIENT, FULLY REVERSIBLE, FOCAL NEUROLOGICAL SYMPTOMS (AURA) PRECEDING THE ATTACK. RECENT ADVANCES: AWARENESS OF THE HYPOTHESIS THAT MIGRAINE ACTUALLY EMBODIES A SPECTRUM OF ILLNESSES-RANGING FROM EPISODIC TO CHRONIC FORMS-IS PROGRESSIVELY INCREASING AND POSES NOVEL CHALLENGES FOR CLARIFYING THE UNDERLYING PATHOPHYSIOLOGICAL MECHANISMS OF MIGRAINE AS WELL AS FOR THE DEVELOPMENT OF NOVEL THERAPEUTIC INTERVENTIONS. SEVERAL THEORIES HAVE EVOLVED TO THE CURRENT CONCEPT THAT A COMBINATION OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS MAY PLAY A ROLE IN MIGRAINE PATHOGENESIS, ALTHOUGH THEIR RELATIVE IMPORTANCE IS STILL BEING DEBATED. CRITICAL ISSUES: ONE CRITICAL ISSUE THAT DESERVES A PARTICULAR ATTENTION IS THE ROLE OF OXIDATIVE STRESS IN MIGRAINE. INDEED, POTENTIALLY HARMFUL OXIDATIVE EVENTS OCCUR DURING THE MIGRAINE ATTACK AND LONG-LASTING OR FREQUENT MIGRAINE EPISODES MAY INCREASE BRAIN EXPOSURE TO OXIDATIVE EVENTS THAT CAN LEAD TO CHRONIC TRANSFORMATION. MOREOVER, A WIDE VARIETY OF DIETARY, ENVIRONMENTAL, PHYSIOLOGICAL, BEHAVIORAL, AND PHARMACOLOGICAL MIGRAINE TRIGGERS MAY ACT THROUGH OXIDATIVE STRESS, WITH CLEAR IMPLICATIONS FOR MIGRAINE TREATMENT AND PROPHYLAXIS. INTERESTINGLY, ALMOST ALL CURRENT PROPHYLACTIC MIGRAINE AGENTS EXERT ANTIOXIDANT EFFECTS. FUTURE DIRECTIONS: INCREASING AWARENESS OF THE ROLE OF OXIDATIVE STRESS AND/OR DECREASED ANTIOXIDANT DEFENSES IN MIGRAINE PATHOGENESIS AND PROGRESSION TO A CHRONIC CONDITION LAYS THE FOUNDATIONS FOR THE DESIGN OF NOVEL PROPHYLACTIC APPROACHES, WHICH, BY REDUCING BRAIN OXIDATIVE PHENOMENA, COULD FAVORABLY MODIFY THE CLINICAL COURSE OF MIGRAINE. ANTIOXID. REDOX SIGNAL. 28, 1144-1183. 2018 7 1250 37 CURRENT PERSPECTIVES ON MITOCHONDRIAL DYSFUNCTION IN MIGRAINE. MITOCHONDRIA ARE AN AUTONOMOUS ORGANELLE THAT PLAYS A CRUCIAL ROLE IN THE METABOLIC ASPECTS OF A CELL. CORTICAL SPREADING DEPRESSION (CSD) AND FLUCTUATIONS IN THE CEREBRAL BLOOD FLOW HAVE FOR LONG BEEN MECHANISMS UNDERLYING MIGRAINE. IT IS A NEUROVASCULAR DISORDER WITH A UNILATERAL MANIFESTATION OF DISTURBING, THROBBING AND PULSATING HEAD PAIN. MIGRAINE AFFECTS 2.6% AND 21.7% OF THE GENERAL POPULATION AND IS THE MAJOR CAUSE OF PARTIAL DISABILITY IN THE AGE GROUP 15-49. HIGHER MUTATION RATES, IMBALANCE IN CONCENTRATION OF PHYSIOLOGICALLY RELEVANT MOLECULES AND OXIDATIVE STRESS BIOMARKERS HAVE BEEN THE MAIN THEMES OF DISCUSSION IN DETERMINING THE ROLE OF MITOCHONDRIAL DISABILITY IN MIGRAINE. THE CORRELATION OF MIGRAINE WITH OTHER DISORDERS LIKE HEMIPLEGIC MIGRAINE; MITOCHONDRIAL MYOPATHY, ENCEPHALOPATHY, LACTIC ACIDOSIS AND STROKE-LIKE EPISODES [MELAS]; TENSION-TYPE HEADACHE (TTH); CYCLIC VOMITING SYNDROME (CVS), ISCHAEMIC STROKE; AND HYPERTENSION HAS HELPED IN THE ASSESSMENT OF THE PHYSIOLOGICAL AND MORPHOGENETIC BASIS OF MIGRAINE. HERE, WE HAVE REVIEWED THE DIFFERENT NUANCES OF MITOCHONDRIAL DYSFUNCTION AND MIGRAINE. THE DIFFERENT MTDNA POLYMORPHISMS THAT CAN AFFECT THE GENERATION AND TRANSMISSION OF NERVE IMPULSE HAS BEEN HIGHLIGHTED AND SUPPORTED WITH RESEARCH FINDINGS. IN ADDITION TO THIS, THE GENETIC BASIS OF MIGRAINE PATHOGENESIS AS A CONSEQUENCE OF MUTATIONS IN NUCLEAR DNA THAT CAN, IN TURN, AFFECT THE SYNTHESIS OF DEFECTIVE MITOCHONDRIAL PROTEINS IS DISCUSSED ALONG WITH A BRIEF OVERVIEW OF EPIGENETIC PROFILE. THIS REVIEW GIVES AN OVERVIEW OF THE PATHOPHYSIOLOGY OF MIGRAINE AND EXPLORES MITOCHONDRIAL DYSFUNCTION AS A POTENTIAL UNDERLYING MECHANISM. ALSO, THERAPEUTIC SUPPLEMENTS FOR MANAGING MIGRAINE HAVE BEEN DISCUSSED AT DIFFERENT JUNCTURES IN THIS PAPER. 2022 8 5500 31 REVISITING MIGRAINE: THE EVOLVING PATHOPHYSIOLOGY AND THE EXPANDING MANAGEMENT ARMAMENTARIUM. MIGRAINE AFFECTS ABOUT ONE BILLION PEOPLE WORLDWIDE YEARLY AND IS ONE OF THE MOST COMMON NEUROLOGIC ILLNESSES, WITH A HIGH PREVALENCE AND MORBIDITY, PARTICULARLY AMONG YOUNG ADULTS AND FEMALES. MIGRAINE IS ASSOCIATED WITH MANY COMORBIDITIES, INCLUDING STRESS, SLEEP DIFFICULTIES, AND SUICIDAL IDEATION. MIGRAINE, DESPITE ITS WIDESPREAD OCCURRENCE, IS UNDERDIAGNOSED AND UNDERTREATED. BECAUSE OF THE COMPLICATED AND PRIMARILY UNKNOWN MECHANISMS OF MIGRAINE FORMATION, SEVERAL SOCIAL AND BIOLOGICAL RISK FACTORS, SUCH AS HORMONE IMBALANCES, GENETIC AND EPIGENETIC IMPACTS, AND CARDIOVASCULAR, NEUROLOGICAL, AND AUTOIMMUNE ILLNESSES, HAVE BEEN PROPOSED. THROUGH THE MID-20TH CENTURY DIVERSION OF THE NOW-DEFUNCT VASCULAR THEORY, THE PATHOPHYSIOLOGY OF MIGRAINE HAS DEVELOPED FROM A HISTORICAL STUDY OF THE "HUMOURS" TO A DISTINCT ENTITY AS A NEUROLOGICAL DISORDER. THE RANGE OF THERAPEUTIC TARGETS HAS BROADENED SIGNIFICANTLY, INCREASING THE NUMBER OF SPECIALIZED CLINICAL TRIALS. UNDERSTANDING THE BIOLOGY OF MIGRAINE THROUGH CAREFUL RESEARCH HAS RESULTED IN THE IDENTIFICATION OF MAJOR THERAPEUTIC CLASSES: (I) TRIPTANS, SEROTONIN 5-HT1B/1D RECEPTOR AGONISTS, (II) GEPANTS, CALCITONIN GENE-RELATED PEPTIDE (CGRP) RECEPTOR ANTAGONISTS, (III) DITANS, 5-HT1F RECEPTOR AGONISTS, (IV) CGRP MONOCLONAL ANTIBODIES, AND (V) GLURANTS, MGLU5 MODULATORS, WITH FURTHER TARGETS BEING EXPLORED. THIS REVIEW PROVIDES A COMPREHENSIVE OVERVIEW OF THE MOST RECENT LITERATURE ON EPIDEMIOLOGY AND RISK FACTORS AND EXPOSES KNOWLEDGE GAPS. 2023 9 2053 30 EPIGENETIC CONNECTIONS OF THE TRPA1 ION CHANNEL IN PAIN TRANSMISSION AND NEUROGENIC INFLAMMATION - A THERAPEUTIC PERSPECTIVE IN MIGRAINE? PERSISTENT REPROGRAMMING OF EPIGENETIC PATTERN LEADS TO CHANGES IN GENE EXPRESSION OBSERVED IN MANY NEUROLOGICAL DISORDERS. TRANSIENT RECEPTOR POTENTIAL CATION CHANNEL SUBFAMILY A MEMBER 1 (TRPA1), A MEMBER OF THE TRP CHANNELS SUPERFAMILY, IS ACTIVATED BY MANY MIGRAINE TRIGGERS AND EXPRESSED IN TRIGEMINAL NEURONS AND BRAIN REGIONS THAT ARE IMPORTANT IN MIGRAINE PATHOGENESIS. TRP CHANNELS CHANGE NOXIOUS STIMULI INTO PAIN SIGNALS WITH THE INVOLVEMENT OF EPIGENETIC REGULATION. THE EXPRESSION OF THE TRPA1 ENCODING GENE, TRPA1, IS MODULATED IN PAIN-RELATED SYNDROMES BY EPIGENETIC ALTERATIONS, INCLUDING DNA METHYLATION, HISTONE MODIFICATIONS, AND EFFECTS OF NON-CODING RNAS: MICRO RNAS (MIRNAS), LONG NON-CODING RNAS, AND CIRCULAR RNAS. TRPA1 MAY CHANGE EPIGENETIC PROFILE OF MANY PAIN-RELATED GENES AS IT MAY MODIFY ENZYMES RESPONSIBLE FOR EPIGENETIC MODIFICATIONS AND EXPRESSION OF NON-CODING RNAS. TRPA1 MAY INDUCE THE RELEASE OF CALCITONIN GENE RELATED PEPTIDE (CGRP), FROM TRIGEMINAL NEURONS AND DURAL TISSUE. THEREFORE, EPIGENETIC REGULATION OF TRPA1 MAY PLAY A ROLE IN EFFICACY AND SAFETY OF ANTI-MIGRAINE THERAPIES TARGETING TRP CHANNELS AND CGRP. TRPA1 IS ALSO INVOLVED IN NEUROGENIC INFLAMMATION, IMPORTANT IN MIGRAINE PATHOGENESIS. THE FUNDAMENTAL ROLE OF TRPA1 IN INFLAMMATORY PAIN TRANSMISSION MAY BE EPIGENETICALLY REGULATED. IN CONCLUSION, EPIGENETIC CONNECTIONS OF TRPA1 MAY PLAY A ROLE IN EFFICACY AND SAFETY OF ANTI-MIGRAINE THERAPY TARGETING TRP CHANNELS OR CGRP AND THEY SHOULD BE FURTHER EXPLORED FOR EFFICIENT AND SAFE ANTIMIGRAINE TREATMENT. THIS NARRATIVE/PERSPECTIVE REVIEW PRESENTS INFORMATION ON THE STRUCTURE AND FUNCTIONS OF TRPA1 AS WELL AS ROLE OF ITS EPIGENETIC CONNECTIONS IN PAIN TRANSMISSION AND POTENTIAL IN MIGRAINE THERAPY. 2023 10 638 44 BIOMARKERS ASSOCIATED WITH MIGRAINE AND THEIR POTENTIAL ROLE IN MIGRAINE MANAGEMENT. OBJECTIVE: THE FOCUS OF THIS REVIEW IS TO REVIEW POTENTIAL DIAGNOSTIC AND THERAPEUTIC BIOMARKERS ASSOCIATED WITH MIGRAINE. BACKGROUND: MIGRAINE HEADACHE IS A COMMON DISEASE THAT AFFECTS MILLIONS OF INDIVIDUALS WORLDWIDE. ALTHOUGH WELL-ACCEPTED DIAGNOSTIC CRITERIA EXIST FOR MIGRAINE, IT IS STILL A COMPLEX DISORDER THAT REMAINS BOTH UNDERDIAGNOSED AND MISDIAGNOSED. THE CAUSES OF MIGRAINE ARE LIKELY A MIX OF GENETIC, EPIGENETIC, AND ENVIRONMENTAL FACTORS THAT, TOGETHER WITH THE INDIVIDUAL'S LIFE HISTORY, TRANSLATE INTO THE OBSERVED CLINICAL HETEROGENEITY. INHERENT CLINICAL HETEROGENEITY IS AN OBSTACLE IN DEVELOPING MORE EFFECTIVE TREATMENTS. THE LACK OF APPROPRIATE BIOMARKERS IS ALSO AN IMPEDIMENT TO DEVELOPING MORE EFFECTIVE THERAPEUTIC/PREVENTIVE APPROACHES. ULTIMATELY, BIOMARKERS MAY FACILITATE THE GOAL OF INDIVIDUALIZED MEDICINE BY ENABLING CLINICIANS TO MORE ACCURATELY DIAGNOSE AND TREAT MIGRAINE AND OTHER TYPES OF HEADACHE. METHODS: A COMPREHENSIVE REVIEW WAS CONDUCTED OF PUBMED CITATIONS CONTAINING THE KEY WORD "MARKER" OR "BIOMARKER" COMBINED WITH "MIGRAINE" OR "HEADACHE." OTHER KEY WORDS INCLUDED "SERUM," "SALIVA," "CEREBROSPINAL FLUID," "GENES," "BLOOD," AND "INFLAMMATION." THE ONLY RESTRICTION WAS ENGLISH-LANGUAGE PUBLICATION. THE ABSTRACTS OF ALL ARTICLES MEETING THESE CRITERIA WERE REVIEWED, AND FULL TEXT WAS RETRIEVED AND EXAMINED FOR RELEVANT REFERENCES. RESULTS: DATA FROM HUMAN STUDIES HAVE BEGUN TO IDENTIFY GENETIC MUTATIONS/POLYMORPHISMS AND ALTERED LEVELS OF SPECIFIC PROINFLAMMATORY AND NEUROMODULATORY MOLECULES THAT STRONGLY CORRELATE WITH MIGRAINE AS WELL AS SYMPTOM SEVERITY. RESULTS FROM A SMALLER NUMBER OF STUDIES HAVE IDENTIFIED PARAMETERS, SUCH AS THE NEUROPEPTIDE CALCITONIN GENE-RELATED PEPTIDE (CGRP), WHICH ARE SIGNIFICANTLY ASSOCIATED WITH RESPONSE TO SPECIFIC TREATMENTS FOR ACUTE MIGRAINE ATTACKS AND PROPHYLAXIS. EPIGENETIC MECHANISMS MAY ALSO BE INVOLVED IN THE DEVELOPMENT OF MIGRAINE, AND UNDERSTANDING ENVIRONMENTALLY INDUCED GENETIC CHANGES ASSOCIATED WITH THIS DISEASE MAY EVENTUALLY GUIDE THE DEVELOPMENT OF THERAPIES CAPABLE OF REVERSING THESE PATHOPHYSIOLOGICAL CHANGES IN GENE FUNCTION. CONCLUSIONS: THE UNDERSTANDING OF THE ETIOLOGY OF MIGRAINE IS INCOMPLETE. ALTHOUGH THE IDENTIFICATION AND VALIDATION OF BIOMARKERS HAS GREATLY ADVANCED DIAGNOSTIC PRECISION AND MEASURES OF THERAPEUTIC EFFICACY IN OTHER DISEASES, THERE ARE NO CURRENTLY ACCEPTED BIOMARKERS FOR CHRONIC OR EPISODIC MIGRAINE. HOWEVER, THE CONTINUED INVESTIGATION AND IDENTIFICATION OF GENETIC, EPIGENETIC, AND MOLECULAR BIOMARKERS IS LIKELY TO FACILITATE THE GOAL OF INDIVIDUALIZING MEDICINE BY ENABLING CLINICIANS TO MORE ACCURATELY DIAGNOSE AND TREAT MIGRAINE AND OTHER HEADACHE DISORDERS. 2013 11 6323 33 THE ROLE OF A POTENTIAL BIOMARKER IN PATIENTS WITH MIGRAINE: REVIEW AND NEW INSIGHTS. INTRODUCTION: THE SEARCH FOR AN IDEAL BIOMARKER FOR MIGRAINE HAS PERSISTED FOR A LONG TIME. THERE IS PLENTIFUL EVIDENCE OF POTENTIAL BIOMARKERS FOR MIGRAINE FOUND IN CEREBROSPINAL FLUID, BLOOD, AND SALIVA.AREAS COVERED: HEREIN, THE AUTHORS HIGHLIGHT AND DISCUSS THE MOST PROMISING CANDIDATES IN THE LITERATURE. AN ELECTRONIC SEARCH WAS PERFORMED FOR STUDIES PUBLISHED BETWEEN 2010 AND 2020 IN MEDLINE, PUBMED, AND EMBASE, RELATED TO POTENTIAL BIOMARKERS IN MIGRAINE PATIENTS, FOUND IN CEREBROSPINAL FLUID, SALIVA, AND SERUM, FOCUSING ON BIOMARKERS THAT CAN BE RELATED TO TREATMENT AND CLINICAL OUTCOMES.EXPERT OPINION: AN IDEAL BIOMARKER, OR A PANEL OF BIOMARKERS, COULD REVOLUTIONIZE THE WAY WE ADDRESS AND PROPOSE TREATMENTS FOR THIS DISEASE. ONCE SEVERE PRESENTATIONS AND PHENOTYPES HAVE BEEN IDENTIFIED USING A RELIABLE BIOMARKER, PATIENTS COULD BE TREATED AT EARLIER DISEASE STAGES WITH MORE SPECIFIC MEDICATIONS. THE MOST IMPORTANT BIOMARKERS WITH THE MOST SIGNIFICANT LEVELS OF EVIDENCE COMPRISED CALCITONIN GENE-RELATED PEPTIDE (CGRP), GLUTAMATE, NERVE GROWTH FACTOR, SOME INFLAMMATORY (CRP, TNF-ALPHA, INTERLEUKINS) AND OXIDATIVE STRESS MARKERS. CGRP WAS ASSOCIATED WITH EPISODIC, CHRONIC MIGRAINE AND RESPONSE TO TREATMENT. PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE IS AN EMERGING NEUROPEPTIDE INVOLVED IN MIGRAINE DIAGNOSTICS AND SEVERITY. NEW GENETIC AND EPIGENETIC BIOMARKERS WILL BE CANDIDATES FOR FUTURE RESEARCH. 2021 12 847 24 CHILDHOOD MALTREATMENT AND HEADACHE DISORDERS. CHILDHOOD MALTREATMENT IS SUBSTANTIATED IN 12 % OF CHILDREN, BUT NEARLY 50 % ADULTS RECALL HAVING BEEN NEGLECTED OR ABUSED AS CHILDREN. MALTREATMENT, ESPECIALLY EMOTIONAL ABUSE, IS ASSOCIATED WITH MIGRAINE. DYSREGULATION OF THE HPA AXIS, AUTONOMIC, IMMUNE, AND METABOLIC SYSTEMS APPEARS TO BE A CONSEQUENCE OF MALTREATMENT, AND IS ALSO REPORTED IN MIGRAINE. AREAS OF THE BRAIN STRUCTURALLY AND FUNCTIONALLY AFFECTED BY CHILDHOOD ABUSE AND BY MIGRAINE ARE ALSO SIMILAR, AND INCLUDE THE LIMBIC SYSTEM STRUCTURES, WHICH CONNECT TO PAIN REGIONS IN THE BRAINSTEM. PUTATIVE MECHANISMS BY WHICH EARLY LIFE STRESS INCREASES THE LIKELIHOOD OF DEVELOPING MIGRAINE INCLUDE GENE X ENVIRONMENT INTERACTIONS, IN ADDITION TO EPIGENETIC MODIFICATIONS VIA DNA METHYLATION. THESE MODIFICATIONS ARE STABLE AND MAY BE TRANSFERRED ACROSS GENERATIONS, BUT THEY MAY ALSO BE REVERSED BY SOME MEDICATIONS COMMONLY USED IN MIGRAINE, INCLUDING VALPROIC ACID AND TOPIRAMATE. 2016 13 5644 14 SEX AND THE MIGRAINE BRAIN. THE BRAIN RESPONDS DIFFERENTLY TO ENVIRONMENTAL AND INTERNAL SIGNALS THAT RELATE TO THE STAGE OF DEVELOPMENT OF NEURAL SYSTEMS. WHILE GENETIC AND EPIGENETIC FACTORS CONTRIBUTE TO A PREMORBID STATE, HORMONAL FLUCTUATIONS IN WOMEN MAY ALTER THE SET POINT OF MIGRAINE. THE CYCLIC SURGES OF GONADAL HORMONES MAY DIRECTLY ALTER NEURONAL, GLIAL AND ASTROCYTE FUNCTION THROUGHOUT THE BRAIN. ESTROGEN IS MAINLY EXCITATORY AND PROGESTERONE INHIBITORY ON BRAIN NEURONAL SYSTEMS. THESE CHANGES CONTRIBUTE TO THE ALLOSTATIC LOAD OF THE MIGRAINE CONDITION THAT MOST NOTABLY STARTS AT PUBERTY IN GIRLS. 2014 14 2029 21 EPIGENETIC CHANGES IN HEADACHE. INTRODUCTION: MULTIPLE FACTORS, INCLUDING BOTH GENETIC AND ENVIRONMENTAL MECHANISMS, APPEAR TO PLAY A ROLE IN THE AETIOLOGY OF HEADACHE. AN INTERESTING AREA OF STUDY IS THE POSSIBLE INVOLVEMENT OF EPIGENETIC MECHANISMS IN HEADACHE DEVELOPMENT AND THE TRANSFORMATION TO CHRONIC HEADACHE, AND THE POTENTIAL ROLE OF THESE FACTORS AS A THERAPEUTIC TARGET. METHODS: WE PERFORMED A LITERATURE REVIEW OF THE INVOLVEMENT OF DIFFERENT EPIGENETIC MECHANISMS IN HEADACHE, MAINLY USING THE MEDLINE/PUBMED DATABASE. TO THIS END, WE USED THE FOLLOWING ENGLISH SEARCH TERMS: HEADACHE, MIGRAINE, EPIGENETICS, DNA METHYLATION, HISTONES, NON-CODING RNA, AND MIRNA. RESULTS: A TOTAL OF 15 ENGLISH-LANGUAGE PUBLICATIONS RELATED TO THE ABOVE TERMS WERE OBTAINED. CONCLUSION: THERE IS LIMITED BUT CONSISTENT EVIDENCE OF THE RELATIONSHIP BETWEEN EPIGENETICS AND HEADACHE; IT IS THEREFORE ESSENTIAL TO CONTINUE RESEARCH OF EPIGENETIC CHANGES IN HEADACHE. THIS MAY HELP TO UNDERSTAND THE PATHOPHYSIOLOGY OF HEADACHE AND EVEN TO IDENTIFY CANDIDATE BIOMARKERS AND NEW, MORE EFFECTIVE, THERAPEUTIC TARGETS. 2021 15 6859 24 [NUTRITIONAL FACTORS ASSOCIATED WITH MIGRAINE]. MIGRAINE IS A CHRONIC, HIGHLY PREVALENT, MULTIDIMENSIONAL, AND COMPLEX DISORDER, INFLUENCED BY GENETIC AND ENVIRONMENTAL FACTORS, AMONG WHICH IS THE DIET. MEDICAL TREATMENTS ARE PARTIALLY EFFECTIVE, AND THAT MAKES NECESSARY TO COMPLEMENT THEM WITH OTHER THERAPEUTIC STRATEGIES. THE NUTRITION PLAYS A PREVALENT ROLE. WE WILL REVIEW DIETARY FACTORS THAT HAVE BEEN LINKED TO MIGRAINE AND THERAPEUTIC NUTRITIONAL GUIDELINES ABOUT IT: ELIMINATION, INTEGRAL, KETOGENIC, EPIGENETIC AND HYPOCALORIC DIETS, AS WELL AS DIETS THAT INTEREST FATTY ACIDS, SODIUM, VITAMINS, AND THE GUT-BRAIN AXIS. TO DATE, THE EVIDENCE OF THE EFFICACY OF NUTRITIONAL TREATMENTS FOR MIGRAINE IS NOT WIDESPREAD AND IT IS NECESSARY TO ADVISE OUR PATIENTS ABOUT PATTERNS CONSISTENT WITH NUTRITIONAL GENERAL RECOMMENDATIONS. 2022 16 3334 33 HISTONE DEACETYLASE INHIBITORS COUNTERACT CGRP SIGNALING AND PRONOCICEPTIVE SENSITIZATION IN A RAT MODEL OF MEDICATION OVERUSE HEADACHE. CHRONIC TRIPTAN EXPOSURE IN RODENTS RECAPITULATES MEDICATION OVERUSE HEADACHE (MOH), CAUSING CEPHALIC PAIN SENSITIZATION AND TRIGEMINAL GANGLION OVEREXPRESSION OF PRONOCICEPTIVE PROTEINS INCLUDING CGRP. BECAUSE OF THESE TRANSCRIPTIONAL DERANGEMENTS, AS WELL AS THE EMERGING ROLE OF EPIGENETICS IN CHRONIC PAIN, IN THE PRESENT STUDY, WE EVALUATED THE EFFECTS OF THE HISTONE DEACETYLASE INHIBITORS (HDACIS) PANOBINOSTAT AND GIVINOSTAT, IN RATS CHRONICALLY EXPOSED TO ELETRIPTAN FOR 1 MONTH. BOTH PANOBINOSTAT AND GIVINOSTAT COUNTERACTED OVEREXPRESSION OF GENES CODING FOR CGRP AND ITS RECEPTOR SUBUNIT RAMP1, HAVING NO EFFECTS ON CLR AND RCP RECEPTOR SUBUNITS IN THE TRIGEMINAL GANGLION (TG) OF ELETRIPTAN-EXPOSED RATS. WITHIN THE TRIGEMINAL NUCLEUS CAUDALIS (TNC), TRANSCRIPTS FOR THESE GENES WERE NEITHER UPREGULATED BY ELETRIPTAN NOR ALTERED BY CONCOMITANT TREATMENT WITH PANOBINOSTAT OR GIVINOSTAT. HDACIS COUNTERACTED HYPERSENSITIVITY TO CAPSAICIN-INDUCED VASODILATATION IN THE TRIGEMINAL TERRITORY, AS WELL AS PHOTOPHOBIC BEHAVIOR AND CEPHALIC ALLODYNIAIN ELETRIPTAN-EXPOSED RATS. ELETRIPTAN DID NOT AFFECT CGRP, CLR, AND RAMP1 EXPRESSION IN CULTURED TRIGEMINAL GANGLIA, WHEREAS BOTH INHIBITORS REDUCED TRANSCRIPTS FOR CLR AND RAMP-1. THE DRUGS, HOWEVER, INCREASED LUCIFERASE EXPRESSION DRIVEN BY CGRP PROMOTER IN CULTURED CELLS. OUR FINDINGS PROVIDE EVIDENCE FOR A KEY ROLE OF HDACS AND EPIGENETICS IN MOH PATHOGENESIS, HIGHLIGHTING THE THERAPEUTIC POTENTIAL OF HDAC INHIBITION IN THE PREVENTION OF MIGRAINE CHRONIFICATION. PERSPECTIVE: THE PRESENT STUDY HIGHLIGHTS A KEY EPIGENETIC ROLE OF HDAC IN THE RODENT MODEL OF MEDICATION OVERUSE HEADACHE, FURTHERING OUR UNDERSTANDING OF THE MOLECULAR MECHANISMS RESPONSIBLE FOR PRONOCICEPTIVE SENSITIZATION DURING HEADACHE CHRONIFICATION. 2022 17 6846 30 [MIGRAINE: IGNITION OF THE BRAIN]. ALTHOUGH OUR KNOWLEDGE OF WHICH SYSTEMS ARE ACTIVATED DURING MIGRAINE IS REASONABLY COMPLETE, WHY THE SYSTEM IS ACTIVATED REMAINS UNKNOWN. INCORPORATING THE FINDINGS OBTAINED IN STUDIES ON PAIN IN GENERAL HAS ALLOWED A MORE INTEGRATED MODEL TO BE GENERATED. ACCORDING TO THIS NEW MODEL, THERE IS AN ANATOMICAL SUBSTRATE CONSISTING IN A COMPLEX FRAMEWORK OF PAIN THAT IS MADE UP NOT ONLY OF THE TRIGEMINOVASCULAR SYSTEM (END PATHWAY) BUT OF A NUMBER OF NETWORKS THAT ARE IN TURN CONNECTED TO ONE ANOTHER, LIKE THE NEUROLIMBIC, THE ASCENDING AND DESCENDING MODULATORY SYSTEM. THIS COMPLEX NETWORK IS RESPONSIBLE FOR MODULATING AND CONVEYING NOCICEPTIVE SIGNALS. IN PATIENTS WITH MIGRAINE, HYPEREXCITABILITY OF THIS FRAMEWORK IS CONDITIONED BY GENETIC AND EPIGENETIC ALTERATIONS. EPIGENETIC CHANGES ARE CHEMICAL MODIFICATIONS AFFECTING CHROMATIN, WHICH MODULATES THE ACTIVITY OF GENES WITHOUT MODIFYING THE DNA SEQUENCE, AND WHICH ARE CAPABLE OF MODULATING THE EXPRESSION OF GENES INVOLVED IN A NUMBER OF DIFFERENT ASPECTS, SUCH AS PLASTICITY, SYSTEM EXCITABILITY, MEMORY OF PAIN OR MOODS. IN TURN, THE PRESENCE OF EXTERNAL FACTORS (SUCH AS ENVIRONMENTAL CHANGES OR ALCOHOL) AND INTERNAL FACTORS (SUCH AS HORMONES OR SLEEP DISORDERS) CONTRIBUTE TO ACTIVATE THIS LOADED ANATOMICAL SUBSTRATE, RESULTING IN THE ATTACK OF MIGRAINE. 2013 18 63 40 A HIGH METHYLATION LEVEL OF A NOVEL -284 BP CPG ISLAND IN THE RAMP1 GENE PROMOTER IS POTENTIALLY ASSOCIATED WITH MIGRAINE IN WOMEN. MIGRAINE IS A COMPLEX NEUROVASCULAR DISORDER AFFECTING ONE BILLION PEOPLE WORLDWIDE, MAINLY FEMALES. IT IS CHARACTERIZED BY ATTACKS OF MODERATE TO SEVERE HEADACHE PAIN, WITH ASSOCIATED SYMPTOMS. RECEPTOR ACTIVITY MODIFYING PROTEIN (RAMP1) IS PART OF THE CALCITONIN GENE-RELATED PEPTIDE (CGRP) RECEPTOR, A PHARMACOLOGICAL TARGET FOR MIGRAINE. EPIGENETIC PROCESSES, SUCH AS DNA METHYLATION, PLAY A ROLE IN CLINICAL PRESENTATION OF VARIOUS DISEASES. DNA METHYLATION OCCURS MOSTLY IN THE GENE PROMOTER AND CAN CONTROL GENE EXPRESSION. WE INVESTIGATED THE METHYLATION STATE OF THE RAMP1 PROMOTER IN 104 FEMALE BLOOD DNA SAMPLES: 54 MIGRAINEURS AND 50 CONTROLS. WE TREATED DNA WITH SODIUM BISULFITE AND PERFORMED PCR, SANGER SEQUENCING, AND EPIGENETIC SEQUENCING METHYLATION (ESME) SOFTWARE ANALYSIS. WE IDENTIFIED 51 CPG DINUCLEOTIDES, AND 5 SHOWED METHYLATION VARIABILITY. MIGRAINEURS HAD A HIGHER NUMBER OF INDIVIDUALS WITH ALL FIVE CPG METHYLATED WHEN COMPARED TO CONTROLS (26% VS. 16%), ALTHOUGH NON-SIGNIFICANT (P = 0.216). WE ALSO FOUND THAT CPG -284 BP, RELATED TO THE TRANSCRIPTION START SITE (TSS), SHOWED HIGHER METHYLATION LEVELS IN CASES (P = 0.011). THIS CPG MAY POTENTIALLY PLAY A ROLE IN MIGRAINE, AFFECTING RAMP1 TRANSCRIPTION OR RECEPTOR MALFUNCTIONING AND/OR ALTERED CGRP BINDING. WE HOPE TO CONFIRM THIS FINDING IN A LARGER COHORT AND ESTABLISH AN EPIGENETIC BIOMARKER TO PREDICT FEMALE MIGRAINE RISK. 2022 19 4649 40 NEUROPEPTIDES AND NEUROPEPTIDE RECEPTORS: DRUG TARGETS, AND PEPTIDE AND NON-PEPTIDE LIGANDS: A TRIBUTE TO PROF. DIETER SEEBACH. THE NUMBER OF NEUROPEPTIDES AND THEIR CORRESPONDING RECEPTORS HAS INCREASED STEADILY OVER THE LAST FOURTY YEARS: INITIALLY, PEPTIDES WERE ISOLATED FROM GUT OR BRAIN (E.G., SUBSTANCE P, SOMATOSTATIN), THEN BY TARGETED MINING IN SPECIFIC REGIONS (E.G., CORTISTATIN, OREXIN IN THE BRAIN), OR BY DEORPHANIZATION OF G-PROTEIN-COUPLED RECEPTORS (GPCRS; OREXIN, GHRELIN RECEPTORS) AND THROUGH THE COMPLETION THE HUMAN GENOME PROJECT. NEUROPEPTIDES (AND THEIR RECEPTORS) HAVE REGIONALLY RESTRICTED DISTRIBUTIONS IN THE CENTRAL AND PERIPHERAL NERVOUS SYSTEM. THE NEUROPEPTIDE SIGNALING IS SOMEWHAT MORE DISTINCT SPATIALLY THAN SIGNALING WITH CLASSICAL, LOW-MOLECULAR-WEIGHT NEUROTRANSMITTERS THAT ARE MORE WIDELY EXPRESSED, AND, THEREFORE, ONE ASSUMES THAT DRUGS ACTING AT NEUROPEPTIDE RECEPTORS MAY HAVE MORE SELECTIVE PHARMACOLOGICAL ACTIONS WITH POSSIBLY FEWER SIDE EFFECTS THAN DRUGS ACTING ON GLUTAMATERGIC, GABAERGIC, MONOAMINERGIC, OR CHOLINERGIC SYSTEMS. NEUROPEPTIDE RECEPTORS, WHICH MAY HAVE A FEW OR MULTIPLE SUBTYPES AND SPLICE VARIANTS, BELONG ALMOST EXCLUSIVELY TO THE GPCR FAMILY ALSO KNOWN AS SEVEN-TRANSMEMBRANE RECEPTORS (7TM), A FAVORITE CLASS OF DRUG TARGETS IN THE PHARMACEUTICAL INDUSTRY. MOST NEUROPEPTIDES ARE CO-STORED AND CO-RELEASED WITH CLASSIC NEUROTRANSMITTERS, ALBEIT OFTEN ONLY AT HIGHER FREQUENCIES OF STIMULATION OR AT BURSTING ACTIVITY, THUS RESTRICTING THE NEUROPEPTIDE SIGNALING TO SPECIFIC CIRCUMSTANCES, ANOTHER REASON TO ASSUME THAT NEUROPEPTIDE DRUG MIMICS MAY HAVE LESS SIDE EFFECTS. NEUROPEPTIDES POSSESS A WIDE SPECTRUM OF FUNCTIONS FROM NEUROHORMONE, NEUROTRANSMITTER TO GROWTH FACTOR, BUT ALSO AS KEY INFLAMMATORY MEDIATORS. NEUROPEPTIDES BECOME 'ACTIVE' WHEN THE NERVOUS SYSTEM IS CHALLENGED, E.G., BY STRESS, INJURY, DRUG ABUSE, OR NEUROPSYCHIATRIC DISORDERS WITH GENETIC, EPIGENETIC, AND/OR ENVIRONMENTAL COMPONENTS. THE UNSUSPECTED NUMBER OF TRUE NEUROPEPTIDES AND THEIR COGNATE RECEPTORS PROVIDES OPPORTUNITIES TO IDENTIFY NOVEL TARGETS FOR THE TREATMENT OF BOTH CENTRAL AND PERIPHERAL NERVOUS SYSTEM DISORDERS. BOTH, RECEPTOR SUBTYPE-SELECTIVE ANTAGONISTS AND AGONISTS ARE BEING DEVELOPED, AS ILLUSTRATED BY THE SUCCESS OF SOMATOSTATIN AGONISTS, ANGIOTENSIN, AND ENDOTHELIN ANTAGONISTS, AND THE EXPECTED CLINICAL APPLICATIONS OF NK-1/2/3 (SUBSTANCE P) RECEPTOR ANTAGONISTS, CRF, VASOPRESSIN, NPY, NEUROTENSIN, OREXIN ANTAGONISTS, OR NEUROPEPTIDE RECEPTOR MODULATORS; SUCH LIGANDS HAVE EFFICACY IN PRECLINICAL OR CLINICAL MODELS OF PAIN AND NEUROPSYCHIATRIC DISEASES, SUCH AS MIGRAINE, CHRONIC/NEUROPATHIC PAIN, ANXIETY, SLEEP DISORDERS, DEPRESSION, AND SCHIZOPHRENIA. IN ADDITION, BOTH POSITIVE AND NEGATIVE ALLOSTERIC MODULATORS HAVE BEEN DESCRIBED WITH INTERESTING IN VIVO ACTIVITIES (E.G., AT GALANIN RECEPTORS). THE FIELD HAS BECOME MORE COMPLEX NOW THAT AN INCREASING NUMBER OF HETEROMERIC NEUROPEPTIDE RECEPTORS ARE DESCRIBED, E.G., GHRELIN RECEPTORS WITH 5-HT(2C) OR DOPAMINE D(1), D(2) RECEPTORS. AT LONG LAST, STRUCTURE-BASED DRUG DISCOVERY CAN NOW BE ENVISAGED WITH CONFIDENCE, SINCE CRYSTAL OR SOLUTION STRUCTURE OF GPCRS AND GPCR-LIGAND COMPLEXES, INCLUDING PEPTIDE RECEPTORS, ARE PUBLISHED ALMOST ON A MONTHLY BASIS. FINALLY, ALTHOUGH MOST COMPOUNDS ACTING AT PEPTIDE RECEPTORS ARE STILL PEPTIDOMIMETICS, THE LAST DECADE HAS SEEN THE EMERGENCE OF LOW-MOLECULAR-WEIGHT NONPEPTIDE LIGANDS (E.G., FOR OREXIN, GHRELIN, OR NEUROKININ RECEPTORS), AND SURPRISING PROGRESS HAS BEEN MADE WITH BETA- AND GAMMA-PEPTIDES AS VERY STABLE AND POTENT MIMETICS OF, E.G., SOMATOSTATIN (SRIF), WHERE THE NATIVE SRIF HAS A HALF-LIFE LIMITED TO 2-3 MIN. THIS LAST POINT WILL BE ILLUSTRATED MORE SPECIFICALLY, AS WE HAVE HAD A LONG-STANDING COLLABORATION WITH PROF. D. SEEBACH TO WHOM THIS REVIEW IS DEDICATED AT THE OCCASION OF HIS 75TH BIRTHDAY. 2012 20 1111 31 COMMON MICRORNAS IN EPILEPSY AND MIGRAINE: THEIR POSSIBILITY AS CANDIDATES FOR BIOMARKERS AND THERAPEUTIC TARGETS DURING COMORBID ONSET OF BOTH CONDITIONS. EPILEPSY AND MIGRAINE ARE CHRONIC NEUROLOGICAL DISORDERS WITH SHARED CLINICAL AS WELL AS PATHOPHYSIOLOGICAL MECHANISMS. EPILEPTIC PATIENTS ARE AT A HIGHER RISK OF DEVELOPING MIGRAINE COMPARED TO NORMAL INDIVIDUALS AND VICE VERSA. SEVERAL GENETIC AND ENVIRONMENTAL RISK FACTORS HAVE BEEN REPORTED TO BE ASSOCIATED WITH THE DEVELOPMENT OF BOTH DISEASES. PREVIOUS STUDIES HAVE ALREADY ESTABLISHED STANDARD GENETIC MARKERS INVOLVED IN VARIOUS PATHWAYS IMPLICATED IN THE PATHOGENESIS OF BOTH THESE COMORBID CONDITIONS. IN ADDITION TO GENETIC MARKERS, EPIGENETIC MARKERS HAVE ALSO BEEN FOUND TO BE INVOLVED IN THE PATHOGENESIS OF EPILEPSY AND MIGRAINE. AMONG THE EPIGENETIC MARKERS, MIRNAS HAVE BEEN EXPLORED AT LENGTH AND HAVE EMERGED AS SIGNIFICANT PLAYERS IN REGULATING THE EXPRESSION OF THEIR TARGET GENES. MIRNAS LIKE MIR-22, MIR-34A, MIR-155, MIR-211, AND LET-7B PLAY A SIGNIFICANT ROLE IN NEURONAL DIFFERENTIATION AND SEEM TO BE ASSOCIATED WITH EPILEPSY AND MIGRAINE AS COMORBID CONDITIONS. HOWEVER, THE EXACT SHARED MECHANISMS UNDERLYING THE ROLE OF THESE MIRNAS IN THESE COMORBID CONDITIONS ARE STILL UNCLEAR. THE CURRENT REVIEW HAS BEEN COMPILED WITH AN AIM TO EXPLORE COMMON MICRORNAS TARGETING THE GENES INVOLVED IN SHARED MOLECULAR PATHWAYS LEADING TO EPILEPSY AND MIGRAINE AS COMORBID CONDITIONS. THE NEW CLASS OF NCRNAS, I.E., TRNA TRANSFER FRAGMENTS, ARE ALSO DISCUSSED. IN ADDITION, THEIR ROLE AS POTENTIAL BIOMARKERS AND THERAPEUTIC TARGETS HAS ALSO BEEN EVALUATED. HOWEVER, LIMITATIONS EXIST, AND BASED ON THE CURRENT LITERATURE AVAILABLE, ONLY A FEW MICRORNAS SEEM TO BE INVOLVED IN THE PATHOGENESIS OF BOTH THESE DISORDERS. 2023