1 1831 118 EFFECTS OF MATERNAL SEPARATION AND ANTIDEPRESSANT DRUG ON EPIGENETIC REGULATION OF THE BRAIN-DERIVED NEUROTROPHIC FACTOR EXON I PROMOTER IN THE ADULT RAT HIPPOCAMPUS. AIM: EARLY LIFE STRESS CAN INDUCE EPIGENETIC CHANGES THROUGH GENETIC AND ENVIRONMENTAL INTERACTIONS AND IS A RISK FACTOR FOR DEPRESSION. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) HAS BEEN IMPLICATED IN THE PATHOPHYSIOLOGY OF DEPRESSION AND ANTIDEPRESSANT DRUG ACTION. WE INVESTIGATED EPIGENETIC CHANGES AT THE BDNF EXON I PROMOTER IN THE HIPPOCAMPUS OF ADULT RATS SUBJECTED TO MATERNAL SEPARATION (MS) DURING EARLY LIFE AND TREATED WITH AN ANTIDEPRESSANT DRUG AS ADULTS. METHODS: RAT PUPS WERE SUBJECTED TO MS FROM POSTNATAL DAY 1 TO 21 AND RECEIVED CHRONIC ESCITALOPRAM (ESC) AS ADULTS. WE ASSESSED THE EFFECTS OF MS AND ESC ON BDNF EXON I AND DNA METHYLTRANSFERASES (DNMT) MRNA LEVELS (QUANTITATIVE REVERSE-TRANSCRIPTION POLYMERASE CHAIN REACTION), ACETYLATED HISTONE H3, AND MECP2 BINDING TO THE BDNF PROMOTER I (CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY REAL-TIME POLYMERASE CHAIN REACTION), AND BDNF PROTEIN LEVELS (ENZYME-LINKED IMMUNOSORBENT ASSAY). RESULTS: THE LEVELS OF BDNF PROTEIN, EXON I MRNA, HISTONE H3 ACETYLATION, AND DNMT1 AND DNMT3A MRNA WERE ALTERED IN THE MS GROUP COMPARED WITH THE CONTROL GROUP. SIGNIFICANT DECREASES WERE OBSERVED IN THE BDNF PROTEIN, EXON I MRNA, AND HISTONE H3 ACETYLATION LEVELS AND THERE WERE SIGNIFICANT INCREASES IN DNMT1 AND DNMT3A MRNA LEVELS. THE COMPARISON BETWEEN THE MS + ESC AND MS GROUPS REVEALED SIGNIFICANT INCREASES IN BDNF PROTEIN, EXON I MRNA, AND HISTONE H3 ACETYLATION LEVELS AND SIGNIFICANT DECREASES IN MECP2 AND DNMT1 AND DNMT3A MRNA LEVELS. CONCLUSION: THESE FINDINGS INDICATE THAT MS INDUCED EPIGENETIC CHANGES AT THE BDNF EXON I PROMOTER AND THESE CHANGES WERE PREVENTED BY ANTIDEPRESSANT DRUG TREATMENT DURING ADULTHOOD. 2018 2 1809 53 EFFECTS OF ANTIPSYCHOTIC DRUGS ON THE EPIGENETIC MODIFICATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR GENE EXPRESSION IN THE HIPPOCAMPI OF CHRONIC RESTRAINT STRESS RATS. RECENT STUDIES HAVE SHOWN THAT ANTIPSYCHOTIC DRUGS HAVE EPIGENETIC EFFECTS. HOWEVER, THE EFFECTS OF ANTIPSYCHOTIC DRUGS ON HISTONE MODIFICATION REMAIN UNCLEAR. THEREFORE, WE INVESTIGATED THE EFFECTS OF ANTIPSYCHOTIC DRUGS ON THE EPIGENETIC MODIFICATION OF THE BDNF GENE IN THE RAT HIPPOCAMPUS. RATS WERE SUBJECTED TO CHRONIC RESTRAINT STRESS (6 H/D FOR 21 D) AND THEN WERE ADMINISTERED WITH EITHER OLANZAPINE (2 MG/KG) OR HALOPERIDOL (1 MG/KG). THE LEVELS OF HISTONE H3 ACETYLATION AND MECP2 BINDING AT BDNF PROMOTER IV WERE ASSESSED WITH CHROMATIN IMMUNOPRECIPITATION ASSAYS. THE MRNA LEVELS OF TOTAL BDNF WITH EXON IV, HDAC5, DNMT1, AND DNMT3A WERE ASSESSED WITH A QUANTITATIVE RT-PCR PROCEDURE. CHRONIC RESTRAINT STRESS RESULTED IN THE DOWNREGULATION OF TOTAL AND EXON IV BDNF MRNA LEVELS AND A DECREASE IN HISTONE H3 ACETYLATION AND AN INCREASE IN MECP2 BINDING AT BDNF PROMOTER IV. FURTHERMORE, THERE WERE ROBUST INCREASES IN THE EXPRESSION OF HDAC5 AND DNMTS. OLANZAPINE ADMINISTRATION LARGELY PREVENTED THESE CHANGES. THE ADMINISTRATION OF HALOPERIDOL HAD NO EFFECT. THESE FINDINGS SUGGEST THAT THE ANTIPSYCHOTIC DRUG OLANZAPINE INDUCED HISTONE MODIFICATION OF BDNF GENE EXPRESSION IN THE HIPPOCAMPUS AND THAT THESE EPIGENETIC ALTERATIONS MAY REPRESENT ONE OF THE MECHANISMS UNDERLYING THE ACTIONS OF ANTIPSYCHOTIC DRUGS. 2018 3 1320 42 DEMETHYLATION REGULATION OF BDNF GENE EXPRESSION IN DORSAL ROOT GANGLION NEURONS IS IMPLICATED IN OPIOID-INDUCED PAIN HYPERSENSITIVITY IN RATS. REPEATED ADMINISTRATION OF MORPHINE MAY RESULT IN OPIOID-INDUCED HYPERSENSITIVITY (OIH), WHICH INVOLVES ALTERED EXPRESSION OF NUMEROUS GENES, INCLUDING BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) IN DORSAL ROOT GANGLION (DRG) NEURONS. YET, IT REMAINS UNCLEAR HOW BDNF EXPRESSION IS INCREASED IN DRG NEURONS AFTER REPEATED MORPHINE TREATMENT. DNA METHYLATION IS AN IMPORTANT MECHANISM OF EPIGENETIC CONTROL OF GENE EXPRESSION. IN THE CURRENT STUDY, WE HYPOTHESIZED THAT THE DEMETHYLATION REGULATION OF CERTAIN BDNF GENE PROMOTERS IN DRG NEURONS MAY CONTRIBUTE TO THE DEVELOPMENT OF OIH. REAL-TIME RT-PCR WAS USED TO ASSESS CHANGES IN THE MRNA TRANSCRIPTION LEVELS OF MAJOR BDNF EXONS INCLUDING EXON I, II, IV, VI, AS WELL AS TOTAL BDNF MRNA IN DRGS FROM RATS AFTER REPEATED MORPHINE ADMINISTRATION. THE LEVELS OF EXON IV AND TOTAL BDNF MRNA WERE SIGNIFICANTLY UPREGULATED BY REPEATED MORPHINE ADMINISTRATION, AS COMPARED TO THAT IN SALINE CONTROL GROUP. FURTHER, ELISA ARRAY AND IMMUNOCYTOCHEMISTRY STUDY REVEALED A ROBUST UPREGULATION OF BDNF PROTEIN EXPRESSION IN DRG NEURONS AFTER REPEATED MORPHINE EXPOSURE. CORRESPONDINGLY, THE METHYLATION LEVELS OF BDNF EXON IV PROMOTER SHOWED A SIGNIFICANT DOWNREGULATION BY MORPHINE TREATMENT. IMPORTANTLY, INTRATHECAL ADMINISTRATION OF A BDNF ANTIBODY, BUT NOT CONTROL IGG, SIGNIFICANTLY INHIBITED MECHANICAL HYPERSENSITIVITY THAT DEVELOPED IN RATS AFTER REPEATED MORPHINE TREATMENT. CONVERSELY, INTRATHECAL ADMINISTRATION OF AN INHIBITOR OF DNA METHYLATION, 5-AZA-2'-DEOXYCYTIDINE (5-AZA-DC) MARKEDLY UPREGULATED THE BDNF PROTEIN EXPRESSION IN DRG NEURONS AND ENHANCED THE MECHANICAL ALLODYNIA AFTER REPEATED MORPHINE EXPOSURE. TOGETHER, OUR FINDINGS SUGGEST THAT DEMETHYLATION REGULATION OF BDNF GENE PROMOTER MAY BE IMPLICATED IN THE DEVELOPMENT OF OIH THROUGH EPIGENETIC CONTROL OF BDNF EXPRESSION IN DRG NEURONS. 2016 4 2300 43 EPIGENETIC REGULATION OF BDNF EXPRESSION IN THE PRIMARY SENSORY NEURONS AFTER PERIPHERAL NERVE INJURY: IMPLICATIONS IN THE DEVELOPMENT OF NEUROPATHIC PAIN. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) IS KNOWN TO BE UP-REGULATED IN THE DORSAL ROOT GANGLION (DRG) AFTER PERIPHERAL NERVE INJURY, AND TO CONTRIBUTE TO NEUROPATHIC PAIN. HERE, WE FOUND THAT THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA AT DAY 7 POST-INJURY WERE INHIBITED ONLY WHEN ANTI-BDNF ANTIBODY WAS INTRATHECALLY ADMINISTRATED AT DAY 2 POST-INJURY. CONSISTENT WITH BEHAVIORAL RESULTS, WESTERN BLOT ANALYSIS SHOWED THAT THE EXPRESSION LEVELS OF BDNF PROTEIN IN THE SPINAL DORSAL HORN WERE MARKEDLY INDUCED DURING EARLY STAGE POST-INJURY. MOREOVER, THE MAXIMAL INCREASE IN BDNF MRNA EXPRESSION IN THE DRG WAS OBSERVED AT DAY 1 POST-INJURY, AND SIGNIFICANTLY ELEVATED LEVELS WERE SUSTAINED FOR AT LEAST 14 DAYS. FOUR OF FIVE BDNF MRNA TRANSCRIPTS WERE UP-REGULATED AFTER NERVE INJURY, AND THE MOST INDUCIBLE TRANSCRIPT WAS EXON I. USING A CHROMATIN IMMUNOPRECIPITATION (CHIP) ASSAY, WE FOUND THAT NERVE INJURY PROMOTES HISTONE H3 AND H4 ACETYLATION, TRANSCRIPTIONALLY ACTIVE MODIFICATIONS, AT BDNF PROMOTER I AT DAY 1 POST-INJURY, AND THE LEVELS OF HISTONE ACETYLATION REMAIN ELEVATED FOR AT LEAST 7 DAYS. TAKEN TOGETHER, OUR FINDINGS SUGGEST THAT AN INITIAL INCREASE IN BDNF EXON I EXPRESSION CONTROLLED BY EPIGENETIC MECHANISMS MIGHT HAVE A CRUCIAL ROLE IN THE DEVELOPMENT OF NEUROPATHIC PAIN. 2013 5 2750 38 EXPRESSION LEVELS OF THE TYROSINE HYDROXYLASE GENE AND HISTONE MODIFICATIONS AROUND ITS PROMOTER IN THE LOCUS COERULEUS AND VENTRAL TEGMENTAL AREA OF RATS DURING FORCED ABSTINENCE FROM MORPHINE. BACKGROUND: EPIGENETIC MECHANISMS SUCH AS HISTONE MODIFICATIONS MAY BE INVOLVED IN THE STRUCTURAL AND BEHAVIORAL CHANGES ASSOCIATED WITH ADDICTION. WE STUDIED WHETHER MORPHINE-INDUCED CHANGES IN MRNA LEVELS OF THE CATECHOLAMINE BIOSYNTHESIS ENZYME, TYROSINE HYDROXYLASE (TH), ARE ASSOCIATED WITH HISTONE MODIFICATIONS AROUND THE PROMOTER OF THIS GENE IN THE LOCUS COERULEUS (LC) AND VENTRAL TEGMENTAL AREA (VTA) OF RATS. METHODS: DEPENDENCE WAS INDUCED IN RATS BY INTRAPERITONEAL INJECTIONS OF MORPHINE FOR 11 DAYS. THE ANIMALS WERE KILLED 2 H (CHRONIC MORPHINE), 24 H AND 7 DAYS (SPONTANEOUS WITHDRAWAL) AFTER THE LAST INJECTION OF MORPHINE. RESULTS: ANALYSIS OF OUR REAL-TIME QUANTITATIVE REVERSE TRANSCRIPTION PCR RESULTS BY 1-WAY ANOVA SHOWED SIGNIFICANT UPREGULATION (5.13 +/- 0.39 FOLDS) OF LC LEVELS OF THE TH TRANSCRIPT 24 H AFTER THE LAST INJECTION OF MORPHINE TO RATS, WHEN COMPARED WITH 2 H AND 7 DAYS TIME POINTS. CHRONIC MORPHINE AND MORPHINE ABSTINENCE FAILED TO CAUSE ANY SIGNIFICANT CHANGES IN THE LEVELS OF TH MRNA IN THE VTA AFTER CESSATION OF MORPHINE. CONSISTENTLY, CHROMATIN IMMUNOPRECIPITATION REAL-TIME QUANTITATIVE PCR ASSAYS REVEALED THAT 24 H AFTER THE LAST INJECTION OF MORPHINE, LEVELS OF H3 ACETYLATION WERE SIGNIFICANTLY INCREASED (4.12 +/- 0.38 FOLDS) AT THE PROMOTER OF THE TH GENE IN THE LC BUT NOT IN THE VTA. OUR DATA ALSO SHOWED THAT HISTONE H3 TRIMETHYLATION FAILED TO CHANGE AROUND THE TH GENE PROMOTER EITHER IN THE VTA OR IN THE LC AFTER MORPHINE ABSTINENCE. CONCLUSIONS: RESULTS OF THE PRESENT STUDY, FOR THE FIRST TIME, DEMONSTRATE THE INVOLVEMENT OF HISTONE H3 ACETYLATION IN THE REGULATION OF TH GENE EXPRESSION IN THE LC OF RATS DURING FORCED ABSTINENCE FROM MORPHINE. 2018 6 5485 35 REVERSAL OF COCAINE-CONDITIONED PLACE PREFERENCE THROUGH METHYL SUPPLEMENTATION IN MICE: ALTERING GLOBAL DNA METHYLATION IN THE PREFRONTAL CORTEX. ANALYSIS OF GLOBAL METHYLATION IN CELLS HAS REVEALED CORRELATIONS BETWEEN OVERALL DNA METHYLATION STATUS AND SOME BIOLOGICAL STATES. RECENT STUDIES SUGGEST THAT EPIGENETIC REGULATION THROUGH DNA METHYLATION COULD BE RESPONSIBLE FOR NEUROADAPTATIONS INDUCED BY ADDICTIVE DRUGS. HOWEVER, THERE IS NO INVESTIGATION TO DETERMINE GLOBAL DNA METHYLATION STATUS FOLLOWING REPEATED EXPOSURE TO ADDICTIVE DRUGS. USING MICE CONDITIONED PLACE PREFERENCE (CPP) PROCEDURE, WE MEASURED GLOBAL DNA METHYLATION LEVEL IN THE NUCLEUS ACCUMBENS (NAC) AND THE PREFRONTAL CORTEX (PFC) ASSOCIATED WITH DRUG REWARDING EFFECTS. WE FOUND THAT COCAINE-, BUT NOT MORPHINE- OR FOOD-CPP TRAINING DECREASED GLOBAL DNA METHYLATION IN THE PFC. CHRONIC TREATMENT WITH METHIONINE, A METHYL DONOR, FOR 25 CONSECUTIVE DAYS PRIOR TO AND DURING CPP TRAINING INHIBITED THE ESTABLISHMENT OF COCAINE, BUT NOT MORPHINE OR FOOD CPP. WE ALSO FOUND THAT BOTH MRNA AND PROTEIN LEVEL OF DNMT (DNA METHYTRANSFERASE) 3B IN THE PFC WERE DOWNREGULATED FOLLOWING THE ESTABLISHMENT OF COCAINE CPP, AND THE DOWNREGULATION COULD BE REVERSED BY REPEATED ADMINISTRATION OF METHIONINE. OUR STUDY INDICATES A CRUCIAL ROLE OF GLOBAL PFC DNA HYPOMETHYLATION IN THE REWARDING EFFECTS OF COCAINE. REVERSAL OF GLOBAL DNA HYPOMETHYLATION COULD SIGNIFICANTLY ATTENUATE THE REWARDING EFFECTS INDUCED BY COCAINE. OUR RESULTS SUGGEST THAT METHIONINE MAY HAVE BECOME A POTENTIAL THERAPEUTIC TARGET TO TREAT COCAINE ADDICTION. 2012 7 3372 41 HISTONE MODIFICATIONS OF THE CRHR1 GENE IN A RAT MODEL OF DEPRESSION FOLLOWING CHRONIC STRESS. MULTIPLE LINES OF EVIDENCE SUGGEST A LINK BETWEEN DEPRESSION AND CHANGES IN HYPOTHALAMIC-PITUITARY-ADRENAL (HPA)-AXIS HORMONE DYNAMICS, INCLUDING ALTERED REGULATION OF THE CORTICOTROPHIN-RELEASING HORMONE (CRH) AND ITS MAIN RECEPTOR, CORTICOTROPHIN-RELEASING HORMONE RECEPTOR 1 (CRHR1). HOWEVER, THE PRECISE MOLECULAR MECHANISMS UNDERLYING DEPRESSION REMAIN POORLY UNDERSTOOD. IN THIS STUDY, WE EMPLOYED A MODEL OF DEPRESSION IN RATS BY SUBJECTING ANIMALS TO 21 DAYS OF CHRONIC UNPREDICTABLE MILD STRESS (CUMS). REAL-TIME PCR AND WESTERN BLOTTING WERE USED TO STUDY THE MRNA AND PROTEIN EXPRESSION LEVELS OF CRHR1 IN THE HYPOTHALAMUS. IN ADDITION, CHROMATIN IMMUNOPRECIPITATION ASSAYS WERE USED TO DETECT HISTONE METHYLATION AT THE CRHR1 GENE PROMOTER; THE LEVELS OF HISTONE H3 TRIMETHYLATION AT LYSINES 4 (H3K4) AND 9 (H3K9) REFLECT ACTIVE TRANSCRIPTION AND TRANSCRIPTIONAL REPRESSION, RESPECTIVELY. RATS EXPOSED TO CUMS EXHIBITED SIGNIFICANT REDUCTION IN LOCOMOTION AND SUCROSE PREFERENCE. THESE BEHAVIORAL ALTERATIONS WERE ASSOCIATED WITH ELEVATED EXPRESSION LEVELS OF CRHR1 MRNA AND PROTEIN IN THE HYPOTHALAMUS OF RATS IN THE CUMS GROUP. WE ALSO FOUND THAT THE LEVELS OF H3K9 TRIMETHYLATION AT THE CRHR1 GENE PROMOTER IN THE CUMS GROUP WERE SIGNIFICANTLY LOWER THAN THOSE IN THE CONTROL GROUP, WHEREAS H3K4 TRIMETHYLATION LEVELS WERE THE SAME FOR BOTH GROUPS. TAKEN TOGETHER, OUR FINDINGS SUGGEST THAT THE INCREASE IN CRHR1 EXPRESSION IN THE HYPOTHALAMUS OF STRESSED RATS CORRELATES WITH A DECREASE IN THE REPRESSIVE CHROMATIN STATE CAUSED BY REDUCED H3K9 TRIMETHYLATION LEVELS. THESE DATA ARE THE FIRST IN VIVO EVIDENCE OF A ROLE FOR CHROMATIN MODIFICATIONS IN THE REGULATION OF CRHR1 GENE EXPRESSION IN THE HYPOTHALAMUS, AND MAY PROVIDE NOVEL INSIGHT INTO THERAPEUTIC APPROACHES TO TREAT DEPRESSION. 2014 8 431 42 ANTIDEPRESSANT ADMINISTRATION MODULATES STRESS-INDUCED DNA METHYLATION AND DNA METHYLTRANSFERASE EXPRESSION IN RAT PREFRONTAL CORTEX AND HIPPOCAMPUS. STRESS AND ANTIDEPRESSANT TREATMENT CAN MODULATE DNA METHYLATION IN PROMOTER REGION OF GENES RELATED TO NEUROPLASTICITY AND MOOD REGULATION, THUS IMPLICATING THIS EPIGENETIC MECHANISM IN DEPRESSION NEUROBIOLOGY AND TREATMENT. ACCORDINGLY, SYSTEMIC ADMINISTRATION OF DNA METHYLTRANSFERASE (DNMT) INHIBITORS INDUCES ANTIDEPRESSANT-LIKE EFFECTS IN RODENTS. DNA METHYLATION IS CONVEYED BY DNMT 1, 3A AND 3B ISOFORMS, WHICH ARE DIFFERENTIALLY EXPRESSED IN THE BRAIN. IN ORDER TO INVESTIGATE IF THE BEHAVIORAL EFFECTS OF ANTIDEPRESSANTS COULD BE ASSOCIATED WITH CHANGES IN DNA METHYLATION AND DNMT EXPRESSION, WE INVESTIGATED THE EFFECTS INDUCED BY ACUTE AND REPEATED ANTIDEPRESSANT TREATMENT ON DNA METHYLATION AND DNMT EXPRESSION (1, 3A AND 3B ISOFORMS) IN DIFFERENT BRAIN REGIONS OF RATS EXPOSED TO A STRESS MODEL OF DEPRESSION, THE LEARNED HELPLESSNESS (LH). THEREFORE, RATS WERE EXPOSED TO PRETEST AND TREATED WITH ONE OR SEVEN INJECTIONS OF VEHICLE OR IMIPRAMINE (15 MG KG(-1)), WITH TEST SESSION PERFORMED ONE HOUR AFTER THE LAST INJECTION. CHRONIC, BUT NOT ACUTE, IMIPRAMINE ADMINISTRATION ATTENUATED ESCAPE FAILURES DURING THE TEST, A WELL DESCRIBED ANTIDEPRESSANT-LIKE EFFECT IN THIS MODEL. DNA METHYLATION AND DNMT (1, 3A AND 3B) LEVELS WERE MEASURED IN THE DORSAL AND VENTRAL HIPPOCAMPUS (DHPC, VHPC) AND IN THE PREFRONTAL CORTEX (PFC) OF RATS EXPOSED TO STRESS AND TREATMENT. STRESS INCREASED DNA METHYLATION, DNMT3A AND DNMT3B EXPRESSION IN THE DHPC AND PFC. CHRONIC, BUT NOT ACUTE, IMIPRAMINE ADMINISTRATION ATTENUATED STRESS EFFECTS ONLY IN THE PFC. THESE RESULTS SUGGEST THE REGULATION OF DNA METHYLATION IN THE PFC MAY BE AN IMPORTANT MECHANISM FOR ANTIDEPRESSANT-LIKE EFFECTS IN THE LH MODEL. 2018 9 1238 29 CURCUMIN BLOCKS CHRONIC MORPHINE ANALGESIC TOLERANCE AND BRAIN-DERIVED NEUROTROPHIC FACTOR UPREGULATION. THIS STUDY WAS CARRIED OUT BASED ON THE ASSUMPTION THAT BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MAY COUNTERBALANCE THE ACTION OF MORPHINE IN THE BRAIN. MORPHINE ANALGESIC TOLERANCE AFTER DAILY ADMINISTRATIONS FOR SIX DAYS WAS BLOCKED BY INTRACEREBROVENTRICULAR INJECTION OF ANTI-BDNF IGG ON DAY 5, BUT NOT BY ADMINISTRATIONS ON DAYS 1-4. CHRONIC MORPHINE TREATMENT SIGNIFICANTLY INCREASED THE EXPRESSION OF EXON I AND IV BDNF TRANSCRIPTS, INDICATING DIFFERENTIAL REGULATION OF BDNF GENE EXPRESSION. DAILY ADMINISTRATION OF THE CREB-BINDING PROTEIN INHIBITOR CURCUMIN ABOLISHED THE UPREGULATION OF BDNF TRANSCRIPTION AND MORPHINE ANALGESIC TOLERANCE. THESE RESULTS SUGGEST THAT CURCUMIN MIGHT BE A PROMISING ADJUVANT TO REDUCE MORPHINE ANALGESIC TOLERANCE, AND THAT EPIGENETIC CONTROL COULD BE A NEW STRATEGY USEFUL FOR THE CONTROL OF THIS PROBLEM. 2009 10 917 41 CHRONIC HIGH-FAT DIET DRIVES POSTNATAL EPIGENETIC REGULATION OF MU-OPIOID RECEPTOR IN THE BRAIN. OPIOID SYSTEM DYSREGULATION HAS BEEN OBSERVED IN BOTH GENETIC AND HIGH-FAT DIET (HFD)-INDUCED MODELS OF OBESITY. AN UNDERSTANDING OF THE MOLECULAR MECHANISMS OF MOR TRANSCRIPTIONAL REGULATION, PARTICULARLY WITHIN AN IN VIVO CONTEXT, IS LACKING. USING A DIET-INDUCED MODEL OF OBESITY (DIO), MICE WERE FED A HIGH-FAT DIET (60% CALORIES FROM FAT) FROM WEANING TO >18 WEEKS OF AGE. COMPARED WITH MICE FED THE CONTROL DIET, DIO MICE HAD A DECREASED PREFERENCE FOR SUCROSE. MOR MRNA EXPRESSION WAS DECREASED IN REWARD-RELATED CIRCUITRY (VENTRAL TEGMENTAL AREA (VTA), NUCLEUS ACCUMBENS (NAC), AND PREFRONTAL CORTEX (PFC)) BUT NOT THE HYPOTHALAMUS, IMPORTANT IN THE HOMEOSTATIC REGULATION OF FEEDING. DNA METHYLATION IS AN EPIGENETIC MODIFICATION THAT LINKS ENVIRONMENTAL EXPOSURES TO ALTERED GENE EXPRESSION. WE FOUND A SIGNIFICANT INCREASE IN DNA METHYLATION IN THE MOR PROMOTER REGION WITHIN THE REWARD-RELATED BRAIN REGIONS. METHYL CPG-BINDING PROTEIN 2 (MECP2) CAN BIND METHYLATED DNA AND REPRESS TRANSCRIPTION, AND DIO MICE SHOWED INCREASED BINDING OF MECP2 TO THE MOR PROMOTER IN REWARD-RELATED REGIONS OF THE BRAIN. FINALLY, USING CHIP ASSAYS WE EXAMINED H3K9 METHYLATION (INACTIVE CHROMATIN) AND H3 ACETYLATION (ACTIVE CHROMATIN) WITHIN THE MOR PROMOTER REGION AND FOUND INCREASED H3K9 METHYLATION AND DECREASED H3 ACETYLATION. THESE DATA ARE THE FIRST TO IDENTIFY DNA METHYLATION, MECP2 RECRUITMENT, AND CHROMATIN REMODELING AS MECHANISMS LEADING TO TRANSCRIPTIONAL REPRESSION OF MOR IN THE BRAINS OF MICE FED A HIGH-FAT DIET. 2011 11 2756 39 EXPRESSION OF DNA METHYLTRANSFERASES IN ADULT DORSAL ROOT GANGLIA IS CELL-TYPE SPECIFIC AND UP REGULATED IN A RODENT MODEL OF NEUROPATHIC PAIN. NEUROPATHIC PAIN IS ASSOCIATED WITH HYPEREXCITABILITY AND INTRINSIC FIRING OF DORSAL ROOT GANGLIA (DRG) NEURONS. THESE PHENOTYPICAL CHANGES CAN BE LONG LASTING, POTENTIALLY SPANNING THE ENTIRE LIFE OF ANIMAL MODELS, AND DEPEND ON ALTERED EXPRESSION OF NUMEROUS PROTEINS, INCLUDING MANY ION CHANNELS. YET, HOW DRGS MAINTAIN LONG-TERM CHANGES IN PROTEIN EXPRESSION IN NEUROPATHIC CONDITIONS REMAINS UNCLEAR. DNA METHYLATION IS A WELL-KNOWN MECHANISM OF EPIGENETIC CONTROL OF GENE EXPRESSION AND IS ACHIEVED BY THE ACTION OF THREE ENZYMES: DNA METHYLTRANSFERASE (DNMT) 1, 3A, AND 3B, WHICH HAVE BEEN STUDIED PRIMARILY DURING DEVELOPMENT. WE FIRST PERFORMED IMMUNOHISTOCHEMICAL ANALYSIS TO ASSESS WHETHER THESE ENZYMES ARE EXPRESSED IN ADULT RAT DRGS (L4-5) AND FOUND THAT DNMT1 IS EXPRESSED IN BOTH GLIA AND NEURONS, DNMT3A IS PREFERENTIALLY EXPRESSED IN GLIA AND DNMT3B IS PREFERENTIALLY EXPRESSED IN NEURONS. A RAT MODEL OF NEUROPATHIC PAIN WAS THEN USED TO DETERMINE WHETHER NERVE INJURY MAY INDUCE EPIGENETIC CHANGES IN DRGS AT MULTIPLE TIME POINTS AFTER PAIN ONSET. REAL-TIME RT PCR ANALYSIS REVEALED ROBUST AND TIME-DEPENDENT CHANGES IN DNMT TRANSCRIPT EXPRESSION IN IPSILATERAL DRGS FROM SPARED NERVE INJURY (SNI) BUT NOT SHAM RATS. INTERESTINGLY, DNMT3B TRANSCRIPT SHOWED A ROBUST UPREGULATION THAT APPEARED ALREADY 1 WEEK AFTER SURGERY AND PERSISTED AT 4 WEEKS (OUR ENDPOINT); IN CONTRAST, DNMT1 AND DNMT3A TRANSCRIPTS SHOWED ONLY MODERATE UPREGULATION THAT WAS TRANSIENT AND DID NOT APPEAR UNTIL THE SECOND WEEK. WE SUGGEST THAT DNMT REGULATION IN ADULT DRGS MAY BE A CONTRIBUTOR TO THE PAIN PHENOTYPE AND MERITS FURTHER STUDY. 2014 12 3177 46 H3K9ME2 REGULATION OF BDNF EXPRESSION IN THE HIPPOCAMPUS AND MEDIAL PREFRONTAL CORTEX IS INVOLVED IN THE DEPRESSIVE-LIKE PHENOTYPE INDUCED BY MATERNAL SEPARATION IN MALE RATS. BACKGROUND: EARLY LIFE STRESS (ELS) INDUCES A DEPRESSIVE-LIKE PHENOTYPE AND INCREASES THE RISK OF DEPRESSION. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) HAS BEEN CONFIRMED TO BE INVOLVED IN THE PATHOPHYSIOLOGY OF DEPRESSION. HOWEVER, THE MECHANISM BY WHICH ELS ALTERS THE EPIGENETIC REGULATION OF BDNF AND CHANGES SUSCEPTIBILITY TO DEPRESSION HAS NOT BEEN FULLY CLARIFIED. METHODS: THE PRESENT STUDY USED MATERNAL SEPARATION (MS) AND CHRONIC UNPREDICTED MILD STRESS (CUMS) TO ESTABLISH AN MS ANIMAL MODEL AND A DEPRESSIVE ANIMAL MODEL. WE ASSESSED DEPRESSIVE-LIKE BEHAVIOURS, INCLUDING ANHEDONIA, LOCOMOTOR ACTIVITY, ANXIETY-LIKE BEHAVIOUR, AND SPATIAL MEMORY, USING THE SUCROSE PREFERENCE TEST, THE OPEN FIELD TEST, THE ELEVATED PLUS MAZE TEST, AND THE MORRIS WATER MAZE TEST. WE ALSO INVESTIGATED BDNF AND H3K9ME2 EXPRESSION IN THE HIPPOCAMPUS AND MEDIAL PREFRONTAL CORTEX (MPFC) BY IMMUNOHISTOCHEMISTRY, WESTERN BLOTTING, AND QPCR ANALYSIS. ADDITIONALLY, WE USED UNC0642, A SMALL MOLECULE INHIBITOR OF HISTONE METHYLTRANSFERASE (G9A), AS AN INTERVENTION. RESULTS: THE RESULTS SHOWED THAT CUMS INDUCED DEPRESSIVE-LIKE BEHAVIOURS IN RATS AND RESULTED IN INCREASED H3K9ME2 EXPRESSION AND DECREASED BDNF EXPRESSION IN THE HIPPOCAMPUS AND MPFC. MORE IMPORTANTLY, ADULT MS RATS EXPERIENCING CUMS HAD MORE SEVERE DEPRESSIVE BEHAVIOURS, HAD HIGHER EXPRESSION OF H3K9ME2 IN THE HIPPOCAMPUS AND MPFC, AND HAD LOWER EXPRESSION OF BDNF IN THE HIPPOCAMPUS AND MPFC. IN ADDITION, ADMINISTRATION OF THE G9A INHIBITOR REVERSED MOST OF THE CHANGES. CONCLUSIONS: OUR STUDY SUGGESTS THAT ELS CHANGED BDNF AND H3K9ME2 EXPRESSION IN THE RAT BRAIN, RESULTING IN A DEPRESSIVE-LIKE PHENOTYPE. 2021 13 219 40 ACUTE IMMOBILIZATION STRESS FOLLOWING CONTEXTUAL FEAR CONDITIONING REDUCES FEAR MEMORY: TIMING IS ESSENTIAL. BACKGROUND: HISTONE ACETYLATION IS REGULATED IN RESPONSE TO STRESS AND PLAYS AN IMPORTANT ROLE IN LEARNING AND MEMORY. CHRONIC STRESS IS KNOWN TO DETERIORATE COGNITION, WHEREAS ACUTE STRESS FACILITATES MEMORY FORMATION. HOWEVER, WHETHER ACUTE STRESS FACILITATES MEMORY FORMATION WHEN IT IS APPLIED AFTER FEAR STIMULATION IS NOT YET KNOWN. THEREFORE, THIS STUDY AIMED TO INVESTIGATE THE EFFECT OF ACUTE STRESS APPLIED AFTER FEAR TRAINING ON MEMORY FORMATION, MRNA EXPRESSION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF), EPIGENETIC REGULATION OF BDNF EXPRESSION, AND CORTICOSTERONE LEVEL IN MICE IN VIVO. METHODS: MICE WERE SUBJECTED TO ACUTE IMMOBILIZATION STRESS FOR 30 MIN AT 60 OR 90 MIN AFTER CONTEXTUAL FEAR CONDITIONING TRAINING, AND ACETYLATION OF HISTONE 3 AT LYSINE 14 (H3K14) AND LEVEL OF CORTICOSTERONE WERE MEASURED USING WESTERN BLOT ANALYSIS AND ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA), RESPECTIVELY. A FREEZING BEHAVIOR TEST WAS PERFORMED 24 H AFTER TRAINING, AND MRNA EXPRESSION OF BDNF WAS MEASURED USING REAL-TIME POLYMERASE CHAIN REACTIONS. DIFFERENT GROUPS OF MICE WERE USED FOR EACH TEST. RESULTS: FREEZING BEHAVIOR SIGNIFICANTLY DECREASED WITH THE DOWN-REGULATION OF BDNF MRNA EXPRESSION CAUSED BY ACUTE IMMOBILIZATION STRESS AT 60 MIN AFTER FEAR CONDITIONING TRAINING OWING TO THE REDUCTION OF H3K14 ACETYLATION. HOWEVER, BDNF MRNA EXPRESSION AND H3K14 ACETYLATION WERE NOT REDUCED IN ANIMALS SUBJECTED TO IMMOBILIZATION STRESS AT 90 MIN AFTER THE TRAINING. FURTHER, THE CORTICOSTERONE LEVEL WAS SIGNIFICANTLY HIGH IN MICE SUBJECTED TO IMMOBILIZATION STRESS AT 60 MIN AFTER THE TRAINING. CONCLUSION: ACUTE IMMOBILIZATION STRESS FOR 30 MIN AT 60 MIN AFTER FEAR CONDITIONING TRAINING IMPAIRED MEMORY FORMATION AND REDUCED BDNF MRNA EXPRESSION AND H3K14 ACETYLATION IN THE HIPPOCAMPUS OF MICE OWING TO THE HIGH LEVEL OF CORTICOSTERONE. 2016 14 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 15 434 39 ANTIDEPRESSANT-LIKE EFFECT OF SODIUM BUTYRATE IS ASSOCIATED WITH AN INCREASE IN TET1 AND IN 5-HYDROXYMETHYLATION LEVELS IN THE BDNF GENE. BACKGROUND: EPIGENETIC DRUGS LIKE SODIUM BUTYRATE (NAB) SHOW ANTIDEPRESSANT-LIKE EFFECTS IN PRECLINICAL STUDIES, BUT THE EXACT MOLECULAR MECHANISMS OF THE ANTIDEPRESSANT EFFECTS REMAIN UNKNOWN. WHILE RESEARCH USING NAB HAS MAINLY FOCUSED ON ITS ROLE AS A HISTONE DEACETYLASE INHIBITOR (HDACI), THERE IS ALSO EVIDENCE THAT NAB AFFECTS DNA METHYLATION. METHODS: THE PURPOSE OF THIS STUDY WAS TO EXAMINE NAB'S PUTATIVE ANTIDEPRESSANT-LIKE EFFICACY IN RELATION TO DNA METHYLATION CHANGES IN THE PREFRONTAL CORTEX OF AN ESTABLISHED GENETIC RAT MODEL OF DEPRESSION (THE FLINDERS SENSITIVE LINE [FSL]) AND ITS CONTROLS (THE FLINDERS RESISTANT LINE). RESULTS: THE FSL RATS HAD LOWER LEVELS OF TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 1 (TET1), WHICH CATALYZES THE CONVERSION OF DNA METHYLATION TO HYDROXYMETHYLATION. AS INDICATED BY THE BEHAVIORAL DESPAIR TEST, CHRONIC ADMINISTRATION OF NAB HAD ANTIDEPRESSANT-LIKE EFFECTS IN THE FSL AND WAS ACCOMPANIED BY INCREASED LEVELS OF TET1. THE TET1 UPREGULATION WAS ALSO ASSOCIATED WITH AN INCREASE OF HYDROXYMETHYLATION AND A DECREASE OF METHYLATION IN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF), A GENE ASSOCIATED WITH NEUROGENESIS AND SYNAPTIC PLASTICITY. THESE EPIGENETIC CHANGES WERE ASSOCIATED WITH A CORRESPONDING BDNF OVEREXPRESSION. CONCLUSIONS: OUR DATA SUPPORT THE ANTIDEPRESSANT EFFICACY OF HDACIS AND SUGGEST THAT THEIR EPIGENETIC EFFECTS MAY ALSO INCLUDE DNA METHYLATION CHANGES THAT ARE MEDIATED BY DEMETHYLATION-FACILITATING ENZYMES LIKE TET1. 2014 16 886 35 CHRONIC CORTICOSTERONE EXPOSURE INCREASES EXPRESSION AND DECREASES DEOXYRIBONUCLEIC ACID METHYLATION OF FKBP5 IN MICE. THERE IS EVIDENCE FOR HYPERCORTISOLEMIA PLAYING A ROLE IN THE GENERATION OF PSYCHIATRIC SYMPTOMS AND FOR EPIGENETIC VARIATION WITHIN HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS GENES MEDIATING BEHAVIORAL CHANGES. WE TESTED THE HYPOTHESIS THAT EXPRESSION CHANGES WOULD BE INDUCED IN FKBP5 AND OTHER HPA AXIS GENES BY CHRONIC EXPOSURE TO CORTICOSTERONE AND THAT THESE CHANGES WOULD OCCUR THROUGH THE EPIGENETIC MECHANISM OF LOSS OR GAIN OF DNA METHYLATION (DNAM). WE ADMINISTERED CORTICOSTERONE (CORT) TO C57BL/6J MICE VIA THEIR DRINKING WATER FOR 4 WK AND TESTED FOR BEHAVIORAL AND PHYSIOLOGICAL CHANGES AND CHANGES IN GENE EXPRESSION LEVELS USING RNA EXTRACTED FROM HIPPOCAMPUS, HYPOTHALAMUS, AND BLOOD FOR THE FOLLOWING HPA GENES: FKBP5, NR3C1, HSP90, CRH, AND CRHR1. THE CORT MICE EXHIBITED ANXIETY-LIKE BEHAVIOR IN THE ELEVATED PLUS MAZE TEST. CHRONIC EXPOSURE TO CORT ALSO CAUSED A SIGNIFICANT DECREASE IN THE HIPPOCAMPAL AND BLOOD MRNA LEVELS OF NR3C1 AND A DECREASE IN HSP90 IN BLOOD AND CAUSED AN INCREASE IN FKBP5 FOR ALL TISSUES. DIFFERENCES WERE SEEN IN FKBP5 METHYLATION IN HIPPOCAMPUS AND HYPOTHALAMUS. TO ISOLATE A SINGLE-CELL TYPE, WE FOLLOWED UP WITH AN HT-22 MOUSE HIPPOCAMPAL NEURONAL CELL LINE EXPOSED TO CORT. AFTER 7 D, WE OBSERVED A 2.4-FOLD INCREASE IN FKBP5 EXPRESSION AND A DECREASE IN DNAM. IN THE CORT-TREATED MICE, WE ALSO OBSERVED CHANGES IN BLOOD DNAM IN FKBP5. OUR RESULTS SUGGEST DNAM PLAYS A ROLE IN MEDIATING EFFECTS OF GLUCOCORTICOID EXPOSURE ON FKBP5 FUNCTION, WITH POTENTIAL CONSEQUENCES FOR BEHAVIOR. 2010 17 1086 36 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 18 4236 26 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 19 1003 29 CHRONIC TREATMENT WITH FLUOXETINE INDUCES SEX-DEPENDENT ANALGESIC EFFECTS AND MODULATES HDAC2 AND MGLU2 EXPRESSION IN FEMALE MICE. GENDER AND SEX DIFFERENCES IN PAIN RECOGNITION AND DRUG RESPONSES HAVE BEEN REPORTED IN CLINICAL TRIALS AND EXPERIMENTAL MODELS OF PAIN. AMONG ANTIDEPRESSANTS, CONTRADICTORY RESULTS HAVE BEEN OBSERVED IN PATIENTS TREATED WITH SELECTIVE SEROTONIN REUPTAKE INHIBITORS (SSRIS). THIS STUDY EVALUATED SEX DIFFERENCES IN RESPONSE TO THE SSRI FLUOXETINE AFTER CHRONIC ADMINISTRATION IN THE MOUSE FORMALIN TEST. ADULT MALE AND FEMALE CD1 MICE WERE INTRAPERITONEALLY INJECTED WITH FLUOXETINE (10 MG/KG) FOR 21 DAYS AND SUBJECTED TO PAIN ASSESSMENT. FLUOXETINE TREATMENT REDUCED THE SECOND PHASE OF THE FORMALIN TEST ONLY IN FEMALE MICE WITHOUT PRODUCING BEHAVIORAL CHANGES IN MALES. WE ALSO OBSERVED THAT FLUOXETINE WAS ABLE TO SPECIFICALLY INCREASE THE EXPRESSION OF METABOTROPIC GLUTAMATE RECEPTOR TYPE-2 (MGLU2) IN FEMALES. ALSO A REDUCED EXPRESSION OF THE EPIGENETIC MODIFYING ENZYME, HISTONE DEACETYLASE 2 (HDAC2), IN DORSAL ROOT GANGLIA (DRG) AND DORSAL HORN (DH) TOGETHER WITH AN INCREASE HISTONE 3 ACETYLATION (H3) LEVEL WAS OBSERVED IN FEMALES BUT NOT IN MALES. WITH THIS STUDY WE PROVIDE EVIDENCE THAT FLUOXETINE INDUCES SEX SPECIFIC CHANGES IN HDAC2 AND MGLU2 EXPRESSION IN THE DH OF THE SPINAL CORD AND IN DRGS AND SUGGESTS A MOLECULAR EXPLANATION FOR THE ANALGESIC EFFECTS IN FEMALE MICE. 2017 20 2156 39 EPIGENETIC MECHANISMS ARE INVOLVED IN THE REGULATION OF ETHANOL CONSUMPTION IN MICE. BACKGROUND: REPEATED ALCOHOL EXPOSURE IS KNOWN TO INCREASE SUBSEQUENT ETHANOL CONSUMPTION IN MICE. HOWEVER, THE UNDERLYING MECHANISMS HAVE NOT BEEN FULLY ELUCIDATED. ONE POSTULATED MECHANISM INVOLVES EPIGENETIC MODIFICATIONS, INCLUDING HISTONE MODIFICATIONS AND DNA METHYLATION OF RELEVANT GENES SUCH AS NR2B OR BDNF. METHODS: TO INVESTIGATE THE ROLE OF EPIGENETIC MECHANISMS IN THE DEVELOPMENT OF ALCOHOL DRINKING BEHAVIOR, AN ESTABLISHED CHRONIC INTERMITTENT ETHANOL EXPOSURE REINFORCED ETHANOL DRINKING MOUSE MODEL WITH VAPOR INHALATION OVER TWO 9-DAY TREATMENT REGIMENS WAS USED. THE DNA METHYLTRANSFERASE INHIBITOR, 5-AZACYTIDINE OR THE HISTONE DEACETYLASE INHIBITOR, TRICHOSTATIN A WAS ADMINISTERED (INTRAPERITONEALLY) TO C57BL/6 MICE 30 MIN BEFORE DAILY EXPOSURE TO CHRONIC INTERMITTENT ETHANOL. CHANGES IN ETHANOL CONSUMPTION WERE MEASURED USING THE 2-BOTTLE CHOICE TEST. RESULTS: THE RESULTS INDICATED THAT SYSTEMIC ADMINISTRATION OF TRICHOSTATIN A (2.5 MICROG/G) FACILITATED CHRONIC INTERMITTENT ETHANOL-INDUCED ETHANOL DRINKING, BUT SYSTEMIC ADMINISTRATION OF 5-AZACYTIDINE (2 MICROG/G) DID NOT CAUSE THE SAME EFFECT. HOWEVER, WHEN 5-AZACYTIDINE WAS ADMINISTERED BY INTRACEREBROVENTRICULAR INJECTION, IT FACILITATED CHRONIC INTERMITTENT ETHANOL-INDUCED ETHANOL DRINKING. FURTHERMORE, THE INCREASED DRINKING CAUSED BY CHRONIC INTERMITTENT ETHANOL WAS PREVENTED BY INJECTION OF A METHYL DONOR, S-ADENOSYL-L-METHIONINE. TO PROVIDE EVIDENCE THAT CHRONIC INTERMITTENT ETHANOL- OR TRICHOSTATIN A-INDUCED DNA DEMETHYLATION AND HISTONE MODIFICATIONS OF THE NR2B PROMOTER MAY UNDERLIE THE ALTERED ETHANOL CONSUMPTION, WE EXAMINED EPIGENETIC MODIFICATIONS AND NR2B EXPRESSION IN THE PREFRONTAL CORTEX OF THESE MICE. CHRONIC INTERMITTENT ETHANOL OR TRICHOSTATIN A DECREASED DNA METHYLATION AND INCREASED HISTONE ACETYLATION IN THE NR2B GENE PROMOTER, AS WELL AS MRNA LEVELS OF NR2B IN THESE MICE. CONCLUSIONS: TAKEN TOGETHER, THESE RESULTS INDICATE THAT EPIGENETIC MODIFICATIONS ARE INVOLVED IN REGULATING ETHANOL DRINKING BEHAVIOR, PARTIALLY THROUGH ALTERING NR2B EXPRESSION. 2014