1 2415 109 EPIGENETIC SIGNALING IN PSYCHIATRIC DISORDERS: STRESS AND DEPRESSION. PSYCHIATRIC DISORDERS ARE COMPLEX MULTIFACTORIAL DISORDERS INVOLVING CHRONIC ALTERATIONS IN NEURAL CIRCUIT STRUCTURE AND FUNCTION. WHILE GENETIC FACTORS PLAY A ROLE IN THE ETIOLOGY OF DISORDERS SUCH AS DEPRESSION, ADDICTION, AND SCHIZOPHRENIA, RELATIVELY HIGH RATES OF DISCORDANCE AMONG IDENTICAL TWINS CLEARLY POINT TO THE IMPORTANCE OF ADDITIONAL FACTORS. ENVIRONMENTAL FACTORS, SUCH AS STRESS, PLAY A MAJOR ROLE IN THE PSYCHIATRIC DISORDERS BY INDUCING STABLE CHANGES IN GENE EXPRESSION, NEURAL CIRCUIT FUNCTION, AND ULTIMATELY BEHAVIOR. INSULTS AT THE DEVELOPMENTAL STAGE AND IN ADULTHOOD APPEAR TO INDUCE DISTINCT MALADAPTATIONS. INCREASING EVIDENCE INDICATES THAT THESE SUSTAINED ABNORMALITIES ARE MAINTAINED BY EPIGENETIC MODIFICATIONS IN SPECIFIC BRAIN REGIONS. INDEED, TRANSCRIPTIONAL DYSREGULATION AND ASSOCIATED ABERRANT EPIGENETIC REGULATION IS A UNIFYING THEME IN PSYCHIATRIC DISORDERS. ASPECTS OF DEPRESSION CAN BE MODELED IN ANIMALS BY INDUCING DISEASE-LIKE STATES THROUGH ENVIRONMENTAL MANIPULATIONS, AND THESE STUDIES CAN PROVIDE A MORE GENERAL UNDERSTANDING OF EPIGENETIC MECHANISMS IN PSYCHIATRIC DISORDERS. UNDERSTANDING HOW ENVIRONMENTAL FACTORS RECRUIT THE EPIGENETIC MACHINERY IN ANIMAL MODELS IS PROVIDING NEW INSIGHTS INTO DISEASE MECHANISMS IN HUMANS. 2014 2 2414 96 EPIGENETIC SIGNALING IN PSYCHIATRIC DISORDERS. PSYCHIATRIC DISORDERS ARE COMPLEX MULTIFACTORIAL ILLNESSES INVOLVING CHRONIC ALTERATIONS IN NEURAL CIRCUIT STRUCTURE AND FUNCTION. WHILE GENETIC FACTORS ARE IMPORTANT IN THE ETIOLOGY OF DISORDERS SUCH AS DEPRESSION AND ADDICTION, RELATIVELY HIGH RATES OF DISCORDANCE AMONG IDENTICAL TWINS CLEARLY INDICATE THE IMPORTANCE OF ADDITIONAL MECHANISMS. ENVIRONMENTAL FACTORS SUCH AS STRESS OR PRIOR DRUG EXPOSURE ARE KNOWN TO PLAY A ROLE IN THE ONSET OF THESE ILLNESSES. SUCH EXPOSURE TO ENVIRONMENTAL INSULTS INDUCES STABLE CHANGES IN GENE EXPRESSION, NEURAL CIRCUIT FUNCTION, AND ULTIMATELY BEHAVIOR, AND THESE MALADAPTATIONS APPEAR DISTINCT BETWEEN DEVELOPMENTAL AND ADULT EXPOSURES. INCREASING EVIDENCE INDICATES THAT THESE SUSTAINED ABNORMALITIES ARE MAINTAINED BY EPIGENETIC MODIFICATIONS IN SPECIFIC BRAIN REGIONS. INDEED, TRANSCRIPTIONAL DYSREGULATION AND ASSOCIATED ABERRANT EPIGENETIC REGULATION IS A UNIFYING THEME IN PSYCHIATRIC DISORDERS. ASPECTS OF DEPRESSION AND ADDICTION CAN BE MODELED IN ANIMALS BY INDUCING DISEASE-LIKE STATES THROUGH ENVIRONMENTAL MANIPULATIONS (E.G., CHRONIC STRESS, DRUG ADMINISTRATION). UNDERSTANDING HOW ENVIRONMENTAL FACTORS RECRUIT THE EPIGENETIC MACHINERY IN ANIMAL MODELS REVEALS NEW INSIGHT INTO DISEASE MECHANISMS IN HUMANS. 2014 3 2011 87 EPIGENETIC BASIS OF MENTAL ILLNESS. PSYCHIATRIC DISORDERS ARE COMPLEX MULTIFACTORIAL ILLNESSES INVOLVING CHRONIC ALTERATIONS IN NEURAL CIRCUIT STRUCTURE AND FUNCTION AS WELL AS LIKELY ABNORMALITIES IN GLIAL CELLS. WHILE GENETIC FACTORS ARE IMPORTANT IN THE ETIOLOGY OF MOST MENTAL DISORDERS, THE RELATIVELY HIGH RATES OF DISCORDANCE AMONG IDENTICAL TWINS, PARTICULARLY FOR DEPRESSION AND OTHER STRESS-RELATED SYNDROMES, CLEARLY INDICATE THE IMPORTANCE OF ADDITIONAL MECHANISMS. ENVIRONMENTAL FACTORS SUCH AS STRESS ARE KNOWN TO PLAY A ROLE IN THE ONSET OF THESE ILLNESSES. EXPOSURE TO SUCH ENVIRONMENTAL INSULTS INDUCES STABLE CHANGES IN GENE EXPRESSION, NEURAL CIRCUIT FUNCTION, AND ULTIMATELY BEHAVIOR, AND THESE MALADAPTATIONS APPEAR DISTINCT BETWEEN DEVELOPMENTAL VERSUS ADULT EXPOSURES. INCREASING EVIDENCE INDICATES THAT THESE SUSTAINED ABNORMALITIES ARE MAINTAINED BY EPIGENETIC MODIFICATIONS IN SPECIFIC BRAIN REGIONS. INDEED, TRANSCRIPTIONAL DYSREGULATION AND THE ABERRANT EPIGENETIC REGULATION THAT UNDERLIES THIS DYSREGULATION IS A UNIFYING THEME IN PSYCHIATRIC DISORDERS. HERE, WE PROVIDE A PROGRESS REPORT OF EPIGENETIC STUDIES OF THE THREE MAJOR PSYCHIATRIC SYNDROMES, DEPRESSION, SCHIZOPHRENIA, AND BIPOLAR DISORDER. WE REVIEW THE LITERATURE DERIVED FROM ANIMAL MODELS OF THESE DISORDERS AS WELL AS FROM STUDIES OF POSTMORTEM BRAIN TISSUE FROM HUMAN PATIENTS. WHILE EPIGENETIC STUDIES OF MENTAL ILLNESS REMAIN AT EARLY STAGES, UNDERSTANDING HOW ENVIRONMENTAL FACTORS RECRUIT THE EPIGENETIC MACHINERY WITHIN SPECIFIC BRAIN REGIONS TO CAUSE LASTING CHANGES IN DISEASE SUSCEPTIBILITY AND PATHOPHYSIOLOGY IS REVEALING NEW INSIGHT INTO THE ETIOLOGY AND TREATMENT OF THESE CONDITIONS. 2016 4 2386 27 EPIGENETIC REGULATORY MECHANISMS IN STRESS-INDUCED BEHAVIOR. STRESS RESPONSE IS CONSIDERED TO HAVE ADAPTIVE VALUE FOR ORGANISMS FACED WITH STRESSFUL CONDITION. CHRONIC STRESS HOWEVER ADVERSELY AFFECTS THE PHYSIOLOGY AND MAY LEAD TO NEUROPSYCHIATRIC DISORDERS. REPEATED STRESSFUL EVENTS IN ANIMAL MODELS HAVE BEEN SHOWN TO CAUSE LONG-LASTING CHANGES IN NEURAL CIRCUITRIES AT MOLECULAR, CELLULAR, AND PHYSIOLOGICAL LEVEL, LEADING TO DISORDERS OF MOOD AS WELL AS COGNITION. MOLECULAR STUDIES IN RECENT YEARS HAVE IMPLICATED DIVERSE EPIGENETIC MECHANISMS, INCLUDING HISTONE MODIFICATIONS, DNA METHYLATION, AND NONCODING RNAS, THAT UNDERLIE DYSREGULATION OF GENES IN THE AFFECTED NEURAL CIRCUITRIES IN CHRONIC STRESS-INDUCED PATHOPHYSIOLOGY. A REVIEW OF THE MYRIAD EPIGENETIC REGULATORY MECHANISMS ASSOCIATED WITH NEURAL AND BEHAVIORAL RESPONSES IN ANIMAL MODELS OF STRESS-INDUCED NEUROPSYCHIATRIC DISORDERS IS PRESENTED HERE. THE REVIEW ALSO DEALS WITH CLINICAL EVIDENCE OF THE EPIGENETIC DYSREGULATION OF GENES IN PSYCHIATRIC DISORDERS WHERE CHRONIC STRESS APPEARS TO UNDERLIE THE ETIOPATHOLOGY. 2014 5 6414 44 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 6 5164 37 PRECLINICAL AND CLINICAL EVIDENCE OF DNA METHYLATION CHANGES IN RESPONSE TO TRAUMA AND CHRONIC STRESS. EXPOSURE TO CHRONIC STRESS, EITHER REPEATED SEVERE ACUTE OR MODERATE SUSTAINED STRESS, IS ONE OF THE STRONGEST RISK FACTORS FOR THE DEVELOPMENT OF PSYCHOPATHOLOGIES SUCH AS POST-TRAUMATIC STRESS DISORDER AND DEPRESSION. CHRONIC STRESS IS LINKED WITH SEVERAL LASTING BIOLOGICAL CONSEQUENCES, PARTICULARLY TO THE STRESS ENDOCRINE SYSTEM BUT ALSO AFFECTING INTERMEDIATE PHENOTYPES SUCH AS BRAIN STRUCTURE AND FUNCTION, IMMUNE FUNCTION, AND BEHAVIOR. ALTHOUGH GENETIC PREDISPOSITION CONFERS A PROPORTION OF THE RISK, THE MOST RELEVANT MOLECULAR MECHANISMS DETERMINING THOSE SUSCEPTIBLE AND RESILIENT TO THE EFFECTS OF STRESS AND TRAUMA MAY BE EPIGENETIC. EPIGENETICS REFERS TO THE MECHANISMS THAT REGULATE GENOMIC INFORMATION BY DYNAMICALLY CHANGING THE PATTERNS OF TRANSCRIPTION AND TRANSLATION OF GENES. MOUNTING EVIDENCE FROM PRECLINICAL RODENT AND CLINICAL POPULATION STUDIES STRONGLY SUPPORT THAT EPIGENETIC MODIFICATIONS CAN OCCUR IN RESPONSE TO TRAUMATIC AND CHRONIC STRESS. HERE, WE DISCUSS THIS LITERATURE EXAMINING STRESS-INDUCED EPIGENETIC CHANGES IN PRECLINICAL MODELS AND CLINICAL COHORTS OF STRESS AND TRAUMA OCCURRING EARLY IN LIFE OR IN ADULTHOOD. WE HIGHLIGHT THAT A COMPLEX RELATIONSHIP BETWEEN THE TIMING OF ENVIRONMENTAL STRESSORS AND GENETIC PREDISPOSITIONS LIKELY MEDIATE THE RESPONSE TO CHRONIC STRESS OVER TIME, AND THAT A BETTER UNDERSTANDING OF EPIGENETIC CHANGES IS NEEDED BY FURTHER INVESTIGATIONS IN LONGITUDINAL AND POSTMORTEM BRAIN CLINICAL COHORTS. 2017 7 2963 27 GENETIC AND EPIGENETIC MECHANISMS LINKING PAIN AND PSYCHIATRIC DISORDERS. THE NEUROPHYSIOLOGICAL LINK BETWEEN NEUROPATHIC PAIN AND DEPRESSION REMAINS UNKNOWN DESPITE EVIDENT HIGH COMORBIDITY OF THESE TWO DISORDERS. HOWEVER, THERE IS CONVINCING EVIDENCE THAT GENOTYPE PLAYS A ROLE IN BOTH PAIN AND DEPRESSION. USING VARIOUS TYPES OF GENETIC ANALYSIS - POPULATION GENETICS, CYTOGENETICS AND MOLECULAR TECHNOLOGIES - SPECIFIC GENES HAVE BEEN IMPLICATED IN MEDIATING ALMOST ALL ASPECTS OF NOCICEPTION AND MOOD DISORDERS. THE CURRENT REVIEW ATTEMPTS TO IDENTIFY SPECIFIC GENES AND EPIGENETIC MECHANISMS COMMON TO BOTH DISORDERS. IT IS CONCLUDED THAT EXTERNAL AND INTERNAL FACTORS (INFLAMMATION, STRESS, GENDER, ETC.) THAT CONTRIBUTE TO THE PATHOLOGIES MAY DO SO THROUGH EPIGENETIC MECHANISMS THAT MAY AFFECT EXPRESSION OF THESE PARTICULAR GENES. THE POSSIBLE INVOLVEMENT OF EPIGENETIC REGULATION IN PAIN AND PSYCHIATRIC DISORDERS SUGGESTS THAT TREATMENTS TARGETING EPIGENETIC MECHANISMS THAT MEDIATE ADVERSE LIFE EVENTS SHOULD BE CONSIDERED. 2015 8 6228 28 THE LINKS BETWEEN STRESS AND DEPRESSION: PSYCHONEUROENDOCRINOLOGICAL, GENETIC, AND ENVIRONMENTAL INTERACTIONS. THE ROLE OF STRESS IN THE ORIGIN AND DEVELOPMENT OF DEPRESSION MAY BE CONCEIVED AS THE RESULT OF MULTIPLE CONVERGING FACTORS, INCLUDING THE CHRONIC EFFECT OF ENVIRONMENTAL STRESSORS AND THE LONG-LASTING EFFECTS OF STRESSFUL EXPERIENCES DURING CHILDHOOD, ALL OF WHICH MAY INDUCE PERSISTENT HYPERACTIVITY OF THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS. THESE CHANGES, INCLUDING INCREASED AVAILABILITY OF CORTICOTROPIN-RELEASING FACTOR AND CORTISOL, ARE ALSO ASSOCIATED WITH HYPERACTIVITY OF THE AMYGDALA, HYPOACTIVITY OF THE HIPPOCAMPUS, AND DECREASED SEROTONERGIC NEUROTRANSMISSION, WHICH TOGETHER RESULT IN INCREASED VULNERABILITY TO STRESS. THE ROLE OF OTHER MONOAMINERGIC NEUROTRANSMITTERS, GENETIC POLYMORPHISMS, EPIGENETIC MECHANISMS, INFLAMMATORY PROCESSES, AND ALTERED COGNITIVE PROCESSING HAS ALSO BEEN CONSIDERED IN THE DEVELOPMENT OF A COMPREHENSIVE MODEL OF THE INTERACTIONS BETWEEN DIFFERENT FACTORS OF VULNERABILITY. FURTHER UNDERSTANDING OF THE UNDERLYING MECHANISMS THAT LINK THESE FACTORS MAY CONTRIBUTE SIGNIFICANTLY TO THE DEVELOPMENT OF MORE EFFECTIVE TREATMENTS AND PREVENTIVE STRATEGIES IN THE INTERFACE BETWEEN STRESS AND MOOD DISORDERS. 2016 9 110 29 A ROLE FOR ACTIVITY-DEPENDENT EPIGENETICS IN THE DEVELOPMENT AND TREATMENT OF MAJOR DEPRESSIVE DISORDER. CHRONIC STRESSORS, DURING DEVELOPMENTAL SENSITIVE PERIODS AND BEYOND, CONTRIBUTE TO THE RISK OF DEVELOPING PSYCHIATRIC CONDITIONS, INCLUDING MAJOR DEPRESSIVE DISORDER (MDD). EPIGENETIC MECHANISMS INCLUDING DNA METHYLATION AND HISTONE MODIFICATIONS, AT KEY STRESS RESPONSE AND NEUROTROPHIN GENES, ARE INCREASINGLY IMPLICATED IN MEDIATING THIS RISK. ALTHOUGH THE EXACT MECHANISMS THROUGH WHICH STRESSFUL ENVIRONMENTAL STIMULI ALTER THE EPIGENOME ARE STILL UNCLEAR, RESEARCH FROM THE LEARNING AND MEMORY FIELDS INDICATES THAT EPIGENOMIC MARKS CAN BE ALTERED, AT LEAST IN PART, THROUGH CALCIUM-DEPENDENT SIGNALING CASCADES IN DIRECT RESPONSE TO NEURONAL ACTIVITY. IN THIS REVIEW, WE HIGHLIGHT KEY FINDINGS FROM THE STRESS, MDD, AND LEARNING AND MEMORY FIELDS TO PROPOSE A MODEL WHERE STRESS REGULATES DOWNSTREAM CELLULAR FUNCTIONING THROUGH ACTIVITY-DEPENDENT EPIGENETIC CHANGES. FURTHERMORE, WE SUGGEST THAT BOTH TYPICAL AND NOVEL ANTIDEPRESSANT TREATMENTS MAY EXERT POSITIVE INFLUENCE THROUGH SIMILAR, ACTIVITY-DEPENDENT PATHWAYS. 2018 10 1329 33 DEPRESSION ASSOCIATED WITH DIABETES: FROM PATHOPHYSIOLOGY TO TREATMENT. DIABETES IS A CHRONIC AND PROGRESSIVE SYNDROME COMMONLY ASSOCIATED WITH SEVERAL NEUROPSYCHIATRIC COMORBITIES, OF WHICH DEPRESSION IS THE MOST STUDIED. THE PREVALENCE OF DEPRESSION IS ABOUT TWO OR THREE TIMES HIGHER IN DIABETIC PATIENTS COMPARED TO THE GENERAL POPULATION. IT IS BELIEVED THAT THE DIABETES - DEPRESSION RELATION MAY BE BIDIRECTIONAL, I.E., THE DEPRESSION CAN LEAD TO DIABETES AND CONVERSELY DIABETES COULD FACILITATE THE EMERGENCE OF DEPRESSION. DEPRESSION IS ONE OF THE MOST NEGLECTED SYMPTOMS IN DIABETIC PATIENTS AND IS DIRECTLY LINKED WITH LOWERING OF QUALITY OF LIFE. THE TREATMENT OF DEPRESSION IN THESE PATIENTS IS STILL QUITE INEFFECTIVE AND IN MANY CASES TREATMENTREFRACTORY. FURTHERMORE, SOME OF THE FIRST CHOICE DRUGS USED TO TREAT THE DEPRESSION AFFECT THE BLOOD GLUCOSE CONTROL, AGGRAVATING THE HYPERGLYCEMIC STATE. THESE ISSUES UNDERSCORE THE URGENCY IN STUDIES SEARCHING FOR NEW PHARMACOLOGICAL TARGETS FOR THE TREATMENT OF DEPRESSION ASSOCIATED WITH DIABETES. FOR THIS, A BETTER UNDERSTANDING OF THE PATHOPHYSIOLOGY THAT RELATES THIS COMORBIDITY BECOMES CRITICAL. IN THIS RESPECT, THIS REVIEW WILL FOCUS ON SOME HYPOTHESES THAT HAVE BEEN PROPOSED TO EXPLAIN THE MECHANISMS UNDERLYING DEPRESSION ASSOCIATED WITH DIABETES, HIGHLIGHTING THE TREATMENT OPTIONS CURRENTLY AVAILABLE AND THEIR LIMITATIONS. AMONG THESE HYPOTHESES, WE WILL POINT OUT THE HYPERGLYCEMIA AS A PRIMARY METABOLIC CAUSE OF THE DEPRESSION DEVELOPMENT, THE INVOLVEMENT OF THE DYSREGULATION OF HYPOTHALAMIC PITUITARY-ADRENAL (HPA) AXIS AND OF NEUROTRANSMITTER SYSTEMS, SPECIALLY MONOAMINERGIC SYSTEM. BESIDES, THE ROLE OF OXIDATIVE STRESS, NEUROINFLAMMATION AND CELL DEATH, ESPECIALLY IN HIPPOCAMPUS AND PREFRONTAL CORTEX, BRAIN AREAS IMPORTANT FOR THE MEDIATION AND MODULATION OF EMOTIONAL BEHAVIOR WILL ALSO BE DISCUSSED. FINALLY, WE WILL BRING UP THE INFLUENCE OF THE EPIGENETIC REGULATION WITH RESPECT TO NEUROPSYCHIATRIC DISORDERS. 2016 11 6184 43 THE IMPACT OF ENVIRONMENTAL FACTORS IN SEVERE PSYCHIATRIC DISORDERS. DURING THE LAST DECADES, SCHIZOPHRENIA HAS BEEN REGARDED AS A DEVELOPMENTAL DISORDER. THE NEURODEVELOPMENTAL HYPOTHESIS PROPOSES SCHIZOPHRENIA TO BE RELATED TO GENETIC AND ENVIRONMENTAL FACTORS LEADING TO ABNORMAL BRAIN DEVELOPMENT DURING THE PRE- OR POSTNATAL PERIOD. FIRST DISEASE SYMPTOMS APPEAR IN EARLY ADULTHOOD DURING THE SYNAPTIC PRUNING AND MYELINATION PROCESS. META-ANALYSES OF STRUCTURAL MRI STUDIES REVEALING HIPPOCAMPAL VOLUME DEFICITS IN FIRST-EPISODE PATIENTS AND IN THE LONGITUDINAL DISEASE COURSE CONFIRM THIS HYPOTHESIS. APART FROM THE INFLUENCE OF RISK GENES IN SEVERE PSYCHIATRIC DISORDERS, ENVIRONMENTAL FACTORS MAY ALSO IMPACT BRAIN DEVELOPMENT DURING THE PERINATAL PERIOD. SEVERAL ENVIRONMENTAL FACTORS SUCH AS ANTENATAL MATERNAL VIRUS INFECTIONS, OBSTETRIC COMPLICATIONS ENTAILING HYPOXIA AS COMMON FACTOR OR STRESS DURING NEURODEVELOPMENT HAVE BEEN IDENTIFIED TO PLAY A ROLE IN SCHIZOPHRENIA AND BIPOLAR DISORDER, POSSIBLY CONTRIBUTING TO SMALLER HIPPOCAMPAL VOLUMES. IN MAJOR DEPRESSION, PSYCHOSOCIAL STRESS DURING THE PERINATAL PERIOD OR IN ADULTHOOD IS AN IMPORTANT TRIGGER. IN ANIMAL STUDIES, CHRONIC STRESS OR REPEATED ADMINISTRATION OF GLUCOCORTICOIDS HAVE BEEN SHOWN TO INDUCE DEGENERATION OF GLUCOCORTICOID-SENSITIVE HIPPOCAMPAL NEURONS AND MAY CONTRIBUTE TO THE PATHOPHYSIOLOGY OF AFFECTIVE DISORDERS. EPIGENETIC MECHANISMS ALTERING THE CHROMATIN STRUCTURE SUCH AS HISTONE ACETYLATION AND DNA METHYLATION MAY MEDIATE EFFECTS OF ENVIRONMENTAL FACTORS TO TRANSCRIPTIONAL REGULATION OF SPECIFIC GENES AND BE A PROMINENT FACTOR IN GENE-ENVIRONMENTAL INTERACTION. IN ANIMAL MODELS, GENE-ENVIRONMENTAL INTERACTION SHOULD BE INVESTIGATED MORE INTENSELY TO UNRAVEL PATHOPHYSIOLOGICAL MECHANISMS. THESE FINDINGS MAY LEAD TO NEW THERAPEUTIC STRATEGIES INFLUENCING EPIGENETIC TARGETS IN SEVERE PSYCHIATRIC DISORDERS. 2014 12 2269 41 EPIGENETIC PROGRAMMING OF THE NEUROENDOCRINE STRESS RESPONSE BY ADULT LIFE STRESS. THE HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS IS CRITICALLY INVOLVED IN THE NEUROENDOCRINE REGULATION OF STRESS ADAPTATION, AND THE RESTORATION OF HOMEOSTASIS FOLLOWING STRESS EXPOSURE. DYSREGULATION OF THIS AXIS IS ASSOCIATED WITH STRESS-RELATED PATHOLOGIES LIKE MAJOR DEPRESSIVE DISORDER, POST-TRAUMATIC STRESS DISORDER, PANIC DISORDER AND CHRONIC ANXIETY. IT HAS LONG BEEN UNDERSTOOD THAT STRESS DURING EARLY LIFE CAN HAVE A SIGNIFICANT LASTING INFLUENCE ON THE DEVELOPMENT OF THE NEUROENDOCRINE SYSTEM AND ITS NEURAL REGULATORS, PARTIALLY BY MODIFYING EPIGENETIC REGULATION OF GENE EXPRESSION, WITH IMPLICATIONS FOR HEALTH AND WELL-BEING IN LATER LIFE. EVIDENCE IS ACCUMULATING THAT EPIGENETIC PLASTICITY ALSO EXTENDS TO ADULTHOOD, PROPOSING IT AS A MECHANISM BY WHICH PSYCHOLOGICAL TRAUMA LATER IN LIFE CAN LONG-LASTINGLY AFFECT HPA AXIS FUNCTION, BRAIN PLASTICITY, NEURONAL FUNCTION AND BEHAVIOURAL ADAPTATION TO NEUROPSYCHOLOGICAL STRESS. FURTHER CORROBORATING THIS CLAIM IS THE PHENOMENON THAT THESE EPIGENETIC CHANGES CORRELATE WITH THE BEHAVIOURAL CONSEQUENCES OF TRAUMA EXPOSURE. THEREBY, EPIGENETIC MODIFICATIONS PROVIDE A PUTATIVE MOLECULAR MECHANISM BY WHICH THE BEHAVIOURAL PHENOTYPE AND TRANSCRIPTIONAL/TRANSLATIONAL POTENTIAL OF GENES INVOLVED IN HPA AXIS REGULATION CAN CHANGE DRASTICALLY IN RESPONSE TO ENVIRONMENTAL CHALLENGES, AND APPEAR AN IMPORTANT TARGET FOR TREATMENT OF STRESS-RELATED DISORDERS. HOWEVER, IMPROVED INSIGHT IS REQUIRED TO INCREASE THEIR THERAPEUTIC (DRUG) POTENTIAL. HERE, WE PROVIDE AN OVERVIEW OF THE GROWING BODY OF LITERATURE DESCRIBING THE EPIGENETIC MODULATION OF THE (PRIMARILY NEUROENDOCRINE) STRESS RESPONSE AS A CONSEQUENCE OF ADULT LIFE STRESS AND INTERPRET THE IMPLICATIONS FOR, AND THE CHALLENGES INVOLVED IN APPLYING THIS KNOWLEDGE TO, THE IDENTIFICATION AND TREATMENT OF STRESS-RELATED PSYCHIATRIC DISORDERS. 2017 13 2598 36 EPIGENETICS OF THE DEPRESSED BRAIN: ROLE OF HISTONE ACETYLATION AND METHYLATION. MAJOR DEPRESSIVE DISORDER IS A CHRONIC, REMITTING SYNDROME INVOLVING WIDELY DISTRIBUTED CIRCUITS IN THE BRAIN. STABLE ALTERATIONS IN GENE EXPRESSION THAT CONTRIBUTE TO STRUCTURAL AND FUNCTIONAL CHANGES IN MULTIPLE BRAIN REGIONS ARE IMPLICATED IN THE HETEROGENEITY AND PATHOGENESIS OF THE ILLNESS. EPIGENETIC EVENTS THAT ALTER CHROMATIN STRUCTURE TO REGULATE PROGRAMS OF GENE EXPRESSION HAVE BEEN ASSOCIATED WITH DEPRESSION-RELATED BEHAVIOR, ANTIDEPRESSANT ACTION, AND RESISTANCE TO DEPRESSION OR 'RESILIENCE' IN ANIMAL MODELS, WITH INCREASING EVIDENCE FOR SIMILAR MECHANISMS OCCURRING IN POSTMORTEM BRAINS OF DEPRESSED HUMANS. IN THIS REVIEW, WE DISCUSS RECENT ADVANCES IN OUR UNDERSTANDING OF EPIGENETIC CONTRIBUTIONS TO DEPRESSION, IN PARTICULAR THE ROLE OF HISTONE ACETYLATION AND METHYLATION, WHICH ARE REVEALING NOVEL MECHANISTIC INSIGHT INTO THE SYNDROME THAT MAY AID IN THE DEVELOPMENT OF NOVEL TARGETS FOR DEPRESSION TREATMENT. 2013 14 2231 33 EPIGENETIC MODIFICATIONS OF MAJOR DEPRESSIVE DISORDER. MAJOR DEPRESSIVE DISORDER (MDD) IS A CHRONIC DISEASE WHOSE NEUROLOGICAL BASIS AND PATHOPHYSIOLOGY REMAIN POORLY UNDERSTOOD. INITIALLY, IT WAS PROPOSED THAT GENETIC VARIATIONS WERE RESPONSIBLE FOR THE DEVELOPMENT OF THIS DISEASE. NEVERTHELESS, SEVERAL STUDIES WITHIN THE LAST DECADE HAVE PROVIDED EVIDENCE SUGGESTING THAT ENVIRONMENTAL FACTORS PLAY AN IMPORTANT ROLE IN MDD PATHOPHYSIOLOGY. ALTERATIONS IN EPIGENETICS MECHANISM, SUCH AS DNA METHYLATION, HISTONE MODIFICATION AND MICRORNA EXPRESSION COULD FAVOR MDD ADVANCE IN RESPONSE TO STRESSFUL EXPERIENCES AND ENVIRONMENTAL FACTORS. THE AIM OF THIS REVIEW IS TO DESCRIBE GENETIC ALTERATIONS, AND PARTICULARLY ALTERED EPIGENETIC MECHANISMS, THAT COULD BE DETERMINANTS FOR MDD PROGRESS, AND HOW THESE ALTERATIONS MAY ARISE AS USEFUL SCREENING, DIAGNOSIS AND TREATMENT MONITORING BIOMARKERS OF DEPRESSIVE DISORDERS. 2016 15 2288 38 EPIGENETIC REGULATION IN MAJOR DEPRESSION AND OTHER STRESS-RELATED DISORDERS: MOLECULAR MECHANISMS, CLINICAL RELEVANCE AND THERAPEUTIC POTENTIAL. MAJOR DEPRESSIVE DISORDER (MDD) IS A CHRONIC, GENERALLY EPISODIC AND DEBILITATING DISEASE THAT AFFECTS AN ESTIMATED 300 MILLION PEOPLE WORLDWIDE, BUT ITS PATHOGENESIS IS POORLY UNDERSTOOD. THE HERITABILITY ESTIMATE OF MDD IS 30-40%, SUGGESTING THAT GENETICS ALONE DO NOT ACCOUNT FOR MOST OF THE RISK OF MAJOR DEPRESSION. ANOTHER FACTOR KNOWN TO ASSOCIATE WITH MDD INVOLVES ENVIRONMENTAL STRESSORS SUCH AS CHILDHOOD ADVERSITY AND RECENT LIFE STRESS. RECENT STUDIES HAVE EMERGED TO SHOW THAT THE BIOLOGICAL IMPACT OF ENVIRONMENTAL FACTORS IN MDD AND OTHER STRESS-RELATED DISORDERS IS MEDIATED BY A VARIETY OF EPIGENETIC MODIFICATIONS. THESE EPIGENETIC MODIFICATION ALTERATIONS CONTRIBUTE TO ABNORMAL NEUROENDOCRINE RESPONSES, NEUROPLASTICITY IMPAIRMENT, NEUROTRANSMISSION AND NEUROGLIA DYSFUNCTION, WHICH ARE INVOLVED IN THE PATHOPHYSIOLOGY OF MDD. FURTHERMORE, EPIGENETIC MARKS HAVE BEEN ASSOCIATED WITH THE DIAGNOSIS AND TREATMENT OF MDD. THE EVALUATION OF EPIGENETIC MODIFICATIONS HOLDS PROMISE FOR FURTHER UNDERSTANDING OF THE HETEROGENEOUS ETIOLOGY AND COMPLEX PHENOTYPES OF MDD, AND MAY IDENTIFY NEW THERAPEUTIC TARGETS. HERE, WE REVIEW PRECLINICAL AND CLINICAL EPIGENETIC FINDINGS, INCLUDING DNA METHYLATION, HISTONE MODIFICATION, NONCODING RNA, RNA MODIFICATION, AND CHROMATIN REMODELING FACTOR IN MDD. IN ADDITION, WE ELABORATE ON THE CONTRIBUTION OF THESE EPIGENETIC MECHANISMS TO THE PATHOLOGICAL TRAIT VARIABILITY IN DEPRESSION AND DISCUSS HOW SUCH MECHANISMS CAN BE EXPLOITED FOR THERAPEUTIC PURPOSES. 2023 16 5829 24 STRESS, PSYCHIATRIC DISORDERS, MOLECULAR TARGETS, AND MORE. MENTAL HEALTH IS CENTRAL TO NORMAL HEALTH OUTCOMES. A WIDELY ACCEPTED THEORY IS THAT CHRONIC PERSISTENT STRESS DURING ADULTHOOD AS WELL AS DURING EARLY LIFE TRIGGERS ONSET OF NEUROPSYCHIATRIC AILMENTS. HOWEVER, QUESTIONS RELATED TO HOW THAT OCCURS, AND WHY ARE SOME INDIVIDUALS RESISTANT TO STRESS WHILE OTHERS ARE NOT, REMAIN UNANSWERED. AN INTEGRATED, MULTISYSTEMIC STRESS RESPONSE INVOLVING NEUROINFLAMMATORY, NEUROENDOCRINE, EPIGENETIC AND METABOLIC CASCADES HAVE BEEN SUGGESTED TO HAVE CAUSATIVE LINKS. SEVERAL THEORIES HAVE BEEN PROPOSED OVER THE YEARS TO CONCEPTUALIZE THIS LINK INCLUDING THE CYTOKINE HYPOTHESIS, THE ENDOCRINE HYPOTHESIS, THE OXIDATIVE STRESS HYPOTHESIS AND THE OXIDO-NEUROINFLAMMATION HYPOTHESIS. THE DATA DISCUSSED IN THIS REVIEW DESCRIBES POTENTIAL BIOCHEMICAL BASIS OF THE LINK BETWEEN STRESS, AND STRESS-INDUCED NEURONAL, BEHAVIORAL AND EMOTIONAL DEFICITS, PROVIDING INSIGHTS INTO POTENTIALLY NOVEL DRUG TARGETS. 2019 17 2573 22 EPIGENETICS OF DRUG ABUSE: PREDISPOSITION OR RESPONSE. DRUG ADDICTION CONTINUES TO BE A SERIOUS MEDICAL AND SOCIAL PROBLEM. VULNERABILITY TO DEVELOP AN ADDICTION TO DRUGS IS DEPENDENT ON GENETIC, ENVIRONMENTAL, SOCIAL AND BIOLOGICAL FACTORS. IN PARTICULAR, THE INTERACTIONS OF ENVIRONMENTAL AND GENETIC FACTORS INDICATE THE SIGNIFICANCE OF EPIGENETIC MECHANISMS, WHICH HAVE BEEN FOUND TO OCCUR IN RESPONSE TO ILLICIT DRUG USE OR AS UNDERLYING FACTORS IN CHRONIC SUBSTANCE ABUSE AND RELAPSE. EPIGENETICS IS DEFINED AS THE HERITABLE AND POSSIBLY REVERSIBLE MODIFICATIONS IN GENE EXPRESSION THAT DO NOT INVOLVE ALTERATIONS IN THE DNA SEQUENCE. THIS REVIEW DISCUSSES THE VARIOUS TYPES OF EPIGENETIC MODIFICATIONS AND THEIR RELEVANCE TO DRUG ADDICTION TO ELUCIDATE WHETHER EPIGENETICS IS A PREDISPOSING FACTOR, OR A RESPONSE TO, DEVELOPING AN ADDICTION TO DRUGS OF ABUSE. 2012 18 4914 25 PAIN VULNERABILITY: A NEUROBIOLOGICAL PERSPECTIVE. THERE ARE MANY KNOWN RISK FACTORS FOR CHRONIC PAIN CONDITIONS, YET THE BIOLOGICAL UNDERPINNINGS THAT LINK THESE FACTORS TO ABNORMAL PROCESSING OF PAINFUL SIGNALS ARE ONLY JUST BEGINNING TO BE EXPLORED. THIS REVIEW WILL DISCUSS THE POTENTIAL MECHANISMS THAT HAVE BEEN PROPOSED TO UNDERLIE VULNERABILITY AND RESILIENCE TOWARD DEVELOPING CHRONIC PAIN. PARTICULAR FOCUS WILL BE GIVEN TO GENETIC AND EPIGENETIC PROCESSES, PRIMING EFFECTS ON A CELLULAR LEVEL, AND ALTERATIONS IN BRAIN NETWORKS CONCERNED WITH REWARD, MOTIVATION/LEARNING AND DESCENDING MODULATORY CONTROL. ALTHOUGH RESEARCH IN THIS AREA IS STILL IN ITS INFANCY, A BETTER UNDERSTANDING OF HOW PAIN VULNERABILITY EMERGES HAS THE POTENTIAL TO HELP IDENTIFY INDIVIDUALS AT RISK AND MAY OPEN UP NEW THERAPEUTIC AVENUES. 2014 19 679 20 BRAIN FOODS - THE ROLE OF DIET IN BRAIN PERFORMANCE AND HEALTH. THE PERFORMANCE OF THE HUMAN BRAIN IS BASED ON AN INTERPLAY BETWEEN THE INHERITED GENOTYPE AND EXTERNAL ENVIRONMENTAL FACTORS, INCLUDING DIET. FOOD AND NUTRITION, ESSENTIAL IN MAINTENANCE OF BRAIN PERFORMANCE, ALSO AID IN PREVENTION AND TREATMENT OF MENTAL DISORDERS. BOTH THE OVERALL COMPOSITION OF THE HUMAN DIET AND SPECIFIC DIETARY COMPONENTS HAVE BEEN SHOWN TO HAVE AN IMPACT ON BRAIN FUNCTION IN VARIOUS EXPERIMENTAL MODELS AND EPIDEMIOLOGICAL STUDIES. THIS NARRATIVE REVIEW PROVIDES AN OVERVIEW OF THE ROLE OF DIET IN 5 KEY AREAS OF BRAIN FUNCTION RELATED TO MENTAL HEALTH AND PERFORMANCE, INCLUDING: (1) BRAIN DEVELOPMENT, (2) SIGNALING NETWORKS AND NEUROTRANSMITTERS IN THE BRAIN, (3) COGNITION AND MEMORY, (4) THE BALANCE BETWEEN PROTEIN FORMATION AND DEGRADATION, AND (5) DETERIORATIVE EFFECTS DUE TO CHRONIC INFLAMMATORY PROCESSES. FINALLY, THE ROLE OF DIET IN EPIGENETIC REGULATION OF BRAIN PHYSIOLOGY IS DISCUSSED. 2021 20 2235 32 EPIGENETIC MODIFICATIONS, ALCOHOLIC BRAIN AND POTENTIAL DRUG TARGETS. ACUTE AND CHRONIC ALCOHOL EXPOSURE EVIDENTLY INFLUENCES EPIGENETIC CHANGES, BOTH TRANSIENTLY AND PERMANENTLY, AND THESE CHANGES IN TURN INFLUENCE A VARIETY OF CELLS AND ORGAN SYSTEMS THROUGHOUT THE BODY. MANY OF THE ALCOHOL-INDUCED EPIGENETIC MODIFICATIONS CAN CONTRIBUTE TO CELLULAR ADAPTATIONS THAT ULTIMATELY LEAD TO BEHAVIORAL TOLERANCE AND ALCOHOL DEPENDENCE. THE PERSISTENCE OF BEHAVIORAL CHANGES DEMONSTRATES THAT LONG-LASTING CHANGES IN GENE EXPRESSION, WITHIN PARTICULAR REGIONS OF THE BRAIN, MAY CONTRIBUTE IMPORTANTLY TO THE ADDICTION PHENOTYPE. THE RESEARCH ACTIVITIES OVER THE PAST YEARS HAVE DEMONSTRATED A CRUCIAL ROLE OF EPIGENETIC MECHANISMS IN CAUSING LONG LASTING AND TRANSIENT CHANGES IN THE EXPRESSION OF SEVERAL GENES IN DIVERSE TISSUES, INCLUDING BRAIN. THIS HAS STIMULATED RECENT RESEARCH WORK THAT IS AIMED AT CHARACTERIZING THE INFLUENCE OF EPIGENETIC REGULATORY EVENTS IN MEDIATING THE LONG LASTING AND TRANSIENT EFFECTS OF ALCOHOL ABUSE ON THE BRAIN IN HUMANS AND ANIMAL MODELS OF ALCOHOL ADDICTION. IN THIS STUDY, WE UPDATE OUR CURRENT UNDERSTANDING OF THE IMPACT OF ALCOHOL EXPOSURE ON EPIGENETIC MECHANISMS IN THE BRAIN AND REFURBISH THE KNOWLEDGE OF EPIGENETICS IN THE DIRECTION OF NEW DRUGS DEVELOPMENT. 2016