1 4846 96 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 2 2259 29 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 3 636 33 BIOLOGICAL SUBSTRATES OF ADDICTION. THIS REVIEW IS AN INTRODUCTION TO ADDICTION, THE REWARD CIRCUITRY, AND LABORATORY ADDICTION MODELS. ADDICTION IS A CHRONIC DISEASE HALLMARKED BY A STATE OF COMPULSIVE DRUG SEEKING THAT PERSISTS DESPITE NEGATIVE CONSEQUENCES. MOST OF THE ADVANCES IN ADDICTION RESEARCH HAVE CENTERED ON THE CANONICAL AND CONTEMPORARY DRUGS OF ABUSE; HOWEVER, ADDICTIONS TO OTHER ACTIVITIES AND STIMULI ALSO EXIST. SUBSTANCES OF ABUSE HAVE THE POTENTIAL TO INDUCE LONG-LASTING CHANGES IN THE BRAIN AT THE BEHAVIORAL, CIRCUIT, AND SYNAPTIC LEVELS. ADDICTION-RELATED BEHAVIORAL CHANGES INVOLVE INITIATION, ESCALATION, AND OBSESSION TO DRUG SEEKING AND MUCH OF THE CURRENT RESEARCH IS FOCUSED ON MAPPING THESE MANIFESTATIONS TO SPECIFIC NEURAL PATHWAYS. DRUG ABUSE IS WELL KNOWN TO RECRUIT COMPONENTS OF THE MESOLIMBIC DOPAMINE SYSTEM, INCLUDING THE NUCLEUS ACCUMBENS AND VENTRAL TEGMENTAL AREA. IN ADDITION, ALTERED FUNCTION OF A WIDE VARIETY OF BRAIN REGIONS IS TIGHTLY ASSOCIATED WITH SPECIFIC MANIFESTATIONS OF DRUG ABUSE. THESE REGIONS PERIPHERAL TO THE MESOLIMBIC PATHWAY LIKELY PLAY A ROLE IN SPECIFIC OBSERVED COMORBIDITIES AND ENDOPHENOTYPES THAT CAN FACILITATE, OR BE CAUSED BY, SUBSTANCE ABUSE. ALTERATIONS IN SYNAPTIC STRUCTURE, FUNCTION, AND CONNECTIVITY, AS WELL AS EPIGENETIC AND GENETIC MECHANISMS ARE THOUGHT TO UNDERLIE THE PATHOLOGIES OF ADDICTION. IN PRECLINICAL MODELS, THESE PERSISTENT CHANGES ARE STUDIED AT THE LEVELS OF MOLECULAR PHARMACOLOGY AND BIOCHEMISTRY, EX VIVO AND IN VIVO ELECTROPHYSIOLOGY, RADIOGRAPHY, AND BEHAVIOR. COORDINATING RESEARCH EFFORTS ACROSS THESE DISCIPLINES AND EXAMINING CELL TYPE- AND CIRCUIT-SPECIFIC PHENOMENA ARE CRUCIAL COMPONENTS FOR TRANSLATING PRECLINICAL FINDINGS TO VIABLE MEDICAL INTERVENTIONS THAT EFFECTIVELY TREAT ADDICTION AND RELATED DISORDERS. WIRES COGN SCI 2014, 5:151-171. DOI: 10.1002/WCS.1273 CONFLICT OF INTEREST: THE AUTHORS HAVE DECLARED NO CONFLICTS OF INTEREST FOR THIS ARTICLE. FOR FURTHER RESOURCES RELATED TO THIS ARTICLE, PLEASE VISIT THE WIRES WEBSITE. 2014 4 1677 26 DRUG ADDICTION: HYPERKATIFEIA/NEGATIVE REINFORCEMENT AS A FRAMEWORK FOR MEDICATIONS DEVELOPMENT. COMPULSIVE DRUG SEEKING THAT IS ASSOCIATED WITH ADDICTION IS HYPOTHESIZED TO FOLLOW A HEURISTIC FRAMEWORK THAT INVOLVES THREE STAGES (BINGE/INTOXICATION, WITHDRAWAL/NEGATIVE AFFECT, AND PREOCCUPATION/ANTICIPATION) AND THREE DOMAINS OF DYSFUNCTION (INCENTIVE SALIENCE/PATHOLOGIC HABITS, NEGATIVE EMOTIONAL STATES, AND EXECUTIVE FUNCTION, RESPECTIVELY) VIA CHANGES IN THE BASAL GANGLIA, EXTENDED AMYGDALA/HABENULA, AND FRONTAL CORTEX, RESPECTIVELY. THIS REVIEW FOCUSES ON NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS THAT CONTRIBUTE TO HYPERKATIFEIA, DEFINED AS A GREATER INTENSITY OF NEGATIVE EMOTIONAL/MOTIVATIONAL SIGNS AND SYMPTOMS DURING WITHDRAWAL FROM DRUGS OF ABUSE IN THE WITHDRAWAL/NEGATIVE AFFECT STAGE OF THE ADDICTION CYCLE. HYPERKATIFEIA PROVIDES AN ADDITIONAL SOURCE OF MOTIVATION FOR COMPULSIVE DRUG SEEKING VIA NEGATIVE REINFORCEMENT. NEGATIVE REINFORCEMENT REFLECTS AN INCREASE IN THE PROBABILITY OF A RESPONSE TO REMOVE AN AVERSIVE STIMULUS OR DRUG SEEKING TO REMOVE HYPERKATIFEIA THAT IS AUGMENTED BY GENETIC/EPIGENETIC VULNERABILITY, ENVIRONMENTAL TRAUMA, AND PSYCHIATRIC COMORBIDITY. NEUROBIOLOGICAL TARGETS FOR HYPERKATIFEIA IN ADDICTION INVOLVE NEUROCIRCUITRY OF THE EXTENDED AMYGDALA AND ITS CONNECTIONS VIA WITHIN-SYSTEM NEUROADAPTATIONS IN DOPAMINE, ENKEPHALIN/ENDORPHIN OPIOID PEPTIDE, AND GAMMA-AMINOBUTYRIC ACID/GLUTAMATE SYSTEMS AND BETWEEN-SYSTEM NEUROADAPTATIONS IN PROSTRESS CORTICOTROPIN-RELEASING FACTOR, NOREPINEPHRINE, GLUCOCORTICOID, DYNORPHIN, HYPOCRETIN, AND NEUROIMMUNE SYSTEMS AND ANTISTRESS NEUROPEPTIDE Y, NOCICEPTIN, ENDOCANNABINOID, AND OXYTOCIN SYSTEMS. SUCH NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS ARE HYPOTHESIZED TO MEDIATE A NEGATIVE HEDONIC SET POINT THAT GRADUALLY GAINS ALLOSTATIC LOAD AND SHIFTS FROM A HOMEOSTATIC HEDONIC STATE TO AN ALLOSTATIC HEDONIC STATE. BASED ON PRECLINICAL STUDIES AND TRANSLATIONAL STUDIES TO DATE, MEDICATIONS AND BEHAVIORAL THERAPIES THAT RESET BRAIN STRESS, ANTISTRESS, AND EMOTIONAL PAIN SYSTEMS AND RETURN THEM TO HOMEOSTASIS WOULD BE PROMISING NEW TARGETS FOR MEDICATION DEVELOPMENT. SIGNIFICANCE STATEMENT: THE FOCUS OF THIS REVIEW IS ON NEUROCHEMICAL/NEUROCIRCUITRY DYSREGULATIONS THAT CONTRIBUTE TO HYPERKATIFEIA, DEFINED AS A GREATER INTENSITY OF NEGATIVE EMOTIONAL/MOTIVATIONAL SIGNS AND SYMPTOMS DURING WITHDRAWAL FROM DRUGS OF ABUSE IN THE WITHDRAWAL/NEGATIVE AFFECT STAGE OF THE DRUG ADDICTION CYCLE AND A DRIVING FORCE FOR NEGATIVE REINFORCEMENT IN ADDICTION. MEDICATIONS AND BEHAVIORAL THERAPIES THAT REVERSE HYPERKATIFEIA BY RESETTING BRAIN STRESS, ANTISTRESS, AND EMOTIONAL PAIN SYSTEMS AND RETURNING THEM TO HOMEOSTASIS WOULD BE PROMISING NEW TARGETS FOR MEDICATION DEVELOPMENT. 2021 5 2513 24 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 6 1091 22 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 7 1088 25 COCAINE DIRECTLY IMPAIRS MEMORY EXTINCTION AND ALTERS BRAIN DNA METHYLATION DYNAMICS IN HONEY BEES. DRUG ADDICTION IS A CHRONIC RELAPSING BEHAVIORAL DISORDER. THE HIGH RELAPSE RATE HAS OFTEN BEEN ATTRIBUTED TO THE PERSEVERANCE OF DRUG-ASSOCIATED MEMORIES DUE TO HIGH INCENTIVE SALIENCE OF STIMULI LEARNT UNDER THE INFLUENCE OF DRUGS. DRUG ADDICTION HAS ALSO BEEN INTERPRETED AS A MEMORY DISORDER SINCE DRUG ASSOCIATED MEMORIES ARE UNUSUALLY ENDURING AND SOME DRUGS, SUCH AS COCAINE, INTERFERE WITH NEUROEPIGENETIC MACHINERY KNOWN TO BE INVOLVED IN MEMORY PROCESSING. HERE WE USED THE HONEY BEE (AN ESTABLISHED INVERTEBRATE MODEL FOR EPIGENOMICS AND BEHAVIORAL STUDIES) TO EXAMINE WHETHER OR NOT COCAINE AFFECTS MEMORY PROCESSING INDEPENDENTLY OF ITS EFFECT ON INCENTIVE SALIENCE. USING THE PROBOSCIS EXTENSION REFLEX TRAINING PARADIGM WE FOUND THAT COCAINE STRONGLY IMPAIRS CONSOLIDATION OF EXTINCTION MEMORY. BASED ON CORRELATION BETWEEN THE OBSERVED EFFECT OF COCAINE ON LEARNING AND EXPRESSION OF EPIGENETIC PROCESSES, WE PROPOSE THAT COCAINE INTERFERES WITH MEMORY PROCESSING INDEPENDENTLY OF INCENTIVE SALIENCE BY DIRECTLY ALTERING DNA METHYLATION DYNAMICS. OUR FINDINGS EMPHASIZE THE IMPACT OF COCAINE ON MEMORY SYSTEMS, WITH RELEVANCE FOR UNDERSTANDING HOW COCAINE CAN HAVE SUCH AN ENDURING IMPACT ON BEHAVIOR. 2018 8 4650 28 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 9 5310 19 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 10 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 11 2670 21 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 12 4469 22 MOLECULAR NEUROLOGICAL CORRELATES OF ENDORPHINERGIC/DOPAMINERGIC MECHANISMS IN REWARD CIRCUITRY LINKED TO ENDORPHINERGIC DEFICIENCY SYNDROME (EDS). THE CONSENSUS OF THE CURRENT LITERATURE STRONGLY SUPPORTS THE CONCEPT THAT BRAIN NEUROTRANSMITTERS, AND SECOND MESSENGERS INVOLVED IN THE NET RELEASE OF DOPAMINE IN THE MESOLIMBIC REGION, ESPECIALLY THE NUCLEUS ACCUMBENS (NAC), IS DIRECTLY LINKED TO MOTIVATION, ANTI-STRESS, INCENTIVE SALIENCE (WANTING), AND WELL-BEING. THE ROLE OF DOPAMINE IN TERMS OF ALCOHOL WITHDRAWAL SYMPTOMOLOGY, COCAINE CRAVING BEHAVIOR, DOPAMINE -CONDENSATION PRODUCTS (TIQS), AND MORE RECENTLY, THE GENETIC ASPECTS OF DRUG-SEEKING AND PRO-DOPAMINE REGULATION, PROVIDE COMPELLING EVIDENCE OF THE RELEVANT MOLECULAR NEUROLOGICAL CORRELATES OF DOPAMINERGIC /ENDORPHINERGIC MECHANISMS IN REWARD CIRCUITRY DUE TO GENETIC POLYMORPHISMS AND EPIGENETIC INSULTS. IN THE FACE OF AN AMERICANS OPIOID EPIDEMIC, THE CLINICAL CONSENSUS IS TO TREAT OPIOID USE DISORDER (OUD) WITH LIFE-LONG OPIOID SUBSTITUTION THERAPY. HOWEVER, THE AUTHORS SUGGEST A PARADIGM SHIFT INVOLVING NOVEL MODALITIES LIKE TARGETING THE ENDORPHINERGIC SYSTEM LINKED TO DOPAMINE RELEASE AT THE NAC, IN TERMS OF THE INDUCTION OF REQUIRED "DOPAMINE HOMEOSTASIS." UTILIZING THE KNOWN GENETIC - ENVIRONMENTAL INTERACTION THEOREM P = G +E, THE AUTHORS PROVIDE A CLEAR RATIONALE FOR THE ADOPTION OF GENETIC RISK TESTING COUPLED WITH ENDORPHINERGIC/DOPAMINE REGULATION TO ADDRESS DYSFUNCTION ACROSS THE BRAIN REWARD CIRCUITRY. THE GOAL OF ALTERING RESTING-STATE, FUNCTIONAL CONNECTIVITY MAY REQUIRE A GENTLE "NEUROTRANSMITTER FIX" VIS ENKEPHALINASE INHIBITION TO OVERCOME OR COMBAT - SELF-INDUCTION OF ACUTE DOPAMINE RELEASE VIA PSYCHOACTIVE SUBSTANCE MISUSE RESULTING IN CHRONIC DOPAMINE DOWN-REGULATION. AS SUBSETS OF REWARD DEFICIENCY, WE ARE POISED TO PROVIDE NOVEL, GENETICALLY GUIDED THERAPY FOR ENDORPHINERGIC, OPIOIDERGIC, AND DOPAMINERGIC DEFICIENCIES AND RELATED SYNDROMES, UTILIZING "PRECISION ADDICTION MANAGEMENT. 2020 13 4418 23 MOLECULAR AND EPIGENETIC ASPECTS OF OPIOID RECEPTORS IN DRUG ADDICTION AND PAIN MANAGEMENT IN SPORT. OPIOIDS ARE SUBSTANCES DERIVED FROM OPIUM (NATURAL OPIOIDS). IN ITS RAW STATE, OPIUM IS A GUMMY LATEX EXTRACTED FROM PAPAVER SOMNIFERUM. THE USE OF OPIOIDS AND THEIR NEGATIVE HEALTH CONSEQUENCES AMONG PEOPLE WHO USE DRUGS HAVE BEEN STUDIED. TODAY, OPIOIDS ARE STILL THE MOST COMMONLY USED AND EFFECTIVE ANALGESIC TREATMENTS FOR SEVERE PAIN, BUT THEIR USE AND ABUSE CAUSES DETRIMENTAL SIDE EFFECTS FOR HEALTH, INCLUDING ADDICTION, THUS IMPACTING THE USER'S QUALITY OF LIFE AND CAUSING OVERDOSE. THE MESOCORTICOLIMBIC DOPAMINERGIC CIRCUITRY REPRESENTS THE BRAIN CIRCUIT MEDIATING BOTH NATURAL REWARDS AND THE REWARDING ASPECTS OF NEARLY ALL DRUGS OF ABUSE, INCLUDING OPIOIDS. HENCE, UNDERSTANDING HOW OPIOIDS AFFECT THE FUNCTION OF DOPAMINERGIC CIRCUITRY MAY BE USEFUL FOR BETTER KNOWLEDGE OF THE PROCESS AND TO DEVELOP EFFECTIVE THERAPEUTIC STRATEGIES IN ADDICTION. THE AIM OF THIS REVIEW WAS TO SUMMARIZE THE MAIN FEATURES OF OPIOIDS AND OPIOID RECEPTORS AND FOCUS ON THE MOLECULAR AND UPCOMING EPIGENETIC MECHANISMS LEADING TO OPIOID ADDICTION. SINCE SYNTHETIC OPIOIDS CAN BE EFFECTIVE FOR PAIN MANAGEMENT, THEIR ABILITY TO INDUCE ADDICTION IN ATHLETES, WITH THE RISK OF INCURRING DOPING, IS ALSO DISCUSSED. 2023 14 3314 28 HIPPOCAMPAL CANNABINOID 1 RECEPTORS ARE MODULATED FOLLOWING COCAINE SELF-ADMINISTRATION IN MALE RATS. COCAINE ADDICTION IS A COMPLEX PATHOLOGY INDUCING LONG-TERM NEUROPLASTIC CHANGES THAT, IN TURN, CONTRIBUTE TO MALADAPTIVE BEHAVIORS. THIS BEHAVIORAL DYSREGULATION IS ASSOCIATED WITH TRANSCRIPTIONAL REPROGRAMMING IN BRAIN REWARD CIRCUITRY, ALTHOUGH THE MECHANISMS UNDERLYING THIS MODULATION REMAIN POORLY UNDERSTOOD. THE ENDOGENOUS CANNABINOID SYSTEM MAY PLAY A ROLE IN THIS PROCESS IN THAT CANNABINOID MECHANISMS MODULATE DRUG REWARD AND CONTRIBUTE TO COCAINE-INDUCED NEURAL ADAPTATIONS. IN THIS STUDY, WE INVESTIGATED WHETHER COCAINE SELF-ADMINISTRATION INDUCES LONG-TERM ADAPTATIONS, INCLUDING TRANSCRIPTIONAL MODIFICATIONS AND ASSOCIATED EPIGENETIC PROCESSES. WE FIRST EXAMINED ENDOCANNABINOID GENE EXPRESSION IN REWARD-RELATED BRAIN REGIONS OF THE RAT FOLLOWING SELF-ADMINISTERED (0.33 MG/KG INTRAVENOUS, FR1, 10 DAYS) COCAINE INJECTIONS. INTERESTINGLY, WE FOUND INCREASED CNR1 EXPRESSION IN SEVERAL STRUCTURES, INCLUDING PREFRONTAL CORTEX, NUCLEUS ACCUMBENS, DORSAL STRIATUM, HIPPOCAMPUS, HABENULA, AMYGDALA, LATERAL HYPOTHALAMUS, VENTRAL TEGMENTAL AREA, AND ROSTROMEDIAL TEGMENTAL NUCLEUS, WITH MOST PRONOUNCED EFFECTS IN THE HIPPOCAMPUS. ENDOCANNABINOID LEVELS, MEASURED BY MASS SPECTROMETRY, WERE ALSO ALTERED IN THIS STRUCTURE. CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY QPCR IN THE HIPPOCAMPUS REVEALED THAT TWO ACTIVATING HISTONE MARKS, H3K4ME3 AND H3K27AC, WERE ENRICHED AT SPECIFIC ENDOCANNABINOID GENES FOLLOWING COCAINE INTAKE. TARGETING CB1 RECEPTORS USING CHROMOSOME CONFORMATION CAPTURE, WE HIGHLIGHTED SPATIAL CHROMATIN RE-ORGANIZATION IN THE HIPPOCAMPUS, AS WELL AS IN THE NUCLEUS ACCUMBENS, SUGGESTING THAT DESTABILIZATION OF THE CHROMATIN MAY CONTRIBUTE TO NEURONAL RESPONSES TO COCAINE. OVERALL, OUR RESULTS HIGHLIGHT A KEY ROLE FOR THE HIPPOCAMPUS IN COCAINE-INDUCED PLASTICITY AND BROADEN THE UNDERSTANDING OF NEURONAL ALTERATIONS ASSOCIATED WITH ENDOCANNABINOID SIGNALING. THE LATTER SUGGESTS THAT EPIGENETIC MODIFICATIONS CONTRIBUTE TO MALADAPTIVE BEHAVIORS ASSOCIATED WITH CHRONIC DRUG USE. 2022 15 3774 20 INTERACTION OF GONADAL HORMONES, DOPAMINERGIC SYSTEM, AND EPIGENETIC REGULATION IN THE GENERATION OF SEX DIFFERENCES IN SUBSTANCE USE DISORDERS: A SYSTEMATIC REVIEW. SUBSTANCE USE DISORDER (SUD) IS A CHRONIC CONDITION CHARACTERIZED BY PATHOLOGICAL DRUG-TAKING AND SEEKING BEHAVIORS. REMARKABLY DIFFERENT BETWEEN MALES AND FEMALES, SUGGESTING THAT DRUG ADDICTION IS A SEXUALLY DIFFERENTIATED DISORDER. THE NEUROBIOLOGICAL BASES OF SEX DIFFERENCES IN SUD INCLUDE SEX-SPECIFIC REWARD SYSTEM ACTIVATION, INFLUENCED BY INTERACTIONS BETWEEN GONADAL HORMONE LEVEL CHANGES, DOPAMINERGIC REWARD CIRCUITS, AND EPIGENETIC MODIFICATIONS OF KEY REWARD SYSTEM GENES. THIS SYSTEMATIC REVIEW, ADHERING TO PICOS AND PRISMA-P 2015 GUIDELINES, HIGHLIGHTS THE SEX-DEPENDENT ROLES OF ESTROGENS, PROGESTERONE, AND TESTOSTERONE IN SUD. IN PARTICULAR, ESTRADIOL ELEVATES AND PROGESTERONE REDUCES DOPAMINERGIC ACTIVITY IN SUD FEMALES, WHILST TESTOSTERONE AND PROGESTERONE AUGMENT SUD BEHAVIOR IN MALES. FINALLY, SUD IS ASSOCIATED WITH A SEX-SPECIFIC INCREASE IN THE RATE OF OPIOID AND MONOAMINERGIC GENE METHYLATION. THE STUDY REVEALS THE NEED FOR DETAILED RESEARCH ON GONADAL HORMONE LEVELS, DOPAMINERGIC OR REWARD SYSTEM ACTIVITY, AND EPIGENETIC LANDSCAPES IN BOTH SEXES FOR EFFICIENT SUD THERAPY DEVELOPMENT. 2023 16 2325 31 EPIGENETIC REGULATION OF HIPPOCAMPAL FOSB EXPRESSION CONTROLS BEHAVIORAL RESPONSES TO COCAINE. DRUG ADDICTION RESULTS IN PART FROM MALADAPTIVE LEARNING, INCLUDING THE FORMATION OF STRONG ASSOCIATIONS BETWEEN THE DRUG AND THE CIRCUMSTANCES OF CONSUMPTION. HOWEVER, DRUG-INDUCED CHANGES IN GENE EXPRESSION UNDERLYING THE SALIENCY OF THESE ASSOCIATIONS REMAIN UNDERSTUDIED. CONSOLIDATION OF EXPLICIT MEMORIES OCCURS WITHIN THE HIPPOCAMPUS, AND WE HAVE SHOWN THAT SPATIAL LEARNING INDUCES EXPRESSION OF THE TRANSCRIPTION FACTOR DELTAFOSB IN HIPPOCAMPUS AND THAT THIS INDUCTION IS CRITICAL FOR LEARNING. DRUGS OF ABUSE ALSO UPREGULATE DELTAFOSB IN HIPPOCAMPUS, BUT THE MECHANISM OF ITS INDUCTION BY COCAINE AND ITS ROLE IN HIPPOCAMPUS-DEPENDENT COCAINE RESPONSES IS UNKNOWN. WE INVESTIGATED DIFFERENCES IN MOUSE DORSAL AND VENTRAL HIPPOCAMPAL DELTAFOSB EXPRESSION IN RESPONSE TO CHRONIC COCAINE, BECAUSE THESE REGIONS APPEAR TO REGULATE DISTINCT COCAINE-RELATED BEHAVIORS. WE FOUND THAT COCAINE-MEDIATED INDUCTION OF DELTAFOSB WAS SUBREGION-SPECIFIC, AND THAT DELTAFOSB TRANSCRIPTIONAL ACTIVITY IN BOTH THE DORSAL AND VENTRAL HIPPOCAMPUS IS NECESSARY FOR COCAINE CONDITIONED PLACE PREFERENCE. FURTHER, WE CHARACTERIZE CHANGES IN HISTONE MODIFICATIONS AT THE FOSB PROMOTER IN HIPPOCAMPUS IN RESPONSE TO CHRONIC COCAINE AND FOUND THAT LOCUS-SPECIFIC EPIGENETIC MODIFICATION IS ESSENTIAL FOR FOSB INDUCTION AND MULTIPLE HIPPOCAMPUS-DEPENDENT BEHAVIORS, INCLUDING COCAINE PLACE PREFERENCE. COLLECTIVELY, THESE FINDINGS SUGGEST THAT EXPOSURE TO COCAINE INDUCES HISTONE MODIFICATION AT THE HIPPOCAMPAL FOSB GENE PROMOTER TO CAUSE DELTAFOSB INDUCTION CRITICAL FOR COCAINE-RELATED LEARNING.SIGNIFICANCE STATEMENT ALTHOUGH COCAINE ADDICTION IS DRIVEN IN PART BY THE FORMATION OF INDELIBLE ASSOCIATIONS BETWEEN THE DRUG AND THE ENVIRONMENT, PARAPHERNALIA, AND CIRCUMSTANCES OF USE, AND ALTHOUGH THIS TYPE OF ASSOCIATIVE LEARNING IS DEPENDENT UPON CHANGES IN GENE EXPRESSION IN A BRAIN REGION CALLED THE HIPPOCAMPUS, THE MECHANISMS BY WHICH COCAINE ALTERS HIPPOCAMPAL GENE EXPRESSION TO DRIVE FORMATION OF THESE ASSOCIATIONS IS POORLY UNDERSTOOD. HERE, WE DEMONSTRATE THAT CHRONIC COCAINE ENGAGES LOCUS-SPECIFIC CHANGES IN THE EPIGENETIC PROFILE OF THE FOSB GENE IN THE HIPPOCAMPUS, AND THAT THESE ALTERATIONS ARE REQUIRED FOR COCAINE-DEPENDENT GENE EXPRESSION AND COCAINE-ENVIRONMENT ASSOCIATIONS. THIS WORK PROVIDES NOVEL INSIGHT INTO ADDICTION ETIOLOGY AND POTENTIAL INROADS FOR THERAPEUTIC INTERVENTION IN COCAINE ADDICTION. 2019 17 3203 23 HDAC3 ACTIVITY WITHIN THE NUCLEUS ACCUMBENS REGULATES COCAINE-INDUCED PLASTICITY AND BEHAVIOR IN A CELL-TYPE-SPECIFIC MANNER. EPIGENETIC MECHANISMS REGULATE PROCESSES OF NEUROPLASTICITY CRITICAL TO COCAINE-INDUCED BEHAVIORS. THIS INCLUDES THE CLASS I HISTONE DEACETYLASE (HDAC) HDAC3, KNOWN TO ACT AS A NEGATIVE REGULATOR OF COCAINE-ASSOCIATED MEMORY FORMATION WITHIN THE NUCLEUS ACCUMBENS (NAC). DESPITE THIS, IT REMAINS UNKNOWN HOW COCAINE ALTERS HDAC3-DEPENDENT MECHANISMS. HERE, WE PROFILED HDAC3 EXPRESSION AND ACTIVITY IN TOTAL NAC MOUSE TISSUE FOLLOWING COCAINE EXPOSURE. ALTHOUGH CHRONIC COCAINE DID NOT AFFECT EXPRESSION OF HDAC3 WITHIN THE NAC, CHRONIC COCAINE DID AFFECT PROMOTER-SPECIFIC CHANGES IN HDAC3 AND H4K8AC OCCUPANCY. THESE CHANGES IN PROMOTER OCCUPANCY CORRELATED WITH COCAINE-INDUCED CHANGES IN EXPRESSION OF PLASTICITY-RELATED GENES. TO CAUSALLY DETERMINE WHETHER COCAINE-INDUCED PLASTICITY IS MEDIATED BY HDAC3'S DEACETYLASE ACTIVITY, WE OVEREXPRESSED A DEACETYLASE-DEAD HDAC3 POINT MUTANT (HDAC3-Y298H-V5) WITHIN THE NAC OF ADULT MALE MICE. WE FOUND THAT DISRUPTING HDAC3'S ENZYMATIC ACTIVITY ALTERED SELECTIVE CHANGES IN GENE EXPRESSION AND SYNAPTIC PLASTICITY FOLLOWING COCAINE EXPOSURE, DESPITE HAVING NO EFFECTS ON COCAINE-INDUCED BEHAVIORS. IN FURTHER ASSESSING HDAC3'S ROLE WITHIN THE NAC, WE OBSERVED THAT CHRONIC COCAINE INCREASES HDAC3 EXPRESSION IN DRD1 BUT NOT DRD2-CELLS OF THE NAC. MOREOVER, WE DISCOVERED THAT HDAC3 ACTS SELECTIVELY WITHIN D1R CELL-TYPES TO REGULATE COCAINE-ASSOCIATED MEMORY FORMATION AND COCAINE-SEEKING. OVERALL, THESE RESULTS SUGGEST THAT COCAINE INDUCES CELL-TYPE-SPECIFIC CHANGES IN EPIGENETIC MECHANISMS TO PROMOTE PLASTICITY IMPORTANT FOR DRIVING COCAINE-RELATED BEHAVIORS.SIGNIFICANCE STATEMENT DRUGS OF ABUSE ALTER MOLECULAR MECHANISMS THROUGHOUT THE REWARD CIRCUITRY THAT CAN LEAD TO PERSISTENT DRUG-ASSOCIATED BEHAVIORS. EPIGENETIC REGULATORS ARE CRITICAL DRIVERS OF DRUG-INDUCED CHANGES IN GENE EXPRESSION. HERE, WE DEMONSTRATE THAT THE ACTIVITY OF AN EPIGENETIC ENZYME PROMOTES NEUROPLASTICITY WITHIN THE NUCLEUS ACCUMBENS (NAC) CRITICAL TO COCAINE ACTION. IN ADDITION, WE DEMONSTRATE THAT THESE CHANGES IN EPIGENETIC ACTIVITY DRIVE COCAINE-SEEKING BEHAVIORS IN A CELL-TYPE-SPECIFIC MANNER. THESE FINDINGS ARE KEY IN UNDERSTANDING AND TARGETING COCAINE'S IMPACT OF NEURAL CIRCUITRY AND BEHAVIOR. 2021 18 6806 24 [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 19 3315 26 HIPPOCAMPAL MU OPIOID RECEPTORS ARE MODULATED FOLLOWING COCAINE SELF-ADMINISTRATION IN RAT. COCAINE ADDICTION IS A COMPLEX PATHOLOGY INDUCED BY LONG-TERM BRAIN CHANGES. UNDERSTANDING THE NEUROCHEMICAL CHANGES UNDERLYING THE REINFORCING EFFECTS OF THIS DRUG OF ABUSE IS CRITICAL FOR REDUCING THE SOCIETAL BURDEN OF DRUG ADDICTION. THE MU OPIOID RECEPTOR PLAYS A MAJOR ROLE IN DRUG REWARD. THIS RECEPTOR IS MODULATED BY CHRONIC COCAINE TREATMENT IN SPECIFIC BRAIN STRUCTURES, BUT FEW STUDIES INVESTIGATED NEUROCHEMICAL ADAPTATIONS INDUCED BY VOLUNTARY COCAINE INTAKE. IN THIS STUDY, WE INVESTIGATED WHETHER INTRAVENOUS COCAINE-SELF ADMINISTRATION (0.33 MG/KG/INJECTION, FIXED-RATIO 1 [FR1], 10 DAYS) IN RATS INDUCES TRANSCRIPTIONAL AND FUNCTIONAL CHANGES OF THE MU OPIOID RECEPTOR IN REWARD-RELATED BRAIN REGIONS. EPIGENETIC PROCESSES WITH HISTONE MODIFICATIONS WERE EXAMINED FOR TWO ACTIVATING MARKS, H3K4ME3, AND H3K27AC. WE FOUND AN INCREASE OF MU OPIOID RECEPTOR GENE EXPRESSION ALONG WITH A POTENTIATION OF ITS FUNCTIONALITY IN HIPPOCAMPUS OF COCAINE SELF-ADMINISTERING ANIMALS COMPARED TO SALINE CONTROLS. CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY QPCR REVEALED NO MODIFICATIONS OF THE HISTONE MARK H3K4ME3 AND H3K27AC LEVELS AT MU OPIOID RECEPTOR PROMOTER. OUR STUDY HIGHLIGHTS THE HIPPOCAMPUS AS AN IMPORTANT TARGET TO FURTHER INVESTIGATE NEUROADAPTIVE PROCESSES LEADING TO COCAINE ADDICTION. 2021 20 242 27 ADOLESCENT CANNABINOID EXPOSURE MODULATES THE VULNERABILITY TO COCAINE-INDUCED CONDITIONED PLACE PREFERENCE AND DNMT3A EXPRESSION IN THE PREFRONTAL CORTEX IN SWISS MICE. RATIONALE: CANNABIS SATIVA IS THE MOST WIDELY USED DRUG BY ADOLESCENTS GLOBALLY. THE RECREATIONAL USE OF SYNTHETIC CANNABINOIDS BY TEENAGERS HAS ALSO GROWN IN RECENT YEARS. DESPITE THE WRONG PERCEPTION THAT EXPOSURE TO THESE DRUGS DOES NOT CAUSE HARM, REPEATED EXPOSURE TO CANNABINOIDS AT EARLY STAGES OF LIFE COMPROMISES IMPORTANT MATURATION PROCESSES AND BRAIN DEVELOPMENT. CHRONIC EARLY CANNABINOID USE HAS BEEN RELATED TO A HIGHER RISK OF PSYCHIATRIC OUTCOMES, INCLUDING COCAINE ADDICTION. EVIDENCE SUGGESTS THAT EXPOSURE TO NATURAL AND SYNTHETIC CANNABINOIDS DURING ADOLESCENCE MODIFIES MOLECULAR AND BEHAVIORAL EFFECTS OF COCAINE IN ADULTHOOD. RESPONSES TO COCAINE ARE REGULATED BY EPIGENETIC MECHANISMS, SUCH AS DNA METHYLATION, IN THE BRAIN'S REWARD REGIONS. HOWEVER, THE INVOLVEMENT OF THESE PROCESSES IN MODULATION OF THE VULNERABILITY TO THE EFFECTS OF COCAINE INDUCED BY PRIOR EXPOSURE TO CANNABINOIDS REMAINS POORLY UNDERSTOOD. OBJECTIVES: INVESTIGATE WHETHER EXPOSURE TO THE SYNTHETIC CANNABINOID WIN55,212-2 DURING ADOLESCENCE MODULATES ANXIETY- AND DEPRESSION-LIKE BEHAVIOR, MEMORY, AND COCAINE REWARD IN ADULT MICE. WE ALSO EVALUATED WHETHER EXPOSURE TO CANNABINOIDS DURING ADOLESCENCE MODULATES THE EXPRESSION OF ENZYMES THAT ARE INVOLVED IN DNA METHYLATION. RESULTS: EXPOSURE TO WIN55,212-2 DURING ADOLESCENCE DID NOT ALTER ANXIETY- OR DEPRESSIVE-LIKE BEHAVIOR. HOWEVER, PRIOR EXPOSURE TO CANNABINOIDS INHIBITED COCAINE-INDUCED CONDITIONED PLACE PREFERENCE WITHOUT MODULATING COCAINE-INDUCED HYPERLOCOMOTION, ACCOMPANIED BY AN INCREASE IN EXPRESSION OF THE ENZYME DNA METHYLTRANSFERASE 3A (DNMT3A) IN THE PREFRONTAL CORTEX. CONCLUSIONS: OUR FINDINGS SUGGEST THAT EXPOSURE TO WIN55,212-2 DURING ADOLESCENCE LEADS TO CHANGES IN DNMT3A EXPRESSION, AND THIS PATHWAY APPEARS TO BE RELEVANT TO MODULATING THE REWARDING EFFECTS OF COCAINE. 2021