1 3880 77 KETAMINE: REPURPOSING AND REDEFINING A MULTIFACETED DRUG. THIS SHORT REVIEW WILL HIGHLIGHT RECENT CLINICAL AND BASIC RESEARCH THAT SUPPORTS THE THERAPEUTIC UTILITY OF KETAMINE AS A RAPID-ACTING, LIFE-SAVING ANTIDEPRESSANT AND A VERSATILE ANALGESIC. AFTER 50 YEARS OF USE AS A DISSOCIATIVE ANESTHETIC AND MISUSE AS A STREET DRUG, KETAMINE HAS RE-EMERGED AS A USEFUL OFF-LABEL AGENT FOR AMELIORATING VARIOUS TYPES OF PAIN AND RESISTANT DEPRESSION. IN ADDITION TO ITS ABILITY TO INHIBIT N-METHYL-D-ASPARTATE (NMDA) RECEPTORS, THE DIVERSE ACTIONS OF KETAMINE MIGHT INVOLVE EPIGENETIC MECHANISMS SUCH AS MICRORNA REGULATION. THUS, KETAMINE IS TRANSITIONING FROM BEING THE PHARMACOLOGIST'S NIGHTMARE TO ONE OF THE MOST INTERESTING DEVELOPMENTS IN THE PHARMACOLOGY OF DEPRESSION AND PAIN. 2014 2 6627 27 UNDERSTANDING RESILIENCE: NEW APPROACHES FOR PREVENTING AND TREATING PTSD. ALL INDIVIDUALS EXPERIENCE STRESSFUL LIFE EVENTS, AND UP TO 84% OF THE GENERAL POPULATION WILL EXPERIENCE AT LEAST ONE POTENTIALLY TRAUMATIC EVENT. IN SOME CASES, ACUTE OR CHRONIC STRESSORS LEAD TO THE DEVELOPMENT OF POSTTRAUMATIC STRESS DISORDER (PTSD) OR OTHER PSYCHOPATHOLOGY; HOWEVER, THE MAJORITY OF PEOPLE ARE RESILIENT TO SUCH EFFECTS. RESILIENCE IS THE ABILITY TO ADAPT SUCCESSFULLY IN THE FACE OF STRESS AND ADVERSITY. A WEALTH OF RESEARCH HAS BEGUN TO IDENTIFY THE GENETIC, EPIGENETIC, NEURAL, AND ENVIRONMENTAL UNDERPINNINGS OF RESILIENCE, AND HAS INDICATED THAT RESILIENCE IS MEDIATED BY ADAPTIVE CHANGES ENCOMPASSING SEVERAL ENVIRONMENTAL FACTORS, NEURAL CIRCUITS, NUMEROUS NEUROTRANSMITTERS, AND MOLECULAR PATHWAYS. THE FIRST PART OF THIS REVIEW FOCUSES ON RECENT FINDINGS REGARDING THE GENETIC, EPIGENETIC, DEVELOPMENTAL, PSYCHOSOCIAL, AND NEUROCHEMICAL FACTORS AS WELL AS NEURAL CIRCUITS AND MOLECULAR PATHWAYS THAT UNDERLIE THE DEVELOPMENT OF RESILIENCE. EMERGING AND EXCITING AREAS OF RESEARCH AND NOVEL METHODOLOGICAL APPROACHES, INCLUDING GENOME-WIDE GENE EXPRESSION STUDIES, IMMUNE, ENDOCANNABINOID, OXYTOCIN, AND GLUTAMATERGIC SYSTEMS, ARE EXPLORED TO HELP DELINEATE INNOVATIVE MECHANISMS THAT MAY CONTRIBUTE TO RESILIENCE. THE SECOND PART REVIEWS SEVERAL INTERVENTIONS AND PREVENTATIVE APPROACHES DESIGNED TO ENHANCE RESILIENCE IN BOTH DEVELOPMENTAL AND ADULT POPULATIONS. SPECIFICALLY, THE REVIEW WILL DELINEATE APPROACHES AIMED TO BOLSTER RESILIENCE IN INDIVIDUALS WITH PTSD. FURTHERMORE, WE DISCUSS NOVEL PHARMACOLOGIC APPROACHES, INCLUDING THE N-METHYL-D-ASPARTATE (NMDA) RECEPTOR KETAMINE AND NEUROPEPTIDE Y (NPY), AS EXCITING NEW PROSPECTS FOR NOT ONLY THE TREATMENT OF PTSD BUT AS NEW TARGETS TO ENHANCE RESILIENCE. OUR GROWING UNDERSTANDING OF RESILIENCE AND INTERVENTIONS WILL HOPEFULLY LEAD TO THE DEVELOPMENT OF NEW STRATEGIES FOR NOT JUST TREATING PTSD BUT ALSO SCREENING AND EARLY IDENTIFICATION OF AT-RISK YOUTH AND ADULTS. TAKEN TOGETHER, EFFORTS AIMED AT DISSEMINATION AND IMPLEMENTATION OF NOVEL INTERVENTIONS TO ENHANCE RESILIENCE WILL HAVE TO KEEP PACE WITH THE GROWTH OF NEW PREVENTIVE AND TREATMENT STRATEGIES. 2016 3 661 24 BLOOD MIR-144-3P: A NOVEL DIAGNOSTIC AND THERAPEUTIC TOOL FOR DEPRESSION. MAJOR DEPRESSIVE DISORDER (MDD) IS THE LEADING CAUSE OF DISABILITY WORLDWIDE. THERE IS AN URGENT NEED FOR OBJECTIVE BIOMARKERS TO DIAGNOSE THIS HIGHLY HETEROGENEOUS SYNDROME, ASSIGN TREATMENT, AND EVALUATE TREATMENT RESPONSE AND PROGNOSIS. MICRORNAS (MIRNAS) ARE SHORT NON-CODING RNAS, WHICH ARE DETECTED IN BODY FLUIDS THAT HAVE EMERGED AS POTENTIAL BIOMARKERS OF MANY DISEASE CONDITIONS. THE PRESENT STUDY EXPLORED THE POTENTIAL USE OF MIRNAS AS BIOMARKERS FOR MDD AND ITS TREATMENT. WE PROFILED THE EXPRESSION LEVELS OF CIRCULATING BLOOD MIRNAS FROM MICE THAT WERE COLLECTED BEFORE AND AFTER EXPOSURE TO CHRONIC SOCIAL DEFEAT STRESS (CSDS), AN EXTENSIVELY VALIDATED MOUSE MODEL USED TO STUDY DEPRESSION, AS WELL AS AFTER EITHER REPEATED IMIPRAMINE OR SINGLE-DOSE KETAMINE TREATMENT. WE OBSERVED ROBUST DIFFERENCES IN BLOOD MIRNA SIGNATURES BETWEEN STRESS-RESILIENT AND STRESS-SUSCEPTIBLE MICE AFTER AN INCUBATION PERIOD, BUT NOT IMMEDIATELY AFTER EXPOSURE TO THE STRESS. FURTHERMORE, KETAMINE TREATMENT WAS MORE EFFECTIVE THAN IMIPRAMINE AT RE-ESTABLISHING BASELINE MIRNA EXPRESSION LEVELS, BUT ONLY IN MICE THAT RESPONDED BEHAVIORALLY TO THE DRUG. WE IDENTIFIED THE RED BLOOD CELL-SPECIFIC MIR-144-3P AS A CANDIDATE BIOMARKER TO AID DEPRESSION DIAGNOSIS AND PREDICT KETAMINE TREATMENT RESPONSE IN STRESS-SUSCEPTIBLE MICE AND MDD PATIENTS. LASTLY, WE DEMONSTRATE THAT SYSTEMIC KNOCKDOWN OF MIR-144-3P, VIA SUBCUTANEOUS ADMINISTRATION OF A SPECIFIC ANTAGOMIR, IS SUFFICIENT TO REDUCE THE DEPRESSION-RELATED PHENOTYPE IN STRESS-SUSCEPTIBLE MICE. RNA-SEQUENCING ANALYSIS OF BLOOD AFTER SUCH MIR-144-3P KNOCKDOWN REVEALED A BLUNTED TRANSCRIPTIONAL STRESS SIGNATURE AS WELL. THESE FINDINGS IDENTIFY MIR-144-3P AS A NOVEL TARGET FOR DIAGNOSIS OF MDD AS WELL AS FOR ANTIDEPRESSANT TREATMENT, AND ENHANCE OUR UNDERSTANDING OF EPIGENETIC PROCESSES ASSOCIATED WITH DEPRESSION. 2022 4 5310 16 PSYCHOBIOLOGY AND MOLECULAR GENETICS OF RESILIENCE. EVERY INDIVIDUAL EXPERIENCES STRESSFUL LIFE EVENTS. IN SOME CASES ACUTE OR CHRONIC STRESS LEADS TO DEPRESSION AND OTHER PSYCHIATRIC DISORDERS, BUT MOST PEOPLE ARE RESILIENT TO SUCH EFFECTS. RECENT RESEARCH HAS BEGUN TO IDENTIFY THE ENVIRONMENTAL, GENETIC, EPIGENETIC AND NEURAL MECHANISMS THAT UNDERLIE RESILIENCE, AND HAS SHOWN THAT RESILIENCE IS MEDIATED BY ADAPTIVE CHANGES IN SEVERAL NEURAL CIRCUITS INVOLVING NUMEROUS NEUROTRANSMITTER AND MOLECULAR PATHWAYS. THESE CHANGES SHAPE THE FUNCTIONING OF THE NEURAL CIRCUITS THAT REGULATE REWARD, FEAR, EMOTION REACTIVITY AND SOCIAL BEHAVIOUR, WHICH TOGETHER ARE THOUGHT TO MEDIATE SUCCESSFUL COPING WITH STRESS. 2009 5 3708 19 INFLUENCE OF PHARMACOLOGICAL AND EPIGENETIC FACTORS TO SUPPRESS NEUROTROPHIC FACTORS AND ENHANCE NEURAL PLASTICITY IN STRESS AND MOOD DISORDERS. STRESS-INDUCED MAJOR DEPRESSION AND MOOD DISORDERS ARE CHARACTERIZED BY BEHAVIOURAL ABNORMALITIES AND PSYCHIATRIC ILLNESS, LEADING TO DISABILITY AND IMMATURE MORTALITY WORLDWIDE. NEUROBIOLOGICAL MECHANISMS OF STRESS AND MOOD DISORDERS ARE DISCUSSED CONSIDERING RECENT FINDINGS, AND CHALLENGES TO ENHANCE PHARMACOLOGICAL EFFECTS OF ANTIDEPRESSANT, AND MOOD STABILIZERS. PHARMACOLOGICAL ENHANCEMENT OF KETAMINE AND SCOPOLAMINE REGULATES DEPRESSION AT THE MOLECULAR LEVEL, INCREASING SYNAPTIC PLASTICITY IN PREFRONTAL REGIONS. BLOOD-DERIVED NEUROTROPHIC FACTORS FACILITATE MOOD-DEFICIT SYMPTOMS. EPIGENETIC FACTORS MAINTAIN STRESS-RESILIENCE IN HIPPOCAMPAL REGION. REGULATION OF NEUROTROPHIC FACTORS BLOCKADES STRESS, AND ENHANCES NEURONAL SURVIVAL THOUGH IT PARALYZES LIMBIC REGIONS. MOLECULAR AGENTS AND NEUROTROPHIC FACTORS ALSO CONTROL BEHAVIORAL AND SYNAPTIC PLASTICITY IN ADDICTION AND STRESS DISORDERS. FUTURE RESEARCH ON NEURONAL DYNAMICS AND CELLULAR ACTIONS CAN BE DIRECTED TO OBTAIN THE ETIOLOGY OF SYNAPTIC DYSREGULATION IN MOOD DISORDER AND STRESS. FOR THE FIRST TIME, THE CURRENT REVIEW CONTRIBUTES TO THE LITERATURE OF SYNAPTIC PLASTICITY REPRESENTING THE ROLE OF EPIGENETIC MECHANISMS AND GLUCOCORTICOID RECEPTORS TO PREDICT DEPRESSION AND ANXIETY IN CLINICAL CONDITIONS. 2019 6 6626 24 UNDERSTANDING RESILIENCE. RESILIENCE IS THE ABILITY TO ADAPT SUCCESSFULLY IN THE FACE OF STRESS AND ADVERSITY. STRESSFUL LIFE EVENTS, TRAUMA, AND CHRONIC ADVERSITY CAN HAVE A SUBSTANTIAL IMPACT ON BRAIN FUNCTION AND STRUCTURE, AND CAN RESULT IN THE DEVELOPMENT OF POSTTRAUMATIC STRESS DISORDER (PTSD), DEPRESSION AND OTHER PSYCHIATRIC DISORDERS. HOWEVER, MOST INDIVIDUALS DO NOT DEVELOP SUCH ILLNESSES AFTER EXPERIENCING STRESSFUL LIFE EVENTS, AND ARE THUS THOUGHT TO BE RESILIENT. RESILIENCE AS SUCCESSFUL ADAPTATION RELIES ON EFFECTIVE RESPONSES TO ENVIRONMENTAL CHALLENGES AND ULTIMATE RESISTANCE TO THE DELETERIOUS EFFECTS OF STRESS, THEREFORE A GREATER UNDERSTANDING OF THE FACTORS THAT PROMOTE SUCH EFFECTS IS OF GREAT RELEVANCE. THIS REVIEW FOCUSES ON RECENT FINDINGS REGARDING GENETIC, EPIGENETIC, DEVELOPMENTAL, PSYCHOSOCIAL, AND NEUROCHEMICAL FACTORS THAT ARE CONSIDERED ESSENTIAL CONTRIBUTORS TO THE DEVELOPMENT OF RESILIENCE. NEURAL CIRCUITS AND PATHWAYS INVOLVED IN MEDIATING RESILIENCE ARE ALSO DISCUSSED. THE GROWING UNDERSTANDING OF RESILIENCE FACTORS WILL HOPEFULLY LEAD TO THE DEVELOPMENT OF NEW PHARMACOLOGICAL AND PSYCHOLOGICAL INTERVENTIONS FOR ENHANCING RESILIENCE AND MITIGATING THE UNTOWARD CONSEQUENCES. 2013 7 3854 21 IS PTSD AN EVOLUTIONARY SURVIVAL ADAPTATION INITIATED BY UNRESTRAINED CYTOKINE SIGNALING AND MAINTAINED BY EPIGENETIC CHANGE? INTRODUCTION: TREATMENT OUTCOMES FOR PTSD WITH CURRENT PSYCHOLOGICAL THERAPIES ARE POOR, WITH VERY FEW PATIENTS ACHIEVING SUSTAINED SYMPTOM REMISSION. A NUMBER OF AUTHORS HAVE IDENTIFIED PHYSIOLOGICAL AND IMMUNE DISTURBANCES IN POST TRAUMATIC STRESS DISORDER (PTSD) PATIENTS, BUT THERE IS NO UNIFYING HYPOTHESIS THAT EXPLAINS THE MYRIAD FEATURES OF THE DISORDER. MATERIALS AND METHODS: THE MEDICAL LITERATURE WAS REVIEWED OVER A 6-YEAR PERIOD PRIMARILY USING THE MEDICAL DATABASE PUBMED. RESULTS: THE LITERATURE CONTAINS NUMEROUS PAPERS THAT HAVE IDENTIFIED A RANGE OF PHYSIOLOGICAL AND IMMUNE DYSFUNCTION IN ASSOCIATION WITH PTSD. THIS PAPER PROPOSES THAT UNRESTRAINED CYTOKINE SIGNALING INDUCES EPIGENETIC CHANGES THAT PROMOTE AN EVOLUTIONARY SURVIVAL ADAPTATION, WHICH MAINTAINS A DEFENSIVE PTSD PHENOTYPE. THE BRAIN CAN ASSOCIATE IMMUNE SIGNALING WITH PAST THREAT AND INITIATE A DEFENSIVE BEHAVIORAL RESPONSE. THE SYMPATHETIC NERVOUS SYSTEM IS PRO-INFLAMMATORY, WHILE THE PARASYMPATHETIC NERVOUS SYSTEM IS ANTI-INFLAMMATORY. PROLONGED CHOLINERGIC WITHDRAWAL WILL PROMOTE A CHRONIC INFLAMMATORY STATE. THE INNATE IMMUNE CYTOKINE IL-1BETA HAS PLEIOTROPIC PROPERTIES AND CAN REGULATE AUTONOMIC, GLUCOCORTICOID, AND GLUTAMATE RECEPTOR FUNCTIONS, SLEEP, MEMORY, AND EPIGENETIC ENZYMES. CHANGES IN EPIGENETIC ENZYME ACTIVITY CAN POTENTIALLY ALTER PHENOTYPE AND INDUCE AN ADAPTATION. LEVELS OF IL-1BETA CORRELATE WITH SEVERITY AND DURATION OF PTSD AND PTSD CAN BE PREVENTED BY BOLUS ADMINISTRATION OF HYDROCORTISONE IN ACUTE SEPSIS, CONSISTENT WITH UNRESTRAINED INFLAMMATION BEING A RISK FACTOR FOR PTSD. THE NERVOUS AND IMMUNE SYSTEMS ENGAGE IN CROSSTALK, GOVERNED BY COMMON RECEPTORS. THE BENEFITS OF CURRENTLY USED PSYCHIATRIC MEDICATION MAY ARISE FROM IMMUNE, AS WELL AS SYNAPTIC, MODULATION. THE PSYCHEDELIC DRUGS (3,4-METHYLENEDIOXYMETHAMPHETAMINE (MDMA), PSILOCYBIN, AND KETAMINE) HAVE POTENT IMMUNOSUPPRESSIVE AND ANTI-INFLAMMATORY EFFECTS ON THE ADAPTIVE IMMUNE SYSTEM, WHICH MAY CONTRIBUTE TO THEIR REPORTED BENEFIT IN PTSD. THERE MAY BE DISTINCT PTSD PHENOTYPES INDUCED BY INNATE AND ADAPTIVE CYTOKINE SIGNALING. CONCLUSION: IN ORDER FOR AN ORGANISM TO SURVIVE, IT MUST ADAPT TO ITS ENVIRONMENT. CYTOKINES SIGNAL DANGER TO THE BRAIN AND CAN INDUCE EPIGENETIC CHANGES THAT RESULT IN A PERSISTENT DEFENSIVE PHENOTYPE. PTSD MAY BE THE PRICE INDIVIDUALS PAY FOR THE GENOMIC FLEXIBILITY THAT PROMOTES ADAPTATION AND SURVIVAL. 2022 8 4632 18 NEUROIMAGING GENETIC APPROACHES TO POSTTRAUMATIC STRESS DISORDER. NEUROIMAGING GENETIC STUDIES THAT ASSOCIATE GENETIC AND EPIGENETIC VARIATION WITH NEURAL ACTIVITY OR STRUCTURE PROVIDE AN OPPORTUNITY TO LINK GENES TO PSYCHIATRIC DISORDERS, OFTEN BEFORE PSYCHOPATHOLOGY IS DISCERNABLE IN BEHAVIOR. HERE WE REVIEW NEUROIMAGING GENETICS STUDIES WITH PARTICIPANTS WHO HAVE POSTTRAUMATIC STRESS DISORDER (PTSD). RESULTS SHOW THAT GENES RELATED TO THE PHYSIOLOGICAL STRESS RESPONSE (E.G., GLUCOCORTICOID RECEPTOR AND ACTIVITY, NEUROENDOCRINE RELEASE), LEARNING AND MEMORY (E.G., PLASTICITY), MOOD, AND PAIN PERCEPTION ARE TIED TO NEURAL INTERMEDIATE PHENOTYPES ASSOCIATED WITH PTSD. THESE GENES ARE ASSOCIATED WITH AND SOMETIMES PREDICT NEURAL STRUCTURE AND FUNCTION IN AREAS INVOLVED IN ATTENTION, EXECUTIVE FUNCTION, MEMORY, DECISION-MAKING, EMOTION REGULATION, SALIENCE OF POTENTIAL THREATS, AND PAIN PERCEPTION. EVIDENCE SUGGESTS THESE RISK POLYMORPHISMS AND NEURAL INTERMEDIATE PHENOTYPES ARE VULNERABILITIES TOWARD DEVELOPING PTSD IN THE AFTERMATH OF TRAUMA, OR VULNERABILITIES TOWARD PARTICULAR SYMPTOMS ONCE PTSD HAS DEVELOPED. WORK DISTINGUISHING BETWEEN THE RE-EXPERIENCING AND DISSOCIATIVE SUB-TYPES OF PTSD, AND EXAMINING OTHER PTSD SYMPTOM CLUSTERS IN ADDITION TO THE RE-EXPERIENCING AND HYPERAROUSAL SYMPTOMS, WILL FURTHER CLARIFY NEUROBIOLOGICAL MECHANISMS AND INCONSISTENT FINDINGS. FURTHERMORE, AN EXCITING POSSIBILITY IS THAT GENETIC ASSOCIATIONS WITH PTSD MAY EVENTUALLY BE UNDERSTOOD THROUGH DIFFERENTIAL INTERMEDIATE PHENOTYPES OF NEURAL CIRCUIT STRUCTURE AND FUNCTION, POSSIBLY UNDERLYING THE DIFFERENT SYMPTOM CLUSTERS SEEN WITHIN PTSD. 2016 9 1750 12 EARLY LIFE STRESS AND PEDIATRIC POSTTRAUMATIC STRESS DISORDER. TRAUMATIC STRESS EXPOSURE DURING CRITICAL PERIODS OF DEVELOPMENT MAY HAVE ESSENTIAL AND LONG-LASTING EFFECTS ON THE PHYSICAL AND MENTAL HEALTH OF INDIVIDUALS. TWO THIRDS OF YOUTH ARE EXPOSED TO POTENTIALLY TRAUMATIC EXPERIENCES BY THE AGE OF 17, AND APPROXIMATELY 5% OF ADOLESCENTS MEET LIFETIME CRITERIA FOR POSTTRAUMATIC STRESS DISORDER (PTSD). THE ROLE OF THE STRESS SYSTEM IS THE MAINTENANCE OF HOMEOSTASIS IN THE PRESENCE OF REAL/PERCEIVED AND ACUTE/CHRONIC STRESSORS. EARLY-LIFE STRESS (ELS) HAS AN IMPACT ON NEURONAL BRAIN NETWORKS INVOLVED IN STRESS REACTIONS, AND COULD EXERT A PROGRAMMING EFFECT ON GLUCOCORTICOID SIGNALING. STUDIES ON PEDIATRIC PTSD REVEAL DIVERSE NEUROENDOCRINE RESPONSES TO ADVERSE EVENTS AND RELATED LONG-TERM NEUROENDOCRINE AND EPIGENETIC ALTERATIONS. NEUROENDOCRINE, NEUROIMAGING, AND GENETIC STUDIES IN CHILDREN WITH PTSD AND ELS EXPERIENCES ARE CRUCIAL IN UNDERSTANDING RISK AND RESILIENCE FACTORS, AND ALSO THE NATURAL HISTORY OF PTSD. 2020 10 4848 17 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 11 6414 22 THE STRESSED SYNAPSE 2.0: PATHOPHYSIOLOGICAL MECHANISMS IN STRESS-RELATED NEUROPSYCHIATRIC DISORDERS. STRESS IS A PRIMARY RISK FACTOR FOR SEVERAL NEUROPSYCHIATRIC DISORDERS. EVIDENCE FROM PRECLINICAL MODELS AND CLINICAL STUDIES OF DEPRESSION HAVE REVEALED AN ARRAY OF STRUCTURAL AND FUNCTIONAL MALADAPTIVE CHANGES, WHEREBY ADVERSE ENVIRONMENTAL FACTORS SHAPE THE BRAIN. THESE CHANGES, OBSERVED FROM THE MOLECULAR AND TRANSCRIPTIONAL LEVELS THROUGH TO LARGE-SCALE BRAIN NETWORKS, TO THE BEHAVIOURS REVEAL A COMPLEX MATRIX OF INTERRELATED PATHOPHYSIOLOGICAL PROCESSES THAT DIFFER BETWEEN SEXES, PROVIDING INSIGHT INTO THE POTENTIAL UNDERPINNINGS OF THE SEX BIAS OF NEUROPSYCHIATRIC DISORDERS. ALTHOUGH MANY PRECLINICAL STUDIES USE CHRONIC STRESS PROTOCOLS, LONG-TERM CHANGES ARE ALSO INDUCED BY ACUTE EXPOSURE TO TRAUMATIC STRESS, OPENING A PATH TO IDENTIFY DETERMINANTS OF RESILIENT VERSUS SUSCEPTIBLE RESPONSES TO BOTH ACUTE AND CHRONIC STRESS. EPIGENETIC REGULATION OF GENE EXPRESSION HAS EMERGED AS A KEY PLAYER UNDERLYING THE PERSISTENT IMPACT OF STRESS ON THE BRAIN. INDEED, HISTONE MODIFICATION, DNA METHYLATION AND MICRORNAS ARE CLOSELY INVOLVED IN MANY ASPECTS OF THE STRESS RESPONSE AND REVEAL THE GLUTAMATE SYSTEM AS A KEY PLAYER. THE SUCCESS OF KETAMINE HAS STIMULATED A WHOLE LINE OF RESEARCH AND DEVELOPMENT ON DRUGS DIRECTLY OR INDIRECTLY TARGETING GLUTAMATE FUNCTION. HOWEVER, THE CHALLENGE OF TRANSLATING THE EMERGING UNDERSTANDING OF STRESS PATHOPHYSIOLOGY INTO EFFECTIVE CLINICAL TREATMENTS REMAINS A MAJOR CHALLENGE. 2022 12 4846 10 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 13 3534 19 IMMEDIATE-EARLY GENES MODULATION BY ANTIPSYCHOTICS: TRANSLATIONAL IMPLICATIONS FOR A PUTATIVE GATEWAY TO DRUG-INDUCED LONG-TERM BRAIN CHANGES. AN INCREASING AMOUNT OF RESEARCH AIMS AT RECOGNIZING THE MOLECULAR MECHANISMS INVOLVED IN LONG-LASTING BRAIN ARCHITECTURAL CHANGES INDUCED BY ANTIPSYCHOTIC TREATMENTS. ALTHOUGH BOTH STRUCTURAL AND FUNCTIONAL MODIFICATIONS HAVE BEEN IDENTIFIED FOLLOWING ACUTE ANTIPSYCHOTIC ADMINISTRATION IN HUMANS, CURRENTLY THERE IS SCARCE KNOWLEDGE ON THE ENDURING CONSEQUENCES OF THESE ACUTE CHANGES. NEW INSIGHTS IN IMMEDIATE-EARLY GENES (IEGS) MODULATION FOLLOWING ACUTE OR CHRONIC ANTIPSYCHOTIC ADMINISTRATION MAY HELP TO FILL THE GAP BETWEEN PRIMARY MOLECULAR RESPONSE AND PUTATIVE LONG-TERM CHANGES. MOREOVER, A CRITICAL APPRAISAL OF THE SPATIAL AND TEMPORAL PATTERNS OF IEGS EXPRESSION MAY SHED LIGHT ON THE FUNCTIONAL "SIGNATURE" OF ANTIPSYCHOTICS, SUCH AS THE PROPENSITY TO INDUCE MOTOR SIDE EFFECTS, THE POTENTIAL NEUROBIOLOGICAL MECHANISMS UNDERLYING THE DIFFERENCES BETWEEN ANTIPSYCHOTICS BEYOND D2 DOPAMINE RECEPTOR AFFINITY, AS WELL AS THE RELEVANT EFFECTS OF BRAIN REGION-SPECIFICITY IN THEIR MECHANISMS OF ACTION. THE INTEREST FOR BRAIN IEGS MODULATION AFTER ANTIPSYCHOTIC TREATMENTS HAS BEEN REVITALIZED BY BREAKTHROUGH FINDINGS SUCH AS THE ROLE OF EARLY GENES IN SCHIZOPHRENIA PATHOPHYSIOLOGY, THE INVOLVEMENT OF IEGS IN EPIGENETIC MECHANISMS RELEVANT FOR COGNITION, AND IN NEURONAL MAPPING BY MEANS OF IEGS EXPRESSION PROFILING. HERE WE CRITICALLY REVIEW THE EVIDENCE ON THE DIFFERENTIAL MODULATION OF IEGS BY ANTIPSYCHOTICS, HIGHLIGHTING THE ASSOCIATION BETWEEN IEGS EXPRESSION AND NEUROPLASTICITY CHANGES IN BRAIN REGIONS IMPACTED BY ANTIPSYCHOTICS, TRYING TO ELUCIDATE THE MOLECULAR MECHANISMS UNDERPINNING THE EFFECTS OF THIS CLASS OF DRUGS ON PSYCHOTIC, COGNITIVE AND BEHAVIORAL SYMPTOMS. 2017 14 5812 24 STRESS AND ANXIETY: STRUCTURAL PLASTICITY AND EPIGENETIC REGULATION AS A CONSEQUENCE OF STRESS. THE BRAIN IS THE CENTRAL ORGAN OF STRESS AND ADAPTATION TO STRESS BECAUSE IT PERCEIVES AND DETERMINES WHAT IS THREATENING, AS WELL AS THE BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO THE STRESSOR. THE ADULT, AS WELL AS DEVELOPING BRAIN, POSSESS A REMARKABLE ABILITY TO SHOW REVERSIBLE STRUCTURAL AND FUNCTIONAL PLASTICITY IN RESPONSE TO STRESSFUL AND OTHER EXPERIENCES, INCLUDING NEURONAL REPLACEMENT, DENDRITIC REMODELING, AND SYNAPSE TURNOVER. THIS IS PARTICULARLY EVIDENT IN THE HIPPOCAMPUS, WHERE ALL THREE TYPES OF STRUCTURAL PLASTICITY HAVE BEEN RECOGNIZED AND INVESTIGATED, USING A COMBINATION OF MORPHOLOGICAL, MOLECULAR, PHARMACOLOGICAL, ELECTROPHYSIOLOGICAL AND BEHAVIORAL APPROACHES. THE AMYGDALA AND THE PREFRONTAL CORTEX, BRAIN REGIONS INVOLVED IN ANXIETY AND FEAR, MOOD, COGNITIVE FUNCTION AND BEHAVIORAL CONTROL, ALSO SHOW STRUCTURAL PLASTICITY. ACUTE AND CHRONIC STRESS CAUSE AN IMBALANCE OF NEURAL CIRCUITRY SUBSERVING COGNITION, DECISION MAKING, ANXIETY AND MOOD THAT CAN INCREASE OR DECREASE EXPRESSION OF THOSE BEHAVIORS AND BEHAVIORAL STATES. IN THE SHORT TERM, SUCH AS FOR INCREASED FEARFUL VIGILANCE AND ANXIETY IN A THREATENING ENVIRONMENT, THESE CHANGES MAY BE ADAPTIVE; BUT, IF THE DANGER PASSES AND THE BEHAVIORAL STATE PERSISTS ALONG WITH THE CHANGES IN NEURAL CIRCUITRY, SUCH MALADAPTATION MAY NEED INTERVENTION WITH A COMBINATION OF PHARMACOLOGICAL AND BEHAVIORAL THERAPIES, AS IS THE CASE FOR CHRONIC OR MOOD ANXIETY DISORDERS. WE SHALL REVIEW CELLULAR AND MOLECULAR MECHANISMS, AS WELL AS RECENT WORK ON INDIVIDUAL DIFFERENCES IN ANXIETY-LIKE BEHAVIOR AND ALSO DEVELOPMENTAL INFLUENCES THAT BIAS HOW THE BRAIN RESPONDS TO STRESSORS. FINALLY, WE SUGGEST THAT SUCH AN APPROACH NEEDS TO BE EXTENDED TO OTHER BRAIN AREAS THAT ARE ALSO INVOLVED IN ANXIETY AND MOOD. THIS ARTICLE IS PART OF A SPECIAL ISSUE ENTITLED 'ANXIETY AND DEPRESSION'. 2012 15 2513 15 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 16 1091 20 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 23 25 60 YEARS OF NEUROENDOCRINOLOGY: REDEFINING NEUROENDOCRINOLOGY: STRESS, SEX AND COGNITIVE AND EMOTIONAL REGULATION. THE DISCOVERY OF STEROID HORMONE RECEPTORS IN BRAIN REGIONS THAT MEDIATE EVERY ASPECT OF BRAIN FUNCTION HAS BROADENED THE DEFINITION OF 'NEUROENDOCRINOLOGY' TO INCLUDE THE RECIPROCAL COMMUNICATION BETWEEN THE BRAIN AND THE BODY VIA HORMONAL AND NEURAL PATHWAYS. THE BRAIN IS THE CENTRAL ORGAN OF STRESS AND ADAPTATION TO STRESS BECAUSE IT PERCEIVES AND DETERMINES WHAT IS THREATENING, AS WELL AS THE BEHAVIORAL AND PHYSIOLOGICAL RESPONSES TO THE STRESSOR. THE ADULT AND DEVELOPING BRAIN POSSESS REMARKABLE STRUCTURAL AND FUNCTIONAL PLASTICITY IN RESPONSE TO STRESS, INCLUDING NEURONAL REPLACEMENT, DENDRITIC REMODELING, AND SYNAPSE TURNOVER. STRESS CAUSES AN IMBALANCE OF NEURAL CIRCUITRY SUBSERVING COGNITION, DECISION-MAKING, ANXIETY AND MOOD THAT CAN ALTER EXPRESSION OF THOSE BEHAVIORS AND BEHAVIORAL STATES. THIS IMBALANCE, IN TURN, AFFECTS SYSTEMIC PHYSIOLOGY VIA NEUROENDOCRINE, AUTONOMIC, IMMUNE AND METABOLIC MEDIATORS. IN THE SHORT TERM, AS FOR INCREASED FEARFUL VIGILANCE AND ANXIETY IN A THREATENING ENVIRONMENT, THESE CHANGES MAY BE ADAPTIVE. BUT, IF THE DANGER PASSES AND THE BEHAVIORAL STATE PERSISTS ALONG WITH THE CHANGES IN NEURAL CIRCUITRY, SUCH MALADAPTATION MAY NEED INTERVENTION WITH A COMBINATION OF PHARMACOLOGICAL AND BEHAVIORAL THERAPIES, AS IS THE CASE FOR CHRONIC ANXIETY AND DEPRESSION. THERE ARE IMPORTANT SEX DIFFERENCES IN THE BRAIN RESPONSES TO STRESSORS THAT ARE IN URGENT NEED OF FURTHER EXPLORATION. MOREOVER, ADVERSE EARLY-LIFE EXPERIENCE, INTERACTING WITH ALLELES OF CERTAIN GENES, PRODUCE LASTING EFFECTS ON BRAIN AND BODY OVER THE LIFE-COURSE VIA EPIGENETIC MECHANISMS. WHILE PREVENTION IS MOST IMPORTANT, THE PLASTICITY OF THE BRAIN GIVES HOPE FOR THERAPIES THAT TAKE INTO CONSIDERATION BRAIN-BODY INTERACTIONS. 2015 18 3606 16 IMPROVING TREATMENT OF NEURODEVELOPMENTAL DISORDERS: RECOMMENDATIONS BASED ON PRECLINICAL STUDIES. INTRODUCTION: NEURODEVELOPMENTAL DISORDERS (NDDS) ARE COMMON AND SEVERELY DEBILITATING. THEIR CHRONIC NATURE AND RELIANCE ON BOTH GENETIC AND ENVIRONMENTAL FACTORS MAKES STUDYING NDDS AND THEIR TREATMENT A CHALLENGING TASK. AREAS COVERED: HEREIN, THE AUTHORS DISCUSS THE NEUROBIOLOGICAL MECHANISMS OF NDDS, AND PRESENT RECOMMENDATIONS ON THEIR TRANSLATIONAL RESEARCH AND THERAPY, OUTLINED BY THE INTERNATIONAL STRESS AND BEHAVIOR SOCIETY. VARIOUS DRUGS CURRENTLY PRESCRIBED TO TREAT NDDS ALSO REPRESENT A HIGHLY DIVERSE GROUP. ACTING ON VARIOUS NEUROTRANSMITTER AND PHYSIOLOGICAL SYSTEMS, THESE DRUGS OFTEN LACK SPECIFICITY OF ACTION, AND ARE COMMONLY USED TO TREAT MULTIPLE OTHER PSYCHIATRIC CONDITIONS. THERE HAS ALSO BEEN RELATIVELY LITTLE PROGRESS IN THE DEVELOPMENT OF NOVEL MEDICATIONS TO TREAT NDDS. BASED ON CLINICAL, PRECLINICAL AND TRANSLATIONAL MODELS OF NDDS, OUR RECOMMENDATIONS COVER A WIDE RANGE OF METHODOLOGICAL APPROACHES AND CONCEPTUAL STRATEGIES. EXPERT OPINION: TO IMPROVE PHARMACOTHERAPY AND DRUG DISCOVERY FOR NDDS, WE NEED A STRONGER EMPHASIS ON TARGETING MULTIPLE ENDOPHENOTYPES, A BETTER DISSECTION OF GENETIC/EPIGENETIC FACTORS OR "HIDDEN HERITABILITY," AND A CAREFUL CONSIDERATION OF POTENTIAL DEVELOPMENTAL/TROPHIC ROLES OF BRAIN NEUROTRANSMITTERS. THE VALIDITY OF ANIMAL NDD MODELS CAN BE IMPROVED THROUGH DISCOVERY OF NOVEL (BEHAVIORAL, PHYSIOLOGICAL AND NEUROIMAGING) BIOMARKERS, APPLYING PROPER ENVIRONMENTAL ENRICHMENT, WIDENING THE SPECTRUM OF MODEL ORGANISMS, TARGETING DEVELOPMENTAL TRAJECTORIES OF NDD-RELATED BEHAVIORS AND COMORBID CONDITIONS BEYOND TRADITIONAL NDDS. WHILE THESE RECOMMENDATIONS CANNOT BE ADDRESSED ALL IN ONCE, OUR INCREASED UNDERSTANDING OF NDD PATHOBIOLOGY MAY TRIGGER INNOVATIVE CROSS-DISCIPLINARY RESEARCH EXPANDING BEYOND TRADITIONAL METHODS AND CONCEPTS. 2016 19 1722 16 DYSREGULATION OF BRAIN DOPAMINE SYSTEMS IN MAJOR DEPRESSIVE DISORDER. MAJOR DEPRESSIVE DISORDER (MDD OR DEPRESSION) IS A DEBILITATING NEUROPSYCHIATRIC SYNDROME WITH GENETIC, EPIGENETIC, AND ENVIRONMENTAL CONTRIBUTIONS. DEPRESSION IS ONE OF THE LARGEST CONTRIBUTORS TO CHRONIC DISEASE BURDEN; IT AFFECTS MORE THAN ONE IN SIX INDIVIDUALS IN THE UNITED STATES. A WIDE ARRAY OF CELLULAR AND MOLECULAR MODIFICATIONS DISTRIBUTED ACROSS A VARIETY OF NEURONAL PROCESSES AND CIRCUITS UNDERLIE THE PATHOPHYSIOLOGY OF DEPRESSION-NO ESTABLISHED MECHANISM CAN EXPLAIN ALL ASPECTS OF THE DISEASE. MDD SUFFERS FROM A VAST TREATMENT GAP WORLDWIDE, AND LARGE NUMBERS OF INDIVIDUALS WHO REQUIRE TREATMENT DO NOT RECEIVE ADEQUATE CARE. THIS MINI-REVIEW FOCUSES ON DYSREGULATION OF BRAIN DOPAMINE (DA) SYSTEMS IN THE PATHOPHYSIOLOGY OF MDD AND DESCRIBING NEW CELLULAR TARGETS FOR POTENTIAL MEDICATION DEVELOPMENT FOCUSED ON DA-MODULATED MICRO-CIRCUITS. WE ALSO EXPLORE HOW NEURODEVELOPMENTAL FACTORS MAY MODIFY RISK FOR LATER EMERGENCE OF MDD, POSSIBLY THROUGH DOPAMINERGIC SUBSTRATES IN THE BRAIN. 2021 20 2259 22 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