1 5515 122 RILUZOLE ADMINISTRATION TO RATS WITH LEVODOPA-INDUCED DYSKINESIA LEADS TO LOSS OF DNA METHYLATION IN NEURONAL GENES. DYSKINESIAS ARE CHARACTERIZED BY ABNORMAL REPETITIVE INVOLUNTARY MOVEMENTS DUE TO DYSFUNCTIONAL NEURONAL ACTIVITY. ALTHOUGH LEVODOPA-INDUCED DYSKINESIA, CHARACTERIZED BY TIC-LIKE ABNORMAL INVOLUNTARY MOVEMENTS, HAS NO CLINICAL TREATMENT FOR PARKINSON'S DISEASE PATIENTS, ANIMAL STUDIES INDICATE THAT RILUZOLE, WHICH INTERFERES WITH GLUTAMATERGIC NEUROTRANSMISSION, CAN IMPROVE THE PHENOTYPE. THE RAT MODEL OF LEVODOPA-INDUCED DYSKINESIA IS A UNILATERAL LESION WITH 6-HYDROXYDOPAMINE IN THE MEDIAL FOREBRAIN BUNDLE, FOLLOWED BY THE REPEATED ADMINISTRATION OF LEVODOPA. THE MOLECULAR PATHOMECHANISM OF LEVODOPA-INDUCED DYSKINESIA IS STILL NOT DECIPHERED; HOWEVER, THE IMPLICATION OF EPIGENETIC MECHANISMS WAS SUGGESTED. IN THIS STUDY, WE INVESTIGATED THE STRIATUM FOR DNA METHYLATION ALTERATIONS UNDER CHRONIC LEVODOPA TREATMENT WITH OR WITHOUT CO-TREATMENT WITH RILUZOLE. OUR DATA SHOW THAT THE LESIONED AND CONTRALATERAL STRIATA HAVE NEARLY IDENTICAL DNA METHYLATION PROFILES. CHRONIC LEVODOPA AND LEVODOPA + RILUZOLE TREATMENTS LED TO DNA METHYLATION LOSS, PARTICULARLY OUTSIDE OF PROMOTERS, IN GENE BODIES AND CPG POOR REGIONS. WE OBSERVED THAT SEVERAL GENES INVOLVED IN THE LEVODOPA-INDUCED DYSKINESIA UNDERWENT METHYLATION CHANGES. FURTHERMORE, THE RILUZOLE CO-TREATMENT, WHICH IMPROVED THE PHENOTYPE, PINPOINTED SPECIFIC METHYLATION TARGETS, WITH A MORE THAN 20% METHYLATION DIFFERENCE RELATIVE TO LEVODOPA TREATMENT ALONE. THESE FINDINGS INDICATE POTENTIAL NEW DRUGGABLE TARGETS FOR LEVODOPA-INDUCED DYSKINESIA. 2021 2 5502 33 RGFP109, A HISTONE DEACETYLASE INHIBITOR ATTENUATES L-DOPA-INDUCED DYSKINESIA IN THE MPTP-LESIONED MARMOSET: A PROOF-OF-CONCEPT STUDY. BACKGROUND: L-3,4-DIHYDROXYPHENYLALANINE (L-DOPA)-INDUCED DYSKINESIA (LID) ARE A COMPLICATION OF CHRONIC DOPAMINE REPLACEMENT THERAPY IN PARKINSON'S DISEASE (PD). RECENT STUDIES HAVE SUGGESTED THAT THE MECHANISMS UNDERLYING DEVELOPMENT AND EXPRESSION OF LID IN PD MAY INVOLVE EPIGENETIC CHANGES THAT INCLUDE DEACETYLATION OF STRIATAL HISTONE PROTEINS. WE HYPOTHESISED THAT INHIBITION OF HISTONE DEACETYLASE, THE ENZYME RESPONSIBLE OF HISTONE DEACETYLATION, WOULD ALLEVIATE LID. METHODS: FOUR FEMALE COMMON MARMOSET (CALLITHRIX JACCHUS) WERE RENDERED PARKINSONIAN BY ADMINISTRATION OF 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE (MPTP). FOLLOWING STABILISATION OF THE PARKINSONIAN PHENOTYPE, MARMOSETS WERE PRIMED TO EXHIBIT DYSKINESIA WITH CHRONIC ADMINISTRATION OF L-DOPA. WE THEN INVESTIGATED THE EFFECTS OF THE BRAIN-PENETRANT HISTONE DEACETYLASE INHIBITOR, RGFP109 (30 MG/KG P.O. ONCE DAILY FOR 6 DAYS), ON LID AND L-DOPA ANTI-PARKINSONIAN EFFICACY. RESULTS: RGFP109 HAD NO ACUTE EFFECTS ON DYSKINESIA AFTER SINGLE OR 6 DAYS ONCE-DAILY TREATMENT (BOTH P > 0.05). HOWEVER, ONE WEEK FOLLOWING CESSATION OF RGFP109, DYSKINESIA AND DURATION OF ON-TIME WITH DISABLING DYSKINESIA WERE REDUCED BY 37% AND 50%, RESPECTIVELY (BOTH P < 0.05), COMPARED TO THAT SEEN PREVIOUSLY WITH L-DOPA ALONE. THERE WAS NO CHANGE IN ANTI-PARKINSONIAN ACTIONS OF, OR ON-TIME DURATION AFFORDED BY, L-DOPA (P > 0.05). CONCLUSIONS: HISTONE DEACETYLATION INHIBITION MAY REPRESENT A NOVEL APPROACH TO REVERSE ESTABLISHED LID IN PD AND IMPROVE QUALITY OF THE ANTI-PARKINSONIAN BENEFIT PROVIDED BY L-DOPA. 2013 3 135 36 ABERRANT CPG METHYLATION MEDIATES ABNORMAL TRANSCRIPTION OF MAO-A INDUCED BY ACUTE AND CHRONIC L-3,4-DIHYDROXYPHENYLALANINE ADMINISTRATION IN SH-SY5Y NEURONAL CELLS. L-3,4-DIHYDROXYPHENYLALANINE (L-DOPA) REMAINS THE MOST EFFECTIVE DRUG FOR THERAPY OF PARKINSON'S DISEASE (PD); HOWEVER, LONG-TERM USE OF IT CAUSES SERIOUS SIDE EFFECTS. L-DOPA-INDUCED DYSKINESIA (LID) HAS CONSISTENTLY BEEN RELATED TO L-DOPA-DERIVED EXCESSIVE DOPAMINE RELEASE, BUT THE MECHANISMS HAVE NOT BEEN ADDRESSED VERY CLEAR. MONOAMINE OXIDASE A (MAO-A) IS ONE OF THE KEY ENZYMES IN DOPAMINE METABOLISM AND THEREFORE MAY BE INVOLVED IN L-DOPA-INDUCED SIDE EFFECTS. AND, EPIGENETIC MODIFICATION CONTROLS MAO-A GENE TRANSCRIPTION. TO INVESTIGATE THE EFFECTS OF L-DOPA ON MAO-A TRANSCRIPTION AND ITS UNDERLYING EPIGENETIC MECHANISM, NEURONAL SH-SY5Y CELLS WERE TREATED WITH L-DOPA FOR 24 H (ACUTE) AND FOR 7-21 DAYS (CHRONIC). RESULTS SHOWED THAT CHRONIC L-DOPA ADMINISTRATION RESULTED IN A DOSE-DEPENDENT AND TIME-DEPENDENT DOWNREGULATION OF MAO-A, WHEREAS ACUTE L-DOPA ADMINISTRATION INDUCED UPREGULATION OF MAO-A TRANSCRIPTION AND EXPRESSION. MEANWHILE, CHRONIC L-DOPA EXPOSURE INDUCED CPG HYPERMETHYLATION IN MAO-A PROMOTER, WHILE ACUTE L-DOPA ADMINISTRATION CAUSED CPG HYPOMETHYLATION. AND, CPG DEMETHYLATION RESULTED IN REACTIVATION OF MAO-A TRANSCRIPTION. THESE RESULTS INDICATED THAT ABERRANT CPG METHYLATION MIGHT PLAY A KEY ROLE IN MAO-A TRANSCRIPTIONAL MISREGULATION IN L-DOPA ADMINISTRATION. IN ADDITION, RESULTS SHOWED THAT ACUTE L-DOPA ADMINISTRATION INDUCED DOWNREGULATION OF DNA METHYLTRANSFERASE 3A (DNMT3A). TRANSCRIPTION OF TEN-ELEVEN TRANSLOCATION 1 (TET1) WERE SIGNIFICANTLY DOWNREGULATED IN CHRONIC L-DOPA ADMINISTRATION. THESE DATA INDICATED THAT IN CHRONIC L-DOPA ADMINISTRATION, TET1 DOWNREGULATION MIGHT MEDIATE CPG HYPERMETHYLATION, WHICH IS RESPONSIBLE FOR THE DOWNREGULATION OF MAO-A TRANSCRIPTION. IN CONTRAST, IN ACUTE L-DOPA ADMINISTRATION, DNMT3A DOWNREGULATION MIGHT MEDIATE HYPOMETHYLATION, CONTRIBUTING TO THE MAO-A UPREGULATION. IN CONCLUSION, OUR FINDINGS SUGGESTED THAT TET1 AND DNMTS MIGHT MEDIATE ABERRANT CPG METHYLATION, ASSOCIATED WITH THE MISREGULATION OF MAO-A IN L-DOPA ADMINISTRATION, WHICH MIGHT CONTRIBUTE TO DOPAMINE RELEASE ABNORMALLY LEADING TO THE SIDE EFFECTS OF L-DOPA. 2017 4 1652 31 DOPAMINE SIGNALING LEADS TO LOSS OF POLYCOMB REPRESSION AND ABERRANT GENE ACTIVATION IN EXPERIMENTAL PARKINSONISM. POLYCOMB GROUP (PCG) PROTEINS BIND TO AND REPRESS GENES IN EMBRYONIC STEM CELLS THROUGH LINEAGE COMMITMENT TO THE TERMINAL DIFFERENTIATED STATE. PCG REPRESSED GENES ARE COMMONLY CHARACTERIZED BY THE PRESENCE OF THE EPIGENETIC HISTONE MARK H3K27ME3, CATALYZED BY THE POLYCOMB REPRESSIVE COMPLEX 2. HERE, WE PRESENT IN VIVO EVIDENCE FOR A PREVIOUSLY UNRECOGNIZED PLASTICITY OF PCG-REPRESSED GENES IN TERMINALLY DIFFERENTIATED BRAIN NEURONS OF PARKISONIAN MICE. WE SHOW THAT ACUTE ADMINISTRATION OF THE DOPAMINE PRECURSOR, L-DOPA, INDUCES A REMARKABLE INCREASE IN H3K27ME3S28 PHOSPHORYLATION. THE INDUCTION OF THE H3K27ME3S28P HISTONE MARK SPECIFICALLY OCCURS IN MEDIUM SPINY NEURONS EXPRESSING DOPAMINE D1 RECEPTORS AND IS DEPENDENT ON MSK1 KINASE ACTIVITY AND DARPP-32-MEDIATED INHIBITION OF PROTEIN PHOSPHATASE-1. CHROMATIN IMMUNOPRECIPITATION (CHIP) EXPERIMENTS SHOWED THAT INCREASED H3K27ME3S28P WAS ACCOMPANIED BY REDUCED PCG BINDING TO REGULATORY REGIONS OF GENES. AN ANALYSIS OF THE GENOME WIDE DISTRIBUTION OF L-DOPA-INDUCED H3K27ME3S28 PHOSPHORYLATION BY CHIP SEQUENCING (CHIP-SEQ) IN COMBINATION WITH EXPRESSION ANALYSIS BY RNA-SEQUENCING (RNA-SEQ) SHOWED THAT THE INDUCTION OF H3K27ME3S28P CORRELATED WITH INCREASED EXPRESSION OF A SUBSET OF PCG REPRESSED GENES. WE FOUND THAT INDUCTION OF H3K27ME3S28P PERSISTED DURING CHRONIC L-DOPA ADMINISTRATION TO PARKISONIAN MICE AND CORRELATED WITH ABERRANT GENE EXPRESSION. WE PROPOSE THAT DOPAMINERGIC TRANSMISSION CAN ACTIVATE PCG REPRESSED GENES IN THE ADULT BRAIN AND THEREBY CONTRIBUTE TO LONG-TERM MALADAPTIVE RESPONSES INCLUDING THE MOTOR COMPLICATIONS, OR DYSKINESIA, CAUSED BY PROLONGED ADMINISTRATION OF L-DOPA IN PARKINSON'S DISEASE. 2014 5 6432 30 THE VICIOUS CIRCLE BETWEEN HOMOCYSTEINE, METHYL GROUP-DONATING VITAMINS AND CHRONIC LEVODOPA INTAKE IN PARKINSON'S DISEASE. A BIOMARKER FOR DECLINED METHYLATION CAPACITY IS ELEVATION OF HOMOCYSTEINE LEVELS. THEY INCREASE THE RISK FOR ONSET OF VASCULAR DISEASE AND CONTRIBUTE TO PROGRESSION OF CHRONIC NEURODEGENERATION AND AGING. THIS NARRATIVE REVIEW DISCUSSES ASSOCIATIONS BETWEEN HOMOCYSTEINE, CONSUMPTION OF METHYL GROUP-DONATING VITAMINS AND IMPACT ON DISEASE-GENERATING MECHANISMS IN LEVODOPA-TREATED PATIENTS WITH PARKINSON'S DISEASE. WE CONCLUDE TO RECOMMEND LEVODOPA-TREATED PATIENTS TO SUBSTITUTE THEMSELVES WITH METHYL GROUP-DONATING VITAMINS. THIS IS HARMLESS IN TERMS OF APPLICATION OF FOLIC ACID, METHYLCOBALAMIN OR HYDROXOCOBALAMIN. MOREOVER, WE SUGGEST A CRUCIAL DISCUSSION ON THE VALUE OF THE VARIOUS POPULAR HYPOTHESES ON PARKINSON'S DISEASE-GENERATING MECHANISMS. FINDINGS FROM STUDIES WITH ACUTE LEVODOPA EXPOSURE DESCRIBE OXIDATIVE STRESS GENERATION AND IMPAIRED METHYLATION CAPACITY, WHICH CAUSES GENE DYSFUNCTION. THEIR REPEATED OCCURRENCES CONTRIBUTE TO ONSET OF MITOCHONDRIAL DYSFUNCTION, IRON ENRICHMENT AND PATHOLOGIC PROTEIN ACCUMULATION IN THE LONG TERM. CURRENT RESEARCH UNDERESTIMATES THESE EPIGENETIC, METABOLIC CONSEQUENCES OF CHRONIC LEVODOPA APPLICATION. SUPPLEMENTARY TREATMENT STRATEGIES ARE RECOMMENDED TO AVOID LEVODOPA-RELATED SIDE EFFECTS. 2023 6 966 36 CHRONIC NEUROLOGICAL DISORDERS: GENETIC AND EPIGENETIC MARKERS FOR MONITORING OF PHARMACOTHERAPY. INTRODUCTION: CHRONIC NEUROLOGICAL DISEASES ARE A MAJOR CAUSE OF MORTALITY AND MORBIDITY IN THE WORLD. WITH INCREASING LIFE EXPECTANCY IN THE DEVELOPING WORLD, THE INCIDENCE AND PREVALENCE OF THESE DISEASES ARE PREDICTED TO RISE EVEN FURTHER. THIS HAS ALSO CONTRIBUTED TO AN INCREASE IN DISABILITY-ADJUSTED LIFE YEARS (DALYS) FOR NONCOMMUNICABLE DISEASES. TREATMENT FOR SUCH DISEASES ALSO POSES A CHALLENGE WITH MULTIPLE GENETIC AND EPIGENETIC FACTORS LEADING TO A VARIED OUTCOME. PERSONALIZATION OF TREATMENT IS ONE WAY THAT TREATMENT OUTCOME/PROGNOSIS OF DISEASE CAN BE IMPROVED, AND PHARMACOGENOMICS PLAYS A SIGNIFICANT ROLE IN THIS CONTEXT. METHODOLOGY: THIS ARTICLE REVIEWED THE EVIDENCE PERTAINING TO THE ASSOCIATION OF GENETIC AND EPIGENETIC MARKERS WITH MAJOR NEUROLOGICAL DISORDERS LIKE MULTIPLE SCLEROSIS (MS), ALZHEIMER'S DISEASE (AD), AND PARKINSON'S DISEASE (PD), WHICH ARE A MAJOR SOURCE OF BURDEN AMONG NEUROLOGICAL DISORDERS. TYPES OF STUDIES INCLUDED ARE PEER-REVIEWED ORIGINAL RESEARCH ARTICLES FROM THE PUBMED DATABASE (1999-2018). RESULTS: THIS STUDY COMPILED DATA REGARDING SPECIFIC GENETIC AND EPIGENETIC MARKERS WITH A SIGNIFICANT CORRELATION BETWEEN THE CLINICAL DIAGNOSIS OF THE DISEASE AND PROGNOSIS OF THERAPY FROM 65 STUDIES. IN A SINGLE PLATFORM, THIS REVIEW HIGHLIGHTS THE CLUES TO SOME VITAL QUESTIONS, SUCH AS WHY INTERFERON BETA (IFN-BETA) THERAPY FAILS TO IMPROVE SYMPTOMS IN ALL MS PATIENTS? WHY CHOLINESTERASE INHIBITORS FAIL TO IMPROVE COGNITIVE IMPAIRMENT IN A SUBSET OF PEOPLE SUFFERING FROM AD? OR WHY SOME INDIVIDUALS ON LEVODOPA (L-DOPA) FOR PD SUFFER FROM SIDE-EFFECTS RANGING FROM DYSKINESIA TO HALLUCINATION WHILE OTHERS DO NOT? CONCLUSION: THIS ARTICLE SUMMARIZES THE GENETIC AND EPIGENETIC FACTORS THAT MAY EITHER REQUIRE MONITORING OR HELP IN DECIDING FUTURE PHARMACOTHERAPY IN A PATIENT SUFFERING FROM MS, AD, AND PD. AS THE HEALTH CARE SYSTEM DEVELOPS AND REACHES NEWER HEIGHTS, WE EXPECT MORE AND MORE OF THESE BIOMARKERS TO BE USED AS PHARMACOTHERAPEUTIC OUTCOME INDICATORS. 2021 7 3345 31 HISTONE DEACETYLASES AS EPIGENETIC TARGETS FOR TREATING PARKINSON'S DISEASE. PARKINSON'S DISEASE (PD) IS A CHRONIC PROGRESSIVE NEURODEGENERATIVE DISEASE THAT IS INCREASINGLY BECOMING A GLOBAL THREAT TO THE HEALTH AND LIFE OF THE ELDERLY WORLDWIDE. ALTHOUGH THERE ARE SOME DRUGS CLINICALLY AVAILABLE FOR TREATING PD, THESE TREATMENTS CAN ONLY ALLEVIATE THE SYMPTOMS OF PD PATIENTS BUT CANNOT COMPLETELY CURE THE DISEASE. THEREFORE, EXPLORING OTHER POTENTIAL MECHANISMS TO DEVELOP MORE EFFECTIVE TREATMENTS THAT CAN MODIFY THE COURSE OF PD IS STILL HIGHLY DESIRABLE. OVER THE LAST TWO DECADES, HISTONE DEACETYLASES, AS AN IMPORTANT GROUP OF EPIGENETIC TARGETS, HAVE ATTRACTED MUCH ATTENTION IN DRUG DISCOVERY. THIS REVIEW FOCUSED ON THE CURRENT KNOWLEDGE ABOUT HISTONE DEACETYLASES INVOLVED IN PD PATHOPHYSIOLOGY AND THEIR INHIBITORS USED IN PD STUDIES. FURTHER PERSPECTIVES RELATED TO SMALL MOLECULES THAT CAN INHIBIT OR DEGRADE HISTONE DEACETYLASES TO TREAT PD WERE ALSO DISCUSSED. 2022 8 2398 29 EPIGENETIC REPROGRAMMING OF CORTICAL NEURONS THROUGH ALTERATION OF DOPAMINERGIC CIRCUITS. ALTERATIONS OF THE DOPAMINERGIC SYSTEM ARE ASSOCIATED WITH THE COGNITIVE AND FUNCTIONAL DYSFUNCTIONS THAT CHARACTERIZE COMPLEX NEUROPSYCHIATRIC DISORDERS. WE MODELED A DYSFUNCTIONAL DOPAMINERGIC SYSTEM USING MICE WITH TARGETED ABLATION OF DOPAMINE (DA) D2 AUTORECEPTORS IN MESENCEPHALIC DOPAMINERGIC NEURONS. LOSS OF D2 AUTORECEPTORS ABOLISHES D2-MEDIATED CONTROL OF DA SYNTHESIS AND RELEASE. HERE, WE SHOW THAT THIS MUTATION LEADS TO A PROFOUND ALTERATION OF THE GENOMIC LANDSCAPE OF NEURONS RECEIVING DOPAMINERGIC AFFERENTS AT DISTAL SITES, SPECIFICALLY IN THE PREFRONTAL CORTEX. INDEED, WE OBSERVED A REMARKABLE DOWNREGULATION OF GENE EXPRESSION IN THIS AREA OF ~2000 GENES, WHICH INVOLVES A WIDESPREAD INCREASE IN THE HISTONE REPRESSIVE MARK H3K9ME2/3. THIS REPROGRAMMING PROCESS IS COUPLED TO PSYCHOTIC-LIKE BEHAVIORS IN THE MUTANT MICE. IMPORTANTLY, CHRONIC TREATMENT WITH A DA AGONIST CAN REVERT THE GENOMIC PHENOTYPE. THUS, CORTICAL NEURONS UNDERGO A PROFOUND EPIGENETIC REPROGRAMMING IN RESPONSE TO DYSFUNCTIONAL D2 AUTORECEPTOR SIGNALING LEADING TO ALTERED DA LEVELS, A PROCESS THAT MAY UNDERLIE A NUMBER OF NEUROPSYCHIATRIC DISORDERS. 2014 9 1732 29 DYSTONIA AND LEVODOPA-INDUCED DYSKINESIAS IN PARKINSON'S DISEASE: IS THERE A CONNECTION? DYSTONIA AND LEVODOPA-INDUCED DYSKINESIA (LID) ARE BOTH HYPERKINETIC MOVEMENT DISORDERS. DYSTONIA ARISES MOST OFTEN SPONTANEOUSLY, ALTHOUGH IT MAY BE SEEN AFTER STROKE, INJURY, OR AS A RESULT OF GENETIC CAUSES. LID IS ASSOCIATED WITH PARKINSON'S DISEASE (PD), EMERGING AS A CONSEQUENCE OF CHRONIC THERAPY WITH LEVODOPA, AND MAY BE EITHER DYSTONIC OR CHOREIFORM. LID AND DYSTONIA SHARE IMPORTANT PHENOMENOLOGICAL PROPERTIES AND MECHANISMS. BOTH LID AND DYSTONIA ARE GENERATED BY AN INTEGRATED CIRCUIT INVOLVING THE CORTEX, BASAL GANGLIA, THALAMUS AND CEREBELLUM. THEY ALSO SHARE DYSREGULATION OF STRIATAL CHOLINERGIC SIGNALING AND ABNORMALITIES OF STRIATAL SYNAPTIC PLASTICITY. THE LONG DURATION NATURE OF BOTH LID AND DYSTONIA SUGGESTS THAT THERE MAY BE UNDERLYING EPIGENETIC DYSREGULATION AS A PROXIMATE CAUSE. WHILE BOTH MAY IMPROVE AFTER INTERVENTIONS SUCH AS DEEP BRAIN STIMULATION (DBS), NEITHER CURRENTLY HAS A SATISFACTORY MEDICAL THERAPY, AND MANY PEOPLE ARE DISABLED BY THE SYMPTOMS OF DYSTONIA AND LID. FURTHER STUDY OF THE FUNDAMENTAL MECHANISMS CONNECTING THESE TWO DISORDERS MAY LEAD TO NOVEL APPROACHES TO TREATMENT OR PREVENTION. 2019 10 1205 22 COULD THE INHIBITOR OF DNA BINDING 2 AND 4 PLAY A ROLE IN WHITE MATTER INJURY? WHITE MATTER INJURY (WMI) PREVENTS THE NORMAL DEVELOPMENT OF MYELINATION, LEADING TO CENTRAL NERVOUS SYSTEM MYELINATION DISORDERS AND THE PRODUCTION OF CHRONIC SEQUELAE ASSOCIATED WITH WMI, SUCH AS CHRONIC DYSKINESIA, COGNITIVE IMPAIRMENT AND CEREBRAL PALSY. THIS RESULTS IN A LARGE EMOTIONAL AND SOCIOECONOMIC BURDEN. DECREASED MYELINATION IN PRETERM INFANT WMI IS ASSOCIATED WITH THE DELAYED DEVELOPMENT OR DESTRUCTION OF OLIGODENDROCYTE (OL) LINEAGE CELLS, PARTICULARLY OLIGODENDROCYTE PRECURSOR CELLS (OPCS). THE DEVELOPMENT OF CELLS FROM THE OL LINEAGE INVOLVES THE MIGRATION, PROLIFERATION AND DIFFERENT STAGES OF OL DIFFERENTIATION, FINALLY LEADING TO MYELINATION. A SERIES OF COMPLEX INTRINSIC, EXTRINSIC AND EPIGENETIC FACTORS REGULATE THE OPC CELL CYCLE WITHDRAWAL, OL LINEAGE PROGRESSION AND MYELINATION. WE FOCUS ON THE INHIBITOR OF DNA BINDING 2 (ID2), BECAUSE IT IS WIDELY INVOLVED IN THE DIFFERENT STAGES OF OL DIFFERENTIATION AND GENESIS. ID2 IS A KEY TRANSCRIPTION FACTOR FOR THE NORMAL DEVELOPMENT OF OL LINEAGE CELLS, AND THE PATHOGENESIS OF WMI IS CLOSELY LINKED WITH OL DEVELOPMENTAL DISORDERS. ID4, ANOTHER FAMILY MEMBER OF THE IDS PROTEIN, ALSO PLAYS A SIMILAR ROLE IN OL DIFFERENTIATION AND GENESIS. ID2 AND ID4 BELONG TO THE HELIX-LOOP-HELIX FAMILY; THEY LACK THE DNA-BINDING SEQUENCES AND INHIBIT OLIGODENDROGENESIS AND OPC DIFFERENTIATION. IN THIS REVIEW, WE MAINLY DISCUSS THE ROLES OF ID2 IN OL DEVELOPMENT, ESPECIALLY DURING OPC DIFFERENTIATION, AND SUMMARIZE THE ID2-MEDIATED INTRACELLULAR AND EXTRACELLULAR SIGNALING PATHWAYS THAT REGULATE THESE PROCESSES. WE ALSO DISCUSS ID4 IN RELATION TO BONE MORPHOGENETIC PROTEIN SIGNALING AND OLIGODENDROGENESIS. IT IS LIKELY THAT THESE DEVELOPMENTAL MECHANISMS ARE ALSO INVOLVED IN THE MYELIN REPAIR OR REMYELINATION IN HUMAN NEUROLOGICAL DISEASES. 2019 11 4275 26 MICROGLIA ACTIVATION IN THE MIDBRAIN OF THE HUMAN NEONATE: THE EFFECT OF PERINATAL HYPOXIC-ISCHEMIC INJURY. PERINATAL HYPOXIA-ISCHEMIA (PHI) IS A MAJOR RISK FACTOR FOR THE DEVELOPMENT OF NEUROPSYCHIATRIC DEFICITS LATER IN LIFE. WE PREVIOUSLY REPORTED THAT AFTER PROLONGED PHI, THE DOPAMINERGIC NEURONS OF THE HUMAN NEONATE SHOWED A DRAMATIC REDUCTION OF TYROSINE HYDROXYLASE (TH) IN THE SUBSTANTIA NIGRA, WITHOUT IMPORTANT SIGNS OF NEURONAL DEGENERATION DESPITE THE SIGNIFICANT REDUCTION IN THEIR CELL SIZE. SINCE MICROGLIA ACTIVATION COULD PRECEDE NEURONAL DEATH, WE NOW INVESTIGATED 2 MICROGLIA ACTIVATION MARKERS, IONIZED CALCIUM-BINDING ADAPTER MOLECULE 1 (IBA1), AND THE PHAGOCYTOSIS MARKER CD68. THE HIGHEST IBA1 IMMUNOREACTIVITY WAS FOUND IN NEONATES WITH NEUROPATHOLOGICAL LESIONS OF SEVERE/ABRUPT PHI, WHILE THE LOWEST IN SUBJECTS WITH MODERATE/PROLONGED OR OLDER PHI. SUBJECTS WITH VERY SEVERE/PROLONGED OR CHRONIC PHI SHOWED AN INCREASED IBA1 EXPRESSION AND VERY ACTIVATED MICROGLIAL MORPHOLOGY. HEAVY ATTACHMENT OF MICROGLIA ON TH NEURONS AND REMARKABLE EXPRESSION OF CD68 WERE ALSO OBSERVED INDICATING PHAGOCYTOSIS IN THIS GROUP. FEMALES APPEAR TO EXPRESS MORE IBA1 THAN MALES, SUGGESTING A GENDER DIFFERENCE IN MICROGLIA MATURATION AND IMMUNE REACTIVITY AFTER PHI INSULT. PHI-INDUCED MICROGLIAL "PRIMING" DURING THE SENSITIVE FOR BRAIN DEVELOPMENT PERINATAL/NEONATAL PERIOD, IN COMBINATION WITH GENETIC OR OTHER EPIGENETIC FACTORS, COULD PREDISPOSE THE SURVIVORS TO NEUROPSYCHIATRIC DISORDERS LATER IN LIFE, POSSIBLY THROUGH A SEXUALLY DIMORPHIC WAY. 2022 12 4401 32 MODULATION OF NEURONAL PLASTICITY FOLLOWING CHRONIC CONCOMITANT ADMINISTRATION OF THE NOVEL ANTIPSYCHOTIC LURASIDONE WITH THE MOOD STABILIZER VALPROIC ACID. RATIONALE: COMBINATORY THERAPY IS WIDELY USED IN PSYCHIATRY OWING TO THE POSSIBILITY THAT DRUGS WITH DIFFERENT MECHANISMS OF ACTION MAY SYNERGIZE TO IMPROVE FUNCTIONS DETERIORATED IN SCHIZOPHRENIA, BIPOLAR DISORDERS, AND MAJOR DEPRESSION. WHILE COMBINATORY STRATEGIES RELY ON RECEPTOR AND SYNAPTIC MECHANISMS, IT SHOULD ALSO BE CONSIDERED THAT TWO DRUGS MAY ALSO "INTERACT" ON THE LONG-TERM TO DETERMINE MORE ROBUST CHANGES IN NEURONAL PLASTICITY, WHICH REPRESENTS A DOWNSTREAM TARGET IMPORTANT FOR FUNCTIONAL RECOVERY. OBJECTIVE: THE AIM OF THE STUDY IS TO INVESTIGATE NEUROADAPTIVE CHANGES SET IN MOTION BY CHRONIC CONCOMITANT ADMINISTRATION OF THE NOVEL ANTIPSYCHOTIC LURASIDONE AND THE MOOD STABILIZER VALPROATE. METHODS: ANIMALS WERE CHRONICALLY TREATED WITH LURASIDONE, VALPROATE, OR THE COMBINATION OF THE TWO DRUGS AND KILLED 24 H AFTER THE LAST INJECTION TO EVALUATE ALTERATIONS OF DIFFERENT MEASURES OF NEURONAL PLASTICITY SUCH AS THE NEUROTROPHIN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF), THE IMMEDIATE EARLY GENE ACTIVITY-REGULATED CYTOSKELETAL ASSOCIATED PROTEIN, AND THE EPIGENETIC REGULATORS HDAC 1, 2, AND 5 IN DORSAL AND VENTRAL HIPPOCAMPUS. RESULTS: THE RESULTS SUGGEST THAT COADMINISTRATION OF LURASIDONE AND VALPROATE PRODUCES, WHEN COMPARED TO THE SINGLE DRUGS, A LARGER INCREASE IN THE EXPRESSION OF BDNF IN THE VENTRAL HIPPOCAMPUS, THROUGH THE REGULATION OF SPECIFIC NEUROTROPHIN TRANSCRIPTS. WE ALSO FOUND THAT THE HISTONE DEACETYLASES WERE REGULATED BY THE DRUG COMBINATION, SUGGESTING THAT SOME OF THE TRANSCRIPTIONAL CHANGES MAY BE SUSTAINED BY EPIGENETIC MECHANISMS. CONCLUSIONS: OUR RESULTS SUGGEST THAT THE BENEFICIAL EFFECTS ASSOCIATED WITH COMBINATORY TREATMENT BETWEEN A SECOND-GENERATION ANTIPSYCHOTIC AND A MOOD STABILIZER COULD RESULT FROM THE ABILITY TO MODULATE NEUROPLASTIC MOLECULES, WHOSE EXPRESSION AND FUNCTION IS DETERIORATED IN DIFFERENT PSYCHIATRIC CONDITIONS. 2013 13 6728 28 VOLTAGE-GATED CALCIUM CHANNELS AND PARKINSON'S DISEASE. A COMPLEX INTERACTION OF ENVIRONMENTAL, GENETIC AND EPIGENETIC FACTORS COMBINE WITH AGEING TO CAUSE THE MOST PREVALENT OF MOVEMENT DISORDERS PARKINSON'S DISEASE. CURRENT PHARMACOLOGICAL TREATMENTS ONLY TACKLE THE SYMPTOMS AND DO NOT STOP PROGRESSION OF THE DISEASE OR REVERSE THE NEURODEGENERATIVE PROCESS. WHILE SOME INCIDENCES OF PARKINSON'S DISEASE ARISE THROUGH HERITABLE GENETIC DEFECTS, THE CAUSE OF THE MAJORITY OF CASES REMAINS UNKNOWN. LIKEWISE, WHY SOME NEURONAL POPULATIONS ARE MORE SUSCEPTIBLE TO NEURODEGENERATION THAN OTHERS IS NOT CLEAR, BUT AS THE MOLECULAR PATHWAYS RESPONSIBLE FOR THE PROCESS OF CELL DEATH ARE UNRAVELLED, IT IS INCREASINGLY APPARENT THAT DISRUPTED CELLULAR ENERGY METABOLISM PLAYS A CENTRAL ROLE. PRECISE CONTROL OF CELLULAR CALCIUM CONCENTRATIONS IS CRUCIAL FOR MAINTENANCE OF ENERGY HOMEOSTASIS. RECENTLY, DIFFERENTIAL CELLULAR EXPRESSION OF NEURONAL VOLTAGE-GATED CALCIUM CHANNEL (CA(V)) ISOFORMS HAS BEEN IMPLICATED IN THE SUSCEPTIBILITY OF VULNERABLE NEURONS TO NEURODEGENERATION IN PARKINSON'S DISEASE. CA(V) CHANNELS ARE ALSO INVOLVED IN THE SYNAPTIC PLASTICITY RESPONSE TO THE DENERVATION THAT OCCURS IN PARKINSON'S DISEASE AND FOLLOWING CHRONIC TREATMENT WITH ANTI-PARKINSONIAN DRUGS. THIS REVIEW WILL EXAMINE THE PUTATIVE ROLE NEURONAL CA(V) CHANNELS HAVE IN THE PATHOGENESIS AND TREATMENT OF PARKINSON'S DISEASE. 2012 14 2259 31 EPIGENETIC PRIMING IN DRUG ADDICTION. DRUG ADDICTION IS A CHRONIC RELAPSING BRAIN DISORDER THAT IS CHARACTERIZED BY COMPULSIVE DRUG SEEKING AND CONTINUED USE DESPITE NEGATIVE OUTCOMES. CURRENT PHARMACOLOGICAL THERAPIES TARGET NEURONAL RECEPTORS OR TRANSPORTERS UPON WHICH DRUGS OF ABUSE ACT INITIALLY, YET THESE TREATMENTS REMAIN INEFFECTIVE FOR MOST INDIVIDUALS AND DO NOT PREVENT DISEASE RELAPSE AFTER ABSTINENCE. DRUGS OF ABUSE, IN ADDITION TO THEIR ACUTE EFFECTS, CAUSE PERSISTENT PLASTICITY AFTER REPEATED USE, INVOLVING DYSREGULATED GENE EXPRESSION IN THE BRAIN'S REWARD REGIONS, WHICH ARE THOUGHT TO MEDIATE THE PERSISTENT BEHAVIORAL ABNORMALITIES THAT CHARACTERIZE ADDICTION. EMERGING EVIDENCE IMPLICATES EPIGENETIC PRIMING AS A KEY MECHANISM THAT UNDERLIES THE LONG-LASTING ALTERATIONS IN NEURONAL GENE REGULATION, WHICH CAN REMAIN LATENT UNTIL TRIGGERED BY RE-EXPOSURE TO DRUG-ASSOCIATED STIMULI OR THE DRUG ITSELF. THUS, TO EFFECTIVELY TREAT DRUG ADDICTION, WE MUST IDENTIFY THE PRECISE EPIGENETIC MECHANISMS THAT ESTABLISH AND PRESERVE THE DRUG-INDUCED PATHOLOGY OF THE BRAIN REWARD CIRCUITRY. 2018 15 4643 27 NEUROPATHIC PAIN AS A TRIGGER FOR HISTONE MODIFICATIONS IN LIMBIC CIRCUITRY. CHRONIC PAIN INVOLVES BOTH CENTRAL AND PERIPHERAL NEURONAL PLASTICITY THAT ENCOMPASSES CHANGES IN THE BRAIN, SPINAL CORD, AND PERIPHERAL NOCICEPTORS. WITHIN THE FOREBRAIN, MESOCORTICOLIMBIC REGIONS ASSOCIATED WITH EMOTIONAL REGULATION HAVE RECENTLY BEEN SHOWN TO EXHIBIT LASTING GENE EXPRESSION CHANGES IN MODELS OF CHRONIC PAIN. TO BETTER UNDERSTAND HOW SUCH ENDURING TRANSCRIPTIONAL CHANGES MIGHT BE REGULATED WITHIN BRAIN STRUCTURES ASSOCIATED WITH PROCESSING OF PAIN OR AFFECT, WE EXAMINED EPIGENETIC MODIFICATIONS INVOLVED WITH ACTIVE OR PERMISSIVE TRANSCRIPTIONAL STATES (HISTONE H3 LYSINE 4 MONO AND TRIMETHYLATION, AND HISTONE H3 LYSINE 27 ACETYLATION) IN PERIAQUEDUCTAL GRAY (PAG), LATERAL HYPOTHALAMUS (LH), NUCLEUS ACCUMBENS (NAC), AND VENTRAL TEGMENTAL AREA (VTA) 5 WEEKS AFTER SCIATIC NERVE INJURY IN MICE TO MODEL CHRONIC PAIN. FOR BOTH MALE AND FEMALE MICE IN CHRONIC PAIN, WE OBSERVED AN OVERALL TREND FOR A REDUCTION OF THESE EPIGENETIC MARKERS IN PERIAQUEDUCTAL GRAY, LH, AND NAC, BUT NOT VTA. MOREOVER, WE DISCOVERED THAT SOME EPIGENETIC MODIFICATIONS EXHIBITED CHANGES ASSOCIATED WITH PAIN HISTORY, WHILE OTHERS WERE ASSOCIATED WITH INDIVIDUAL DIFFERENCES IN PAIN SENSITIVITY. WHEN TAKEN TOGETHER, THESE RESULTS SUGGEST THAT NERVE INJURY LEADS TO CHRONIC CHROMATIN-MEDIATED SUPPRESSION OF TRANSCRIPTION IN KEY LIMBIC BRAIN STRUCTURES AND CIRCUITS, WHICH MAY UNDERLIE ENDURING CHANGES IN PAIN PROCESSING AND SENSITIVITY WITHIN THESE SYSTEMS. 2023 16 1091 27 COGNITIVE ENHANCERS AS A TREATMENT FOR HEROIN RELAPSE AND ADDICTION. HEROIN ADDICTION IS A DISORDER THAT STEMS FROM MALADAPTIVE PLASTICITY WITHIN NEURAL CIRCUITS AND PRODUCES BROAD COGNITIVE DEFICITS. DESPITE CONSIDERABLE ADVANCES IN PSYCHOTHERAPY AND PHARMACOTHERAPY FOR HEROIN RELAPSE AND ADDICTION, EFFECTIVE TREATMENTS FOR HEROIN USE DISORDER ARE STILL LACKING. INCREASING PRECLINICAL EVIDENCE INDICATES THAT HEROIN SEEKING BEHAVIOR IS PERSISTENT AFTER WITHDRAWAL, WHILE COGNITIVE DYSFUNCTIONS ASSOCIATED WITH CHRONIC HEROIN USE ARE AN IMPORTANT CONTRIBUTING FACTOR TO RISK OF HEROIN RELAPSE AND ADDICTION. COGNITIVE ENHANCERS MAY BE USED TO STIMULATE TREATMENT SUCCESS AND ENHANCE TREATMENT EFFICACY. THE PURPOSE OF THIS REVIEW IS TO OUTLINE THE LITERATURE THAT DEMONSTRATES THE COGNITIVE DEFICITS DURING THE DEVELOPMENT OF HEROIN ADDICTION AND WITHDRAWAL PROCESS, AND SEVERAL FACTORS THAT UNDERLINE THE EFFICACY OF COGNITIVE ENHANCERS FOR HEROIN USE DISORDERS. THE REVIEW, THEN, EXAMINES THE POTENTIAL USE AND PHARMACOLOGICAL MECHANISMS OF COGNITIVE ENHANCERS THAT ACT ON CHOLINERGIC, GLUTAMATERGIC, DOPAMINERGIC OR ADRENERGIC PATHWAYS. IT ALSO EXAMINES THE EFFECTS OF COMPOUNDS THAT ALTER CREB SIGNALING AND EPIGENETIC MECHANISMS IN ANIMAL MODEL OF HEROIN RELAPSE. THE CURRENT BODY OF RESEARCH REVEALS THE NEW INSIGHTS INTO THE PHARMACOLOGICAL MECHANISMS UNDERLYING HEROIN ADDICTION AND HOLDS A SIGNIFICANT PROMISE FOR COGNITIVE ENHANCERS AS AN IMPROVED APPROACH TO TREAT HEROIN USE DISORDER IN A MORE EFFICIENT AND PERSISTENT WAY. 2019 17 2350 32 EPIGENETIC REGULATION OF NEUROINFLAMMATION IN PARKINSON'S DISEASE. NEUROINFLAMMATION IS ONE OF THE MOST SIGNIFICANT FACTORS INVOLVED IN THE INITIATION AND PROGRESSION OF PARKINSON'S DISEASE. PD IS A NEURODEGENERATIVE DISORDER WITH A MOTOR DISABILITY LINKED WITH VARIOUS COMPLEX AND DIVERSIFIED RISK FACTORS. THESE FACTORS TRIGGER MYRIADS OF CELLULAR AND MOLECULAR PROCESSES, SUCH AS MISFOLDING DEFECTIVE PROTEINS, OXIDATIVE STRESS, MITOCHONDRIAL DYSFUNCTION, AND NEUROTOXIC SUBSTANCES THAT INDUCE SELECTIVE NEURODEGENERATION OF DOPAMINE NEURONS. THIS NEURONAL DAMAGE ACTIVATES THE NEURONAL IMMUNE SYSTEM, INCLUDING GLIAL CELLS AND INFLAMMATORY CYTOKINES, TO TRIGGER NEUROINFLAMMATION. THE TRANSITION OF ACUTE TO CHRONIC NEUROINFLAMMATION ENHANCES THE SUSCEPTIBILITY OF INFLAMMATION-INDUCED DOPAMINERGIC NEURON DAMAGE, FORMING A VICIOUS CYCLE AND PROMPTING AN INDIVIDUAL TO PD DEVELOPMENT. EPIGENETIC MECHANISMS RECENTLY HAVE BEEN AT THE FOREFRONT OF THE REGULATION OF NEUROINFLAMMATORY FACTORS IN PD, PROPOSING A NEW DAWN FOR BREAKING THIS VICIOUS CYCLE. THIS REVIEW EXAMINED THE CORE EPIGENETIC MECHANISMS INVOLVED IN THE ACTIVATION AND PHENOTYPIC TRANSFORMATION OF GLIAL CELLS MEDIATED NEUROINFLAMMATION IN PD. WE FOUND THAT EPIGENETIC MECHANISMS DO NOT WORK INDEPENDENTLY, DESPITE BEING COORDINATED WITH EACH OTHER TO ACTIVATE NEUROINFLAMMATORY PATHWAYS. IN THIS REGARD, WE ATTEMPTED TO FIND THE SYNERGIC CORRELATION AND CONTRIBUTION OF THESE EPIGENETIC MODIFICATIONS WITH VARIOUS NEUROINFLAMMATORY PATHWAYS TO BROADEN THE CANVAS OF UNDERLYING PATHOLOGICAL MECHANISMS INVOLVED IN PD DEVELOPMENT. MOREOVER, THIS STUDY HIGHLIGHTED THE DUAL CHARACTERISTICS (NEUROPROTECTIVE/NEUROTOXIC) OF THESE EPIGENETIC MARKS, WHICH MAY COUNTERACT PD PATHOGENESIS AND MAKE THEM POTENTIAL CANDIDATES FOR DEVISING FUTURE PD DIAGNOSIS AND TREATMENT. 2021 18 2412 40 EPIGENETIC SIDE-EFFECTS OF COMMON PHARMACEUTICALS: A POTENTIAL NEW FIELD IN MEDICINE AND PHARMACOLOGY. THE TERM "EPIGENETICS" REFERS TO DNA AND CHROMATIN MODIFICATIONS THAT PERSIST FROM ONE CELL DIVISION TO THE NEXT, DESPITE A LACK OF CHANGE IN THE UNDERLYING DNA SEQUENCE. THE "EPIGENOME" REFERS TO THE OVERALL EPIGENETIC STATE OF A CELL, AND SERVES AS AN INTERFACE BETWEEN THE ENVIRONMENT AND THE GENOME. THE EPIGENOME IS DYNAMIC AND RESPONSIVE TO ENVIRONMENTAL SIGNALS NOT ONLY DURING DEVELOPMENT, BUT ALSO THROUGHOUT LIFE; AND IT IS BECOMING INCREASINGLY APPARENT THAT CHEMICALS CAN CAUSE CHANGES IN GENE EXPRESSION THAT PERSIST LONG AFTER EXPOSURE HAS CEASED. HERE WE PRESENT THE HYPOTHESIS THAT COMMONLY-USED PHARMACEUTICAL DRUGS CAN CAUSE SUCH PERSISTENT EPIGENETIC CHANGES. DRUGS MAY ALTER EPIGENETIC HOMEOSTASIS BY DIRECT OR INDIRECT MECHANISMS. DIRECT EFFECTS MAY BE CAUSED BY DRUGS WHICH AFFECT CHROMATIN ARCHITECTURE OR DNA METHYLATION. FOR EXAMPLE THE ANTIHYPERTENSIVE HYDRALAZINE INHIBITS DNA METHYLATION. AN EXAMPLE OF AN INDIRECTLY ACTING DRUG IS ISOTRETINOIN, WHICH HAS TRANSCRIPTION FACTOR ACTIVITY. A TWO-TIER MECHANISM IS POSTULATED FOR INDIRECT EFFECTS IN WHICH ACUTE EXPOSURE TO A DRUG INFLUENCES SIGNALING PATHWAYS THAT MAY LEAD TO AN ALTERATION OF TRANSCRIPTION FACTOR ACTIVITY AT GENE PROMOTERS. THIS STIMULATION RESULTS IN THE ALTERED EXPRESSION OF RECEPTORS, SIGNALING MOLECULES, AND OTHER PROTEINS NECESSARY TO ALTER GENETIC REGULATORY CIRCUITS. WITH MORE CHRONIC EXPOSURE, CELLS ADAPT BY AN UNKNOWN HYPOTHETICAL PROCESS THAT RESULTS IN MORE PERMANENT MODIFICATIONS TO DNA METHYLATION AND CHROMATIN STRUCTURE, LEADING TO ENDURING ALTERATION OF A GIVEN EPIGENETIC NETWORK. THEREFORE, ANY EPIGENETIC SIDE-EFFECT CAUSED BY A DRUG MAY PERSIST AFTER THE DRUG IS DISCONTINUED. IT IS FURTHER PROPOSED THAT SOME IATROGENIC DISEASES SUCH AS TARDIVE DYSKINESIA AND DRUG-INDUCED SLE ARE EPIGENETIC IN NATURE. IF THIS HYPOTHESIS IS CORRECT THE CONSEQUENCES FOR MODERN MEDICINE ARE PROFOUND, SINCE IT WOULD IMPLY THAT OUR CURRENT UNDERSTANDING OF PHARMACOLOGY IS AN OVERSIMPLIFICATION. WE PROPOSE THAT EPIGENETIC SIDE-EFFECTS OF PHARMACEUTICALS MAY BE INVOLVED IN THE ETIOLOGY OF HEART DISEASE, CANCER, NEUROLOGICAL AND COGNITIVE DISORDERS, OBESITY, DIABETES, INFERTILITY, AND SEXUAL DYSFUNCTION. IT IS SUGGESTED THAT A SYSTEMS BIOLOGY APPROACH EMPLOYING MICROARRAY ANALYSES OF GENE EXPRESSION AND METHYLATION PATTERNS CAN LEAD TO A BETTER UNDERSTANDING OF LONG-TERM SIDE-EFFECTS OF DRUGS, AND THAT IN THE FUTURE, EPIGENETIC ASSAYS SHOULD BE INCORPORATED INTO THE SAFETY ASSESSMENT OF ALL PHARMACEUTICAL DRUGS. THIS NEW APPROACH TO PHARMACOLOGY HAS BEEN TERMED "PHAMACOEPIGENOMICS", THE IMPACT OF WHICH MAY BE EQUAL TO OR GREATER THAN THAT OF PHARMACOGENETICS. WE PROVIDE HERE AN OVERVIEW OF THIS POTENTIALLY MAJOR NEW FIELD IN PHARMACOLOGY AND MEDICINE. 2009 19 4848 28 OPIOID-INDUCED STRUCTURAL AND FUNCTIONAL PLASTICITY OF MEDIUM-SPINY NEURONS IN THE NUCLEUS ACCUMBENS. OPIOID USE DISORDER (OUD) IS A CHRONIC RELAPSING CLINICAL CONDITION WITH TREMENDOUS MORBIDITY AND MORTALITY THAT FREQUENTLY PERSISTS, DESPITE TREATMENT, DUE TO AN INDIVIDUAL'S UNDERLYING PSYCHOLOGICAL, NEUROBIOLOGICAL, AND GENETIC VULNERABILITIES. EVIDENCE SUGGESTS THAT THESE VULNERABILITIES MAY HAVE NEUROCHEMICAL, CELLULAR, AND MOLECULAR BASES. KEY NEUROPLASTIC EVENTS WITHIN THE MESOCORTICOLIMBIC SYSTEM THAT EMERGE THROUGH CHRONIC EXPOSURE TO OPIOIDS MAY HAVE A DETERMINATIVE INFLUENCE ON BEHAVIORAL SYMPTOMS ASSOCIATED WITH OUD. IN PARTICULAR, STRUCTURAL AND FUNCTIONAL ALTERATIONS IN THE DENDRITIC SPINES OF MEDIUM SPINY NEURONS (MSNS) WITHIN THE NUCLEUS ACCUMBENS (NAC) AND ITS DOPAMINERGIC PROJECTIONS FROM THE VENTRAL TEGMENTAL AREA (VTA) ARE BELIEVED TO FACILITATE THESE BEHAVIORAL SEQUELAE. ADDITIONALLY, GLUTAMATERGIC NEURONS FROM THE PREFRONTAL CORTEX, THE BASOLATERAL AMYGDALA, THE HIPPOCAMPUS, AND THE THALAMUS PROJECT TO THESE SAME MSNS, PROVIDING AN ENRICHED TARGET FOR SYNAPTIC PLASTICITY. HERE, WE REVIEW LITERATURE RELATED TO NEUROADAPTATIONS IN NAC MSNS FROM DOPAMINERGIC AND GLUTAMATERGIC PATHWAYS IN OUD. WE ALSO DESCRIBE NEW FINDINGS RELATED TO TRANSCRIPTIONAL, EPIGENETIC, AND MOLECULAR MECHANISMS IN MSN PLASTICITY IN THE DIFFERENT STAGES OF OUD. 2021 20 6525 35 TRANSCRIPTIONAL AND EPIGENETIC SUBSTRATES OF METHAMPHETAMINE ADDICTION AND WITHDRAWAL: EVIDENCE FROM A LONG-ACCESS SELF-ADMINISTRATION MODEL IN THE RAT. METHAMPHETAMINE USE DISORDER IS A CHRONIC NEUROPSYCHIATRIC DISORDER CHARACTERIZED BY RECURRENT BINGE EPISODES, INTERVALS OF ABSTINENCE, AND RELAPSES TO DRUG USE. HUMANS ADDICTED TO METHAMPHETAMINE EXPERIENCE VARIOUS DEGREES OF COGNITIVE DEFICITS AND OTHER NEUROLOGICAL ABNORMALITIES THAT COMPLICATE THEIR ACTIVITIES OF DAILY LIVING AND THEIR PARTICIPATION IN TREATMENT PROGRAMS. IMPORTANTLY, MODELS OF METHAMPHETAMINE ADDICTION IN RODENTS HAVE SHOWN THAT ANIMALS WILL READILY LEARN TO GIVE THEMSELVES METHAMPHETAMINE. RATS ALSO ACCELERATE THEIR INTAKE OVER TIME. MICROARRAY STUDIES HAVE ALSO SHOWN THAT METHAMPHETAMINE TAKING IS ASSOCIATED WITH MAJOR TRANSCRIPTIONAL CHANGES IN THE STRIATUM MEASURED WITHIN A SHORT OR LONGER TIME AFTER CESSATION OF DRUG TAKING. AFTER A 2-H WITHDRAWAL TIME, THERE WAS INCREASED EXPRESSION OF GENES THAT PARTICIPATE IN TRANSCRIPTION REGULATION. THESE INCLUDED CYCLIC AMP RESPONSE ELEMENT BINDING (CREB), ETS DOMAIN-CONTAINING PROTEIN (ELK1), AND MEMBERS OF THE FOS FAMILY OF TRANSCRIPTION FACTORS. OTHER GENES OF INTEREST INCLUDE BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF), TYROSINE KINASE RECEPTOR, TYPE 2 (TRKB), AND SYNAPTOPHYSIN. METHAMPHETAMINE-INDUCED TRANSCRIPTION WAS FOUND TO BE REGULATED VIA PHOSPHORYLATED CREB-DEPENDENT EVENTS. AFTER A 30-DAY WITHDRAWAL FROM METHAMPHETAMINE SELF-ADMINISTRATION, HOWEVER, THERE WAS MOSTLY DECREASED EXPRESSION OF TRANSCRIPTION FACTORS INCLUDING JUND. THERE WAS ALSO DOWNREGULATION OF GENES WHOSE PROTEIN PRODUCTS ARE CONSTITUENTS OF CHROMATIN-REMODELING COMPLEXES. ALTOGETHER, THESE GENOME-WIDE RESULTS SHOW THAT METHAMPHETAMINE ABUSE MIGHT BE ASSOCIATED WITH ALTERED REGULATION OF A DIVERSITY OF GENE NETWORKS THAT IMPACT CELLULAR AND SYNAPTIC FUNCTIONS. THESE TRANSCRIPTIONAL CHANGES MIGHT SERVE AS TRIGGERS FOR THE NEUROPSYCHIATRIC PRESENTATIONS OF HUMANS WHO ABUSE THIS DRUG. BETTER UNDERSTANDING OF THE WAY THAT GENE PRODUCTS INTERACT TO CAUSE METHAMPHETAMINE ADDICTION WILL HELP TO DEVELOP BETTER PHARMACOLOGICAL TREATMENT OF METHAMPHETAMINE ADDICTS. 2015