1 2116 130 EPIGENETIC HISTONE DEACETYLATION INHIBITION PREVENTS THE DEVELOPMENT AND PERSISTENCE OF TEMPORAL LOBE EPILEPSY. EPILEPSY IS A CHRONIC BRAIN DISEASE CHARACTERIZED BY REPEATED UNPROVOKED SEIZURES. CURRENTLY, NO DRUG THERAPY EXISTS FOR CURING EPILEPSY OR DISEASE MODIFICATION IN PEOPLE AT RISK. DESPITE SEVERAL EMERGING MECHANISMS, THERE HAVE BEEN FEW STUDIES OF EPIGENETIC SIGNALING IN EPILEPTOGENESIS, THE PROCESS WHEREBY A NORMAL BRAIN BECOMES PROGRESSIVELY EPILEPTIC BECAUSE OF PRECIPITATING FACTORS. HERE, WE REPORT A NOVEL ROLE OF HISTONE DEACETYLATION AS A CRITICAL EPIGENETIC MECHANISM IN EPILEPTOGENESIS. EXPERIMENTS WERE CONDUCTED USING THE HISTONE DEACETYLASE (HDAC) INHIBITOR SODIUM BUTYRATE IN THE HIPPOCAMPUS KINDLING MODEL OF TEMPORAL LOBE EPILEPSY (TLE), A CLASSIC MODEL HEAVILY USED TO APPROVE DRUGS FOR TREATMENT OF EPILEPSY. DAILY TREATMENT WITH BUTYRATE SIGNIFICANTLY INHIBITED HDAC ACTIVITY AND RETARDED THE DEVELOPMENT OF LIMBIC EPILEPTOGENESIS WITHOUT AFFECTING AFTER-DISCHARGE SIGNAL. HDAC INHIBITION MARKEDLY IMPAIRED THE PERSISTENCE OF SEIZURE EXPRESSION MANY WEEKS AFTER EPILEPSY DEVELOPMENT. MOREOVER, SUBCHRONIC HDAC INHIBITION FOR 2 WEEKS RESULTED IN A STRIKING RETARDATION OF EPILEPTOGENESIS. HDAC INHIBITION, UNEXPECTEDLY, ALSO SHOWED ERASURE OF THE EPILEPTOGENIC STATE IN EPILEPTIC ANIMALS. FINALLY, BUTYRATE-TREATED ANIMALS EXHIBITED A POWERFUL REDUCTION IN MOSSY FIBER SPROUTING, A MORPHOLOGIC INDEX OF EPILEPTOGENESIS. TOGETHER THESE RESULTS UNDERSCORE THAT HDAC INHIBITION PREVENTS THE DEVELOPMENT OF TLE, INDICATING HDAC'S CRITICAL SIGNALING ROLE IN EPILEPTOGENESIS. THESE FINDINGS, THEREFORE, ENVISAGE A UNIQUE NOVEL THERAPY FOR PREVENTING OR CURING EPILEPSY BY TARGETING THE EPIGENETIC HDAC PATHWAY. 2018 2 5617 43 SARCOSINE SUPPRESSES EPILEPTOGENESIS IN RATS WITH EFFECTS ON HIPPOCAMPAL DNA METHYLATION. EPILEPTOGENESIS IS A COMMON CONSEQUENCE OF BRAIN INSULTS, HOWEVER, THE PREVENTION OR DELAY OF THE EPILEPTOGENIC PROCESS REMAINS AN IMPORTANT UNMET MEDICAL CHALLENGE. OVEREXPRESSION OF GLYCINE TRANSPORTER 1 (GLYT1) IS PROPOSED AS A PATHOLOGICAL HALLMARK IN THE HIPPOCAMPUS OF PATIENTS WITH TEMPORAL LOBE EPILEPSY (TLE), AND WE PREVIOUSLY DEMONSTRATED IN RODENT EPILEPSY MODELS THAT AUGMENTATION OF GLYCINE SUPPRESSED CHRONIC SEIZURES AND ALTERED ACUTE SEIZURE THRESHOLDS. IN THE PRESENT STUDY WE EVALUATED THE EFFECT OF THE GLYT1 INHIBITOR, SARCOSINE (AKA N-METHYLGLYCINE), ON EPILEPTOGENESIS AND ALSO INVESTIGATED POSSIBLE MECHANISMS. WE DEVELOPED A MODIFIED RAPID KINDLING MODEL OF EPILEPTOGENESIS IN RATS COMBINED WITH SEIZURE SCORE MONITORING TO EVALUATE THE ANTIEPILEPTOGENIC EFFECT OF SARCOSINE. WE USED IMMUNOHISTOCHEMISTRY AND WESTERN BLOT ANALYSIS FOR THE EVALUATION OF GLYT1 EXPRESSION AND EPIGENETIC CHANGES OF 5-METHYLCYTOSINE (5MC) AND 5-HYDROXYMETHYLCYTOSINE (5HMC) IN THE EPILEPTOGENIC HIPPOCAMPI OF RATS, AND FURTHER EVALUATED EXPRESSION CHANGES IN ENZYMES INVOLVED IN THE REGULATION OF DNA METHYLATION, TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 1 (TET1), DNA-METHYLTRANSFERASE 1 (DNMT1), AND DNMT3A. OUR RESULTS DEMONSTRATED: (I) EXPERIMENTAL EVIDENCE THAT SARCOSINE (3 G/KG, I.P. DAILY) SUPPRESSED KINDLING EPILEPTOGENESIS IN RATS; (II) THE SARCOSINE-INDUCED ANTIEPILEPTOGENIC EFFECT WAS ACCOMPANIED BY A SUPPRESSED HIPPOCAMPAL GLYT1 EXPRESSION AS WELL AS A REDUCTION OF HIPPOCAMPAL 5MC LEVELS AND A CORRESPONDING INCREASE IN 5HMC; AND (III) SARCOSINE TREATMENT CAUSED DIFFERENTIAL EXPRESSION CHANGES OF TET1 AND DNMTS. TOGETHER, THESE FINDINGS SUGGEST THAT SARCOSINE HAS UNPRECEDENTED DISEASE-MODIFYING PROPERTIES IN A KINDLING MODEL OF EPILEPTOGENESIS IN RATS, WHICH WAS ASSOCIATED WITH ALTERED HIPPOCAMPAL DNA METHYLATION. THUS, MANIPULATION OF THE GLYCINE SYSTEM IS A POTENTIAL THERAPEUTIC APPROACH TO ATTENUATE THE DEVELOPMENT OF EPILEPSY. 2020 3 5852 23 SUBLIMINAL (LATENT) PROCESSING OF PAIN AND ITS EVOLUTION TO CONSCIOUS AWARENESS. BY UNCONSCIOUS OR COVERT PROCESSING OF PAIN WE REFER TO NASCENT INTERACTIONS THAT AFFECT THE EVENTUAL DELIVERANCE OF PAIN AWARENESS. THUS, INTERNAL PROCESSES (VIZ., REPEATED NOCICEPTIVE EVENTS, INFLAMMATORY KINDLING, REORGANIZATION OF BRAIN NETWORKS, GENETIC) OR EXTERNAL PROCESSES (VIZ., ENVIRONMENT, SOCIOECONOMIC LEVELS, MODULATION OF EPIGENETIC STATUS) CONTRIBUTE TO ENHANCING OR INHIBITING THE PRESENTATION OF PAIN AWARENESS. HERE WE PUT FORWARD THE NOTION THAT FOR MANY PATIENTS, ONGOING SUB-CONSCIOUS CHANGES IN BRAIN FUNCTION ARE SIGNIFICANT PLAYERS IN THE EVENTUAL MANIFESTATION OF CHRONIC PAIN. IN THIS REVIEW, WE PROVIDE CLINICAL EXAMPLES OF NASCENT OR WHAT WE TERM PRE-PAIN PROCESSES AND THE NEUROBIOLOGICAL MECHANISMS OF HOW THESE CHANGES MAY CONTRIBUTE TO PAIN, BUT ALSO POTENTIAL OPPORTUNITIES TO DEFINE THE PROCESS FOR EARLY THERAPEUTIC INTERVENTIONS. 2018 4 2449 40 EPIGENETIC SUPPRESSION OF HIPPOCAMPAL CALBINDIN-D28K BY DELTAFOSB DRIVES SEIZURE-RELATED COGNITIVE DEFICITS. THE CALCIUM-BINDING PROTEIN CALBINDIN-D28K IS CRITICAL FOR HIPPOCAMPAL FUNCTION AND COGNITION, BUT ITS EXPRESSION IS MARKEDLY DECREASED IN VARIOUS NEUROLOGICAL DISORDERS ASSOCIATED WITH EPILEPTIFORM ACTIVITY AND SEIZURES. IN ALZHEIMER'S DISEASE (AD) AND EPILEPSY, BOTH OF WHICH ARE ACCOMPANIED BY RECURRENT SEIZURES, THE SEVERITY OF COGNITIVE DEFICITS REFLECTS THE DEGREE OF CALBINDIN REDUCTION IN THE HIPPOCAMPAL DENTATE GYRUS (DG). HOWEVER, DESPITE THE IMPORTANCE OF CALBINDIN IN BOTH NEURONAL PHYSIOLOGY AND PATHOLOGY, THE REGULATORY MECHANISMS THAT CONTROL ITS EXPRESSION IN THE HIPPOCAMPUS ARE POORLY UNDERSTOOD. HERE WE REPORT AN EPIGENETIC MECHANISM THROUGH WHICH SEIZURES CHRONICALLY SUPPRESS HIPPOCAMPAL CALBINDIN EXPRESSION AND IMPAIR COGNITION. WE DEMONSTRATE THAT DELTAFOSB, A HIGHLY STABLE TRANSCRIPTION FACTOR, IS INDUCED IN THE HIPPOCAMPUS IN MOUSE MODELS OF AD AND SEIZURES, IN WHICH IT BINDS AND TRIGGERS HISTONE DEACETYLATION AT THE PROMOTER OF THE CALBINDIN GENE (CALB1) AND DOWNREGULATES CALB1 TRANSCRIPTION. NOTABLY, INCREASING DG CALBINDIN LEVELS, EITHER BY DIRECT VIRUS-MEDIATED EXPRESSION OR INHIBITION OF DELTAFOSB SIGNALING, IMPROVES SPATIAL MEMORY IN A MOUSE MODEL OF AD. MOREOVER, LEVELS OF DELTAFOSB AND CALBINDIN EXPRESSION ARE INVERSELY RELATED IN THE DG OF INDIVIDUALS WITH TEMPORAL LOBE EPILEPSY (TLE) OR AD AND CORRELATE WITH PERFORMANCE ON THE MINI-MENTAL STATE EXAMINATION (MMSE). WE PROPOSE THAT CHRONIC SUPPRESSION OF CALBINDIN BY DELTAFOSB IS ONE MECHANISM THROUGH WHICH INTERMITTENT SEIZURES DRIVE PERSISTENT COGNITIVE DEFICITS IN CONDITIONS ACCOMPANIED BY RECURRENT SEIZURES. 2017 5 510 33 ASSOCIATION OF RASGRF1 METHYLATION WITH EPILEPTIC SEIZURES. DNA METHYLATION, ONE OF THE MECHANISMS OF EPIGENETIC REGULATION, HAS BEEN SUGGESTED TO BE RELATED WITH EPILEPSY. RASGRF1 IS A PATERNALLY IMPRINTED GENE AND HAS A DIFFERENTIALLY METHYLATED REGION (DMR) AT THE PROMOTER THAT CAN SILENCE GENE EXPRESSION. WE HAVE PREVIOUSLY OBSERVED THE DOWN-REGULATION OF RASGRF1 IN THE TEMPORAL NEOCORTEX OF EPILEPSY PATIENTS AND IN THE HIPPOCAMPUS OF EPILEPTIC ANIMALS. HERE, WE FURTHER EXPLORED THE DYNAMIC CHANGE (1-DAY ACUTE PERIOD, 10-DAY LATENT PERIOD AND 45-DAY CHRONIC PHASE) OF DNA METHYLATION AND RASGRF1 EXPRESSION AFTER ACUTE EPILEPTIC SEIZURES IN KAINIC ACID (KA)-TREATED MICE, AND WE OBSERVED THE IMPACT OF N-PHTHALYL-L-TRYPTOPHAN (RG108), A DNA METHYLTRANSFERASE (DNMT) INHIBITOR, ON AN ACUTE EPILEPTIC MODEL BY POLYMERASE CHAIN REACTION (PCR), WESTERN BLOTTING, AND BISULFITE SEQUENCING PCR (BSP). THE RESULTS DIRECTLY SHOWED THAT THE METHYLATION OF THE RASGRF1 PROMOTER GRADUALLY INCREASED AND REACHED A MAXIMAL LEVEL AT THE LATENT PERIOD, WITH SUBSEQUENT SUPPRESSION OF RASGRF1 MRNA AND PROTEIN EXPRESSION LEVELS, WHICH REACHED A MINIMUM LEVEL IN THE CHRONIC PHASE. RG108 INHIBITED THE INCREASED METHYLATION OF THE RASGRF1 GENE, WITH SIGNIFICANT INHIBITION OCCURRING AT THE LATENT PERIOD, AND RESTORED RASGRF1 EXPRESSION LEVELS IN THE CHRONIC PHASE. IN ADDITION, WE DEMONSTRATED THAT RG108 COULD SUPPRESS ACUTE EPILEPTIC SEIZURES IN KA-TREATED MICE AND EPILEPTIC DISCHARGES IN 4-AMINOPYRIDINE (4-AP)-TREATED HIPPOCAMPAL SLICES. THESE FINDINGS DEMONSTRATE THAT RASGRF1 IS CLOSELY ASSOCIATED WITH EPILEPSY VIA THE ABERRANT METHYLATION OF RASGRF1, AND REGULATING THE METHYLATION STATUS OF RELEVANT GENES MIGHT BE AN INTRIGUING TOPIC IN FUTURE RESEARCH ON EPILEPSY. 2017 6 1827 51 EFFECTS OF HISTONE DEACETYLASE INHIBITORS ON THE DEVELOPMENT OF EPILEPSY AND PSYCHIATRIC COMORBIDITY IN WAG/RIJ RATS. EPIGENETIC MECHANISMS, SUCH AS ALTERATIONS IN HISTONE ACETYLATION BASED ON HISTONE DEACETYLASES (HDACS) ACTIVITY, HAVE BEEN LINKED NOT ONLY TO NORMAL BRAIN FUNCTION BUT ALSO TO SEVERAL BRAIN DISORDERS INCLUDING EPILEPSY AND THE EPILEPTOGENIC PROCESS. IN WAG/RIJ RATS, A GENETIC MODEL OF ABSENCE EPILEPSY, EPILEPTOGENESIS AND MILD-DEPRESSION COMORBIDITY, WE INVESTIGATED THE EFFECTS OF TWO HDAC INHIBITORS (HDACI), NAMELY SODIUM BUTYRATE (NAB), VALPROIC ACID (VPA) AND THEIR CO-ADMINISTRATION, ON THE DEVELOPMENT OF ABSENCE SEIZURES AND RELATED PSYCHIATRIC/NEUROLOGIC COMORBIDITIES FOLLOWING TWO DIFFERENT EXPERIMENTAL PARADIGMS. TREATMENT EFFECTS HAVE BEEN EVALUATED BY EEG RECORDINGS (EEG) AND BEHAVIOURAL TESTS AT DIFFERENT TIME POINTS. PROLONGED AND DAILY VPA AND NAB TREATMENT, STARTED BEFORE ABSENCE SEIZURE ONSET (P30), SIGNIFICANTLY REDUCED THE DEVELOPMENT OF ABSENCE EPILEPSY SHOWING ANTIEPILEPTOGENIC EFFECTS. THESE EFFECTS WERE ENHANCED BY NAB/VPA CO-ADMINISTRATION. FURTHERMORE, EARLY-CHRONIC HDACI TREATMENT IMPROVED DEPRESSIVE-LIKE BEHAVIOUR AND COGNITIVE PERFORMANCE 1 MONTH AFTER TREATMENT WITHDRAWAL. WAG/RIJ RATS OF 7 MONTHS OF AGE SHOWED REDUCED ACETYLATED LEVELS OF HISTONE H3 AND H4, ANALYSED BY WESTERN BLOTTING OF HOMOGENIZED BRAIN, IN COMPARISON TO WAG/RIJ BEFORE SEIZURE ONSET (P30). THE BRAIN HISTONE ACETYLATION INCREASED SIGNIFICANTLY DURING TREATMENT WITH NAB OR VPA ALONE AND MORE MARKEDLY DURING CO-ADMINISTRATION. WE ALSO OBSERVED DECREASED EXPRESSION OF BOTH HDAC1 AND 3 FOLLOWING HDACI TREATMENT COMPARED TO CONTROL GROUP. OUR RESULTS SUGGEST THAT HISTONE MODIFICATIONS MAY HAVE A CRUCIAL ROLE IN THE DEVELOPMENT OF EPILEPSY AND EARLY TREATMENT WITH HDACI MIGHT BE A POSSIBLE STRATEGY FOR PREVENTING EPILEPTOGENESIS ALSO AFFECTING BEHAVIOURAL COMORBIDITIES. 2020 7 5497 45 REVIEW: ANIMAL MODELS OF ACQUIRED EPILEPSY: INSIGHTS INTO MECHANISMS OF HUMAN EPILEPTOGENESIS. IN MANY PATIENTS WHO SUFFER FROM EPILEPSIES, RECURRENT EPILEPTIC SEIZURES DO NOT START AT BIRTH BUT DEVELOP LATER IN LIFE. THIS HOLDS PARTICULARLY TRUE FOR EPILEPSIES WITH A FOCAL SEIZURE ORIGIN INCLUDING FOCAL CORTICAL DYSPLASIAS AND TEMPORAL LOBE EPILEPSY (TLE). TLE MOST FREQUENTLY HAS ITS SEIZURE ONSET IN THE HIPPOCAMPAL FORMATION. HIPPOCAMPAL BIOPSIES OF PHARMACORESISTANT TLE PATIENTS UNDERGOING EPILEPSY SURGERY FOR SEIZURE CONTROL MOST FREQUENTLY REVEAL THE DAMAGE PATTERN OF HIPPOCAMPAL SCLEROSIS, THAT IS, SEGMENTAL NEURONAL CELL LOSS AND CONCOMITANT ASTROGLIOSIS. MANY TLE PATIENTS REPORT ON TRANSIENT BRAIN INSULTS EARLY IN LIFE, WHICH IS FOLLOWED BY A 'LATENCY' PERIOD LACKING SEIZURE ACTIVITY OF MONTHS OR EVEN YEARS BEFORE CHRONIC RECURRENT SEIZURES START. THE PLETHORA OF STRUCTURAL AND CELLULAR MECHANISMS THAT CONVERT THE HIPPOCAMPAL FORMATION TO BECOME CHRONICALLY HYPEREXCITABLE AFTER A TRANSIENT INSULT TO THE BRAIN ARE SUMMARIZED UNDER THE TERM EPILEPTOGENESIS. IN CONTRAST TO THE OBSTACLES ARISING FOR EXPERIMENTAL STUDIES OF EPILEPTOGENESIS ASPECTS IN HUMAN SURGICAL HIPPOCAMPAL TISSUE, RECENT ANIMAL MODEL APPROACHES ALLOW INSIGHTS INTO MECHANISMS OF EPILEPTOGENESIS. RELEVANT MODELS OF TRANSIENT BRAIN INSULTS IN THIS CONTEXT COMPRISE SEVERAL DISTINCT TYPES OF LESIONS INCLUDING EXCITOXIC STATUS EPILEPTICUS (SE), ELECTRICAL SEIZURE INDUCTION, TRAUMATIC BRAIN INJURY, INDUCTION OF INFLAMMATORY PROCESSES BY HYPERTHERMIA AND VIRAL INFLAMMATION AND OTHERS. IN PATHOGENETIC TERMS, ABERRANT TRANSCRIPTIONAL AND EPIGENETIC REPROGRAMMING, ACQUIRED CHANNEL- AND SYNAPTOPATHIES, NEURONAL NETWORK AND BLOOD-BRAIN BARRIER DYSFUNCTION AS WELL AS INNATE AND ADAPTIVE IMMUNITY-MEDIATED DAMAGE PLAY MAJOR ROLES. IN SUBSEQUENT STEPS, RESPECTIVE ANIMAL MODELS HAVE BEEN USED IN ORDER TO TEST WHETHER THIS DYNAMIC PROCESS CAN BE EITHER RETARDED OR EVEN ABOLISHED BY INTERFERING WITH EPILEPTOGENIC MECHANISMS. WELL-CONTROLLED SUBSEQUENT ANALYSES OF EPILEPTOGENIC CASCADES CHARACTERIZED IN ANIMAL MODELS USING CAREFULLY STRATIFIED HUMAN HIPPOCAMPAL BIOPSIES TO EXPLOIT THE UNIQUE OPPORTUNITIES GIVEN BY THESE RARE AND PRECIOUS BRAIN TISSUE SAMPLES AIM TO TRANSLATE INTO NOVEL ANTIEPILEPTOGENIC APPROACHES. RESPECTIVE PRECLINICAL TESTS CAN OPEN ENTIRELY NEW PERSPECTIVES FOR TAILOR-MADE TREATMENTS IN PATIENTS WITH THE POTENTIAL TO AVOID THE EMERGENCE OF CHRONIC FOCAL SEIZURE EVENTS. 2018 8 3647 32 INCREASED REELIN PROMOTER METHYLATION IS ASSOCIATED WITH GRANULE CELL DISPERSION IN HUMAN TEMPORAL LOBE EPILEPSY. MESIAL TEMPORAL SCLEROSIS (MTS) IS THE MOST COMMON LESION IN CHRONIC, INTRACTABLE TEMPORAL LOBE EPILEPSIES (TLE) AND CHARACTERIZED BY SEGMENTAL NEURONAL CELL LOSS IN MAJOR HIPPOCAMPAL SEGMENTS. ANOTHER HISTOPATHOLOGICAL HALLMARK INCLUDES GRANULE CELL DISPERSION (GCD), AN ARCHITECTURAL DISTURBANCE OF THE DENTATE GYRUS ENCOUNTERED IN APPROXIMATELY 50% OF PATIENTS WITH MESIAL TEMPORAL SCLEROSIS. REELIN, WHICH PLAYS A KEY ROLE DURING HIPPOCAMPAL DEVELOPMENT AND MAINTENANCE OF LAMINAR ORGANIZATION, IS SYNTHESIZED AND RELEASED BY CAJAL-RETZIUS CELLS OF THE DENTATE MOLECULAR LAYER, AND PREVIOUS STUDIES HAVE SHOWN THAT REELIN TRANSCRIPT LEVELS ARE DOWNREGULATED IN HUMAN TEMPORAL LOBE EPILEPSIES SPECIMENS. TO INVESTIGATE WHETHER EPIGENETIC SILENCING BY REELIN PROMOTER METHYLATION MAY BE AN UNDERLYING PATHOGENETIC MECHANISM OF GCD, DNA WAS HARVESTED FROM 3 MICRODISSECTED HIPPOCAMPAL SUBREGIONS (I.E. MOLECULAR AND GRANULE CELL LAYERS OF THE DENTATE GYRUS AND PRESUBICULUM) FROM 8 MTS SPECIMENS WITH GCD, 5 TLE SAMPLES WITHOUT GCD, AND 3 AUTOPSY CONTROLS. PROMOTER METHYLATION WAS ANALYZED AFTER BISULFITE TREATMENT, CLONING, AND DIRECT SEQUENCING; IMMUNOHISTOCHEMISTRY WAS PERFORMED TO IDENTIFY CAJAL-RETZIUS CELLS. REELIN PROMOTER METHYLATION WAS FOUND TO BE GREATER IN TLE SPECIMENS THAN IN CONTROLS; PROMOTER METHYLATION CORRELATED WITH GCD AMONG TLE SPECIMENS (P < 0.0002). NO OTHER CLINICAL OR HISTOPATHOLOGICAL PARAMETER (I.E. SEX, AGE, SEIZURE DURATION, MEDICATION OR EXTENT, OF MTS) CORRELATED WITH PROMOTER METHYLATION. THESE DATA SUPPORT A COMPROMISED REELIN-SIGNALING PATHWAY AND IDENTIFY PROMOTER METHYLATION AS AN EPIGENETIC MECHANISM IN THE PATHOGENESIS OF TLE. 2009 9 5348 30 RASGRF1, A POTENTIAL METHYLATIC MEDIATOR OF ANTI-EPILEPTOGENESIS? EPILEPTOGENESIS, INDUCED BY STATUS EPILEPTICUS (SE), IS A CHRONIC PROCESS, AND INTERVENTION IN THIS PROGRESS MAY PREVENT CHRONIC EPILEPSY. IT HAS BEEN PROPOSED THAT DNA METHYLATION MIGHT BE RELATED WITH EPILEPTOGENESIS. RASGRF1 HAS A DIFFERENTIALLY METHYLATED REGION AT THE PROMOTER WHICH CAN SILENCE GENE EXPRESSION. WE HAVE PREVIOUSLY OBSERVED THE DOWN-REGULATION OF RASGRF1 IN EPILEPSY PATIENTS AND PROVED THAT HYPERMETHYLATION OF RASGRF1 REACHES MAXIMAL LEVEL AT THE LATENT PERIOD IN MICE AFTER KAINATE-INDUCED SE (KA MICE), WITH CORRESPONDING ALTERATION OF RASGRF1 EXPRESSION. IN THE PRESENT STUDY, N-PHTHALYL-L-TRYPTOPHAN (RG108), A DNA METHYLTRANSFERASE INHIBITOR, WAS APPLIED IN KA MICE AT LATENT PHASE AND THE BEHAVIOR, ELECTROENCEPHALOGRAM AND PATHOLOGICAL CHANGES WERE OBSERVED IN CHRONIC PHASE. METHYLATION AND EXPRESSION OF RASGRF1 WERE DETERMINED BY POLYMERASE CHAIN REACTION (PCR), WESTERN BLOTTING, AND BISULFITE SEQUENCING PCR. THE RESULTS SHOWED THAT THE INCIDENCE OF SPONTANEOUS RECURRENT SEIZURES (SRS) WAS SIGNIFICANTLY LOWER IN THE RG108 GROUP THAN THE NORMAL SALINE (NS) GROUP. SUBGROUP ANALYSIS SHOWED SIGNIFICANT HYPERMETHYLATION AND LOWER EXPRESSION OF RASGRF1 IN THE RG108-SRS SUBGROUP AND THE NS-SRS SUBGROUP BUT NOT IN THE RG108-NSRS (NO SRS) SUBGROUP AND THE NS-NSRS SUBGROUP COMPARED WITH THE CONTROL GROUP. NO SIGNIFICANT DIFFERENCE WAS FOUND BETWEEN THE RG108-SRS AND NS-SRS SUBGROUPS. MEANWHILE, HIPPOCAMPAL NEURONAL LOSS WAS OBSERVED IN RG108-SRS AND NS-SRS SUBGROUPS. WE THUS DEMONSTRATED THAT RG108 COULD MODIFY THE PROGRESSION OF EPILEPTOGENESIS AFTER KA INDUCED SE AND PREVENT CHRONIC EPILEPSY. MEANWHILE, HYPERMETHYLATION OF RASGRF1 AFTER KA INDUCED SE COULD BE REVERSED WITH CORRESPONDING CHANGES OF RASGRF1 EXPRESSION. ADDITIONALLY, WE SPECULATED THAT RASGRF1 MIGHT BE A POTENTIAL EPIGENETIC MEDIATOR IN EPILEPTOGENESIS AND CHRONIC EPILEPSY. 2018 10 239 40 ADENOSINERGIC SIGNALING IN EPILEPSY. DESPITE THE INTRODUCTION OF AT LEAST 20 NEW ANTIEPILEPTIC DRUGS (AEDS) INTO CLINICAL PRACTICE OVER THE PAST DECADES, ABOUT ONE THIRD OF ALL EPILEPSIES REMAIN REFRACTORY TO CONVENTIONAL FORMS OF TREATMENT. IN ADDITION, CURRENTLY USED AEDS HAVE BEEN DEVELOPED TO SUPPRESS NEURONAL HYPEREXCITABILITY, BUT NOT NECESSARILY TO ADDRESS PATHOGENIC MECHANISMS INVOLVED IN EPILEPSY DEVELOPMENT OR PROGRESSION (EPILEPTOGENESIS). FOR THOSE REASONS ENDOGENOUS SEIZURE CONTROL MECHANISMS OF THE BRAIN MAY PROVIDE ALTERNATIVE THERAPEUTIC OPPORTUNITIES. ADENOSINE IS A WELL CHARACTERIZED ENDOGENOUS ANTICONVULSANT AND SEIZURE TERMINATOR OF THE BRAIN. SEVERAL LINES OF EVIDENCE SUGGEST THAT ENDOGENOUS ADENOSINE-MEDIATED SEIZURE CONTROL MECHANISMS FAIL IN CHRONIC EPILEPSY, WHEREAS THERAPEUTIC ADENOSINE AUGMENTATION EFFECTIVELY PREVENTS EPILEPTIC SEIZURES, EVEN THOSE THAT ARE REFRACTORY TO CONVENTIONAL AEDS. NEW FINDINGS DEMONSTRATE THAT DYSREGULATION OF ADENOSINERGIC MECHANISMS ARE INTRICATELY INVOLVED IN THE DEVELOPMENT OF EPILEPSY AND ITS COMORBIDITIES, WHEREAS ADENOSINE-ASSOCIATED EPIGENETIC MECHANISMS MAY PLAY A ROLE IN EPILEPTOGENESIS. THE FIRST GOAL OF THIS REVIEW IS TO DISCUSS HOW MALADAPTIVE CHANGES OF ADENOSINERGIC MECHANISMS CONTRIBUTE TO THE EXPRESSION OF SEIZURES (ICTOGENESIS) AND THE DEVELOPMENT OF EPILEPSY (EPILEPTOGENESIS) BY FOCUSING ON PHARMACOLOGICAL (ADENOSINE RECEPTOR DEPENDENT) AND BIOCHEMICAL (ADENOSINE RECEPTOR INDEPENDENT) MECHANISMS AS WELL AS ON ENZYMATIC AND TRANSPORT BASED MECHANISMS THAT CONTROL THE AVAILABILITY (HOMEOSTASIS) OF ADENOSINE. THE SECOND GOAL OF THIS REVIEW IS TO HIGHLIGHT INNOVATIVE ADENOSINE-BASED OPPORTUNITIES FOR THERAPEUTIC INTERVENTION AIMED AT RECONSTRUCTING NORMAL ADENOSINE FUNCTION AND SIGNALING FOR IMPROVED SEIZURE CONTROL IN CHRONIC EPILEPSY. NEW FINDINGS SUGGEST THAT TRANSIENT ADENOSINE AUGMENTATION CAN HAVE LASTING EPIGENETIC EFFECTS WITH DISEASE MODIFYING AND ANTIEPILEPTOGENIC OUTCOME. THIS ARTICLE IS PART OF THE SPECIAL ISSUE ENTITLED 'PURINES IN NEURODEGENERATION AND NEUROREGENERATION'. 2016 11 6024 34 THE BIOCHEMISTRY AND EPIGENETICS OF EPILEPSY: FOCUS ON ADENOSINE AND GLYCINE. EPILEPSY, ONE OF THE MOST PREVALENT NEUROLOGICAL CONDITIONS, PRESENTS AS A COMPLEX DISORDER OF NETWORK HOMEOSTASIS CHARACTERIZED BY SPONTANEOUS NON-PROVOKED SEIZURES AND ASSOCIATED COMORBIDITIES. CURRENTLY USED ANTIEPILEPTIC DRUGS HAVE BEEN DESIGNED TO SUPPRESS NEURONAL HYPEREXCITABILITY AND THEREBY TO SUPPRESS EPILEPTIC SEIZURES. HOWEVER, THE CURRENT ARMAMENTARIUM OF ANTIEPILEPTIC DRUGS IS NOT EFFECTIVE IN OVER 30% OF PATIENTS, DOES NOT AFFECT THE COMORBIDITIES OF EPILEPSY, AND DOES NOT PREVENT THE DEVELOPMENT AND PROGRESSION OF EPILEPSY (EPILEPTOGENESIS). PREVENTION OF EPILEPSY AND ITS PROGRESSION REMAINS THE HOLY GRAIL FOR EPILEPSY RESEARCH AND THERAPY DEVELOPMENT, REQUIRING NOVEL CONCEPTUAL ADVANCES TO FIND A SOLUTION TO THIS URGENT MEDICAL NEED. THE METHYLATION HYPOTHESIS OF EPILEPTOGENESIS SUGGESTS THAT CHANGES IN DNA METHYLATION ARE IMPLICATED IN THE PROGRESSION OF THE DISEASE. IN PARTICULAR, GLOBAL DNA HYPERMETHYLATION APPEARS TO BE ASSOCIATED WITH CHRONIC EPILEPSY. CLINICAL AS WELL AS EXPERIMENTAL EVIDENCE DEMONSTRATES THAT EPILEPSY AND ITS PROGRESSION CAN BE PREVENTED BY BIOCHEMICAL MANIPULATIONS AND THOSE THAT TARGET PREVIOUSLY UNRECOGNIZED EPIGENETIC FUNCTIONS CONTRIBUTING TO EPILEPSY DEVELOPMENT AND MAINTENANCE OF THE EPILEPTIC STATE. THIS MINI-REVIEW WILL DISCUSS, EPIGENETIC MECHANISMS IMPLICATED IN EPILEPTOGENESIS AND BIOCHEMICAL INTERACTIONS BETWEEN ADENOSINE AND GLYCINE AS A CONCEPTUAL ADVANCE TO UNDERSTAND THE CONTRIBUTION OF MALADAPTIVE CHANGES IN BIOCHEMISTRY AS A MAJOR CONTRIBUTING FACTOR TO THE DEVELOPMENT OF EPILEPSY. NEW FINDINGS BASED ON BIOCHEMICAL MANIPULATION OF THE DNA METHYLOME SUGGEST THAT: (I) EPIGENETIC MECHANISMS PLAY A FUNCTIONAL ROLE IN EPILEPTOGENESIS; AND (II) THERAPEUTIC RECONSTRUCTION OF THE EPIGENOME IS AN EFFECTIVE ANTIEPILEPTOGENIC THERAPY. 2016 12 656 36 BLOCKADE OF THE IL-1R1/TLR4 PATHWAY MEDIATES DISEASE-MODIFICATION THERAPEUTIC EFFECTS IN A MODEL OF ACQUIRED EPILEPSY. WE RECENTLY DISCOVERED THAT FOREBRAIN ACTIVATION OF THE IL-1 RECEPTOR/TOLL-LIKE RECEPTOR (IL-1R1/TLR4) INNATE IMMUNITY SIGNAL PLAYS A PIVOTAL ROLE IN NEURONAL HYPEREXCITABILITY UNDERLYING SEIZURES IN RODENTS. SINCE THIS PATHWAY IS ACTIVATED IN NEURONS AND GLIA IN HUMAN EPILEPTOGENIC FOCI, IT REPRESENTS A POTENTIAL TARGET FOR DEVELOPING DRUGS INTERFERING WITH THE MECHANISMS OF EPILEPTOGENESIS THAT LEAD TO SPONTANEOUS SEIZURES. THE LACK OF SUCH DRUGS REPRESENTS A MAJOR UNMET CLINICAL NEED. WE TESTED THEREFORE NOVEL THERAPIES INHIBITING THE IL-1R1/TLR4 SIGNALING IN AN ESTABLISHED MURINE MODEL OF ACQUIRED EPILEPSY. WE USED AN EPIGENETIC APPROACH BY INJECTING A SYNTHETIC MIMIC OF MICRO(MI)RNA-146A THAT IMPAIRS IL1R1/TLR4 SIGNAL TRANSDUCTION, OR WE BLOCKED RECEPTOR ACTIVATION WITH ANTIINFLAMMATORY DRUGS. BOTH INTERVENTIONS WHEN TRANSIENTLY APPLIED TO MICE AFTER EPILEPSY ONSET, PREVENTED DISEASE PROGRESSION AND DRAMATICALLY REDUCED CHRONIC SEIZURE RECURRENCE, WHILE THE ANTICONVULSANT DRUG CARBAMAZEPINE WAS INEFFECTIVE. WE CONCLUDE THAT IL-1R1/TLR4 IS A NOVEL POTENTIAL THERAPEUTIC TARGET FOR ATTAINING DISEASE-MODIFICATIONS IN PATIENTS WITH DIAGNOSED EPILEPSY. 2017 13 5345 40 RAPID CHANGES IN EXPRESSION OF CLASS I AND IV HISTONE DEACETYLASES DURING EPILEPTOGENESIS IN MOUSE MODELS OF TEMPORAL LOBE EPILEPSY. A PROMINENT ROLE OF EPIGENETIC MECHANISMS IN MANIFESTATION OF EPILEPSY HAS BEEN PROPOSED. THUS ALTERED HISTONE H3 AND H4 ACETYLATION HAS BEEN DEMONSTRATED IN EXPERIMENTAL MODELS OF TEMPORAL LOBE EPILEPSY (TLE). WE NOW INVESTIGATED CHANGES IN THE EXPRESSION OF THE CLASS I AND CLASS IV HISTONE DEACETYLASES (HDAC) IN TWO COMPLEMENTARY MOUSE TLE MODELS. UNILATERAL INTRAHIPPOCAMPAL INJECTION OF KAINIC ACID (KA) INDUCED A STATUS EPILEPTICUS LASTING 6 TO 24H, DEVELOPMENT OF SPONTANEOUS LIMBIC SEIZURES (2 TO 3 DAYS AFTER KA INJECTION) AND CHRONIC EPILEPSY, AS REVEALED BY TELEMETRIC RECORDINGS OF THE EEGS. MICE WERE KILLED AT DIFFERENT INTERVALS AFTER KA INJECTION AND EXPRESSION OF HDAC MRNAS WAS INVESTIGATED BY IN SITU HYBRIDIZATION. WE OBSERVED MARKED DECREASES IN THE EXPRESSION OF HDACS 1, 2 AND 11 (BY UP TO 75%) IN THE GRANULE CELL AND PYRAMIDAL CELL LAYERS OF THE HIPPOCAMPUS DURING THE ACUTE STATUS EPILEPTICUS (2 TO 6H AFTER KA INJECTION). THIS WAS FOLLOWED BY INCREASED EXPRESSION OF ALL CLASS I HDAC MRNAS IN ALL PRINCIPAL CELL LAYERS OF THE HIPPOCAMPUS AFTER 12 TO 48 H. IN THE CHRONIC PHASE, 14 AND 28 DAYS AFTER KA, ONLY MODEST INCREASES IN THE EXPRESSION OF HDAC1 MRNA WERE OBSERVED IN GRANULE AND PYRAMIDAL CELLS. IMMUNOHISTOCHEMISTRY USING AN ANTIBODY DETECTING HDAC2 REVEALED RESULTS CONSISTENT WITH THE MRNA DATA AND INDICATES ALSO EXPRESSION IN GLIAL CELLS ON THE INJECTION SIDE. SIMILAR CHANGES AS SEEN IN THE KA MODEL WERE OBSERVED AFTER A PILOCARPINE-INDUCED STATUS EPILEPTICUS EXCEPT THAT DECREASES IN HDACS 2, 3 AND 8 WERE ALSO SEEN AT THE CHRONIC 28 DAY INTERVAL. THE PROMINENT DECREASES IN HDAC EXPRESSION DURING STATUS EPILEPTICUS ARE CONSISTENT WITH THE PREVIOUSLY DEMONSTRATED INCREASED EXPRESSION OF NUMEROUS PROTEINS AND WITH THE AUGMENTED ACETYLATION OF HISTONE H4. IT IS SUGGESTED THAT RESPECTIVE PUTATIVE GENE PRODUCTS COULD FACILITATE PROCONVULSIVE AS WELL AS ANTICONVULSIVE MECHANISMS. THE INCREASED EXPRESSION OF ALL CLASS I HDACS DURING THE "SILENT PHASE", ON THE OTHER HAND, MAY BE RELATED TO DECREASED HISTONE ACETYLATION, WHICH COULD CAUSE A DECREASE IN EXPRESSION OF CERTAIN PROTEINS, A MECHANISM THAT COULD ALSO PROMOTE EPILEPTOGENESIS. THUS, ADDRESSING HDAC EXPRESSION MAY HAVE A THERAPEUTIC POTENTIAL IN INTERFERING WITH A STATUS EPILEPTICUS AND WITH THE MANIFESTATION OF TLE. 2015 14 3433 34 HYDROXYMETHYLATION OF MICRORNA-365-3P REGULATES NOCICEPTIVE BEHAVIORS VIA KCNH2. DNA 5-HYDROXYLMETHYLCYTOSINE (5HMC) CATALYZED BY TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE (TET) OCCURS ABUNDANTLY IN NEURONS OF MAMMALS. HOWEVER, THE IN VIVO CAUSAL LINK BETWEEN TET DYSREGULATION AND NOCICEPTIVE MODULATION HAS NOT BEEN ESTABLISHED. HERE, WE FOUND THAT SPINAL TET1 AND TET3 WERE SIGNIFICANTLY INCREASED IN THE MODEL OF FORMALIN-INDUCED ACUTE INFLAMMATORY PAIN, WHICH WAS ACCOMPANIED WITH THE AUGMENT OF GENOME-WIDE 5HMC CONTENT IN SPINAL CORD. KNOCKDOWN OF SPINAL TET1 OR TET3 ALLEVIATED THE FORMALIN-INDUCED NOCICEPTIVE BEHAVIOR AND OVEREXPRESSION OF SPINAL TET1 OR TET3 IN NAIVE MICE PRODUCED PAIN-LIKE BEHAVIOR AS EVIDENCED BY DECREASED THERMAL PAIN THRESHOLD. FURTHERMORE, WE FOUND THAT TET1 OR TET3 REGULATED THE NOCICEPTIVE BEHAVIOR BY TARGETING MICRORNA-365-3P (MIR-365-3P). FORMALIN INCREASED 5HMC IN THE MIR-365-3P PROMOTER, WHICH WAS INHIBITED BY KNOCKDOWN OF TET1 OR TET3 AND MIMICKED BY OVEREXPRESSION OF TET1 OR TET3 IN NAIVE MICE. NOCICEPTIVE BEHAVIOR INDUCED BY FORMALIN OR OVEREXPRESSION OF SPINAL TET1 OR TET3 COULD BE PREVENTED BY DOWNREGULATION OF MIR-365-3P, AND MIMICKED BY OVEREXPRESSION OF SPINAL MIR-365-3P. FINALLY, WE DEMONSTRATED THAT A POTASSIUM CHANNEL, VOLTAGE-GATED EAG-RELATED SUBFAMILY H MEMBER 2 (KCNH2), VALIDATED AS A TARGET OF MIR-365-3P, PLAYED A CRITICAL ROLE IN NOCICEPTIVE MODULATION BY SPINAL TET OR MIR-365-3P. TOGETHER, WE CONCLUDED THAT TET-MEDIATED HYDROXYMETHYLATION OF MIR-365-3P REGULATES NOCICEPTIVE BEHAVIOR VIA KCNH2. SIGNIFICANCE STATEMENT: MOUNTING EVIDENCE INDICATES THAT EPIGENETIC MODIFICATIONS IN THE NOCICEPTIVE PATHWAY CONTRIBUTE TO PAIN PROCESSES AND ANALGESIA RESPONSE. HERE, WE FOUND THAT THE INCREASE OF 5HMC CONTENT MEDIATED BY TET1 OR TET3 IN MIR-365-3P PROMOTER IN THE SPINAL CORD IS INVOLVED IN NOCICEPTIVE MODULATION THROUGH TARGETING A POTASSIUM CHANNEL, KCNH2. OUR STUDY REVEALS A NEW EPIGENETIC MECHANISM UNDERLYING NOCICEPTIVE INFORMATION PROCESSING, WHICH MAY BE A NOVEL TARGET FOR DEVELOPMENT OF ANTINOCICEPTIVE DRUGS. 2016 15 213 31 ACUTE AND CHRONIC ELECTROCONVULSIVE SEIZURES (ECS) DIFFERENTIALLY REGULATE THE EXPRESSION OF EPIGENETIC MACHINERY IN THE ADULT RAT HIPPOCAMPUS. BACKGROUND: ELECTROCONVULSIVE SEIZURE TREATMENT IS A FAST-ACTING ANTIDEPRESSANT THERAPY THAT EVOKES RAPID TRANSCRIPTIONAL, NEUROGENIC, AND BEHAVIORAL CHANGES. EPIGENETIC MECHANISMS CONTRIBUTE TO ALTERED GENE REGULATION, WHICH UNDERLIES THE NEUROGENIC AND BEHAVIORAL EFFECTS OF ELECTROCONVULSIVE SEIZURE. WE HYPOTHESIZED THAT ELECTROCONVULSIVE SEIZURE MAY MODULATE THE EXPRESSION OF EPIGENETIC MACHINERY, THUS ESTABLISHING POTENTIAL ALTERATIONS IN THE EPIGENETIC LANDSCAPE. METHODS: WE EXAMINED THE INFLUENCE OF ACUTE AND CHRONIC ELECTROCONVULSIVE SEIZURE ON THE GENE EXPRESSION OF HISTONE MODIFIERS, NAMELY HISTONE ACETYLTRANSFERASES, HISTONE DEACETYLASES, HISTONE METHYLTRANSFERASES, AND HISTONE (LYSINE) DEMETHYLASES AS WELL AS DNA MODIFYING ENZYMES, INCLUDING DNA METHYLTRANSFERASES, DNA DEMETHYLASES, AND METHYL-CPG-BINDING PROTEINS IN THE HIPPOCAMPI OF ADULT MALE WISTAR RATS USING QUANTITATIVE REAL TIME-PCR ANALYSIS. FURTHER, WE EXAMINED THE INFLUENCE OF ACUTE AND CHRONIC ELECTROCONVULSIVE SEIZURE ON GLOBAL AND RESIDUE-SPECIFIC HISTONE ACETYLATION AND METHYLATION LEVELS WITHIN THE HIPPOCAMPUS, A BRAIN REGION IMPLICATED IN THE CELLULAR AND BEHAVIORAL EFFECTS OF ELECTROCONVULSIVE SEIZURE. RESULTS: ACUTE AND CHRONIC ELECTROCONVULSIVE SEIZURE INDUCED A PRIMARILY UNIQUE, AND IN CERTAIN CASES BIDIRECTIONAL, REGULATION OF HISTONE AND DNA MODIFIERS, AND METHYL-CPG-BINDING PROTEINS, WITH AN OVERLAPPING PATTERN OF GENE REGULATION RESTRICTED TO SIRT4, MLL3, JMJD3, GADD45B, TET2, AND TET3. GLOBAL HISTONE ACETYLATION AND METHYLATION LEVELS WERE PREDOMINANTLY UNCHANGED, WITH THE EXCEPTION OF A SIGNIFICANT DECLINE IN H3K9 ACETYLATION IN THE HIPPOCAMPUS FOLLOWING CHRONIC ELECTROCONVULSIVE SEIZURE. CONCLUSIONS: ELECTROCONVULSIVE SEIZURE TREATMENT EVOKES THE TRANSCRIPTIONAL REGULATION OF SEVERAL HISTONE AND DNA MODIFIERS, AND METHYL-CPG-BINDING PROTEINS WITHIN THE HIPPOCAMPUS, WITH A PREDOMINANTLY DISTINCT PATTERN OF REGULATION INDUCED BY ACUTE AND CHRONIC ELECTROCONVULSIVE SEIZURE. 2016 16 2057 34 EPIGENETIC CONTROL OF EPILEPSY TARGET GENES CONTRIBUTES TO A CELLULAR MEMORY OF EPILEPTOGENESIS IN CULTURED RAT HIPPOCAMPAL NEURONS. HYPERSYNCHRONOUS NEURONAL EXCITATION MANIFESTS CLINICALLY AS SEIZURE (ICTOGENESIS), AND MAY RECUR SPONTANEOUSLY AND REPETITIVELY AFTER A VARIABLE LATENCY PERIOD (EPILEPTOGENESIS). DESPITE TREMENDOUS RESEARCH EFFORTS TO DESCRIBE MOLECULAR PATHWAYS AND SIGNATURES OF EPILEPTOGENESIS, MOLECULAR PATHOMECHANISMS LEADING TO CHRONIC EPILEPSY REMAIN TO BE CLARIFIED. WE HYPOTHESIZED THAT EPIGENETIC MODIFICATIONS MAY FORM THE BASIS FOR A CELLULAR MEMORY OF EPILEPTOGENESIS, AND USED A PRIMARY NEURONAL CELL CULTURE MODEL OF THE RAT HIPPOCAMPUS TO STUDY THE TRANSLATION OF MASSIVE NEURONAL EXCITATION INTO PERSISTING CHANGES OF EPIGENETIC SIGNATURES AND PRO-EPILEPTOGENIC TARGET GENE EXPRESSION. INCREASED SPONTANEOUS ACTIVATION OF CULTURED NEURONS WAS DETECTED 3 AND 7 DAYS AFTER STIMULATION WITH 10 MUM GLUTAMATE WHEN COMPARED TO SHAM-TREATED TIME-MATCHED CONTROLS USING CALCIUM-IMAGING IN VITRO. CHROMATIN-IMMUNOPRECIPITATION EXPERIMENTS REVEALED SHORT-TERM (3 H, 7 H, AND 24 H) AND LONG-TERM (3 D AND 2 WEEKS) CHANGES IN HISTONE MODIFICATIONS, WHICH WERE DIRECTLY LINKED TO DECREASED EXPRESSION OF TWO SELECTED EPILEPSY TARGET GENES, E.G. EXCITATORY GLUTAMATE RECEPTOR GENES GRIA2 AND GRIN2A. INCREASED PROMOTER METHYLATION OBSERVED 4 WEEKS AFTER GLUTAMATE STIMULATION AT RESPECTIVE GENES SUGGESTED LONG-TERM REPRESSION OF GRIA2 AND GRIN2A GENES. INHIBITION OF GLUTAMATERGIC ACTIVATION OR BLOCKING THE PROPAGATION OF ACTION POTENTIALS IN CULTURED NEURONS RESCUED ALTERED GENE EXPRESSION AND REGULATORY EPIGENETIC MODIFICATIONS. OUR DATA SUPPORT THE CONCEPT OF A CELLULAR MEMORY OF EPILEPTOGENESIS AND PERSISTING EPIGENETIC MODIFICATIONS OF EPILEPSY TARGET GENES, WHICH ARE ABLE TO TURN NORMAL INTO PRO-EPILEPTIC NEURONS AND CIRCUITS. 2017 17 21 16 5-HYDROXYMETHYLCYTOSINE (5HMC) AND TEN-ELEVEN TRANSLOCATION 1-3 (TET1-3) PROTEINS IN THE DORSAL ROOT GANGLIA OF MOUSE: EXPRESSION AND DYNAMIC REGULATION IN NEUROPATHIC PAIN. EPIGENETIC MECHANISMS ARE INCREASINGLY IMPLICATED IN CHRONIC PAIN PATHOLOGY. IN THIS STUDY, WE DEMONSTRATE THAT THE NOVEL EPIGENETIC MARK 5-HYDROXYMETHYLCYTOSINE (5HMC) IS PRESENT IN DORSAL ROOT GANGLIA (DRG) NEURONS AND GLIA, AND ITS LEVELS INCREASE FOLLOWING NERVE INJURY. FURTHERMORE, WE SHOW THAT THE 5HMC-GENERATING TEN-ELEVEN TRANSLOCATION 1-3 (TET1-3) PROTEINS ARE EXPRESSED IN A CELL-TYPE SPECIFIC MANNER IN THE DRG, WITH TET3 DISPLAYING DIFFERENTIAL UPREGULATION AFTER INJURY, SUGGESTING A POTENTIAL ROLE IN NEUROPATHIC PAIN. 2017 18 4913 39 PAIN MODULATION IN WAG/RIJ EPILEPTIC RATS (A GENETIC MODEL OF ABSENCE EPILEPSY): EFFECTS OF BIOLOGICAL AND PHARMACOLOGICAL HISTONE DEACETYLASE INHIBITORS. EPIGENETIC MECHANISMS ARE INVOLVED IN EPILEPSY AND CHRONIC PAIN DEVELOPMENT. ABOUT THAT, WE STUDIED THE EFFECTS OF THE NATURAL HISTONE DEACETYLASE (HDAC) INHIBITOR SODIUM BUTYRATE (BUT) IN COMPARISON WITH VALPROIC ACID (VPA) IN A VALIDATED GENETIC MODEL OF GENERALIZED ABSENCE EPILEPSY AND EPILEPTOGENESIS. WAG/RIJ RATS WERE TREATED WITH BUT (30 MG/KG), VPA (300 MG/KG), AND THEIR COMBINATION (BUT + VPA) DAILY PER OS FOR 6 MONTHS. RATS WERE SUBJECTED AT RANDALL-SELITTO, VON FREY, HOT PLATE, AND TAIL FLICK TESTS AFTER 1, 3, AND 6 MONTHS OF TREATMENT TO EVALUATE HYPERSENSITIVITY TO NOXIOUS AND NON-NOXIUOUS STIMULI. MOREOVER, PPAR-GAMMA (G3335 1 MG/KG), GABA-B (CGP35348 80 MG/KG), AND OPIOID (NALOXONE 1 MG/KG) RECEPTOR ANTAGONISTS WERE ADMINISTRATED TO INVESTIGATE THE POSSIBLE MECHANISMS INVOLVED IN ANALGESIC ACTIVITY. THE EXPRESSION OF NFKB, GLUTATHIONE REDUCTASE, AND PROTEIN OXIDATION (CARBONYLATION) WAS ALSO EVALUATED BY WESTERN BLOT ANALYSIS. WAG/RIJ RATS SHOWED AN ALTERED PAIN THRESHOLD THROUGHOUT THE STUDY (P < 0.001). BUT AND BUT + VPA TREATMENT REDUCED HYPERSENSITIVITY (P < 0.01). VPA WAS SIGNIFICANTLY EFFECTIVE ONLY AFTER 1 MONTH (P < 0.01). ALL THE THREE RECEPTORS ARE INVOLVED IN BUT + VPA EFFECTS (P < 0.001). BUT AND BUT + VPA DECREASED THE EXPRESSION OF NFKB AND ENHANCED GLUTATHIONE REDUCTASE (P < 0.01); PROTEIN OXIDATION (CARBONYLATION) WAS REDUCED (P < 0.01). NO EFFECT WAS REPORTED WITH VPA. IN CONCLUSION BUT, ALONE OR IN COADMINISTRATION WITH VPA, IS A VALUABLE CANDIDATE FOR MANAGING THE EPILEPSY-RELATED PERSISTENT PAIN. 2020 19 3334 32 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 20 1425 34 DIFFERENTIAL DNA METHYLATION PROFILES OF CODING AND NON-CODING GENES DEFINE HIPPOCAMPAL SCLEROSIS IN HUMAN TEMPORAL LOBE EPILEPSY. TEMPORAL LOBE EPILEPSY IS ASSOCIATED WITH LARGE-SCALE, WIDE-RANGING CHANGES IN GENE EXPRESSION IN THE HIPPOCAMPUS. EPIGENETIC CHANGES TO DNA ARE ATTRACTIVE MECHANISMS TO EXPLAIN THE SUSTAINED HYPEREXCITABILITY OF CHRONIC EPILEPSY. HERE, THROUGH METHYLATION ANALYSIS OF ALL ANNOTATED C-PHOSPHATE-G ISLANDS AND PROMOTER REGIONS IN THE HUMAN GENOME, WE REPORT A PILOT STUDY OF THE METHYLATION PROFILES OF TEMPORAL LOBE EPILEPSY WITH OR WITHOUT HIPPOCAMPAL SCLEROSIS. FURTHERMORE, BY COMPARATIVE ANALYSIS OF EXPRESSION AND PROMOTER METHYLATION, WE IDENTIFY METHYLATION SENSITIVE NON-CODING RNA IN HUMAN TEMPORAL LOBE EPILEPSY. A TOTAL OF 146 PROTEIN-CODING GENES EXHIBITED ALTERED DNA METHYLATION IN TEMPORAL LOBE EPILEPSY HIPPOCAMPUS (N = 9) WHEN COMPARED TO CONTROL (N = 5), WITH 81.5% OF THE PROMOTERS OF THESE GENES DISPLAYING HYPERMETHYLATION. UNIQUE METHYLATION PROFILES WERE EVIDENT IN TEMPORAL LOBE EPILEPSY WITH OR WITHOUT HIPPOCAMPAL SCLEROSIS, IN ADDITION TO A COMMON METHYLATION PROFILE REGARDLESS OF PATHOLOGY GRADE. GENE ONTOLOGY TERMS ASSOCIATED WITH DEVELOPMENT, NEURON REMODELLING AND NEURON MATURATION WERE OVER-REPRESENTED IN THE METHYLATION PROFILE OF WATSON GRADE 1 SAMPLES (MILD HIPPOCAMPAL SCLEROSIS). IN ADDITION TO GENES ASSOCIATED WITH NEURONAL, NEUROTRANSMITTER/SYNAPTIC TRANSMISSION AND CELL DEATH FUNCTIONS, DIFFERENTIAL HYPERMETHYLATION OF GENES ASSOCIATED WITH TRANSCRIPTIONAL REGULATION WAS EVIDENT IN TEMPORAL LOBE EPILEPSY, BUT OVERALL FEW GENES PREVIOUSLY ASSOCIATED WITH EPILEPSY WERE AMONG THE DIFFERENTIALLY METHYLATED. FINALLY, A PANEL OF 13, METHYLATION-SENSITIVE MICRORNA WERE IDENTIFIED IN TEMPORAL LOBE EPILEPSY INCLUDING MIR27A, MIR-193A-5P (MIR193A) AND MIR-876-3P (MIR876), AND THE DIFFERENTIAL METHYLATION OF LONG NON-CODING RNA DOCUMENTED FOR THE FIRST TIME. THE PRESENT STUDY THEREFORE REPORTS SELECT, GENOME-WIDE DNA METHYLATION CHANGES IN HUMAN TEMPORAL LOBE EPILEPSY THAT MAY CONTRIBUTE TO THE MOLECULAR ARCHITECTURE OF THE EPILEPTIC BRAIN. 2015