1 695 133 BRG1 IN THE NUCLEUS ACCUMBENS REGULATES COCAINE-SEEKING BEHAVIOR. BACKGROUND: DRUG ADDICTION IS DEFINED AS A CHRONIC DISEASE CHARACTERIZED BY COMPULSIVE DRUG SEEKING AND EPISODES OF RELAPSE DESPITE PROLONGED PERIODS OF DRUG ABSTINENCE. NEUROBIOLOGICAL ADAPTATIONS, INCLUDING TRANSCRIPTIONAL AND EPIGENETIC ALTERATIONS IN THE NUCLEUS ACCUMBENS, ARE THOUGHT TO CONTRIBUTE TO THIS LIFE-LONG DISEASE STATE. WE PREVIOUSLY DEMONSTRATED THAT THE TRANSCRIPTION FACTOR SMAD3 IS INCREASED AFTER 7 DAYS OF WITHDRAWAL FROM COCAINE SELF-ADMINISTRATION. HOWEVER, IT IS STILL UNKNOWN WHICH ADDITIONAL FACTORS PARTICIPATE IN THE PROCESS OF CHROMATIN REMODELING AND FACILITATE THE BINDING OF SMAD3 TO PROMOTER REGIONS OF TARGET GENES. HERE, WE EXAMINED THE POSSIBLE INTERACTION OF BRG1-ALSO KNOWN AS SMARCA4, AN ADENOSINE TRIPHOSPHATASE-CONTAINING CHROMATIN REMODELER-AND SMAD3 IN RESPONSE TO COCAINE EXPOSURE. METHODS: THE EXPRESSION OF BRG1, AS WELL AS ITS BINDING TO SMAD3 AND TARGET GENE PROMOTER REGIONS, WAS EVALUATED IN THE NUCLEUS ACCUMBENS AND DORSAL STRIATUM OF RATS USING WESTERN BLOTTING, CO-IMMUNOPRECIPITATION, AND CHROMATIN IMMUNOPRECIPITATION FOLLOWING ABSTINENCE FROM COCAINE SELF-ADMINISTRATION. RATS WERE ASSESSED FOR COCAINE-SEEKING BEHAVIORS AFTER EITHER INTRA-ACCUMBAL INJECTIONS OF THE BRG1 INHIBITOR PFI3 OR VIRAL-MEDIATED OVEREXPRESSION OF BRG1. RESULTS: AFTER WITHDRAWAL FROM COCAINE SELF-ADMINISTRATION, BRG1 EXPRESSION AND COMPLEX FORMATION WITH SMAD3 ARE INCREASED IN THE NUCLEUS ACCUMBENS, RESULTING IN INCREASED BINDING OF BRG1 TO THE PROMOTER REGIONS OF CTNNB1, MEF2D, AND DBN1. INTRA-ACCUMBAL INFUSION OF PFI3 ATTENUATED, WHEREAS VIRAL OVEREXPRESSION OF BRG1 ENHANCED, COCAINE-REINSTATEMENT BEHAVIOR. CONCLUSIONS: BRG1 IS A KEY MEDIATOR OF THE SMAD3-DEPENDENT REGULATION OF CELLULAR AND BEHAVIORAL PLASTICITY THAT MEDIATES COCAINE SEEKING AFTER A PERIOD OF WITHDRAWAL. 2016 2 882 40 CHRONIC COCAINE-INDUCED H3 ACETYLATION AND TRANSCRIPTIONAL ACTIVATION OF CAMKIIALPHA IN THE NUCLEUS ACCUMBENS IS CRITICAL FOR MOTIVATION FOR DRUG REINFORCEMENT. THE REGULATION OF GENE EXPRESSION IN THE BRAIN REWARD REGIONS IS KNOWN TO CONTRIBUTE TO THE PATHOGENESIS AND PERSISTENCE OF DRUG ADDICTION. INCREASING EVIDENCE SUGGESTS THAT THE REGULATION OF GENE TRANSCRIPTION IS MEDIATED BY EPIGENETIC MECHANISMS THAT ALTER THE CHROMATIN STRUCTURE AT SPECIFIC GENE PROMOTERS. TO BETTER UNDERSTAND THE INVOLVEMENT OF EPIGENETIC REGULATION IN DRUG REINFORCEMENT PROPERTIES, RATS WERE SUBJECTED TO COCAINE SELF-ADMINISTRATION PARADIGM. DAILY HISTONE DEACETYLASE (HDAC) INHIBITOR INFUSIONS IN THE SHELL OF THE NUCLEUS ACCUMBENS (NAC) CAUSED AN UPWARD SHIFT IN THE DOSE-RESPONSE CURVE UNDER FIXED-RATIO SCHEDULE AND INCREASED THE BREAK POINT UNDER PROGRESSIVE-RATIO SCHEDULE, INDICATING ENHANCED MOTIVATION FOR SELF-ADMINISTERED DRUG. THE EFFECT OF THE HDAC INHIBITOR IS ATTRIBUTED TO THE INCREASED ELEVATION OF HISTONE ACETYLATION INDUCED BY CHRONIC, BUT NOT ACUTE, COCAINE EXPERIENCE. IN CONTRAST, NEUTRALIZING THE CHRONIC COCAINE-INDUCED INCREASE IN HISTONE MODIFICATION BY THE BILATERAL OVEREXPRESSION OF HDAC4 IN THE NAC SHELL REDUCED DRUG MOTIVATION. THE ASSOCIATION BETWEEN THE MOTIVATION FOR COCAINE AND THE TRANSCRIPTIONAL ACTIVATION OF ADDICTION-RELATED GENES BY H3 ACETYLATION IN THE NAC SHELL WAS ANALYZED. AMONG THE GENES ACTIVATED BY CHRONIC COCAINE EXPERIENCES, THE EXPRESSION OF CAMKIIALPHA, BUT NOT CAMKIIBETA, CORRELATED POSITIVELY WITH MOTIVATION FOR THE DRUG. LENTIVIRUS-MEDIATED SHRNA KNOCKDOWN EXPERIMENTS SHOWED THAT CAMKIIALPHA, BUT NOT CAMKIIBETA, IN THE NAC SHELL IS ESSENTIAL FOR THE MAINTENANCE OF MOTIVATION TO SELF-ADMINISTERED COCAINE. THESE FINDINGS SUGGEST THAT CHRONIC DRUG-USE-INDUCED TRANSCRIPTIONAL ACTIVATION OF GENES, SUCH AS CAMKIIALPHA, MODULATED BY H3 ACETYLATION IN THE NAC IS A CRITICAL REGULATORY MECHANISM UNDERLYING MOTIVATION FOR DRUG REINFORCEMENT. 2010 3 4878 48 OVEREXPRESSION OF THE HISTONE DIMETHYLTRANSFERASE G9A IN NUCLEUS ACCUMBENS SHELL INCREASES COCAINE SELF-ADMINISTRATION, STRESS-INDUCED REINSTATEMENT, AND ANXIETY. REPEATED EXPOSURE TO COCAINE INDUCES LASTING EPIGENETIC CHANGES IN NEURONS THAT PROMOTE THE DEVELOPMENT AND PERSISTENCE OF ADDICTION. ONE EPIGENETIC ALTERATION INVOLVES REDUCTIONS IN LEVELS OF THE HISTONE DIMETHYLTRANSFERASE G9A IN NUCLEUS ACCUMBENS (NAC) AFTER CHRONIC COCAINE ADMINISTRATION. THIS REDUCTION IN G9A MAY ENHANCE COCAINE REWARD BECAUSE OVEREXPRESSING G9A IN THE NAC DECREASES COCAINE-CONDITIONED PLACE PREFERENCE. THEREFORE, WE HYPOTHESIZED THAT HSV-MEDIATED G9A OVEREXPRESSION IN THE NAC SHELL (NACSH) WOULD ATTENUATE COCAINE SELF-ADMINISTRATION (SA) AND COCAINE-SEEKING BEHAVIOR. INSTEAD, WE FOUND THAT G9A OVEREXPRESSION, AND THE RESULTING INCREASE IN HISTONE 3 LYSINE 9 DIMETHYLATION (H3K9ME2), INCREASES SENSITIVITY TO COCAINE REINFORCEMENT AND ENHANCES MOTIVATION FOR COCAINE IN SELF-ADMINISTERING MALE RATS. MOREOVER, WHEN G9A OVEREXPRESSION IS LIMITED TO THE INITIAL 15 D OF COCAINE SA TRAINING, IT PRODUCES AN ENDURING POSTEXPRESSION ENHANCEMENT IN COCAINE SA AND PROLONGED (OVER 5 WEEKS) INCREASES IN REINSTATEMENT OF COCAINE SEEKING INDUCED BY FOOT-SHOCK STRESS, BUT IN THE ABSENCE OF CONTINUED GLOBAL ELEVATIONS IN H3K9ME2. THE INCREASE IN STRESS-INDUCED REINSTATEMENT IS PARALLELED BY HEIGHTENED ANXIETY MEASURES, SUGGESTING THAT COUNTERING THE COCAINE-INDUCED DECREASES IN ENDOGENOUS G9A WITH ECTOPIC G9A OVEREXPRESSION LEADS TO LASTING ANXIOGENIC EFFECTS. FINALLY, WE FOUND AN ENDURING REDUCTION IN PHOSPHORYLATED CAMP-RESPONSE ELEMENT BINDING PROTEIN LEVELS IN THE NACSH THAT COULD ACCOUNT FOR THE INCREASED ANXIETY. THESE DATA DEMONSTRATE A NOVEL ROLE FOR G9A IN PROMOTING COMORBID COCAINE ADDICTION AND ANXIETY AND SUGGEST THAT INCREASED EPIGENETIC REPRESSION OF TRANSCRIPTION THROUGH H3K9 DURING COCAINE USE CAN HAVE LONG-LASTING AND UNEXPECTED NEGATIVE CONSEQUENCES ON BEHAVIOR.SIGNIFICANCE STATEMENT COCAINE ADDICTION IS A NEUROPSYCHIATRIC DISORDER THAT IS DETRIMENTAL TO SOCIETY AND CURRENTLY HAS NO EFFECTIVE TREATMENTS. THE DIFFICULTY IN TREATING DRUG ADDICTION IS COMPOUNDED BY THE HIGH COMORBIDITY WITH OTHER PSYCHIATRIC ILLNESSES, INCLUDING ANXIETY DISORDERS. HERE, WE DEMONSTRATE THAT G9A, AN EPIGENETIC REPRESSOR OF GENE EXPRESSION, ACTING IN THE NUCLEUS ACCUMBENS, A BRAIN REWARD REGION, IS CAPABLE OF INCREASING BOTH ADDICTION- AND ANXIETY-LIKE BEHAVIORS IN RATS. THESE FINDINGS ARE INTRIGUING BECAUSE REPEATED COCAINE EXPOSURE DECREASES G9A IN THIS REGION AND THEREBY ENHANCES EXPRESSION OF CERTAIN ADDICTION-PROMOTING GENES. HOWEVER, OUR RESULTS SUGGEST THAT COUNTERING THIS COCAINE-INDUCED DECREASE IN G9A ACTIVITY ACTUALLY EXACERBATES ADDICTION AND SENSITIVITY TO RELAPSE UNDER STRESSFUL SITUATIONS. 2018 4 2325 43 EPIGENETIC REGULATION OF HIPPOCAMPAL FOSB EXPRESSION CONTROLS BEHAVIORAL RESPONSES TO COCAINE. DRUG ADDICTION RESULTS IN PART FROM MALADAPTIVE LEARNING, INCLUDING THE FORMATION OF STRONG ASSOCIATIONS BETWEEN THE DRUG AND THE CIRCUMSTANCES OF CONSUMPTION. HOWEVER, DRUG-INDUCED CHANGES IN GENE EXPRESSION UNDERLYING THE SALIENCY OF THESE ASSOCIATIONS REMAIN UNDERSTUDIED. CONSOLIDATION OF EXPLICIT MEMORIES OCCURS WITHIN THE HIPPOCAMPUS, AND WE HAVE SHOWN THAT SPATIAL LEARNING INDUCES EXPRESSION OF THE TRANSCRIPTION FACTOR DELTAFOSB IN HIPPOCAMPUS AND THAT THIS INDUCTION IS CRITICAL FOR LEARNING. DRUGS OF ABUSE ALSO UPREGULATE DELTAFOSB IN HIPPOCAMPUS, BUT THE MECHANISM OF ITS INDUCTION BY COCAINE AND ITS ROLE IN HIPPOCAMPUS-DEPENDENT COCAINE RESPONSES IS UNKNOWN. WE INVESTIGATED DIFFERENCES IN MOUSE DORSAL AND VENTRAL HIPPOCAMPAL DELTAFOSB EXPRESSION IN RESPONSE TO CHRONIC COCAINE, BECAUSE THESE REGIONS APPEAR TO REGULATE DISTINCT COCAINE-RELATED BEHAVIORS. WE FOUND THAT COCAINE-MEDIATED INDUCTION OF DELTAFOSB WAS SUBREGION-SPECIFIC, AND THAT DELTAFOSB TRANSCRIPTIONAL ACTIVITY IN BOTH THE DORSAL AND VENTRAL HIPPOCAMPUS IS NECESSARY FOR COCAINE CONDITIONED PLACE PREFERENCE. FURTHER, WE CHARACTERIZE CHANGES IN HISTONE MODIFICATIONS AT THE FOSB PROMOTER IN HIPPOCAMPUS IN RESPONSE TO CHRONIC COCAINE AND FOUND THAT LOCUS-SPECIFIC EPIGENETIC MODIFICATION IS ESSENTIAL FOR FOSB INDUCTION AND MULTIPLE HIPPOCAMPUS-DEPENDENT BEHAVIORS, INCLUDING COCAINE PLACE PREFERENCE. COLLECTIVELY, THESE FINDINGS SUGGEST THAT EXPOSURE TO COCAINE INDUCES HISTONE MODIFICATION AT THE HIPPOCAMPAL FOSB GENE PROMOTER TO CAUSE DELTAFOSB INDUCTION CRITICAL FOR COCAINE-RELATED LEARNING.SIGNIFICANCE STATEMENT ALTHOUGH COCAINE ADDICTION IS DRIVEN IN PART BY THE FORMATION OF INDELIBLE ASSOCIATIONS BETWEEN THE DRUG AND THE ENVIRONMENT, PARAPHERNALIA, AND CIRCUMSTANCES OF USE, AND ALTHOUGH THIS TYPE OF ASSOCIATIVE LEARNING IS DEPENDENT UPON CHANGES IN GENE EXPRESSION IN A BRAIN REGION CALLED THE HIPPOCAMPUS, THE MECHANISMS BY WHICH COCAINE ALTERS HIPPOCAMPAL GENE EXPRESSION TO DRIVE FORMATION OF THESE ASSOCIATIONS IS POORLY UNDERSTOOD. HERE, WE DEMONSTRATE THAT CHRONIC COCAINE ENGAGES LOCUS-SPECIFIC CHANGES IN THE EPIGENETIC PROFILE OF THE FOSB GENE IN THE HIPPOCAMPUS, AND THAT THESE ALTERATIONS ARE REQUIRED FOR COCAINE-DEPENDENT GENE EXPRESSION AND COCAINE-ENVIRONMENT ASSOCIATIONS. THIS WORK PROVIDES NOVEL INSIGHT INTO ADDICTION ETIOLOGY AND POTENTIAL INROADS FOR THERAPEUTIC INTERVENTION IN COCAINE ADDICTION. 2019 5 5535 40 ROLE OF BRD4 PHOSPHORYLATION IN THE NUCLEUS ACCUMBENS IN RELAPSE TO COCAINE-SEEKING BEHAVIOR IN MICE. COCAINE ADDICTION IS A CHRONIC RELAPSING BRAIN DISORDER CHARACTERIZED BY COMPULSIVE DRUG SEEKING. PRELIMINARY STUDY SUGGESTED THAT BROMODOMAIN-CONTAINING PROTEIN 4 (BRD4), AN EPIGENETIC READER PROTEIN, PARTICIPATES IN COCAINE-INDUCED REWARD AND NEUROPLASTICITY. HOWEVER, THE EXACT ROLE OF BRD4 IN COCAINE ADDICTION, PARTICULARLY COCAINE RELAPSE, REMAINS ELUSIVE. IN THIS STUDY, WE FOUND THAT BRD4 PHOSPHORYLATION IN THE NUCLEUS ACCUMBENS (NAC) WAS CLOSELY RELATED TO THE MAINTENANCE OF COCAINE REINFORCEMENT AND RELAPSE IN DIFFERENT COCAINE EXPOSURE PARADIGMS. COCAINE SIGNIFICANTLY INCREASED THE BINDING OF PHOSPHORYLATED BRD4 (PBRD4) AT THE PROMOTER OF GRIA2 AND BDNF GENES IN THE NAC. (+)JQ1, A SELECTIVE BRD4 INHIBITOR, MARKEDLY REDUCED THE REINFORCEMENT AND REINSTATEMENT OF COCAINE-SEEKING BEHAVIORS, WHICH WAS ACCOMPANIED BY THE DECREASED EXPRESSIONS OF GRIA2 AND BDNF. FURTHERMORE, CHROMATIN IMMUNOPRECIPITATION ASSAY SHOWED THAT (+)JQ1 CLEARLY ATTENUATED COCAINE-ENHANCED BINDING OF PBRD4 AT THE PROMOTOR OF GRIA2 AND BDNF GENES. BLOCKADE OF CASEIN KINASE II SIGNIFICANTLY ATTENUATED BRD4 PHOSPHORYLATION AND COCAINE RELAPSE-LIKE BEHAVIORS, SUGGESTING THE IMPORTANT ROLE OF PBRD4 IN MODULATING COCAINE EFFECT. TOGETHER, OUR FINDINGS SUGGEST THAT BRD4 PHOSPHORYLATION IN THE NAC MODULATES MULTIPLE ADDICTION-RELATED BEHAVIORS OF COCAINE AND PARTICULARLY RELAPSE TO COCAINE-SEEKING BEHAVIORS. INHIBITION OF BRD4 ACTIVITY MAY BE A NOVEL TARGET AGAINST COCAINE ADDICTION AND RELAPSE. 2020 6 4299 30 MICRORNA-15B CONTRIBUTES TO DEPRESSION-LIKE BEHAVIOR IN MICE BY AFFECTING SYNAPTIC PROTEIN LEVELS AND FUNCTION IN THE NUCLEUS ACCUMBENS. MAJOR DEPRESSION IS A PREVALENT AFFECTIVE DISORDER CHARACTERIZED BY RECURRENT LOW MOOD. IT PRESUMABLY RESULTS FROM STRESS-INDUCED DETERIORATIONS OF MOLECULAR NETWORKS AND SYNAPTIC FUNCTIONS IN BRAIN REWARD CIRCUITS OF GENETICALLY-SUSCEPTIBLE INDIVIDUALS THROUGH EPIGENETIC PROCESSES. EPIGENETIC REGULATOR MICRORNA-15B INHIBITS NEURONAL PROGENITOR PROLIFERATION AND IS UP-REGULATED IN THE MEDIAL PREFRONTAL CORTEX OF MICE THAT DEMONSTRATE DEPRESSION-LIKE BEHAVIOR, INDICATING THE CONTRIBUTION OF MICRORNA-15 TO MAJOR DEPRESSION. USING A MOUSE MODEL OF MAJOR DEPRESSION INDUCED BY CHRONIC UNPREDICTABLE MILD STRESS (CUMS), HERE WE EXAMINED THE EFFECTS OF MICRORNA-15B ON SYNAPSES AND SYNAPTIC PROTEINS IN THE NUCLEUS ACCUMBENS OF THESE MICE. THE APPLICATION OF A MICRORNA-15B ANTAGOMIR INTO THE NUCLEUS ACCUMBENS SIGNIFICANTLY REDUCED THE INCIDENCE OF CUMS-INDUCED DEPRESSION AND REVERSED THE ATTENUATIONS OF EXCITATORY SYNAPSE AND SYNTAXIN-BINDING PROTEIN 3 (STXBP3A)/VESICLE-ASSOCIATED PROTEIN 1 (VAMP1) EXPRESSION. IN CONTRAST, THE INJECTION OF A MICRORNA-15B ANALOG INTO THE NUCLEUS ACCUMBENS INDUCED DEPRESSION-LIKE BEHAVIOR AS WELL AS ATTENUATED EXCITATORY SYNAPSES AND STXBP3A/VAMP1 EXPRESSION SIMILAR TO THE DOWN-REGULATION OF THESE PROCESSES INDUCED BY THE CUMS. WE CONCLUDE THAT MICRORNA-15B-5P MAY PLAY A CRITICAL ROLE IN CHRONIC STRESS-INDUCED DEPRESSION BY DECREASING SYNAPTIC PROTEINS, INNERVATIONS, AND ACTIVITIES IN THE NUCLEUS ACCUMBENS. WE PROPOSE THAT THE TREATMENT OF ANTI-MICRORNA-15B-5P MAY CONVERT STRESS-INDUCED DEPRESSION INTO RESILIENCE. 2020 7 2328 37 EPIGENETIC REGULATION OF IMMEDIATE-EARLY GENE NR4A2/NURR1 IN THE MEDIAL HABENULA DURING REINSTATEMENT OF COCAINE-ASSOCIATED BEHAVIOR. PROPENSITY TO RELAPSE FOLLOWING LONG PERIODS OF ABSTINENCE IS A KEY FEATURE OF SUBSTANCE USE DISORDER. DRUGS OF ABUSE, SUCH AS COCAINE, CAUSE LONG-TERM CHANGES IN THE NEURAL CIRCUITRY REGULATING REWARD, MOTIVATION, AND MEMORY PROCESSES THROUGH DYSREGULATION OF VARIOUS MOLECULAR MECHANISMS, INCLUDING EPIGENETIC REGULATION OF ACTIVITY-DEPENDENT GENE EXPRESSION. UNDERLYING DRUG-INDUCED CHANGES TO NEURAL CIRCUIT FUNCTION ARE THE MOLECULAR MECHANISMS REGULATING ACTIVITY-DEPENDENT GENE EXPRESSION. OF NOTE, HISTONE ACETYLTRANSFERASES AND HISTONE DEACETYLASES (HDACS), POWERFUL EPIGENETIC REGULATORS OF GENE EXPRESSION, ARE DYSREGULATED FOLLOWING BOTH ACUTE AND CHRONIC COCAINE EXPOSURE AND ARE LINKED TO COCAINE-INDUCED CHANGES IN NEURAL CIRCUIT FUNCTION. TO BETTER UNDERSTAND THE EFFECT OF DRUG-INDUCED CHANGES ON EPIGENETIC FUNCTION AND BEHAVIOR, WE INVESTIGATED HDAC3-MEDIATED REGULATION OF NR4A2/NURR1 IN THE MEDIAL HABENULA, AN UNDERSTUDIED PATHWAY IN COCAINE-ASSOCIATED BEHAVIORS. NR4A2, A TRANSCRIPTION FACTOR CRITICAL IN COCAINE-ASSOCIATED BEHAVIORS AND NECESSARY FOR MHB DEVELOPMENT, IS ENRICHED IN THE CHOLINERGIC CELL-POPULATION OF THE MHB; YET, THE ROLE OF NR4A2 WITHIN THE MHB IN THE ADULT BRAIN REMAINS ELUSIVE. HERE, WE EVALUATED WHETHER EPIGENETIC REGULATION OF NR4A2 IN THE MHB HAS A ROLE IN REINSTATEMENT OF COCAINE-ASSOCIATED BEHAVIORS. WE FOUND THAT HDAC3 DISENGAGES FROM NR4A2 IN THE MHB IN RESPONSE TO COCAINE-PRIMED REINSTATEMENT. WHEREAS ENHANCING HDAC3 FUNCTION IN THE MHB HAD NO EFFECT ON REINSTATEMENT, WE FOUND, USING A DOMINANT-NEGATIVE SPLICE VARIANT (NURR2C), THAT LOSS OF NR4A2 FUNCTION IN THE MHB BLOCKED REINSTATEMENT BEHAVIORS. THESE RESULTS SHOW FOR THE FIRST TIME THAT REGULATION OF NR4A2 FUNCTION IN THE MHB IS CRITICAL IN RELAPSE-LIKE BEHAVIORS. 2019 8 6207 47 THE INHIBITION OF HISTONE DEACETYLASES REDUCES THE REINSTATEMENT OF COCAINE-SEEKING BEHAVIOR IN RATS. DRUG ADDICTION IS A CHRONIC BRAIN DISEASE CHARACTERIZED BY A PERSISTENT RISK OF RELAPSE, EVEN AFTER A LONG PERIOD OF ABSTINENCE. A CURRENT HYPOTHESIS STATES THAT RELAPSE RESULTS FROM LASTING NEUROADAPTATIONS THAT ARE INDUCED IN RESPONSE TO REPEATED DRUG ADMINISTRATION. THE ADAPTATIONS REQUIRE GENE EXPRESSION, SOME OF WHICH BEING UNDER THE CONTROL OF STABLE EPIGENETIC REGULATIONS. WE HAVE PREVIOUSLY DEMONSTRATED THAT PRETREATMENT WITH HISTONE DEACETYLASE (HDAC) INHIBITORS REDUCES THE COCAINE REINFORCING PROPERTIES AS WELL AS THE MOTIVATION OF RATS FOR COCAINE. WE SHOW HERE THAT THE SAME HDAC INHIBITORS, TRICHOSTATIN A AND PHENYLBUTYRATE, SIGNIFICANTLY REDUCED THE COCAINE-SEEKING BEHAVIOR INDUCED BY THE COMBINATION OF A COCAINE INJECTION TOGETHER WITH THE EXPOSURE TO A LIGHT CUE PREVIOUSLY ASSOCIATED WITH COCAINE TAKING. REINSTATEMENT OF DRUG-SEEKING BEHAVIOR WAS CARRIED OUT AFTER A 3-WEEK WITHDRAWAL PERIOD, WHICH CAME AFTER TEN DAILY SESSIONS OF COCAINE INTRAVENOUS SELF-ADMINISTRATION. OUR RESULTS SUGGEST THAT PHARMACOLOGICAL TREATMENT AIMED AT MODULATING EPIGENETIC REGULATION, AND PARTICULARLY TREATMENT THAT WOULD INHIBIT HDAC ACTIVITY, COULD REDUCE THE RISK OF RELAPSE, A MAJOR DRAWBACK IN THE TREATMENT OF DRUG ADDICTION. 2011 9 2280 44 EPIGENETIC REGULATION IN DRUG ADDICTION. THE INTERACTION BETWEEN ENVIRONMENTAL SIGNALS AND GENES HAS NOW TAKEN ON A CLEAR MOLECULAR FORM AS DEMONSTRATED BY STABLE CHANGES IN CHROMATIN STRUCTURE. THESE CHANGES OCCUR THROUGH ACTIVATION OR REPRESSION OF SPECIFIC GENE PROGRAMMES BY A COMBINATION OF CHROMATIN REMODELLING, ACTIVATION AND ENZYMATIC MODIFICATION OF DNA AND HISTONES AS WELL AS NUCLEOSOMAL SUBUNIT EXCHANGE. RECENT RESEARCH INVESTIGATING THE MOLECULAR MECHANISMS CONTROLLING DRUG-INDUCED TRANSCRIPTIONAL, BEHAVIOURAL AND SYNAPTIC ACTIVITY HAS SHOWN A DIRECT ROLE FOR CHROMATIN REMODELLING--TERMED AS EPIGENETIC REGULATION--OF NEURONAL GENE PROGRAMMES AND SUBSEQUENT ADDICTIVE BEHAVIOUR ARISING FROM IT. RECENT DATA SUGGEST THAT REPEATED EXPOSURE TO CERTAIN DRUGS PROMOTES CHANGES IN LEVELS OF HISTONE ACETYLATION, PHOSPHORYLATION AND METHYLATION, TOGETHER WITH ALTERATIONS IN DNA METHYLATION LEVELS IN THE NEURONS OF THE BRAIN REWARD CENTRE, LOCALISED IN THE NUCLEUS ACCUMBENS (NAC) REGION OF THE LIMBIC SYSTEM. THE COMBINATION OF ACETYLATING, PHOSPHORYLATING AND METHYLATING H3 AND H4 HISTONE TAILS ALTER CHROMATIN COMPACTION THEREBY PROMOTING ALTERED LEVELS OF CELLULAR GENE EXPRESSION. HISTONE MODIFICATIONS, WHICH WEAKEN HISTONE INTERACTION WITH DNA OR THAT PROMOTE RECRUITMENT OF TRANSCRIPTIONAL ACTIVATING COMPLEXES, CORRELATE WITH PERMISSIVE GENE EXPRESSION. HISTONE DEACETYLATION, (WHICH STRENGTHEN HISTONE: DNA CONTACTS), OR HISTONE METHYLATION, (WHICH RECRUITS REPRESSIVE COMPLEXES TO CHROMATIN), PROMOTE A STATE OF TRANSCRIPTIONAL REPRESSION. USING ANIMAL MODELS, ACUTE COCAINE TREATMENT INCREASES H4 ACETYLATION AT ACUTELY REGULATED GENE PROMOTERS, WHEREAS H3 ACETYLATION APPEARS TO PREDOMINATE AT CHRONICALLY INDUCED PROMOTERS. CHRONIC COCAINE AND ALCOHOL TREATMENT ACTIVATE AND REPRESS MANY GENES SUCH AS FOSB, CDK5, AND BDNF, WHERE THEIR DYSREGULATION, AT THE CHROMATIN LEVEL, CONTRIBUTE TO THE DEVELOPMENT AND MAINTENANCE OF ADDICTION. FOLLOWING DRUG EXPOSURE, IT IS STILL UNKNOWN, HOWVER, HOW LONG THESE CHANGES IN CHROMATIN STRUCTURE PERSIST IN AFFECTING NEURONAL FUNCTION, BUT SOME DO SO FOR LIFE. 2012 10 1086 43 COCAINE ADMINISTRATION AND ITS WITHDRAWAL ENHANCE THE EXPRESSION OF GENES ENCODING HISTONE-MODIFYING ENZYMES AND HISTONE ACETYLATION IN THE RAT PREFRONTAL CORTEX. CHRONIC EXPOSURE TO COCAINE, CRAVING, AND RELAPSE ARE ATTRIBUTED TO LONG-LASTING CHANGES IN GENE EXPRESSION ARISING THROUGH EPIGENETIC AND TRANSCRIPTIONAL MECHANISMS. ALTHOUGH SEVERAL BRAIN REGIONS ARE INVOLVED IN THESE PROCESSES, THE PREFRONTAL CORTEX SEEMS TO PLAY A CRUCIAL ROLE NOT ONLY IN MOTIVATION AND DECISION-MAKING BUT ALSO IN EXTINCTION AND SEEKING BEHAVIOR. IN THIS STUDY, WE APPLIED COCAINE SELF-ADMINISTRATION AND EXTINCTION TRAINING PROCEDURES IN RATS WITH A YOKED TRIAD TO DETERMINE DIFFERENTIALLY EXPRESSED GENES IN PREFRONTAL CORTEX. MICROARRAY ANALYSIS SHOWED SIGNIFICANT UPREGULATION OF SEVERAL GENES ENCODING HISTONE MODIFICATION ENZYMES DURING EARLY EXTINCTION TRAINING. SUBSEQUENT REAL-TIME PCR TESTING OF THESE GENES FOLLOWING COCAINE SELF-ADMINISTRATION OR EARLY (THIRD DAY) AND LATE (TENTH DAY) EXTINCTION REVEALED ELEVATED LEVELS OF THEIR TRANSCRIPTS. INTERESTINGLY, WE FOUND THE ENRICHMENT OF BRD1 MESSENGER RNA IN RATS SELF-ADMINISTERING COCAINE THAT LASTED UNTIL EXTINCTION TRAINING DURING COCAINE WITHDRAWAL WITH CONCOMITANT INCREASED ACETYLATION OF H3K9 AND H4K8. HOWEVER, DESPITE ELEVATED LEVELS OF METHYL- AND DEMETHYLTRANSFERASE-ENCODED TRANSCRIPTS, NO CHANGES IN GLOBAL DI- AND TRI-METHYLATION OF HISTONE H3 AT LYSINE 4, 9, 27, AND 79 WERE OBSERVED. SURPRISINGLY, AT THE END OF EXTINCTION TRAINING (10 DAYS OF COCAINE WITHDRAWAL), MOST OF THE ANALYZED GENES IN THE RATS ACTIVELY AND PASSIVELY ADMINISTERING COCAINE RETURNED TO THE CONTROL LEVEL. TOGETHER, THE ALTERATIONS IDENTIFIED IN THE RAT PREFRONTAL CORTEX MAY SUGGEST ENHANCED CHROMATIN REMODELING AND TRANSCRIPTIONAL ACTIVITY INDUCED BY EARLY COCAINE ABSTINENCE; HOWEVER, TO KNOW WHETHER THEY ARE BENEFICIAL OR NOT FOR THE EXTINCTION OF DRUG-SEEKING BEHAVIOR, FURTHER IN VIVO EVALUATION IS REQUIRED. 2017 11 883 47 CHRONIC COCAINE-REGULATED EPIGENOMIC CHANGES IN MOUSE NUCLEUS ACCUMBENS. BACKGROUND: INCREASING EVIDENCE SUPPORTS A ROLE FOR ALTERED GENE EXPRESSION IN MEDIATING THE LASTING EFFECTS OF COCAINE ON THE BRAIN, AND RECENT WORK HAS DEMONSTRATED THE INVOLVEMENT OF CHROMATIN MODIFICATIONS IN THESE ALTERATIONS. HOWEVER, ALL SUCH STUDIES TO DATE HAVE BEEN RESTRICTED BY THEIR RELIANCE ON MICROARRAY TECHNOLOGIES THAT HAVE INTRINSIC LIMITATIONS. RESULTS: WE USE NEXT GENERATION SEQUENCING METHODS, RNA-SEQ AND CHIP-SEQ FOR RNA POLYMERASE II AND SEVERAL HISTONE METHYLATION MARKS, TO OBTAIN A MORE COMPLETE VIEW OF COCAINE-INDUCED CHANGES IN GENE EXPRESSION AND ASSOCIATED ADAPTATIONS IN NUMEROUS MODES OF CHROMATIN REGULATION IN THE MOUSE NUCLEUS ACCUMBENS, A KEY BRAIN REWARD REGION. WE DEMONSTRATE AN UNEXPECTEDLY LARGE NUMBER OF PRE-MRNA SPLICING ALTERATIONS IN RESPONSE TO REPEATED COCAINE TREATMENT. IN ADDITION, WE IDENTIFY COMBINATIONS OF CHROMATIN CHANGES, OR SIGNATURES, THAT CORRELATE WITH COCAINE-DEPENDENT REGULATION OF GENE EXPRESSION, INCLUDING THOSE INVOLVING PRE-MRNA ALTERNATIVE SPLICING. THROUGH BIOINFORMATIC PREDICTION AND BIOLOGICAL VALIDATION, WE IDENTIFY ONE PARTICULAR SPLICING FACTOR, A2BP1(RBFOX1/FOX-1), WHICH IS ENRICHED AT GENES THAT DISPLAY CERTAIN CHROMATIN SIGNATURES AND CONTRIBUTES TO DRUG-INDUCED BEHAVIORAL ABNORMALITIES. TOGETHER, THIS DELINEATION OF THE COCAINE-INDUCED EPIGENOME IN THE NUCLEUS ACCUMBENS REVEALS SEVERAL NOVEL MODES OF REGULATION BY WHICH COCAINE ALTERS THE BRAIN. CONCLUSIONS: WE ESTABLISH COMBINATORIAL CHROMATIN AND TRANSCRIPTIONAL PROFILES IN MOUSE NUCLEUS ACCUMBENS AFTER REPEATED COCAINE TREATMENT. THESE RESULTS SERVE AS AN IMPORTANT RESOURCE FOR THE FIELD AND PROVIDE A TEMPLATE FOR THE ANALYSIS OF OTHER SYSTEMS TO REVEAL NEW TRANSCRIPTIONAL AND EPIGENETIC MECHANISMS OF NEURONAL REGULATION. 2014 12 2012 28 EPIGENETIC BASIS OF OPIATE SUPPRESSION OF BDNF GENE EXPRESSION IN THE VENTRAL TEGMENTAL AREA. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) HAS A CRUCIAL ROLE IN MODULATING NEURAL AND BEHAVIORAL PLASTICITY TO DRUGS OF ABUSE. WE FOUND A PERSISTENT DOWNREGULATION OF EXON-SPECIFIC BDNF EXPRESSION IN THE VENTRAL TEGMENTAL AREA (VTA) IN RESPONSE TO CHRONIC OPIATE EXPOSURE, WHICH WAS MEDIATED BY SPECIFIC EPIGENETIC MODIFICATIONS AT THE CORRESPONDING BDNF GENE PROMOTERS. EXPOSURE TO CHRONIC MORPHINE INCREASED STALLING OF RNA POLYMERASE II AT THESE BDNF PROMOTERS IN VTA AND ALTERED PERMISSIVE AND REPRESSIVE HISTONE MODIFICATIONS AND OCCUPANCY OF THEIR REGULATORY PROTEINS AT THE SPECIFIC PROMOTERS. FURTHERMORE, WE FOUND THAT MORPHINE SUPPRESSED BINDING OF PHOSPHO-CREB (CAMP RESPONSE ELEMENT BINDING PROTEIN) TO BDNF PROMOTERS IN VTA, WHICH RESULTED FROM ENRICHMENT OF TRIMETHYLATED H3K27 AT THE PROMOTERS, AND THAT DECREASED NURR1 (NUCLEAR RECEPTOR RELATED-1) EXPRESSION ALSO CONTRIBUTED TO BDNF REPRESSION AND ASSOCIATED BEHAVIORAL PLASTICITY TO MORPHINE. OUR FINDINGS SUGGEST PREVIOUSLY UNKNOWN EPIGENETIC MECHANISMS OF MORPHINE-INDUCED MOLECULAR AND BEHAVIORAL NEUROADAPTATIONS. 2015 13 4173 36 MELATONIN INDUCES HISTONE HYPERACETYLATION IN THE RAT BRAIN. WE HAVE REPORTED THAT MELATONIN INDUCES HISTONE HYPERACETYLATION IN MOUSE NEURAL STEM CELLS, SUGGESTING AN EPIGENETIC ROLE FOR THIS PLEIOTROPIC HORMONE. TO SUPPORT SUCH A ROLE, IT IS NECESSARY TO DEMONSTRATE THAT MELATONIN PRODUCES SIMILAR EFFECTS IN VIVO. HISTONE ACETYLATION, FOLLOWING CHRONIC TREATMENT WITH MELATONIN (4MUG/ML IN DRINKING WATER FOR 17 DAYS), WAS EXAMINED BY WESTERN BLOTTING IN SELECTED RAT BRAIN REGIONS. MELATONIN INDUCED SIGNIFICANT INCREASES IN HISTONE H3 AND HISTONE H4 ACETYLATION IN THE HIPPOCAMPUS. HISTONE H4 WAS ALSO HYPERACETYLATED IN THE STRIATUM, BUT THERE WERE NO SIGNIFICANT CHANGES IN HISTONE H3 ACETYLATION IN THIS BRAIN REGION. NO SIGNIFICANT CHANGES IN THE ACETYLATION OF EITHER HISTONE H3 OR H4 WERE OBSERVED IN THE MIDBRAIN AND CEREBELLUM. AN EXAMINATION OF KINASE ACTIVATION, WHICH MAY BE RELATED TO THESE CHANGES, REVEALED THAT MELATONIN TREATMENT INCREASED THE LEVELS OF PHOSPHO-ERK (EXTRACELLULAR SIGNAL-REGULATED KINASE) IN THE HIPPOCAMPUS AND STRIATUM, BUT PHOSPHO-AKT (PROTEIN KINASE B) LEVELS WERE UNCHANGED. THESE FINDINGS SUGGEST THAT CHROMATIN REMODELING AND ASSOCIATED CHANGES IN THE EPIGENETIC REGULATION OF GENE EXPRESSION UNDERLIE THE MULTIPLE PHYSIOLOGICAL EFFECTS OF MELATONIN. 2013 14 3314 53 HIPPOCAMPAL CANNABINOID 1 RECEPTORS ARE MODULATED FOLLOWING COCAINE SELF-ADMINISTRATION IN MALE RATS. COCAINE ADDICTION IS A COMPLEX PATHOLOGY INDUCING LONG-TERM NEUROPLASTIC CHANGES THAT, IN TURN, CONTRIBUTE TO MALADAPTIVE BEHAVIORS. THIS BEHAVIORAL DYSREGULATION IS ASSOCIATED WITH TRANSCRIPTIONAL REPROGRAMMING IN BRAIN REWARD CIRCUITRY, ALTHOUGH THE MECHANISMS UNDERLYING THIS MODULATION REMAIN POORLY UNDERSTOOD. THE ENDOGENOUS CANNABINOID SYSTEM MAY PLAY A ROLE IN THIS PROCESS IN THAT CANNABINOID MECHANISMS MODULATE DRUG REWARD AND CONTRIBUTE TO COCAINE-INDUCED NEURAL ADAPTATIONS. IN THIS STUDY, WE INVESTIGATED WHETHER COCAINE SELF-ADMINISTRATION INDUCES LONG-TERM ADAPTATIONS, INCLUDING TRANSCRIPTIONAL MODIFICATIONS AND ASSOCIATED EPIGENETIC PROCESSES. WE FIRST EXAMINED ENDOCANNABINOID GENE EXPRESSION IN REWARD-RELATED BRAIN REGIONS OF THE RAT FOLLOWING SELF-ADMINISTERED (0.33 MG/KG INTRAVENOUS, FR1, 10 DAYS) COCAINE INJECTIONS. INTERESTINGLY, WE FOUND INCREASED CNR1 EXPRESSION IN SEVERAL STRUCTURES, INCLUDING PREFRONTAL CORTEX, NUCLEUS ACCUMBENS, DORSAL STRIATUM, HIPPOCAMPUS, HABENULA, AMYGDALA, LATERAL HYPOTHALAMUS, VENTRAL TEGMENTAL AREA, AND ROSTROMEDIAL TEGMENTAL NUCLEUS, WITH MOST PRONOUNCED EFFECTS IN THE HIPPOCAMPUS. ENDOCANNABINOID LEVELS, MEASURED BY MASS SPECTROMETRY, WERE ALSO ALTERED IN THIS STRUCTURE. CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY QPCR IN THE HIPPOCAMPUS REVEALED THAT TWO ACTIVATING HISTONE MARKS, H3K4ME3 AND H3K27AC, WERE ENRICHED AT SPECIFIC ENDOCANNABINOID GENES FOLLOWING COCAINE INTAKE. TARGETING CB1 RECEPTORS USING CHROMOSOME CONFORMATION CAPTURE, WE HIGHLIGHTED SPATIAL CHROMATIN RE-ORGANIZATION IN THE HIPPOCAMPUS, AS WELL AS IN THE NUCLEUS ACCUMBENS, SUGGESTING THAT DESTABILIZATION OF THE CHROMATIN MAY CONTRIBUTE TO NEURONAL RESPONSES TO COCAINE. OVERALL, OUR RESULTS HIGHLIGHT A KEY ROLE FOR THE HIPPOCAMPUS IN COCAINE-INDUCED PLASTICITY AND BROADEN THE UNDERSTANDING OF NEURONAL ALTERATIONS ASSOCIATED WITH ENDOCANNABINOID SIGNALING. THE LATTER SUGGESTS THAT EPIGENETIC MODIFICATIONS CONTRIBUTE TO MALADAPTIVE BEHAVIORS ASSOCIATED WITH CHRONIC DRUG USE. 2022 15 4218 40 METHYL SUPPLEMENTATION ATTENUATES COCAINE-SEEKING BEHAVIORS AND COCAINE-INDUCED C-FOS ACTIVATION IN A DNA METHYLATION-DEPENDENT MANNER. EPIGENETIC MECHANISMS, SUCH AS HISTONE MODIFICATIONS, REGULATE RESPONSIVENESS TO DRUGS OF ABUSE, SUCH AS COCAINE, BUT RELATIVELY LITTLE IS KNOWN ABOUT THE REGULATION OF ADDICTIVE-LIKE BEHAVIORS BY DNA METHYLATION. TO INVESTIGATE THE INFLUENCE OF DNA METHYLATION ON THE LOCOMOTOR-ACTIVATING EFFECTS OF COCAINE AND ON DRUG-SEEKING BEHAVIOR, RATS RECEIVING METHYL SUPPLEMENTATION VIA CHRONIC L-METHIONINE (MET) UNDERWENT EITHER A SENSITIZATION REGIMEN OF INTERMITTENT COCAINE INJECTIONS OR INTRAVENOUS SELF-ADMINISTRATION OF COCAINE, FOLLOWED BY CUE-INDUCED AND DRUG-PRIMED REINSTATEMENT. MET BLOCKED SENSITIZATION TO THE LOCOMOTOR-ACTIVATING EFFECTS OF COCAINE AND ATTENUATED DRUG-PRIMED REINSTATEMENT, WITH NO EFFECT ON CUE-INDUCED REINSTATEMENT OR SUCROSE SELF-ADMINISTRATION AND REINSTATEMENT. FURTHERMORE, UPREGULATION OF DNA METHYLTRANSFERASE 3A AND 3B AND GLOBAL DNA HYPOMETHYLATION WERE OBSERVED IN THE NUCLEUS ACCUMBENS CORE (NAC), BUT NOT IN THE MEDIAL PREFRONTAL CORTEX (MPFC), OF COCAINE-PRETREATED RATS. GLUTAMATERGIC PROJECTIONS FROM THE MPFC TO THE NAC ARE CRITICALLY INVOLVED IN THE REGULATION OF COCAINE-PRIMED REINSTATEMENT, AND ACTIVATION OF BOTH BRAIN REGIONS IS SEEN IN HUMAN ADDICTS WHEN REEXPOSED TO THE DRUG. WHEN COMPARED WITH VEHICLE-PRETREATED RATS, THE IMMEDIATE EARLY GENE C-FOS (A MARKER OF NEURONAL ACTIVATION) WAS UPREGULATED IN THE NAC AND MPFC OF COCAINE-PRETREATED RATS AFTER COCAINE-PRIMED REINSTATEMENT, AND CHRONIC MET TREATMENT BLOCKED ITS INDUCTION IN BOTH REGIONS. COCAINE-INDUCED C-FOS EXPRESSION IN THE NAC WAS ASSOCIATED WITH REDUCED METHYLATION AT CPG DINUCLEOTIDES IN THE C-FOS GENE PROMOTER, EFFECTS REVERSED BY MET TREATMENT. OVERALL, THESE DATA SUGGEST THAT DRUG-SEEKING BEHAVIORS ARE, IN PART, ATTRIBUTABLE TO A DNA METHYLATION-DEPENDENT PROCESS, LIKELY OCCURRING AT SPECIFIC GENE LOCI (E.G., C-FOS) IN THE REWARD PATHWAY. 2015 16 6804 39 [EPIGENETIC REGULATION IN DEPRESSION]. RECENT RESEARCH HAS RAISED THE NOTION THAT EPIGENETIC MECHANISMS (E.G., DNA METHYLATION AND HISTONE MODIFICATIONS), WHICH EXERT LASTING CONTROL OVER GENE EXPRESSION WITHOUT ALTERING THE GENETIC CODE, COULD MEDIATE STABLE CHANGES IN BRAIN FUNCTION. HOWEVER, THE ROLE OF ENVIRONMENTAL FACTORS ALONG WITH GENETIC FACTORS IN THE EPIGENETIC REGULATION OF THE PATHOGENESIS OF DEPRESSION IS LARGELY UNKNOWN. TWO GENETICALLY DISTINCT MICE STRAINS, BALB/C (BALB) AND C57BL/6 (B6), EXHIBIT DIFFERENT BEHAVIORAL RESPONSES TO CHRONIC STRESS. WITH CHRONIC STRESS, BALB MICE SHOWED DEPRESSIVE-LIKE BEHAVIORS, BUT NOT B6 MICE, AND GLIAL CELL-DERIVED NEUROTROPHIC FACTOR (GDNF) EXPRESSION LEVEL WAS DECREASED IN THE VENTRAL STRIATUM OF BALB MICE BUT INCREASED IN B6 MICE. IN BALB MICE, DEPRESSIVE-LIKE BEHAVIORS AND DECREASED GDNF EXPRESSION WERE RECOVERED BY CHRONIC ANTIDEPRESSANT TREATMENT. THEREFORE, WE USED THESE TWO MICE STRAINS TO INVESTIGATE HOW THE EPIGENETIC STATUS OF THE GDNF GENE IN THE VENTRAL STRIATUM MODULATES STRESS VULNERABILITY. BOTH MICE STRAINS SHOWED INCREASED DNA METHYLATION LEVELS AND MECP2 RECRUITMENT IN THE GDNF PROMOTER REGION. HOWEVER, HISTONE H3 ACETYLATION LEVEL WAS DECREASED IN BALB MICE, BUT INCREASED IN B6 MICE. FURTHERMORE, BALB MICE SHOWED INCREASED HISTONE DEACETYLASE2 (HDAC2) EXPRESSION LEVEL AND RE-CHIP ASSAY REVEALED HDAC2-MECP2 COMPLEX IN BALB MICE. OUR RESULTS INDICATE THE CRUCIAL ROLE OF HISTONE MODIFICATION BY HDAC2 AND MECP2 COMPLEX FOR THE CONTROL OF GDNF EXPRESSION AND SUBSEQUENT BEHAVIORAL RESPONSES TO CHRONIC STRESS, IN OTHER WORDS, THE SUSCEPTIBILITY TO STRESS. IN ADDITION, WE INVESTIGATED THE EFFECT OF ANTIDEPRESSANTS ON THE EPIGENETIC REGULATION OF GDNF EXPRESSION. WE FOUND A REDUCED LEVEL OF HDAC4 RECRUITMENT AT THE GDNF PROMOTER REGION WITH ANTIDEPRESSANTS. THUS, OUR DATA SUGGEST THAT ANTIDEPRESSANTS INCREASE TRANSCRIPTIONAL ACTIVITY OF THE GDNF GENE THROUGH THE MODULATION OF HISTONE ACETYLATION BY HDAC4. FINALLY, WE EXAMINED THE EXPRESSIONS OF GDNF AND EPIGENETIC-RELATED MOLECULES MRNAS WITH MAJOR DEPRESSIVE AND BIPOLAR DISORDER PATIENTS BY USING QUANTITATIVE REAL-TIME PCR. WE FOUND THE ABERRANT EXPRESSION OF GDNF AND EPIGENETIC-RELATED GENES INCLUDING HDAC2 AND HDAC4 IN MOOD DISORDER PATIENTS. THUS, OUR DATA PROVIDE NOVEL INSIGHTS SUGGESTING THAT EPIGENETIC MECHANISMS OF GDNF EXPRESSION ARE INVOLVED IN THE PATHOGENESIS OR PATHOPHYSIOLOGY OF DEPRESSION. 2012 17 5624 30 SELECTIVE BOOSTING OF TRANSCRIPTIONAL AND BEHAVIORAL RESPONSES TO DRUGS OF ABUSE BY HISTONE DEACETYLASE INHIBITION. HISTONE ACETYLATION AND OTHER MODIFICATIONS OF THE CHROMATIN ARE IMPORTANT REGULATORS OF GENE EXPRESSION AND, CONSEQUENTLY, MAY CONTRIBUTE TO DRUG-INDUCED BEHAVIORS AND NEUROPLASTICITY. EARLIER STUDIES HAVE SHOWN THAT A REDUCTION IN HISTONE DEACETYLASE (HDAC) ACTIVITY RESULTS IN THE ENHANCEMENT OF SOME PSYCHOSTIMULANT-INDUCED BEHAVIORS. IN THIS STUDY, WE EXTEND THOSE SEMINAL FINDINGS BY SHOWING THAT THE ADMINISTRATION OF THE HDAC INHIBITOR SODIUM BUTYRATE ENHANCES MORPHINE-INDUCED LOCOMOTOR SENSITIZATION AND CONDITIONED PLACE PREFERENCE. IN CONTRAST, THIS COMPOUND HAS NO EFFECTS ON THE DEVELOPMENT OF MORPHINE TOLERANCE AND DEPENDENCE. SIMILAR EFFECTS WERE OBSERVED FOR COCAINE AND ETHANOL-INDUCED BEHAVIORS. THESE BEHAVIORAL CHANGES WERE ACCOMPANIED BY A SELECTIVE BOOSTING OF A COMPONENT OF THE TRANSCRIPTIONAL PROGRAM ACTIVATED BY CHRONIC MORPHINE ADMINISTRATION THAT INCLUDED CIRCADIAN CLOCK GENES AND OTHER GENES RELEVANT TO ADDICTIVE BEHAVIOR. OUR RESULTS SUPPORT A SPECIFIC FUNCTION FOR HISTONE ACETYLATION AND THE EPIGENETIC MODULATION OF TRANSCRIPTION AT A REDUCED NUMBER OF BIOLOGICALLY RELEVANT LOCI ON NON-HOMEOSTATIC, LONG-LASTING, DRUG-INDUCED BEHAVIORAL PLASTICITY. 2009 18 3203 44 HDAC3 ACTIVITY WITHIN THE NUCLEUS ACCUMBENS REGULATES COCAINE-INDUCED PLASTICITY AND BEHAVIOR IN A CELL-TYPE-SPECIFIC MANNER. EPIGENETIC MECHANISMS REGULATE PROCESSES OF NEUROPLASTICITY CRITICAL TO COCAINE-INDUCED BEHAVIORS. THIS INCLUDES THE CLASS I HISTONE DEACETYLASE (HDAC) HDAC3, KNOWN TO ACT AS A NEGATIVE REGULATOR OF COCAINE-ASSOCIATED MEMORY FORMATION WITHIN THE NUCLEUS ACCUMBENS (NAC). DESPITE THIS, IT REMAINS UNKNOWN HOW COCAINE ALTERS HDAC3-DEPENDENT MECHANISMS. HERE, WE PROFILED HDAC3 EXPRESSION AND ACTIVITY IN TOTAL NAC MOUSE TISSUE FOLLOWING COCAINE EXPOSURE. ALTHOUGH CHRONIC COCAINE DID NOT AFFECT EXPRESSION OF HDAC3 WITHIN THE NAC, CHRONIC COCAINE DID AFFECT PROMOTER-SPECIFIC CHANGES IN HDAC3 AND H4K8AC OCCUPANCY. THESE CHANGES IN PROMOTER OCCUPANCY CORRELATED WITH COCAINE-INDUCED CHANGES IN EXPRESSION OF PLASTICITY-RELATED GENES. TO CAUSALLY DETERMINE WHETHER COCAINE-INDUCED PLASTICITY IS MEDIATED BY HDAC3'S DEACETYLASE ACTIVITY, WE OVEREXPRESSED A DEACETYLASE-DEAD HDAC3 POINT MUTANT (HDAC3-Y298H-V5) WITHIN THE NAC OF ADULT MALE MICE. WE FOUND THAT DISRUPTING HDAC3'S ENZYMATIC ACTIVITY ALTERED SELECTIVE CHANGES IN GENE EXPRESSION AND SYNAPTIC PLASTICITY FOLLOWING COCAINE EXPOSURE, DESPITE HAVING NO EFFECTS ON COCAINE-INDUCED BEHAVIORS. IN FURTHER ASSESSING HDAC3'S ROLE WITHIN THE NAC, WE OBSERVED THAT CHRONIC COCAINE INCREASES HDAC3 EXPRESSION IN DRD1 BUT NOT DRD2-CELLS OF THE NAC. MOREOVER, WE DISCOVERED THAT HDAC3 ACTS SELECTIVELY WITHIN D1R CELL-TYPES TO REGULATE COCAINE-ASSOCIATED MEMORY FORMATION AND COCAINE-SEEKING. OVERALL, THESE RESULTS SUGGEST THAT COCAINE INDUCES CELL-TYPE-SPECIFIC CHANGES IN EPIGENETIC MECHANISMS TO PROMOTE PLASTICITY IMPORTANT FOR DRIVING COCAINE-RELATED BEHAVIORS.SIGNIFICANCE STATEMENT DRUGS OF ABUSE ALTER MOLECULAR MECHANISMS THROUGHOUT THE REWARD CIRCUITRY THAT CAN LEAD TO PERSISTENT DRUG-ASSOCIATED BEHAVIORS. EPIGENETIC REGULATORS ARE CRITICAL DRIVERS OF DRUG-INDUCED CHANGES IN GENE EXPRESSION. HERE, WE DEMONSTRATE THAT THE ACTIVITY OF AN EPIGENETIC ENZYME PROMOTES NEUROPLASTICITY WITHIN THE NUCLEUS ACCUMBENS (NAC) CRITICAL TO COCAINE ACTION. IN ADDITION, WE DEMONSTRATE THAT THESE CHANGES IN EPIGENETIC ACTIVITY DRIVE COCAINE-SEEKING BEHAVIORS IN A CELL-TYPE-SPECIFIC MANNER. THESE FINDINGS ARE KEY IN UNDERSTANDING AND TARGETING COCAINE'S IMPACT OF NEURAL CIRCUITRY AND BEHAVIOR. 2021 19 4236 38 METHYLATION OF THE TYROSINE HYDROXYLASE GENE IS DYSREGULATED BY COCAINE DEPENDENCE IN THE HUMAN STRIATUM. COCAINE DEPENDENCE IS A CHRONIC, RELAPSING DISORDER CAUSED BY LASTING CHANGES IN THE BRAIN. ANIMAL STUDIES HAVE IDENTIFIED COCAINE-RELATED ALTERATIONS IN STRIATAL DNA METHYLATION; HOWEVER, IT IS UNCLEAR HOW METHYLATION IS RELATED TO COCAINE DEPENDENCE IN HUMANS. WE GENERATED METHYLOMIC PROFILES OF THE NUCLEUS ACCUMBENS USING HUMAN POSTMORTEM BRAINS FROM A COHORT OF INDIVIDUALS WITH COCAINE DEPENDENCE AND HEALTHY CONTROLS (N = 25 PER GROUP). WE FOUND HYPERMETHYLATION IN A CLUSTER OF CPGS WITHIN THE GENE BODY OF TYROSINE HYDROXYLASE (TH), CONTAINING A PUTATIVE BINDING SITE FOR THE EARLY GROWTH RESPONSE 1 (EGR1) TRANSCRIPTION FACTOR, WHICH IS HYPERMETHYLATED IN THE CAUDATE NUCLEUS OF COCAINE-DEPENDENT INDIVIDUALS. WE REPLICATED THIS FINDING AND FOUND IT TO BE SPECIFIC TO STRIATAL NEURONAL NUCLEI. FURTHERMORE, THIS LOCUS DEMONSTRATES ENHANCER ACTIVITY WHICH IS ATTENUATED BY METHYLATION AND ENHANCED BY EGR1 OVEREXPRESSION. THESE RESULTS SUGGEST THAT COCAINE DEPENDENCE ALTERS THE EPIGENETIC REGULATION OF DOPAMINERGIC SIGNALING GENES. 2021 20 4498 38 MORPHINE REGULATES ARGONAUTE 2 AND TH EXPRESSION AND ACTIVITY BUT NOT MIR-133B IN MIDBRAIN DOPAMINERGIC NEURONS. EPIGENETIC CHANGES SUCH AS MICRORNAS (MIRS)/AGO2-INDUCED GENE SILENCING REPRESENT COMPLEX MOLECULAR SIGNATURE THAT REGULATE CELLULAR PLASTICITY. RECENT STUDIES SHOWED INVOLVEMENT OF MIRS AND AGO2 IN DRUG ADDICTION. IN THIS STUDY, WE SHOW THAT CHANGES IN GENE EXPRESSION INDUCED BY MORPHINE AND MORPHINE WITHDRAWAL OCCUR WITH CONCOMITANT EPIGENETIC MODIFICATIONS IN THE MESOLIMBIC DOPAMINERGIC (DA) PATHWAY [VENTRAL TEGMENTAL AREA (VTA)/NUCLEUS ACCUMBENS (NAC) SHELL], WHICH IS CRITICALLY INVOLVED IN DRUG-INDUCED DEPENDENCE. WE FOUND THAT ACUTE OR CHRONIC MORPHINE ADMINISTRATION AS WELL AS MORPHINE WITHDRAWAL DID NOT MODIFY MIR-133B MESSENGER RNA (MRNA) EXPRESSION IN THE VTA, WHEREAS AGO2 PROTEIN LEVELS WERE DECREASED AND INCREASED IN MORPHINE-DEPENDENT RATS AND AFTER MORPHINE WITHDRAWAL, RESPECTIVELY. THESE CHANGES WERE PARALLELED WITH ENHANCED AND DECREASED NAC TYROSINE HYDROXYLASE (TH) PROTEIN (AN EARLY DA MARKER) IN MORPHINE-DEPENDENT RATS AND AFTER WITHDRAWAL, RESPECTIVELY. WE ALSO OBSERVED CHANGES IN TH MRNA EXPRESSION IN THE VTA THAT COULD BE RELATED TO AGO2-INDUCED TRANSLATIONAL REPRESSION OF TH MRNA DURING MORPHINE WITHDRAWAL. HOWEVER, THE VTA NUMBER OF TH-POSITIVE NEURONS SUFFERED NO ALTERATIONS AFTER THE DIFFERENT TREATMENT. ACUTE MORPHINE ADMINISTRATION PRODUCED A MARKED INCREASE IN TH ACTIVITY AND DA TURNOVER IN THE NAC (SHELL). IN CONTRAST, PRECIPITATED MORPHINE WITHDRAWAL DECREASED TH ACTIVATION AND DID NOT CHANGE DA TURNOVER. THESE FINDINGS PROVIDE NEW INFORMATION INTO THE POSSIBLE CORRELATION BETWEEN AGO2/MIRS COMPLEX REGULATION AND DA NEURONS PLASTICITY DURING OPIATE ADDICTION. 2015