1 1761 129 EARLY STRESS EVOKES AGE-DEPENDENT BIPHASIC CHANGES IN HIPPOCAMPAL NEUROGENESIS, BDNF EXPRESSION, AND COGNITION. BACKGROUND: ADULT-ONSET STRESSORS EXERT OPPOSING EFFECTS ON HIPPOCAMPAL NEUROGENESIS AND COGNITION, WITH ENHANCEMENT OBSERVED FOLLOWING MILD STRESS AND DYSFUNCTION FOLLOWING SEVERE CHRONIC STRESS. WHILE EARLY LIFE STRESS EVOKES PERSISTENT CHANGES IN ANXIETY, IT IS UNKNOWN WHETHER EARLY STRESS DIFFERENTIALLY REGULATES HIPPOCAMPAL NEUROGENESIS, TROPHIC FACTOR EXPRESSION, AND COGNITION ACROSS THE LIFE SPAN. METHODS: HIPPOCAMPAL-DEPENDENT COGNITIVE BEHAVIOR, NEUROGENESIS, AND EPIGENETIC REGULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION WAS EXAMINED AT DISTINCT TIME POINTS ACROSS THE LIFE SPAN IN RATS SUBJECTED TO THE EARLY STRESS OF MATERNAL SEPARATION (ES) AND CONTROL GROUPS. WE ALSO EXAMINED THE INFLUENCE OF CHRONIC ANTIDEPRESSANT TREATMENT ON THE NEUROGENIC, NEUROTROPHIC, AND COGNITIVE CHANGES IN MIDDLE-AGED ES ANIMALS. RESULTS: ANIMALS SUBJECTED TO EARLY STRESS OF MATERNAL SEPARATION EXAMINED DURING POSTNATAL LIFE AND YOUNG ADULTHOOD EXHIBITED ENHANCED HIPPOCAMPAL NEUROGENESIS, DECREASED REPRESSIVE HISTONE METHYLATION AT THE BDNF IV PROMOTER ALONG WITH ENHANCED BDNF LEVELS, AND IMPROVED PERFORMANCE ON THE STRESS-ASSOCIATED MORRIS WATER MAZE. STRIKINGLY, OPPOSING CHANGES IN HIPPOCAMPAL NEUROGENESIS AND EPIGENETIC REGULATION OF BDNF IV EXPRESSION, CONCOMITANT WITH IMPAIRMENTS ON HIPPOCAMPAL-DEPENDENT COGNITIVE TASKS, WERE OBSERVED IN MIDDLE-AGED ES ANIMALS. CHRONIC ANTIDEPRESSANT TREATMENT WITH AMITRIPTYLINE ATTENUATED THE MALADAPTIVE NEUROGENIC, EPIGENETIC, TRANSCRIPTIONAL, AND COGNITIVE EFFECTS IN MIDDLE-AGED ES ANIMALS. CONCLUSIONS: OUR STUDY PROVIDES NOVEL INSIGHTS INTO THE SHORT- AND LONG-TERM CONSEQUENCES OF ES, DEMONSTRATING BOTH BIPHASIC AND UNIQUE, AGE-DEPENDENT CHANGES AT THE MOLECULAR, EPIGENETIC, NEUROGENIC, AND BEHAVIORAL LEVELS. THESE RESULTS INDICATE THAT EARLY STRESS MAY TRANSIENTLY ENDOW ANIMALS WITH A POTENTIAL ADAPTIVE ADVANTAGE IN STRESSFUL ENVIRONMENTS BUT ACROSS A LIFE SPAN IS ASSOCIATED WITH LONG-TERM DELETERIOUS EFFECTS. 2013 2 5812 40 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 3 3177 41 H3K9ME2 REGULATION OF BDNF EXPRESSION IN THE HIPPOCAMPUS AND MEDIAL PREFRONTAL CORTEX IS INVOLVED IN THE DEPRESSIVE-LIKE PHENOTYPE INDUCED BY MATERNAL SEPARATION IN MALE RATS. BACKGROUND: EARLY LIFE STRESS (ELS) INDUCES A DEPRESSIVE-LIKE PHENOTYPE AND INCREASES THE RISK OF DEPRESSION. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) HAS BEEN CONFIRMED TO BE INVOLVED IN THE PATHOPHYSIOLOGY OF DEPRESSION. HOWEVER, THE MECHANISM BY WHICH ELS ALTERS THE EPIGENETIC REGULATION OF BDNF AND CHANGES SUSCEPTIBILITY TO DEPRESSION HAS NOT BEEN FULLY CLARIFIED. METHODS: THE PRESENT STUDY USED MATERNAL SEPARATION (MS) AND CHRONIC UNPREDICTED MILD STRESS (CUMS) TO ESTABLISH AN MS ANIMAL MODEL AND A DEPRESSIVE ANIMAL MODEL. WE ASSESSED DEPRESSIVE-LIKE BEHAVIOURS, INCLUDING ANHEDONIA, LOCOMOTOR ACTIVITY, ANXIETY-LIKE BEHAVIOUR, AND SPATIAL MEMORY, USING THE SUCROSE PREFERENCE TEST, THE OPEN FIELD TEST, THE ELEVATED PLUS MAZE TEST, AND THE MORRIS WATER MAZE TEST. WE ALSO INVESTIGATED BDNF AND H3K9ME2 EXPRESSION IN THE HIPPOCAMPUS AND MEDIAL PREFRONTAL CORTEX (MPFC) BY IMMUNOHISTOCHEMISTRY, WESTERN BLOTTING, AND QPCR ANALYSIS. ADDITIONALLY, WE USED UNC0642, A SMALL MOLECULE INHIBITOR OF HISTONE METHYLTRANSFERASE (G9A), AS AN INTERVENTION. RESULTS: THE RESULTS SHOWED THAT CUMS INDUCED DEPRESSIVE-LIKE BEHAVIOURS IN RATS AND RESULTED IN INCREASED H3K9ME2 EXPRESSION AND DECREASED BDNF EXPRESSION IN THE HIPPOCAMPUS AND MPFC. MORE IMPORTANTLY, ADULT MS RATS EXPERIENCING CUMS HAD MORE SEVERE DEPRESSIVE BEHAVIOURS, HAD HIGHER EXPRESSION OF H3K9ME2 IN THE HIPPOCAMPUS AND MPFC, AND HAD LOWER EXPRESSION OF BDNF IN THE HIPPOCAMPUS AND MPFC. IN ADDITION, ADMINISTRATION OF THE G9A INHIBITOR REVERSED MOST OF THE CHANGES. CONCLUSIONS: OUR STUDY SUGGESTS THAT ELS CHANGED BDNF AND H3K9ME2 EXPRESSION IN THE RAT BRAIN, RESULTING IN A DEPRESSIVE-LIKE PHENOTYPE. 2021 4 6108 44 THE ENRICHED ENVIRONMENT AMELIORATES CHRONIC UNPREDICTABLE MILD STRESS-INDUCED DEPRESSIVE-LIKE BEHAVIORS AND COGNITIVE IMPAIRMENT BY ACTIVATING THE SIRT1/MIR-134 SIGNALING PATHWAY IN HIPPOCAMPUS. BACKGROUND: CHRONIC UNPREDICTABLE MILD STRESS (CUMS) IS AN IMPORTANT RISK FACTOR FOR DEPRESSION AND COGNITIVE DEFICITS IN HUMANS. ENRICHED ENVIRONMENT (EE) SHOWED A BENEFICIAL EFFECT ON DEPRESSION AND COGNITION BY ENHANCING BRAIN DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION AND SYNAPTIC PLASTICITY. HOWEVER, IT IS STILL NOT CLEARLY UNDERSTOOD WHETHER AN EPIGENETIC MECHANISM IS INVOLVED IN THE BDNF MODULATION AND SYNAPTIC PLASTICITY THAT OCCURS AFTER EE TREATMENT FOR THE DEPRESSIVE-LIKE BEHAVIORS AND COGNITIVE DEFICITS ELICITED BY CUMS. IN THIS STUDY, WE INVESTIGATED THE POSSIBLE MECHANISM OF THE NEUROPROTECTIVE EFFECT OF EE. METHODS: ALL RATS WERE EXPOSED TO THE 5-WEEK CUMS PROCEDURE EXCEPT THE CONTROL GROUP. AFTER CUMS PROCEDURE, SOME RATS WERE STEREOTAXICALLY INJECTED WITH SIRT1 PHARMACOLOGIC INHIBITOR EX527 OR SIRT1 KNOCKING DOWN LENTIVIRUS (SH-SIRT1) IN THE HIPPOCAMPUS FOLLOWED BY EE TREATMENT FOR 3 WEEKS. OTHER RATS WERE DIRECTLY SUBJECTED TO EE TREATMENT WITHOUT STEREOTAXIC INJECTION. BEHAVIORAL TESTS WERE USED TO APPRAISE DEPRESSION AND COGNITION AFTER EE TREATMENT. THEN EPIGENETIC MOLECULES, SYNAPTIC PROTEINS, DENDRITIC SPINE DENSITY AND BRANCHES, AND SYNAPTIC MORPHOLOGY OF THE DORSAL HIPPOCAMPUS WERE DETERMINED. RESULTS: WE FOUND THAT CUMS INDUCED DEPRESSIVE-LIKE BEHAVIORS INCLUDING DECREASED SUCROSE PREFERENCE RATIO, PROLONGED IMMOBILITY AND REDUCED LOCOMOTOR AND EXPLORATORY ACTIVITY; COGNITIVE DEFICITS INCLUDING SPATIAL LEARNING AND MEMORY IMPAIRMENT; REDUCED DENDRITIC SPINE DENSITY AND NUMBER OF BRANCHES; THINNED POSTSYNAPTIC DENSITY; DOWNREGULATED SIRT1/MICRORNA-134 PATHWAY, DECREASED BDNF AND SYNAPTIC PROTEINS INCLUDING SYNAPTOPHYSIN (SYN) AND POSTSYNAPTIC DENSITY PROTEIN 95 (PSD95) EXPRESSION IN THE HIPPOCAMPUS. HOWEVER, THE CUMS-INDUCED DEPRESSIVE-LIKE BEHAVIORS, COGNITIVE DEFICITS, DENDRITIC SPINE DENSITY AND BRANCH NUMBER REDUCTION, POSTSYNAPTIC DENSITY THINNING, SIRT1/MICRORNA-134 PATHWAY DOWNREGULATION, BDNF AND SYNAPTIC PROTEINS REDUCTION, INCLUDING SYNAPTOPHYSIN (SYN) AND POSTSYNAPTIC DENSITY PROTEIN 95 (PSD95), WERE REVERSED BY EE TREATMENT. HOWEVER, DEPRESSIVE-LIKE BEHAVIORS AND COGNITIVE DEFICITS WERE OBSERVED AGAIN IN RATS SUBJECTED TO STEREOTAXIC INJECTION WITH EX527 OR SH-SIRT1. FURTHERMORE, THIS STUDY ALSO FOUND THAT SIRT1/MICRORNA-134 REGULATES THE DOWNSTREAM MOLECULES BDNF, AND THE SYNAPTIC PROTEINS SYN AND PSD95 IN PRIMARY CULTURED HIPPOCAMPAL NEURONS. CONCLUSIONS: THIS STUDY PROVIDES EVIDENCE FOR THE NEUROPROTECTIVE ROLE OF EE ON DEPRESSION AND COGNITIVE DEFICITS BY ACTIVATING THE SIRT1/MICRORNA-134 PATHWAY, WHICH ACCOUNTS FOR THE REGULATION OF SYNAPTIC PROTEINS, INCLUDING BDNF, PSD95 AND SYN, DENDRITIC REMODELING AND ULTRASTRUCTURE CHANGES OF SYNAPSES IN THE HIPPOCAMPUS. 2019 5 869 32 CHRONIC AGOMELATINE TREATMENT CORRECTS BEHAVIORAL, CELLULAR, AND BIOCHEMICAL ABNORMALITIES INDUCED BY PRENATAL STRESS IN RATS. RATIONALE AND OBJECTIVES: THE RAT MODEL OF PRENATAL RESTRAINT STRESS (PRS) REPLICATES FACTORS THAT ARE IMPLICATED IN THE ETIOLOGY OF ANXIOUS/DEPRESSIVE DISORDERS. WE USED THIS MODEL TO TEST THE THERAPEUTIC EFFICACY OF AGOMELATINE, A NOVEL ANTIDEPRESSANT THAT BEHAVES AS A MIXED MT1/MT2 MELATONIN RECEPTOR AGONIST/5-HT(2C) SEROTONIN RECEPTOR ANTAGONIST. RESULTS: ADULT PRS RATS SHOWED BEHAVIORAL, CELLULAR, AND BIOCHEMICAL ABNORMALITIES THAT WERE CONSISTENT WITH AN ANXIOUS/DEPRESSIVE PHENOTYPE. THESE INCLUDED AN INCREASED IMMOBILITY IN THE FORCED SWIM TEST, AN ANXIETY-LIKE BEHAVIOR IN THE ELEVATED PLUS MAZE, REDUCED HIPPOCAMPAL LEVELS OF PHOSPHORYLATED CAMP-RESPONSIVE ELEMENT BINDING PROTEIN (P-CREB), REDUCED HIPPOCAMPAL LEVELS OF MGLU2/3 AND MGLU5 METABOTROPIC GLUTAMATE RECEPTORS, AND REDUCED NEUROGENESIS IN THE VENTRAL HIPPOCAMPUS, THE SPECIFIC PORTION OF THE HIPPOCAMPUS THAT ENCODES MEMORIES RELATED TO STRESS AND EMOTIONS. ALL OF THESE CHANGES WERE REVERSED BY A 3- OR 6-WEEK TREATMENT WITH AGOMELATINE (40-50 MG/KG, I.P., ONCE A DAY). REMARKABLY, AGOMELATINE HAD NO EFFECT IN AGE-MATCHED CONTROL RATS, THEREBY BEHAVING AS A "DISEASE-DEPENDENT" DRUG. CONCLUSIONS: THESE DATA INDICATE THAT AGOMELATINE DID NOT ACT ON INDIVIDUAL SYMPTOMS BUT CORRECTED ALL ASPECTS OF THE PATHOLOGICAL EPIGENETIC PROGRAMMING TRIGGERED BY PRS. OUR FINDINGS STRONGLY SUPPORT THE ANTIDEPRESSANT ACTIVITY OF AGOMELATINE AND SUGGEST THAT THE DRUG IMPACTS MECHANISMS THAT LIE AT THE CORE OF ANXIOUS/DEPRESSIVE DISORDERS. 2011 6 3977 43 LONG-TERM EFFECT OF POST-TRAUMATIC STRESS IN ADOLESCENCE ON DENDRITE DEVELOPMENT AND H3K9ME2/BDNF EXPRESSION IN MALE RAT HIPPOCAMPUS AND PREFRONTAL CORTEX. EXPOSURE TO A HARSH ENVIRONMENT IN EARLY LIFE INCREASES IN THE RISK OF POST-TRAUMATIC STRESS DISORDER (PTSD) OF AN INDIVIDUAL. BRAIN DERIVED NEUROTROPHIC FACTOR (BDNF) PLAYS AN IMPORTANT ROLE IN NEURODEVELOPMENT IN DEVELOPMENTAL STAGES. BOTH CHRONIC AND TRAUMATIC STRESSES INDUCE A DECREASE IN THE LEVEL OF BDNF AND REDUCE NEURAL PLASTICITY, WHICH IS LINKED TO THE PATHOGENESIS OF PTSD. ALSO, STUDIES HAVE SHOWN THAT STRESS ALTERS THE EPIGENETIC MARKER H3K9ME2, WHICH CAN BIND TO THE PROMOTER REGION OF THE BDNF GENE AND REDUCE BDNF PROTEIN LEVEL. HOWEVER, THE LONG-TERM EFFECTS OF TRAUMATIC STRESS DURING ADOLESCENCE ON H3K9ME2, BDNF EXPRESSION AND DENDRITE DEVELOPMENT ARE NOT WELL-KNOWN. THE PRESENT STUDY ESTABLISHED A MODEL OF PTSD IN ADOLESCENT RATS USING AN INESCAPABLE FOOT SHOCK (IFS) PROCEDURE. ANXIETY-LIKE BEHAVIORS, SOCIAL INTERACTION BEHAVIOR AND MEMORY FUNCTION WERE ASSESSED BY THE OPEN FIELD TEST, ELEVATED PLUS MAZE TEST, THREE-CHAMBER SOCIABILITY TEST AND MORRIS WATER MAZE TEST. IN ADDITION, NEURONAL DEVELOPMENT AND H3K9ME2/BDNF EXPRESSION IN HIPPOCAMPUS (HIP) AND PREFRONTAL CORTEX (PFC) WERE EVALUATED BY GOLGI STAINING, WESTERN BLOTTING, QRT-PCR ANALYSIS AND CHIP-QPCR ANALYSIS. ADDITIONALLY, THE UNC0642, A SMALL MOLECULE INHIBITOR OF HISTONE METHYLTRANSFERASE (EHMT2) WAS USED FOR INTERVENTION. THE RESULTS SHOWED THAT THE IFS PROCEDURE INDUCED THE PTSD-LIKE BEHAVIORS IN RATS, RESULTED IN FEWER DENDRITE BRANCHES AND SHORTER DENDRITE LENGTH IN CA1 OF HIP AND PFC, INCREASED H3K9ME2 LEVEL AND DECREASED BDNF EXPRESSION IN HIP AND PFC. ALSO, ALTHOUGH ALL THE CHANGES CAN PERSIST TO ADULTHOOD, UNC0642 ADMINISTRATION RELIEVED MOST OF ALTERATIONS. OUR STUDY SUGGESTS THAT TRAUMATIC STRESS IN ADOLESCENCE LEADS TO IMMEDIATE AND LONG-TERM MENTAL DISORDERS, NEURONAL MORPHOLOGICAL CHANGES, LOWER BDNF LEVEL AND INCREASED H3K9ME2 LEVEL IN THE HIP AND PFC, INDICATING THAT H3K9ME2/BDNF DYSFUNCTION PLAYS A KEY ROLE IN PATHOGENESIS OF PTSD. 2020 7 5752 39 SOCIAL ISOLATION AND SOCIAL SUPPORT AT ADULTHOOD AFFECT EPIGENETIC MECHANISMS, BRAIN-DERIVED NEUROTROPHIC FACTOR LEVELS AND BEHAVIOR OF CHRONICALLY STRESSED RATS. EPIGENETIC MODULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) PROVIDES ONE POSSIBLE EXPLANATION FOR THE DYSFUNCTIONS INDUCED BY STRESS, SUCH AS PSYCHIATRIC DISORDERS AND COGNITIVE DECLINE. INTERESTINGLY, SOCIAL SUPPORT CAN BE PROTECTIVE AGAINST SOME OF THESE EFFECTS, BUT THE MECHANISMS OF SOCIAL BUFFERING ARE POORLY UNDERSTOOD. CONVERSELY, EARLY ISOLATION EXACERBATES THE RESPONSES TO STRESSORS, ALTHOUGH ITS EFFECTS IN ADULTHOOD REMAIN UNCLEAR. THIS STUDY INVESTIGATED THE EFFECTS OF SOCIAL ISOLATION AND SOCIAL BUFFERING ON HIPPOCAMPAL EPIGENETIC MECHANISMS, BDNF LEVELS AND BEHAVIORAL RESPONSES OF CHRONICALLY STRESSED YOUNG ADULT RATS. MALE WISTAR RATS (3 MONTHS) WERE ASSIGNED TO ACCOMPANIED (PAIRED) OR ISOLATED HOUSING. AFTER ONE-MONTH HALF OF EACH GROUP WAS SUBMITTED TO A CHRONIC UNPREDICTABLE STRESS (CUS) PROTOCOL FOR 18 DAYS. AMONG ACCOMPANIED ANIMALS, ONLY ONE WAS EXPOSED TO STRESS. BEHAVIORAL ANALYSIS ENCOMPASSED THE OPEN FIELD, PLUS MAZE AND INHIBITORY AVOIDANCE TASKS. HIPPOCAMPAL H3K9 AND H4K12 ACETYLATION, HDAC5 EXPRESSION AND BDNF LEVELS WERE EVALUATED. ISOLATED HOUSING INCREASED HDAC5 EXPRESSION, DECREASED H3K9 AND H4K12 ACETYLATION, REDUCED BDNF LEVELS, AND IMPAIRED LONG-TERM MEMORY. STRESS AFFECTED WEIGHT GAIN, INDUCED ANXIETY-LIKE BEHAVIOR AND DECREASED ACK9H3 LEVELS. INTERACTIONS BETWEEN HOUSING CONDITIONS AND SOCIAL STRESS WERE SEEN ONLY FOR HDAC5 EXPRESSION, WHICH SHOWED A FURTHER INCREASE IN THE ISOLATED + CUS GROUP BUT REMAINED CONSTANT IN ACCOMPANIED ANIMALS. IN CONCLUSION, SOCIAL ISOLATION AT ADULTHOOD INDUCED EPIGENETIC ALTERATIONS AND EXACERBATED THE EFFECTS OF CHRONIC STRESS ON HDAC5. NOTWITHSTANDING, SOCIAL SUPPORT COUNTERACTED THE ADVERSE EFFECTS OF STRESS ON HDAC5 EXPRESSION. 2019 8 5019 33 PERSISTENT INFLAMMATORY PAIN IS LINKED WITH ANXIETY-LIKE BEHAVIORS, INCREASED BLOOD CORTICOSTERONE, AND REDUCED GLOBAL DNA METHYLATION IN THE RAT AMYGDALA. CHRONIC PAIN INCREASES THE RISK OF DEVELOPING ANXIETY, WITH LIMBIC AREAS BEING LIKELY NEUROLOGICAL SUBSTRATES. DESPITE HIGH CLINICAL RELEVANCE, LITTLE IS KNOWN ABOUT THE PRECISE BEHAVIORAL, HORMONAL, AND BRAIN NEUROPLASTIC CORRELATES OF ANXIETY IN THE CONTEXT OF PERSISTENT PAIN. PREVIOUS STUDIES HAVE SHOWN THAT DECREASED NOCICEPTIVE THRESHOLDS IN CHRONIC PAIN MODELS ARE PARALLELED BY ANXIETY-LIKE BEHAVIOR IN RATS, BUT THERE ARE CONFLICTING IDEAS REGARDING ITS EFFECTS ON THE STRESS RESPONSE AND CIRCULATING CORTICOSTERONE LEVELS. EVEN LESS IS KNOWN ABOUT THE MOLECULAR MECHANISMS THROUGH WHICH THE BRAIN ENCODES PAIN-RELATED ANXIETY. THIS STUDY EXAMINES HOW PERSISTENT INFLAMMATORY PAIN IN A RAT MODEL WOULD IMPACT ANXIETY-LIKE BEHAVIORS AND CORTICOSTERONE RELEASE, AND WHETHER THESE CHANGES WOULD BE REFLECTED IN LEVELS OF GLOBAL DNA METHYLATION IN BRAIN AREAS INVOLVED IN STRESS REGULATION. COMPLETE FREUND'S ADJUVANT (CFA) OR SALINE WAS ADMINISTERED IN THE RIGHT HINDPAW OF ADULT MALE WISTAR RATS. BEHAVIORAL TESTING INCLUDED THE MEASUREMENT OF NOCICEPTIVE THRESHOLDS (DIGITAL ANESTHESIOMETER), MOTOR FUNCTION (OPEN FIELD TEST), AND ANXIETY-LIKE BEHAVIORS (ELEVATED PLUS MAZE AND THE DARK-LIGHT BOX TEST). CORTICOSTERONE WAS MEASURED VIA RADIOIMMUNOASSAY. GLOBAL DNA METHYLATION (ENZYME IMMUNOASSAY) AS WELL AS DNMT3A LEVELS (WESTERN BLOTTING) WERE QUANTIFIED IN THE AMYGDALA, PREFRONTAL CORTEX, AND VENTRAL HIPPOCAMPUS. CFA ADMINISTRATION RESULTED IN PERSISTENT REDUCTION IN NOCICEPTIVE THRESHOLD IN THE ABSENCE OF LOCOMOTOR ABNORMALITIES. INCREASED ANXIETY-LIKE BEHAVIORS WERE OBSERVED IN THE ELEVATED PLUS MAZE AND WERE ACCOMPANIED BY INCREASED BLOOD CORTICOSTERONE LEVELS 10 DAYS AFTER PAIN INDUCTION. GLOBAL DNA METHYLATION WAS DECREASED IN THE AMYGDALA, WITH NO CHANGES IN DNMT3A ABUNDANCE IN ANY OF THE REGIONS EXAMINED. PERSISTENT INFLAMMATORY PAIN PROMOTES ANXIETY -LIKE BEHAVIORS, HPA AXIS ACTIVATION, AND EPIGENETIC REGULATION THROUGH DNA METHYLATION IN THE AMYGDALA. THESE FINDINGS DESCRIBE A MOLECULAR MECHANISM THAT LINKS PAIN AND STRESS IN A WELL-CHARACTERIZED RODENT MODEL. 2022 9 23 34 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 10 3313 30 HIPPOCAMPAL BDNF IN PHYSIOLOGICAL CONDITIONS AND SOCIAL ISOLATION. EXPOSURE OF AN ORGANISM TO CHRONIC PSYCHOSOCIAL STRESS MAY AFFECT BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) EXPRESSION THAT HAS BEEN IMPLICATED IN THE ETIOLOGY OF PSYCHIATRIC DISORDERS, SUCH AS DEPRESSION. GIVEN THAT DEPRESSION IN HUMANS HAS BEEN LINKED WITH SOCIAL STRESS, THE CHRONIC SOCIAL STRESS PARADIGMS FOR MODELING PSYCHIATRIC DISORDERS IN ANIMALS HAVE THUS BEEN DEVELOPED. CHRONIC SOCIAL ISOLATION IN ANIMAL MODELS GENERALLY CAUSES CHANGES IN HYPOTHALAMIC-PITUITARY-ADRENAL AXIS FUNCTIONING, ASSOCIATED WITH ANXIETY- AND DEPRESSIVE-LIKE BEHAVIORS. ALSO, THIS CHRONIC STRESS CAUSES DOWNREGULATION OF BDNF PROTEIN AND MRNA IN THE HIPPOCAMPUS, A STRESS-SENSITIVE BRAIN REGION CLOSELY RELATED TO THE PATHOPHYSIOLOGY OF DEPRESSION. IN THIS REVIEW, WE DISCUSS THE CURRENT KNOWLEDGE REGARDING THE STRUCTURE, FUNCTION, INTRACELLULAR SIGNALING, INTER-INDIVIDUAL DIFFERENCES AND EPIGENETIC REGULATION OF BDNF IN BOTH PHYSIOLOGICAL CONDITIONS AND DEPRESSION AND CHANGES IN CORTICOSTERONE LEVELS, AS A MARKER OF STRESS RESPONSE. SINCE BDNF LEVELS ARE AGE DEPENDENT IN HUMANS AND RODENTS, THIS REVIEW WILL ALSO HIGHLIGHT THE EFFECTS OF ADOLESCENT AND ADULT CHRONIC SOCIAL ISOLATION MODELS OF BOTH GENDERS ON THE BDNF EXPRESSION. 2017 11 4848 25 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 12 1005 42 CHRONIC VARIABLE PHYSICAL STRESS DURING THE PERIPUBERTAL-JUVENILE PERIOD CAUSES DIFFERENTIAL DEPRESSIVE AND ANXIOGENIC EFFECTS IN THE NOVELTY-SEEKING PHENOTYPE: FUNCTIONAL IMPLICATIONS FOR HIPPOCAMPAL AND AMYGDALAR BRAIN-DERIVED NEUROTROPHIC FACTOR AND THE MOSSY FIBRE PLASTICITY. EXPERIMENTALLY NAIVE RATS SHOW VARIANCE IN THEIR LOCOMOTOR REACTIVITY TO NOVELTY, SOME DISPLAYING HIGHER (HR) WHILE OTHERS DISPLAYING LOWER (LR) REACTIVITY, ASSOCIATED WITH VULNERABILITY TO STRESS. WE EMPLOYED A CHRONIC VARIABLE PHYSICAL STRESS REGIMEN INCORPORATING INTERMITTENT AND RANDOM EXPOSURES OF PHYSICAL STRESSORS OR CONTROL HANDLING DURING THE PERIPUBERTAL-JUVENILE PERIOD TO ASSESS INTERACTIONS BETWEEN STRESS AND THE LRHR PHENOTYPE IN DEPRESSIVE- AND ANXIETY-LIKE BEHAVIORS ON THE FORCED SWIM AND SOCIAL INTERACTION TESTS, RESPECTIVELY. A DECREASE IN IMMOBILITY IN THE FORCED SWIM TEST ALONG WITH A DECREASE IN SOCIAL CONTACT IN THE SOCIAL INTERACTION TEST WERE OBSERVED IN THE JUVENILE HRS, COUPLED WITH INCREASES IN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA IN THE HIPPOCAMPUS AND IN THE BASOLATERAL AMYGDALA WITH CHRONIC VARIABLE PHYSICAL STRESS. IN CONTRAST, AN INCREASE IN IMMOBILITY IN THE FORCED SWIM TEST AND A DECREASE IN SOCIAL CONTACT WAS OBSERVED IN THE LR COUNTERPARTS COUPLED WITH AN INCREASE IN THE BDNF MRNA IN THE BASOLATERAL AMYGDALA FOLLOWING CHRONIC VARIABLE PHYSICAL STRESS. FURTHERMORE, CHRONIC PHYSICAL STRESS LED TO INCREASED H3 AND H4 ACETYLATION AT THE P2 AND P4 PROMOTERS OF THE HIPPOCAMPAL BDNF GENE IN THE HR RATS THAT IS ASSOCIATED WITH INCREASED SUPRAPYRAMIDAL MOSSY FIBRE (SP-MF) TERMINAL FIELD VOLUME. IN CONTRAST, CHRONIC VARIABLE PHYSICAL STRESS LED TO DECREASED H4 ACETYLATION AT THE P4 PROMOTER, ASSOCIATED WITH DECREASED SP-MF VOLUME IN THE LR RATS. THESE FINDINGS SHOW DISSOCIATION IN DEPRESSIVE- AND ANXIETY-LIKE BEHAVIORS FOLLOWING CHRONIC VARIABLE PHYSICAL STRESS IN THE JUVENILE HR ANIMALS THAT MAY BE MEDIATED BY INCREASED LEVELS OF BDNF IN THE HIPPOCAMPUS AND IN THE AMYGDALA, RESPECTIVELY. MOREOVER, CHRONIC VARIABLE PHYSICAL STRESS DURING THE PERIPUBERTAL-JUVENILE PERIOD RESULTS IN OPPOSITE EFFECTS IN DEPRESSIVE-LIKE BEHAVIOR IN THE LRHR RATS BY WAY OF INDUCING DIFFERENTIAL EPIGENETIC REGULATION OF THE HIPPOCAMPAL BDNF GENE THAT, IN TURN, MAY MEDIATE MOSSY FIBRE SPROUTING. 2011 13 4632 19 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 14 3973 41 LONG-TERM BEHAVIORAL AND NEUROENDOCRINE ALTERATIONS FOLLOWING CHRONIC SOCIAL STRESS IN MICE: IMPLICATIONS FOR STRESS-RELATED DISORDERS. THE PERIOD OF ADOLESCENCE IS CHARACTERIZED BY A HIGH VULNERABILITY TO STRESS AND TRAUMA, WHICH MIGHT RESULT IN LONG-LASTING CONSEQUENCES AND AN INCREASED RISK TO DEVELOP PSYCHIATRIC DISORDERS. USING A RECENTLY DEVELOPED MOUSE MODEL FOR CHRONIC SOCIAL STRESS DURING ADOLESCENCE, WE STUDIED PERSISTENT NEUROENDOCRINE AND BEHAVIORAL EFFECTS OF CHRONIC SOCIAL STRESS OBTAINED 12 MONTHS AFTER CESSATION OF THE STRESSOR. AS A REFERENCE, WE INVESTIGATED IMMEDIATE EFFECTS OF CHRONIC STRESS EXPOSURE OBTAINED AT THE END OF THE CHRONIC STRESS PERIOD. IMMEDIATELY AFTER THE 7 WEEK CHRONIC STRESS PERIOD STRESSED ANIMALS SHOW SIGNIFICANTLY INCREASED ADRENAL WEIGHTS, DECREASED THYMUS WEIGHT, INCREASED BASAL CORTICOSTERONE SECRETION AND A FLATTENED CIRCADIAN RHYTHM. FURTHERMORE, STRESSED ANIMALS DISPLAY AN INCREASED ANXIETY-LIKE BEHAVIOR IN THE ELEVATED PLUS MAZE AND THE NOVELTY-INDUCED SUPPRESSION OF FEEDING TEST. HIPPOCAMPAL MINERALOCORTICOID RECEPTOR (MR) AND THE GLUCOCORTICOID RECEPTOR (GR) MRNA LEVELS WERE SIGNIFICANTLY DECREASED. TO INVESTIGATE PERSISTENT CONSEQUENCES OF THIS EARLY STRESSFUL EXPERIENCE, THE SAME PARAMETERS WERE ASSESSED IN AGED MICE 12 MONTHS AFTER THE CESSATION OF THE STRESSOR. INTERESTINGLY, WE STILL FOUND DIFFERENCES BETWEEN FORMERLY STRESSED AND CONTROL MICE IN IMPORTANT STRESS-RELATED PARAMETERS. MR EXPRESSION LEVELS WERE SIGNIFICANTLY LOWER IN STRESSED ANIMALS, SUGGESTING LASTING, POSSIBLY EPIGENETIC ALTERATIONS IN GENE EXPRESSION REGULATION. FURTHERMORE, WE OBSERVED LONG-TERM BEHAVIORAL ALTERATIONS IN ANIMALS STRESSED DURING ADOLESCENCE. THUS, WE COULD DEMONSTRATE THAT CHRONIC STRESS EXPOSURE DURING A CRUCIAL DEVELOPMENTAL TIME PERIOD RESULTS IN LONG-TERM, PERSISTENT EFFECTS ON PHYSIOLOGICAL AND BEHAVIORAL PARAMETERS THROUGHOUT LIFE, WHICH MAY CONTRIBUTE TO AN ENHANCED VULNERABILITY TO STRESS-INDUCED DISEASES. 2008 15 3312 37 HIPPOCAMPAL AND BEHAVIORAL DYSFUNCTIONS IN A MOUSE MODEL OF ENVIRONMENTAL STRESS: NORMALIZATION BY AGOMELATINE. STRESS-INDUCED ALTERATIONS IN NEURONAL PLASTICITY AND IN HIPPOCAMPAL FUNCTIONS HAVE BEEN SUGGESTED TO BE INVOLVED IN THE DEVELOPMENT OF MOOD DISORDERS. IN THIS CONTEXT, WE INVESTIGATED IN THE HIPPOCAMPUS THE ACTIVATION OF INTRACELLULAR SIGNALING CASCADES, THE EXPRESSION OF EPIGENETIC MARKERS AND PLASTICITY-RELATED GENES IN A MOUSE MODEL OF STRESS-INDUCED HYPERACTIVITY AND OF MIXED AFFECTIVE DISORDERS. WE ALSO DETERMINED WHETHER THE ANTIDEPRESSANT DRUG AGOMELATINE, A MT1/MT2 MELATONERGIC RECEPTOR AGONIST/5-HT2C RECEPTOR ANTAGONIST, COULD PREVENT SOME NEUROBIOLOGICAL AND BEHAVIORAL ALTERATIONS PRODUCED BY STRESS. C57BL/6J MICE, EXPOSED FOR 3 WEEKS TO DAILY UNPREDICTABLE SOCIO-ENVIRONMENTAL STRESSORS OF MILD INTENSITY, WERE TREATED DURING THE WHOLE PROCEDURE WITH AGOMELATINE (50 MG KG(-1) PER DAY, INTRAPERITONEAL). STRESSED MICE DISPLAYED ROBUST INCREASES IN EMOTIONAL AROUSAL, VIGILANCE AND MOTOR ACTIVITY, TOGETHER WITH A REWARD DEFICIT AND A REDUCTION IN ANXIETY-LIKE BEHAVIOR. NEUROBIOLOGICAL INVESTIGATIONS SHOWED AN INCREASED PHOSPHORYLATION OF INTRACELLULAR SIGNALING PROTEINS, INCLUDING ATF1, CREB AND P38, IN THE HIPPOCAMPUS OF STRESSED MICE. DECREASED HIPPOCAMPAL LEVEL OF THE REPRESSIVE EPIGENETIC MARKS HDAC2 AND H3K9ME2, AS WELL AS INCREASED LEVEL OF THE PERMISSIVE MARK H3K9/14AC SUGGESTED THAT CHRONIC MILD STRESS WAS ASSOCIATED WITH INCREASED GENE TRANSCRIPTION, AND CLEAR-CUT EVIDENCE WAS FURTHER INDICATED BY CHANGES IN NEUROPLASTICITY-RELATED GENES, INCLUDING ARC, BCL2, BDNF, GDNF, IGF1 AND NEUROD1. TOGETHER WITH OTHER FINDINGS, THE PRESENT DATA SUGGEST THAT CHRONIC ULTRA-MILD STRESS CAN MODEL THE HYPERACTIVITY OR PSYCHOMOTOR AGITATION, AS WELL AS THE MIXED AFFECTIVE BEHAVIORS OFTEN OBSERVED DURING THE MANIC STATE OF BIPOLAR DISORDER PATIENTS. INTERESTINGLY, AGOMELATINE COULD NORMALIZE BOTH THE BEHAVIORAL AND THE MOLECULAR ALTERATIONS INDUCED BY STRESS, PROVIDING FURTHER INSIGHTS INTO THE MECHANISM OF ACTION OF THIS NEW GENERATION ANTIDEPRESSANT DRUG. 2014 16 1548 42 DNA METHYLATION IN THE DEVELOPING HIPPOCAMPUS AND AMYGDALA OF ANXIETY-PRONE VERSUS RISK-TAKING RATS. ALL ORGANISMS EXHIBIT A WIDE RANGE OF EMOTIONAL BEHAVIORS AND INTERACT WITH THE ENVIRONMENT IN DIFFERENT WAYS. SOME INDIVIDUALS MAY BE MORE QUIET AND SHY WHEREAS OTHERS ARE MORE OUTGOING AND ADVENTUROUS. THESE TEMPERAMENTAL AND PERSONALITY DIFFERENCES CAN PREDISPOSE INDIVIDUALS TO CERTAIN PSYCHOPATHOLOGIES WHICH MAY BE INFLUENCED BY GENETIC VULNERABILITY AND/OR EARLY LIFE EXPERIENCES. RODENT MODELS CAN BE USED TO RECAPITULATE EMOTIONAL REACTIVITY DIFFERENCES, AND THESE MODELS CAN, IN TURN, BE USED TO EXAMINE POTENTIAL NEUROBIOLOGICAL UNDERPINNINGS OF THESE TRAITS. THE PRESENT STUDY UTILIZES TWO STRAINS OF RATS THAT WERE SELECTIVELY BRED FOR DIFFERENCES IN NOVELTY SEEKING. HIGH NOVELTY-RESPONDING (BHR) RATS ARE VERY ACTIVE IN RESPONSE TO NOVELTY, EXHIBIT EXAGGERATED RISK-TAKING, AGGRESSION, IMPULSIVITY, AND SHOW INCREASED BEHAVIORAL RESPONSE TO COCAINE. LOW NOVELTY-RESPONDING (BLR) RATS SHOW INCREASED ANXIETY, DEPRESSIVE BEHAVIOR AND VULNERABILITY TO CHRONIC STRESS. ONE WAY IN WHICH THE BHR VERSUS BLR BEHAVIORAL PHENOTYPES MAY DIFFER IS THROUGH EPIGENETIC MODIFICATION OF DNA. DNA CAN BE MODIFIED THROUGH PROCESSES SUCH AS ACETYLATION OR METHYLATION TO EITHER ENHANCE OR SUBDUE GENE EXPRESSION. THIS STUDY EXAMINES PUTATIVE DIFFERENCES IN METHYLATION LEVELS IN THE HIPPOCAMPUS AND AMYGDALA OF DEVELOPING BHR-BLR RATS. PREVIOUS RESEARCH OBSERVED WIDESPREAD GENE EXPRESSION DIFFERENCES IN THE BLR DEVELOPING HIPPOCAMPUS, AND THE CURRENT STUDY AIMS TO BEGIN TO EXAMINE POTENTIAL EPIGENETIC FACTORS THAT MAY CONTRIBUTE TO THOSE GENE DIFFERENCES. THE AMYGDALA WAS CHOSEN BECAUSE IT IS INVOLVED IN EMOTIONAL PROCESSES, IN PART THROUGH ITS CONNECTIONS WITH THE HIPPOCAMPUS. THEREFORE, THE PRESENT STUDY USED IN SITU HYBRIDIZATION TO ASSESS THE EXPRESSION OF DNA METHYLTRANSFERASE-1 (DNMT1) MRNA IN THE HIPPOCAMPUS, AMYGDALA AND SEVERAL OTHER BRAIN AREAS OF BHR AND BLR PUPS AT THREE DEVELOPMENTAL TIME POINTS: POSTNATAL DAYS (P) 7, 14, AND 21. WE FOCUSED ON THE FIRST 3 POSTNATAL WEEKS, IN PART TO PARALLEL OUR EARLY MICROARRAY GENE EXPRESSION WORK, AND BECAUSE THIS REPRESENTS A CRITICAL PERIOD OF BRAIN DEVELOPMENT, WHICH SHAPES INDIVIDUALS' LIFELONG EMOTIONAL AND STRESS REACTIVITY. WE FOUND SIGNIFICANT DIFFERENCES IN DENTATE GYRUS AND CA3 REGIONS OF THE HIPPOCAMPUS AT P7 WITH NO DIFFERENCES SEEN AT P14 OR P21. INTERESTINGLY, WE ALSO FOUND SIGNIFICANT BHR-BLR DNMT1 DIFFERENCES AT P7 WITHIN THE LATERAL, BASOLATERAL AND MEDIAL NUCLEI OF THE AMYGDALA, WITH NO DIFFERENCE AT P14 AND P21, SUGGESTING THAT THE FIRST POSTNATAL WEEK IS A CRITICAL PERIOD FOR DNA METHYLATION DURING BRAIN DEVELOPMENT. 2012 17 5310 23 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 18 6266 21 THE NEUROBIOLOGY OF SUICIDE. THE STRESS-DIATHESIS MODEL POSITS THAT SUICIDE IS THE RESULT OF AN INTERACTION BETWEEN STATE-DEPENDENT (ENVIRONMENTAL) STRESSORS AND A TRAIT-LIKE DIATHESIS OR SUSCEPTIBILITY TO SUICIDAL BEHAVIOUR, INDEPENDENT OF PSYCHIATRIC DISORDERS. FINDINGS FROM POST-MORTEM STUDIES OF THE BRAIN AND FROM GENOMIC AND IN-VIVO NEUROIMAGING STUDIES INDICATE A BIOLOGICAL BASIS FOR THIS DIATHESIS, INDICATING THE IMPORTANCE OF NEUROBIOLOGICAL SCREENING AND INTERVENTIONS, IN ADDITION TO COGNITIVE AND MOOD INTERVENTIONS, IN THE PREVENTION OF SUICIDE. EARLY-LIFE ADVERSITY AND EPIGENETIC MECHANISMS MIGHT EXPLAIN SOME OF THE LINK BETWEEN SUICIDE RISK AND BRAIN CIRCUITRY AND NEUROCHEMISTRY ABNORMALITIES. RESULTS FROM A RANGE OF STUDIES USING DIVERSE DESIGNS AND POST-MORTEM AND IN-VIVO TECHNIQUES SHOW IMPAIRMENTS OF THE SEROTONIN NEUROTRANSMITTER SYSTEM AND THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS STRESS-RESPONSE SYSTEM IN THE DIATHESIS FOR SUICIDAL BEHAVIOUR. THESE IMPAIRMENTS MANIFEST AS IMPAIRED COGNITIVE CONTROL OF MOOD, PESSIMISM, REACTIVE AGGRESSIVE TRAITS, IMPAIRED PROBLEM SOLVING, OVER-REACTIVITY TO NEGATIVE SOCIAL SIGNS, EXCESSIVE EMOTIONAL PAIN, AND SUICIDAL IDEATION, LEADING TO SUICIDAL BEHAVIOUR. BIOMARKERS RELATED TO THE DIATHESIS MIGHT HELP TO INFORM RISK-ASSESSMENT PROCEDURES AND TREATMENT CHOICE IN THE PREVENTION OF SUICIDE. 2014 19 2187 40 EPIGENETIC MECHANISMS UNDERLYING STRESS-INDUCED VISCERAL PAIN: RESILIENCE VERSUS VULNERABILITY IN A TWO-HIT MODEL OF EARLY LIFE STRESS AND CHRONIC ADULT STRESS. BACKGROUND: WOMEN WITH A HISTORY OF EARLY LIFE STRESS (ELS) HAVE A HIGHER RISK OF DEVELOPING IRRITABLE BOWEL SYNDROME (IBS). IN ADDITION, CHRONIC STRESS IN ADULTHOOD CAN EXACERBATE IBS SYMPTOMS SUCH AS ABDOMINAL PAIN DUE TO VISCERAL HYPERSENSITIVITY. WE PREVIOUSLY SHOWED THAT SEX AND THE PREDICTABILITY OF ELS DETERMINE WHETHER RATS DEVELOP VISCERAL HYPERSENSITIVITY IN ADULTHOOD. IN FEMALE RATS, UNPREDICTABLE ELS CONFERS VULNERABILITY AND RESULTS IN VISCERAL HYPERSENSITIVITY, WHEREAS PREDICTABLE ELS INDUCES RESILIENCE AND DOES NOT INDUCE VISCERAL HYPERSENSITIVITY IN ADULTHOOD. HOWEVER, THIS RESILIENCE IS LOST AFTER EXPOSURE TO CHRONIC STRESS IN ADULTHOOD LEADING TO AN EXACERBATION OF VISCERAL HYPERSENSITIVITY. EVIDENCE SUGGESTS THAT CHANGES IN HISTONE ACETYLATION AT THE PROMOTER REGIONS OF GLUCOCORTICOID RECEPTOR (GR) AND CORTICOTROPHIN-RELEASING FACTOR (CRF) IN THE CENTRAL NUCLEUS OF THE AMYGDALA (CEA) UNDERLIE STRESS-INDUCED VISCERAL HYPERSENSITIVITY. HERE, WE AIMED TO INVESTIGATE THE ROLE OF HISTONE ACETYLATION IN THE CEA ON VISCERAL HYPERSENSITIVITY IN A TWO-HIT MODEL OF ELS FOLLOWED BY CHRONIC STRESS IN ADULTHOOD. METHODS: MALE AND FEMALE NEONATAL RATS WERE EXPOSED TO UNPREDICTABLE, PREDICTABLE ELS, OR ODOR ONLY (NO STRESS CONTROL) FROM POSTNATAL DAYS 8 TO 12. IN ADULTHOOD, RATS UNDERWENT STEREOTAXIC IMPLANTATION OF INDWELLING CANNULAS. RATS WERE EXPOSED TO CHRONIC WATER AVOIDANCE STRESS (WAS, 1 H/DAY FOR 7 DAYS) OR SHAM STRESS AND RECEIVED INFUSIONS OF VEHICLE, THE HISTONE DEACETYLASE INHIBITOR TRICHOSTATIN A (TSA) OR THE HISTONE ACETYLTRANSFERASE INHIBITOR GARCINOL (GAR) AFTER EACH WAS SESSION. 24 H AFTER THE FINAL INFUSION, VISCERAL SENSITIVITY WAS ASSESSED AND THE CEA WAS REMOVED FOR MOLECULAR EXPERIMENTS. RESULTS: IN THE TWO-HIT MODEL (ELS + WAS), FEMALE RATS PREVIOUSLY EXPOSED TO PREDICTABLE ELS, SHOWED A SIGNIFICANT REDUCTION IN HISTONE 3 LYSINE 9 (H3K9) ACETYLATION AT THE GR PROMOTER AND A SIGNIFICANT INCREASE IN H3K9 ACETYLATION AT THE CRF PROMOTER. THESE EPIGENETIC CHANGES WERE ASSOCIATED WITH CHANGES IN GR AND CRF MRNA EXPRESSION IN THE CEA AND AN EXACERBATION OF STRESS-INDUCED VISCERAL HYPERSENSITIVITY IN FEMALE ANIMALS. TSA INFUSIONS IN THE CEA ATTENUATED THE EXACERBATED STRESS-INDUCED VISCERAL HYPERSENSITIVITY, WHEREAS GAR INFUSIONS ONLY PARTIALLY AMELIORATED ELS+WAS INDUCED VISCERAL HYPERSENSITIVITY. CONCLUSION: THE TWO-HIT MODEL OF ELS FOLLOWED BY WAS IN ADULTHOOD REVEALED THAT EPIGENETIC DYSREGULATION OCCURS AFTER EXPOSURE TO STRESS IN TWO IMPORTANT PERIODS OF LIFE AND CONTRIBUTES TO THE DEVELOPMENT OF VISCERAL HYPERSENSITIVITY. THESE ABERRANT UNDERLYING EPIGENETIC CHANGES MAY EXPLAIN THE EXACERBATION OF STRESS-INDUCED ABDOMINAL PAIN IN IBS PATIENTS. 2023 20 1783 32 EFFECT OF AGOMELATINE ON MEMORY DEFICITS AND HIPPOCAMPAL GENE EXPRESSION INDUCED BY CHRONIC SOCIAL DEFEAT STRESS IN MICE. CHRONIC STRESS IS KNOWN TO INDUCE NOT ONLY ANXIETY AND DEPRESSIVE-LIKE PHENOTYPES IN MICE BUT ALSO COGNITIVE IMPAIRMENTS, FOR WHICH THE ACTION OF CLASSICAL ANTIDEPRESSANT COMPOUNDS REMAINS UNSATISFACTORY. IN THIS CONTEXT, WE INVESTIGATED THE EFFECTS OF CHRONIC SOCIAL DEFEAT STRESS (CSDS) ON ANXIETY-, SOCIAL- AND COGNITIVE-RELATED BEHAVIORS, AS WELL AS HIPPOCAMPAL BDNF, SYNAPTIC PLASTICITY MARKERS (PSD-95, SYNAPTOPHYSIN, SPINOPHILIN, SYNAPSIN I AND MAP-2), AND EPIGENETIC MODIFYING ENZYMES (MYST2, HDAC2, HDAC6, MLL3, KDM5B, DNMT3B, GADD45B) GENE EXPRESSION IN C57BL/6J MICE. CSDS FOR 10 DAYS PROVOKED LONG-LASTING ANXIOUS-LIKE PHENOTYPE IN THE OPEN FIELD AND EPISODIC MEMORY DEFICITS IN THE NOVEL OBJECT RECOGNITION TEST. WHILE TOTAL BDNF MRNA LEVEL WAS UNCHANGED, BDNF EXON IV, MAP-2, HDAC2, HDAC6 AND MLL3 GENE EXPRESSION WAS SIGNIFICANTLY DECREASED IN THE CSDS MOUSE HIPPOCAMPUS. IN CSDS MICE TREATED 3 WEEKS WITH 50 MG/KG/D AGOMELATINE, AN ANTIDEPRESSANT WITH MELATONERGIC RECEPTOR AGONIST AND 5-HT(2C) RECEPTOR ANTAGONIST PROPERTIES, THE ANXIOUS-LIKE PHENOTYPE WAS NOT REVERSED, BUT THE TREATMENT SUCCESSFULLY PREVENTED THE COGNITIVE IMPAIRMENTS AND HIPPOCAMPAL GENE EXPRESSION MODIFICATIONS. ALTOGETHER, THESE DATA EVIDENCED THAT, IN MICE, AGOMELATINE WAS EFFECTIVE IN ALLEVIATING STRESS-INDUCED ALTERED COGNITIVE FUNCTIONS, POSSIBLY THROUGH A MECHANISM INVOLVING BDNF SIGNALING, SYNAPTIC PLASTICITY AND EPIGENETIC REMODELING. 2017