1 2259 104 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 2 1091 35 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 3 6806 35 [EPIGENETICS AND DRUG ADDICTION: A FOCUS ON MECP2 AND ON HISTONE ACETYLATION]. CHRONIC DRUG EXPOSURE ALTERS GENE EXPRESSION IN THE BRAIN, WHICH IS BELIEVED TO UNDERLIE COMPULSIVE DRUG SEEKING AND DRUG TAKING BEHAVIOR. RECENT EVIDENCE SHOWS THAT DRUG-INDUCED LONG-TERM NEUROADAPTATIONS IN THE BRAIN ARE MEDIATED IN PART BY EPIGENETIC MECHANISMS. BY REMODELING CHROMATIN, THIS TYPE OF REGULATION CONTRIBUTES TO DRUG-INDUCED SYNAPTIC PLASTICITY THAT TRANSLATES INTO BEHAVIORAL MODIFICATIONS. HOW DRUG-INDUCED ALTERATIONS IN DNA METHYLATION REGULATE GENE EXPRESSION IS REVIEWED HERE, WITH A FOCUS ON MECP2, A PROTEIN BINDING METHYLATED DNA. THE IMPORTANCE OF HISTONE MODIFICATIONS, ESPECIALLY ACETYLATION IS ALSO DISCUSSED, WITH AN EMPHASIS ON THE EFFECTS OF INHIBITORS OF HISTONE DEACETYLASES ON DRUG-INDUCED BEHAVIORAL CHANGES. THE PRECISE IDENTIFICATION OF THE EPIGENETIC MECHANISMS THAT ARE UNDER THE CONTROL OF DRUGS OF ABUSE MAY HELP TO UNCOVER NOVEL TARGETS FOR THE TREATMENT OF DRUG SEEKING AND RELAPSE. 2015 4 1160 22 CONTINUING WAR ON PAIN: A PERSONALIZED APPROACH TO THE THERAPY WITH NONSTEROIDAL ANTI-INFLAMMATORY DRUGS AND OPIOIDS. SUCCESSFUL PAIN MANAGEMENT REQUIRES THE DELIVERY OF ANALGESIA WITH MINIMAL RISK OF ADVERSE DRUG REACTIONS. NONSTEROIDAL ANTI-INFLAMMATORY DRUGS AND OPIOIDS REMAIN THE MAINSTAY OF TREATMENT FOR THE MAJORITY OF PATIENTS. UNFORTUNATELY, ALMOST 50% OF ALL PATIENTS EXPERIENCE INADEQUATE PAIN RELIEF AND SERIOUS SIDE EFFECTS. ALLELIC VARIANTS IN GENES CODING FOR TARGET PROTEINS, TRANSPORTERS AND ENZYMES, WHICH GOVERN ANALGESIC DRUGS ACTION AND THEIR FATE IN THE ORGANISM, MIGHT EXPLAIN INTER-INDIVIDUAL VARIABILITY IN PAIN SEVERITY AND IN DRUG-INDUCED PAIN RELIEF AND TOXICITIES. ADDITIONALLY, IT SEEMS THAT EPIGENETIC CHANGES CONTRIBUTE TO THE HIGHLY VARIABLE RESPONSE TO PAIN TREATMENT. THEREFORE, PHARMACOGENOMIC TESTING MIGHT BE A VALUABLE TOOL FOR PERSONALIZATION OF PAIN TREATMENT, WITH A MULTIDISCIPLINARY TEAM APPROACH INVOLVED. 2019 5 4327 36 MICRORNAS MODULATE INTERACTIONS BETWEEN STRESS AND RISK FOR COCAINE ADDICTION. EXPOSURE TO STRESS INCREASES VULNERABILITY TO DRUG ABUSE, AS WELL AS RELAPSE LIABILITY IN ADDICTED INDIVIDUALS. CHRONIC DRUG USE ALTERS STRESS RESPONSE IN A MANNER THAT INCREASES DRUG SEEKING BEHAVIORS AND RELAPSE. DRUG EXPOSURE AND WITHDRAWAL HAVE BEEN SHOWN TO ALTER STRESS RESPONSES, AND CORTICOSTEROID MEDIATORS OF STRESS HAVE BEEN SHOWN TO IMPACT ADDICTION-RELATED BRAIN FUNCTION AND DRUG-SEEKING BEHAVIOR. DESPITE THE DOCUMENTED INTERPLAY BETWEEN STRESS AND SUBSTANCE ABUSE, THE MECHANISMS BY WHICH STRESS EXPOSURE AND DRUG SEEKING INTERACT REMAIN LARGELY UNKNOWN. RECENT STUDIES INDICATE THAT MICRORNAS (MIRNA) PLAY A SIGNIFICANT ROLE IN STRESS MODULATION AS WELL AS ADDICTION-RELATED PROCESSES INCLUDING NEUROGENESIS, SYNAPSE DEVELOPMENT, PLASTICITY, DRUG ACQUISITION, WITHDRAWAL AND RELAPSE. MIRNAS ARE SHORT NON-CODING RNAS THAT FUNCTION AS BIDIRECTIONAL EPIGENETIC MODULATORS OF GENE EXPRESSION THROUGH IMPERFECT SEQUENCE TARGETED DEGRADATION AND/OR TRANSLATIONAL REPRESSION OF MRNAS. THEY SERVE AS DYNAMIC REGULATORS OF CNS PHYSIOLOGY AND PATHOPHYSIOLOGY, AND FACILITATE RAPID AND LONG-LASTING CHANGES TO COMPLEX SYSTEMS AND BEHAVIORS. MIRNAS FUNCTION IN GLUCOCORTICOID SIGNALING AND THE MESOLIMBIC DOPAMINE REWARD SYSTEM, AS WELL AS MOOD DISORDERS RELATED TO DRUG WITHDRAWAL. THE LITERATURE SUGGESTS MIRNAS PLAY A PIVOTAL ROLE IN THE INTERACTION BETWEEN EXPOSURES TO STRESS, ADDICTION-RELATED PROCESSES, AND NEGATIVE AFFECTIVE STATES RESULTING FROM EXTENDED DRUG WITHDRAWAL. THIS MANUSCRIPT REVIEWS RECENT EVIDENCE FOR THE ROLE OF MIRNAS IN THE MODULATION OF STRESS AND COCAINE RESPONSES, AND DISCUSSES POTENTIAL MEDIATION OF THE INTERACTION OF THESE SYSTEMS BY MIRNAS. UNCOVERING THE MECHANISM BEHIND THE ASSOCIATION OF STRESS AND DRUG TAKING HAS THE POTENTIAL TO IMPACT THE TREATMENT OF DRUG ABUSE AND PREVENTION OF RELAPSE. FURTHER COMPREHENSION OF THESE COMPLEX INTERACTIONS MAY PROVIDE PROMISING NEW TARGETS FOR THE TREATMENT OF DRUG ADDICTION. 2016 6 4846 29 OPIATE ADDICTION AND COCAINE ADDICTION: UNDERLYING MOLECULAR NEUROBIOLOGY AND GENETICS. ADDICTIVE DISEASES, INCLUDING ADDICTION TO HEROIN, PRESCRIPTION OPIOIDS, OR COCAINE, POSE MASSIVE PERSONAL AND PUBLIC HEALTH COSTS. ADDICTIONS ARE CHRONIC RELAPSING DISEASES OF THE BRAIN CAUSED BY DRUG-INDUCED DIRECT EFFECTS AND PERSISTING NEUROADAPTATIONS AT THE EPIGENETIC, MRNA, NEUROPEPTIDE, NEUROTRANSMITTER, OR PROTEIN LEVELS. THESE NEUROADAPTATIONS, WHICH CAN BE SPECIFIC TO DRUG TYPE, AND THEIR RESULTANT BEHAVIORS ARE MODIFIED BY VARIOUS INTERNAL AND EXTERNAL ENVIRONMENTAL FACTORS, INCLUDING STRESS RESPONSIVITY, ADDICT MINDSET, AND SOCIAL SETTING. SPECIFIC GENE VARIANTS, INCLUDING VARIANTS ENCODING PHARMACOLOGICAL TARGET PROTEINS OR GENES MEDIATING NEUROADAPTATIONS, ALSO MODIFY VULNERABILITY AT PARTICULAR STAGES OF ADDICTION. GREATER UNDERSTANDING OF THESE INTERACTING FACTORS THROUGH LABORATORY-BASED AND TRANSLATIONAL STUDIES HAVE THE POTENTIAL TO OPTIMIZE EARLY INTERVENTIONS FOR THE THERAPY OF CHRONIC ADDICTIVE DISEASES AND TO REDUCE THE BURDEN OF RELAPSE. HERE, WE REVIEW THE MOLECULAR NEUROBIOLOGY AND GENETICS OF OPIATE ADDICTION, INCLUDING HEROIN AND PRESCRIPTION OPIOIDS, AND COCAINE ADDICTION. 2012 7 4639 42 NEURONAL EXTRACELLULAR SIGNAL-REGULATED KINASE (ERK) ACTIVITY AS MARKER AND MEDIATOR OF ALCOHOL AND OPIOID DEPENDENCE. EARLY PIONEERING WORK IN THE FIELD OF BIOCHEMISTRY IDENTIFIED PHOSPHORYLATION AS A CRUCIAL POST-TRANSLATIONAL MODIFICATION OF PROTEINS WITH THE ABILITY TO BOTH INDICATE AND ARBITRATE COMPLEX PHYSIOLOGICAL PROCESSES. MORE RECENT INVESTIGATIONS HAVE FUNCTIONALLY LINKED PHOSPHORYLATION OF EXTRACELLULAR SIGNAL-REGULATED KINASE (ERK) TO A VARIETY OF NEUROPHYSIOLOGICAL MECHANISMS RANGING FROM ACUTE NEUROTRANSMITTER ACTION TO LONG-TERM GENE EXPRESSION. ERK PHOSPHORYLATION SERVES AS AN INTRACELLULAR BRIDGING MECHANISM THAT FACILITATES NEURONAL COMMUNICATION AND PLASTICITY. DRUGS OF ABUSE, INCLUDING ALCOHOL AND OPIOIDS, ACT AS ARTIFICIAL YET POWERFUL REWARDS THAT IMPINGE UPON NATURAL REINFORCEMENT PROCESSES CRITICAL FOR SURVIVAL. THE GRADED PROGRESSION FROM INITIAL EXPOSURE TO ADDICTION (OR SUBSTANCE DEPENDENCE) IS BELIEVED TO RESULT FROM DRUG- AND DRUG CONTEXT-INDUCED ADAPTATIONS IN NEURONAL SIGNALING PROCESSES ACROSS BRAIN REWARD AND STRESS CIRCUITS FOLLOWING EXCESSIVE DRUG USE. IN THIS REGARD, COMMONLY ABUSED DRUGS AS WELL AS DRUG-ASSOCIATED EXPERIENCES ARE CAPABLE OF MODIFYING THE PHOSPHORYLATION OF ERK WITHIN CENTRAL REINFORCEMENT SYSTEMS. IN ADDITION, CHRONIC DRUG AND ALCOHOL EXPOSURE MAY DRIVE ERK-REGULATED EPIGENETIC AND STRUCTURAL ALTERATIONS THAT UNDERLIE A LONG-TERM PROPENSITY FOR ESCALATING DRUG USE. UNDER THE INFLUENCE OF SUCH A NEUROBIOLOGICAL VULNERABILITY, ENCOUNTERING DRUG-ASSOCIATED CUES AND CONTEXTS CAN PRODUCE SUBSEQUENT ALTERATIONS IN ERK SIGNALING THAT DRIVE RELAPSE TO DRUG AND ALCOHOL SEEKING. CURRENT STUDIES ARE DETERMINING PRECISELY WHICH MOLECULAR AND REGIONAL ERK PHOSPHORYLATION-ASSOCIATED EVENTS CONTRIBUTE TO THE ADDICTION PROCESS, AS WELL AS WHICH NEUROADAPTATIONS NEED TO BE TARGETED IN ORDER TO RETURN DEPENDENT INDIVIDUALS TO A HEALTHY STATE. 2014 8 2250 30 EPIGENETIC MODULATION OF OPIOID RECEPTORS BY DRUGS OF ABUSE. CHRONIC EXPOSURE TO DRUGS OF ABUSE PRODUCES PROFOUND CHANGES IN GENE EXPRESSION AND NEURAL ACTIVITY ASSOCIATED WITH DRUG-SEEKING AND TAKING BEHAVIOR. DYSREGULATION OF OPIOID RECEPTOR GENE EXPRESSION IS COMMONLY OBSERVED ACROSS A VARIETY OF ABUSED SUBSTANCES INCLUDING OPIOIDS, COCAINE, AND ALCOHOL. EARLY STUDIES IN CULTURED CELLS SHOWED THAT THE SPATIAL AND TEMPORAL GENE EXPRESSION OF OPIOID RECEPTORS ARE REGULATED BY EPIGENETIC MECHANISMS INCLUDING DNA AND HISTONE MODIFICATIONS AND NON-CODING RNAS. ACCUMULATING EVIDENCE INDICATE THAT DRUGS OF ABUSE CAN MODULATE OPIOID RECEPTOR GENE EXPRESSION BY TARGETING VARIOUS EPIGENETIC REGULATORY NETWORKS. BASED ON CURRENT CELLULAR AND ANIMAL MODELS OF SUBSTANCE USE DISORDER AND CLINICAL EVIDENCE, THIS REVIEW SUMMARIZES HOW CHRONIC DRUG EXPOSURE ALTERS THE GENE EXPRESSION OF MU, DELTA, KAPPA, AND NOCICEPTIN RECEPTORS VIA DNA AND HISTONE MODIFICATIONS. THE INFLUENCE OF DRUGS OF ABUSE ON EPIGENETIC MODULATORS, SUCH AS NON-CODING RNAS AND TRANSCRIPTION FACTORS, IS ALSO PRESENTED. FINALLY, THE THERAPEUTIC POTENTIAL OF MANIPULATING EPIGENETIC PROCESSES AS AN AVENUE TO TREAT SUBSTANCE USE DISORDER IS DISCUSSED. 2022 9 2513 33 EPIGENETICS AND PSYCHOSTIMULANT ADDICTION. CHRONIC DRUG EXPOSURE ALTERS GENE EXPRESSION IN THE BRAIN AND PRODUCES LONG-TERM CHANGES IN NEURAL NETWORKS THAT UNDERLIE COMPULSIVE DRUG TAKING AND SEEKING. EXACTLY HOW DRUG-INDUCED CHANGES IN SYNAPTIC PLASTICITY AND SUBSEQUENT GENE EXPRESSION ARE TRANSLATED INTO PERSISTENT NEUROADAPTATIONS REMAINS UNCLEAR. EMERGING EVIDENCE SUGGESTS THAT COMPLEX DRUG-INDUCED NEUROADAPTATIONS IN THE BRAIN ARE MEDIATED BY HIGHLY SYNCHRONIZED AND DYNAMIC PATTERNS OF GENE REGULATION. RECENTLY, IT HAS BECOME CLEAR THAT EPIGENETIC MECHANISMS CONTRIBUTE TO DRUG-INDUCED STRUCTURAL, SYNAPTIC, AND BEHAVIORAL PLASTICITY BY REGULATING EXPRESSION OF GENE NETWORKS. HERE WE REVIEW HOW ALTERATIONS IN HISTONE MODIFICATIONS, DNA METHYLATION, AND MICRORNAS REGULATE GENE EXPRESSION AND CONTRIBUTE TO PSYCHOSTIMULANT ADDICTION WITH A FOCUS ON THE EPIGENETIC MECHANISMS THAT REGULATE BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION FOLLOWING CHRONIC COCAINE EXPOSURE. IDENTIFYING EPIGENETIC SIGNATURES THAT DEFINE PSYCHOSTIMULANT ADDICTION MAY LEAD TO NOVEL, EFFICACIOUS TREATMENTS FOR DRUG CRAVING AND RELAPSE. 2013 10 4650 35 NEUROPLASTICITY IN ADDICTION: CELLULAR AND TRANSCRIPTIONAL PERSPECTIVES. DRUG ADDICTION IS A CHRONIC, RELAPSING BRAIN DISORDER WHICH CONSISTS OF COMPULSIVE PATTERNS OF DRUG-SEEKING AND TAKING THAT OCCURS AT THE EXPENSE OF OTHER ACTIVITIES. THE TRANSITION FROM CASUAL TO COMPULSIVE DRUG USE AND THE ENDURING PROPENSITY TO RELAPSE IS THOUGHT TO BE UNDERPINNED BY LONG-LASTING NEUROADAPTATIONS IN SPECIFIC BRAIN CIRCUITRY, ANALOGOUS TO THOSE THAT UNDERLIE LONG-TERM MEMORY FORMATION. RESEARCH SPANNING THE LAST TWO DECADES HAS MADE GREAT PROGRESS IN IDENTIFYING CELLULAR AND MOLECULAR MECHANISMS THAT CONTRIBUTE TO DRUG-INDUCED CHANGES IN PLASTICITY AND BEHAVIOR. ALTERATIONS IN SYNAPTIC TRANSMISSION WITHIN THE MESOCORTICOLIMBIC AND CORTICOSTRIATAL PATHWAYS, AND CHANGES IN THE TRANSCRIPTIONAL POTENTIAL OF CELLS BY EPIGENETIC MECHANISMS ARE TWO IMPORTANT MEANS BY WHICH DRUGS OF ABUSE CAN INDUCE LASTING CHANGES IN BEHAVIOR. IN THIS REVIEW WE PROVIDE A SUMMARY OF MORE RECENT RESEARCH THAT HAS FURTHERED OUR UNDERSTANDING OF DRUG-INDUCED NEUROPLASTIC CHANGES BOTH AT THE LEVEL OF THE SYNAPSE, AND ON A TRANSCRIPTIONAL LEVEL, AND HOW THESE CHANGES MAY RELATE TO THE HUMAN DISEASE OF ADDICTION. 2012 11 1688 22 DUAL BET/HDAC INHIBITION TO RELIEVE NEUROPATHIC PAIN: RECENT ADVANCES, PERSPECTIVES, AND FUTURE OPPORTUNITIES. DESPITE THE INTENSE RESEARCH ON DEVELOPING NEW THERAPIES FOR NEUROPATHIC PAIN STATES, AVAILABLE TREATMENTS HAVE LIMITED EFFICACY AND UNFAVORABLE SAFETY PROFILES. EPIGENETIC ALTERATIONS HAVE A GREAT INFLUENCE ON THE DEVELOPMENT OF CANCER AND NEUROLOGICAL DISEASES, AS WELL AS NEUROPATHIC PAIN. HISTONE ACETYLATION HAS PREVAILED AS ONE OF THE WELL INVESTIGATED EPIGENETIC MODIFICATIONS IN THESE DISEASES. ALTERED SPINAL ACTIVITY OF HISTONE DEACETYLASE (HDAC) AND BROMO AND EXTRA TERMINAL DOMAIN (BET) HAVE BEEN DESCRIBED IN NEUROPATHIC PAIN MODELS AND RESTORATION OF THESE ABERRANT EPIGENETIC MODIFICATIONS SHOWED PAIN-RELIEVING ACTIVITY. OVER THE LAST DECADES HDACS AND BETS HAVE BEEN THE FOCUS OF DRUG DISCOVERY STUDIES, LEADING TO THE DEVELOPMENT OF NUMEROUS SMALL-MOLECULE INHIBITORS. CLINICAL TRIALS TO EVALUATE THEIR ANTICANCER ACTIVITY SHOWED GOOD EFFICACY BUT RAISED TOXICITY CONCERNS THAT LIMITED TRANSLATION TO THE CLINIC. TO MAXIMIZE ACTIVITY AND MINIMIZE TOXICITY, THESE COMPOUNDS CAN BE APPLIED IN COMBINATION OF SUB-MAXIMAL DOSES TO PRODUCE ADDITIVE OR SYNERGISTIC INTERACTIONS (COMBINATION THERAPY). RECENTLY, OF PARTICULAR INTEREST, DUAL BET/HDAC INHIBITORS (MULTI-TARGET DRUGS) HAVE BEEN DEVELOPED TO ASSURE SIMULTANEOUS MODULATION OF BET AND HDAC ACTIVITY BY A SINGLE MOLECULE. THIS REVIEW WILL SUMMARIZE THE MOST RECENT ADVANCES WITH THESE STRATEGIES, DESCRIBING ADVANTAGES AND LIMITATIONS OF SINGLE DRUG TREATMENT VS COMBINATION REGIMENS. THIS REVIEW WILL ALSO PROVIDE A FOCUS ON DUAL BET/HDAC DRUG DISCOVERY INVESTIGATIONS AS FUTURE THERAPEUTIC OPPORTUNITY FOR HUMAN THERAPY OF NEUROPATHIC PAIN. 2021 12 2773 38 EXTRACELLULAR SIGNAL-REGULATED PROTEIN KINASES 1 AND 2 ACTIVATION BY ADDICTIVE DRUGS: A SIGNAL TOWARD PATHOLOGICAL ADAPTATION. ADDICTION IS A CHRONIC AND RELAPSING PSYCHIATRIC DISORDER THAT IS THOUGHT TO OCCUR IN VULNERABLE INDIVIDUALS. SYNAPTIC PLASTICITY EVOKED BY DRUGS OF ABUSE IN THE SO-CALLED NEURONAL CIRCUITS OF REWARD HAS BEEN PROPOSED TO UNDERLIE BEHAVIORAL ADAPTATIONS THAT CHARACTERIZE ADDICTION. BY INCREASING DOPAMINE IN THE STRIATUM, ADDICTIVE DRUGS ALTER THE BALANCE OF DOPAMINE AND GLUTAMATE SIGNALS CONVERGING ONTO STRIATAL MEDIUM-SIZED SPINY NEURONS (MSNS) AND ACTIVATE INTRACELLULAR EVENTS INVOLVED IN LONG-TERM BEHAVIORAL ALTERATIONS. OUR LABORATORY CONTRIBUTED TO THE IDENTIFICATION OF SALIENT MOLECULAR CHANGES INDUCED BY ADMINISTRATION OF ADDICTIVE DRUGS TO RODENTS. WE PIONEERED THE OBSERVATION THAT A COMMON FEATURE OF ADDICTIVE DRUGS IS TO ACTIVATE, BY A DOUBLE TYROSINE/THREONINE PHOSPHORYLATION, THE EXTRACELLULAR SIGNAL-REGULATED KINASES 1 AND 2 (ERK1/2) IN THE STRIATUM, WHICH CONTROL A PLETHORA OF SUBSTRATES, SOME OF THEM BEING CRITICALLY INVOLVED IN COCAINE-MEDIATED MOLECULAR AND BEHAVIORAL ADAPTATIONS. HEREIN, WE REVIEW HOW THE INTERPLAY BETWEEN DOPAMINE AND GLUTAMATE SIGNALING CONTROLS COCAINE-INDUCED ERK1/2 ACTIVATION IN MSNS. WE EMPHASIZE THE KEY ROLE OF N-METHYL-D-ASPARTATE RECEPTOR POTENTIATION BY D1 RECEPTOR TO TRIGGER ERK1/2 ACTIVATION AND ITS SUBSEQUENT NUCLEAR TRANSLOCATION WHERE IT MODULATES BOTH EPIGENETIC AND GENETIC PROCESSES ENGAGED BY COCAINE. WE DISCUSS HOW COCAINE-INDUCED LONG-TERM SYNAPTIC AND STRUCTURAL PLASTICITY OF MSNS, AS WELL AS BEHAVIORAL ADAPTATIONS, ARE INFLUENCED BY ERK1/2-CONTROLLED TARGETS. WE CONCLUDE THAT A BETTER KNOWLEDGE OF MOLECULAR MECHANISMS UNDERLYING ERK1/2 ACTIVATION BY DRUGS OF ABUSE AND/OR ITS ROLE IN LONG-TERM NEURONAL PLASTICITY IN THE STRIATUM MAY PROVIDE A NEW ROUTE FOR THERAPEUTIC TREATMENT IN ADDICTION. 2014 13 6617 32 UNDERPINNING THE NEUROBIOLOGICAL INTRICACIES ASSOCIATED WITH OPIOID TOLERANCE. THE OPIOID CRISIS IS A MAJOR THREAT OF THE 21ST CENTURY, WITH A REMARKABLE JUXTAPOSITION OF USE AND ABUSE. OPIOIDS ARE THE MOST POTENT AND EFFICACIOUS CLASS OF ANALGESICS, BUT DESPITE THEIR PROVEN THERAPEUTIC EFFICACY, THEY HAVE RECENTLY BEEN DEGRADED TO THIRD-LINE THERAPY FOR THE MANAGEMENT OF CHRONIC PAIN IN CLINICS. THE REASON BEHIND THIS IS THE DEVELOPMENT OF POTENTIAL SIDE EFFECTS AND TOLERANCE AFTER REPEATED DOSING. OPIOID TOLERANCE IS THE MAJOR LIMITING FACTOR LEADING TO THE WITHDRAWAL OF TREATMENT, SEVERE SIDE EFFECTS DUE TO DOSE ESCALATION, AND SOMETIMES EVEN DEATH OF THE PATIENTS. EVERY DAY MORE THAN 90 PEOPLE DIE DUE TO OPIOIDS OVERDOSE IN AMERICA, AND A SIMILAR TREND HAS BEEN SEEN ACROSS THE GLOBE. OVER THE PAST TWO DECADES, RESEARCHERS HAVE BEEN TRYING TO DISSECT THE NEUROBIOLOGICAL MECHANISM OF OPIOID TOLERANCE. RESEARCH ON OPIOID TOLERANCE SHIFTED TOWARD CENTRAL NERVOUS SYSTEM-BASED ADAPTATIONS BECAUSE TOLERANCE IS MUCH MORE THAN JUST A CELLULAR PHENOMENON. THUS, NEUROBIOLOGICAL ADAPTATIONS ASSOCIATED WITH OPIOID TOLERANCE ARE IMPORTANT TO UNDERSTAND IN ORDER TO FIND NEWER PAIN THERAPEUTICS. THESE ADAPTATIONS ARE ASSOCIATED WITH ALTERATIONS IN ASCENDING AND DESCENDING PAIN PATHWAYS, REWARD CIRCUITRY MODULATIONS, RECEPTOR DESENSITIZATION AND DOWN-REGULATION, RECEPTOR INTERNALIZATION, HETERODIMERIZATION, AND ALTERED EPIGENETIC REGULATION. THE PRESENT REVIEW IS FOCUSED ON NOVEL CIRCUITRIES ASSOCIATED WITH OPIOID TOLERANCE IN DIFFERENT AREAS OF THE BRAIN, SUCH AS PERIAQUEDUCTAL GRAY, ROSTRAL VENTROMEDIAL MEDULLA, DORSAL RAPHE NUCLEUS, VENTRAL TEGMENTAL AREA, AND NUCLEUS ACCUMBENS. UNDERSTANDING THE NEUROBIOLOGICAL MODULATIONS ASSOCIATED WITH CHRONIC OPIOID EXPOSURE AND TOLERANCE WILL PAVE THE WAY FOR THE DEVELOPMENT OF NOVEL PHARMACOLOGICAL TOOLS FOR SAFER AND BETTER MANAGEMENT OF CHRONIC PAIN IN PATIENTS. 2020 14 6207 33 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 15 2141 34 EPIGENETIC INTERVENTIONS FOR EPILEPTOGENESIS: A NEW FRONTIER FOR CURING EPILEPSY. THIS ARTICLE HIGHLIGHTS THE EMERGING THERAPEUTIC POTENTIAL OF SPECIFIC EPIGENETIC MODULATORS AS PROMISING ANTIEPILEPTOGENIC OR DISEASE-MODIFYING AGENTS FOR CURING EPILEPSY. CURRENTLY, THERE IS AN UNMET NEED FOR ANTIEPILEPTOGENIC AGENTS THAT TRULY PREVENT THE DEVELOPMENT OF EPILEPSY IN PEOPLE AT RISK. THERE IS STRONG EVIDENCE THAT EPIGENETIC SIGNALING, WHICH EXERTS HIGH FIDELITY REGULATION OF GENE EXPRESSION, PLAYS A CRUCIAL ROLE IN THE PATHOPHYSIOLOGY OF EPILEPTOGENESIS AND CHRONIC EPILEPSY. THESE MODIFICATIONS ARE NOT HARD-WIRED INTO THE GENOME AND ARE CONSTANTLY REPROGRAMMED BY ENVIRONMENTAL INFLUENCES. THE POTENTIAL EPIGENETIC MECHANISMS, INCLUDING HISTONE MODIFICATIONS, DNA METHYLATION, MICRORNA-BASED TRANSCRIPTIONAL CONTROL, AND BROMODOMAIN READING ACTIVITY, CAN DRASTICALLY ALTER THE NEURONAL GENE EXPRESSION PROFILE BY EXERTING THEIR SUMMATIVE EFFECTS IN A COORDINATED FASHION. SUCH AN EPIGENETIC INTERVENTION APPEARS MORE RATIONAL STRATEGY FOR PREVENTING EPILEPSY BECAUSE IT TARGETS THE PRIMARY PATHWAY THAT INITIALLY TRIGGERS THE NUMEROUS DOWNSTREAM CELLULAR AND MOLECULAR EVENTS MEDIATING EPILEPTOGENESIS. AMONG CURRENTLY APPROVED EPIGENETIC DRUGS, THE MAJORITY ARE ANTICANCER DRUGS WITH WELL-ESTABLISHED PROFILES IN CLINICAL TRIALS AND PRACTICE. EVIDENCE FROM PRECLINICAL STUDIES SUPPORTS THE PREMISE THAT THESE DRUGS MAY BE APPLIED TO A WIDE RANGE OF BRAIN DISORDERS. TARGETING HISTONE DEACETYLATION BY INHIBITING HISTONE DEACETYLASE ENZYMES APPEARS TO BE ONE PROMISING EPIGENETIC THERAPY SINCE CERTAIN INHIBITORS HAVE BEEN SHOWN TO PREVENT EPILEPTOGENESIS IN ANIMAL MODELS. HOWEVER, DEVELOPING NEURONAL SPECIFIC EPIGENETIC MODULATORS REQUIRES RATIONAL, PATHOPHYSIOLOGY-BASED OPTIMIZATION TO EFFICIENTLY INTERCEPT THE UPSTREAM PATHWAYS IN EPILEPTOGENESIS. OVERALL, EPIGENETIC AGENTS HAVE BEEN WELL POSITIONED AS NEW FRONTIER TOOLS TOWARDS THE NATIONAL GOAL OF CURING EPILEPSY. 2017 16 1252 36 CURRENT PERSPECTIVES ON THE NEUROBIOLOGY OF DRUG ADDICTION: A FOCUS ON GENETICS AND FACTORS REGULATING GENE EXPRESSION. DRUG ADDICTION IS A CHRONIC, RELAPSING DISORDER DEFINED BY CYCLIC PATTERNS OF COMPULSIVE DRUG SEEKING AND TAKING INTERSPERSED WITH EPISODES OF ABSTINENCE. WHILE GENETIC VARIABILITY MAY INCREASE THE RISK OF ADDICTIVE BEHAVIOURS IN AN INDIVIDUAL, EXPOSURE TO A DRUG RESULTS IN NEUROADAPTATIONS IN INTERCONNECTED BRAIN CIRCUITS WHICH, IN SUSCEPTIBLE INDIVIDUALS, ARE BELIEVED TO UNDERLIE THE TRANSITION TO, AND MAINTENANCE OF, AN ADDICTED STATE. THESE ADAPTATIONS CAN OCCUR AT THE CELLULAR, MOLECULAR, OR (EPI)GENETIC LEVEL AND ARE ASSOCIATED WITH SYNAPTIC PLASTICITY AND ALTERED GENE EXPRESSION, THE LATTER BEING MEDIATED VIA BOTH FACTORS AFFECTING TRANSLATION (EPIGENETICS) AND TRANSCRIPTION (NON CODING MICRORNAS) OF THE DNA OR RNA ITSELF. NEW ADVANCES USING TECHNIQUES SUCH AS OPTOGENETICS HAVE THE POTENTIAL TO INCREASE OUR UNDERSTANDING OF THE MICROCIRCUITRY MEDIATING ADDICTIVE BEHAVIOURS. HOWEVER, THE PROCESSES LEADING TO ADDICTION ARE COMPLEX AND MULTIFACTORIAL AND THUS WE FACE A MAJOR CONTEMPORARY CHALLENGE TO ELUCIDATE THE FACTORS IMPLICATED IN THE DEVELOPMENT AND MAINTENANCE OF AN ADDICTED STATE. 2012 17 3376 29 HISTONE-MEDIATED EPIGENETICS IN ADDICTION. MANY OF THE BRAIN REGIONS, NEUROTRANSMITTER SYSTEMS, AND BEHAVIORAL CHANGES THAT OCCUR AFTER OCCASIONAL DRUG USE IN HEALTHY SUBJECTS AND AFTER CHRONIC DRUG ABUSE IN ADDICTED PATIENTS ARE WELL CHARACTERIZED. AN EMERGING LITERATURE SUGGESTS THAT EPIGENETIC PROCESSES, THOSE PROCESSES THAT REGULATE THE ACCESSIBILITY OF DNA TO REGULATORY PROTEINS WITHIN THE NUCLEUS, ARE KEYS TO HOW ADDICTION DEVELOPS AND HOW IT MAY BE TREATED. INVESTIGATIONS OF THE REGULATION OF CHROMATIN, THE ORGANIZATIONAL SYSTEM OF DNA, BY HISTONE MODIFICATION ARE LEADING TO A NEW UNDERSTANDING OF THE CELLULAR AND BEHAVIORAL ALTERATIONS THAT OCCUR AFTER DRUG USE. WE WILL DESCRIBE HOW, WHEN, AND WHERE HISTONE TAILS ARE MODIFIED AND HOW SOME OF THE MOST RECOGNIZED HISTONE REGULATION PATTERNS ARE INVOLVED IN THE CYCLE OF ADDICTION, INCLUDING INITIAL AND CHRONIC DRUG INTAKE, WITHDRAWAL, ABSTINENCE, AND RELAPSE. FINALLY, WE CONSIDER HOW AN APPROACH THAT TARGETS HISTONE MODIFICATIONS MAY PROMOTE SUCCESSFUL TREATMENT. 2014 18 2670 33 ETHANOL ACTIONS ON THE VENTRAL TEGMENTAL AREA: NOVEL POTENTIAL TARGETS ON REWARD PATHWAY NEURONS. THE VENTRAL TEGMENTAL AREA (VTA) EVALUATES SALIENCE OF ENVIRONMENTAL STIMULI AND PROVIDES DOPAMINERGIC INNERVATION TO MANY BRAIN AREAS AFFECTED BY ACUTE AND CHRONIC ETHANOL EXPOSURE. WHILE PRIMARILY ASSOCIATED WITH REWARDING AND REINFORCING STIMULI, RECENT EVIDENCE INDICATES A ROLE FOR THE VTA IN AVERSION AS WELL. ETHANOL ACTIONS IN THE VTA MAY TRIGGER NEUROADAPTATION RESULTING IN REDUCTION OF THE AVERSIVE RESPONSES TO ALCOHOL AND A RELATIVE INCREASE IN THE REWARDING RESPONSES. IN SEARCHING FOR EFFECTIVE PHARMACOTHERAPIES FOR THE TREATMENT OF ALCOHOL ABUSE AND ALCOHOLISM, RECOGNITION OF THIS IMBALANCE MAY REVEAL NOVEL STRATEGIES. IN ADDITION TO CONVENTIONAL RECEPTOR/ION CHANNEL PHARMACOTHERAPIES, EPIGENETIC FACTORS THAT CONTROL NEUROADAPTATION TO CHRONIC ETHANOL TREATMENT CAN BE TARGETED AS AN AVENUE FOR DEVELOPMENT OF THERAPEUTIC APPROACHES TO RESTORE THE BALANCE. FURTHERMORE, WHEN EXPLORING THERAPIES TO ADDRESS REWARD/AVERSION IMBALANCE IN THE ACTION OF ALCOHOL IN THE VTA, SEX DIFFERENCES HAVE TO BE TAKEN INTO ACCOUNT TO ENSURE EFFECTIVE TREATMENT FOR BOTH MEN AND WOMEN. THESE PRINCIPLES APPLY TO A VTA-CENTRIC APPROACH TO THERAPIES, BUT SHOULD HOLD TRUE WHEN THINKING ABOUT THE OVERALL APPROACH IN THE DEVELOPMENT OF NEUROACTIVE DRUGS TO TREAT ALCOHOL USE DISORDERS. ALTHOUGH THE FUNCTIONS OF THE VTA ITSELF ARE COMPLEX, IT IS A USEFUL MODEL SYSTEM TO EVALUATE THE REWARD/AVERSION IMBALANCE THAT OCCURS WITH ETHANOL EXPOSURE AND COULD BE USED TO PROVIDE NEW LEADS IN THE EFFORTS TO DEVELOP NOVEL DRUGS TO TREAT ALCOHOLISM. 2018 19 6061 22 THE DEVELOPMENT PROSPECTION OF HDAC INHIBITORS AS A POTENTIAL THERAPEUTIC DIRECTION IN ALZHEIMER'S DISEASE. ALZHEIMER'S DISEASE (AD) IS A CHRONIC NEURODEGENERATIVE DISEASE, WHICH IS ASSOCIATED WITH LEARNING AND MEMORY IMPAIRMENT IN THE ELDERLY. RECENT STUDIES HAVE FOUND THAT TREATING AD IN THE WAY OF CHROMATIN REMODELING VIA HISTONE ACETYLATION IS A PROMISING THERAPEUTIC REGIMEN. IN A NUMBER OF RECENT STUDIES, INHIBITORS OF HISTONE DEACETYLASE (HDACS) HAVE BEEN FOUND TO BE A NOVEL PROMISING THERAPEUTIC AGENTS FOR NEUROLOGICAL DISORDERS, PARTICULARLY FOR AD AND OTHER NEURODEGENERATIVE DISEASES. ALTHOUGH HDAC INHIBITORS HAVE THE ABILITY TO AMELIORATE COGNITIVE IMPAIRMENT, SUCCESSFUL TREATMENTS IN THE CLASSIC AD ANIMAL MODEL ARE RARELY TRANSLATED INTO CLINICAL TRIALS. AS FOR THE REDUCTION OF UNWANTED SIDE EFFECTS, THE DEVELOPMENT OF HDAC INHIBITORS WITH INCREASED ISOFORM SELECTIVITY OR SEEKING OTHER DIRECTIONS IS A KEY ISSUE THAT NEEDS TO BE ADDRESSED. THE REVIEW FOCUSED ON LITERATURES ON EPIGENETIC MECHANISMS IN RECENT YEARS, ESPECIALLY ON HISTONE ACETYLATION IN TERMS OF THE ENHANCEMENT OF SPECIFICITY, EFFICACY AND AVOIDING SIDE EFFECTS FOR TREATING AD. 2017 20 1687 37 DRUGS OF ABUSE: EPIGENETIC MECHANISMS IN TOXICITY AND ADDICTION. THE ABUSE OF SUBSTANCES SUCH AS ETHANOL, COCAINE, AMPHETAMINES AND HEROIN IS ASSOCIATED WITH TOXIC EFFECTS ON ALMOST EVERY SYSTEM OF THE ORGANISM. FURTHERMORE, THE TRANSITION FROM OCCASIONAL-RECREATIONAL USE TO CHRONIC ABUSE AND ADDICTION IS A SERIOUS PSYCHIATRIC DISORDER WITH ONLY FEW CHANCES FOR EFFECTIVE AND DEFINITIVE TREATMENT SINCE MOST INDIVIDUALS RELAPSE, EVEN AFTER LONG PERIODS OF ABSTINENCE. IT IS THEREFORE OF UTMOST IMPORTANCE TO ELUCIDATE THE MECHANISMS BY WHICH THESE SUBSTANCES EXERT THEIR TOXICITY AND MEDIATE ADDICTION, IN ORDER TO DEVELOP NEW, EFFICIENT THERAPEUTIC STRATEGIES WITH A LONG-TERM OUTCOME, WHICH ARE CURRENTLY LACKING. WE ALREADY KNOW THAT IN A GREAT NUMBER OF THESE MECHANISMS, ALTERED GENE FUNCTION IS INVOLVED. BUT, WITH THE NEW FIELD OF EPIGENETICS, THERE IS INCREASING EVIDENCE THAT CHANGES IN THE EPIGENOME ARE RESPONSIBLE FOR THE ALTERED GENE FUNCTION. THE ADVANCES IN THE FIELD OF EPIGENETICS TOWARDS ELUCIDATION OF THE MECHANISMS UNDERLYING TOXICITY AND ADDICTION FOR ETHANOL, COCAINE, AMPHETAMINES AND HEROIN ARE CURRENTLY PRESENTED AND DISCUSSED IN THIS REVIEW. 2011