1 2827 144 FLUOXETINE INCREASES HIPPOCAMPAL NEUROGENESIS AND INDUCES EPIGENETIC FACTORS BUT DOES NOT IMPROVE FUNCTIONAL RECOVERY AFTER TRAUMATIC BRAIN INJURY. THE SELECTIVE SEROTONIN REUPTAKE INHIBITOR FLUOXETINE INDUCES HIPPOCAMPAL NEUROGENESIS, STIMULATES MATURATION AND SYNAPTIC PLASTICITY OF ADULT HIPPOCAMPAL NEURONS, AND REDUCES MOTOR/SENSORY AND MEMORY IMPAIRMENTS IN SEVERAL CNS DISORDERS. IN THE SETTING OF TRAUMATIC BRAIN INJURY (TBI), ITS EFFECTS ON NEUROPLASTICITY AND FUNCTION HAVE YET TO BE THOROUGHLY INVESTIGATED. HERE WE EXAMINED THE EFFICACY OF FLUOXETINE AFTER A MODERATE TO SEVERE TBI, PRODUCED BY A CONTROLLED CORTICAL IMPACT. THREE DAYS AFTER TBI OR SHAM SURGERY, MICE WERE TREATED WITH FLUOXETINE (10 MG/KG/D) OR VEHICLE FOR 4 WEEKS. TO EVALUATE THE EFFECTS OF FLUOXETINE ON NEUROPLASTICITY, HIPPOCAMPAL NEUROGENESIS AND EPIGENETIC MODIFICATION WERE STUDIED. STEREOLOGIC ANALYSIS OF THE DENTATE GYRUS REVEALED A SIGNIFICANT INCREASE IN DOUBLECORTIN-POSITIVE CELLS IN BRAIN-INJURED ANIMALS TREATED WITH FLUOXETINE RELATIVE TO CONTROLS, A FINDING CONSISTENT WITH ENHANCED HIPPOCAMPAL NEUROGENESIS. EPIGENETIC MODIFICATIONS, INCLUDING AN INCREASE IN HISTONE 3 ACETYLATION AND INDUCTION OF METHYL-CPG-BINDING PROTEIN, A TRANSCRIPTION FACTOR INVOLVED IN DNA METHYLATION, WERE LIKEWISE SEEN BY IMMUNOHISTOCHEMISTRY AND QUANTITATIVE WESTERN IMMUNOBLOTS, RESPECTIVELY, IN BRAIN-INJURED ANIMALS TREATED WITH FLUOXETINE. TO DETERMINE IF FLUOXETINE IMPROVES NEUROLOGICAL OUTCOMES AFTER TBI, GAIT FUNCTION AND SPATIAL LEARNING AND MEMORY WERE ASSESSED BY THE CATWALK-ASSISTED GAIT TEST AND BARNES MAZE TEST, RESPECTIVELY. NO DIFFERENCES IN THESE PARAMETERS WERE SEEN BETWEEN FLUOXETINE- AND VEHICLE-TREATED ANIMALS. THUS WHILE FLUOXETINE ENHANCED NEUROPLASTICITY IN THE HIPPOCAMPUS AFTER TBI, ITS CHRONIC ADMINISTRATION DID NOT RESTORE LOCOMOTOR FUNCTION OR AMELIORATE MEMORY DEFICITS. 2011 2 1999 29 EPIGENETIC AND NEURONAL ACTIVITY MARKERS SUGGEST THE RECRUITMENT OF THE PREFRONTAL CORTEX AND HIPPOCAMPUS IN THE THREE-HIT MODEL OF DEPRESSION IN MALE PACAP HETEROZYGOUS MICE. DEPRESSION AND ITS INCREASING PREVALENCE CHALLENGE PATIENTS, THE HEALTHCARE SYSTEM, AND THE ECONOMY. WE RECENTLY CREATED A MOUSE MODEL BASED ON THE THREE-HIT CONCEPT OF DEPRESSION. AS GENETIC PREDISPOSITION (FIRST HIT), WE APPLIED PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE HETEROZYGOUS MICE ON CD1 BACKGROUND. MATERNAL DEPRIVATION MODELED THE EPIGENETIC FACTOR (SECOND HIT), AND THE CHRONIC VARIABLE MILD STRESS WAS THE ENVIRONMENTAL FACTOR (THIRD HIT). FLUOXETINE TREATMENT WAS APPLIED TO TEST THE PREDICTIVE VALIDITY OF OUR MODEL. WE AIMED TO EXAMINE THE DYNAMICS OF THE EPIGENETIC MARKER ACETYL-LYSINE 9 H3 HISTONE (H3K9AC) AND THE NEURONAL ACTIVITY MARKER FOSB IN THE PREFRONTAL CORTEX (PFC) AND HIPPOCAMPUS. FLUOXETINE DECREASED H3K9AC IN PFC IN NON-DEPRIVED ANIMALS, BUT A HISTORY OF MATERNAL DEPRIVATION ABOLISHED THE EFFECT OF STRESS AND SSRI TREATMENT ON H3K9AC IMMUNOREACTIVITY. IN THE HIPPOCAMPUS, STRESS DECREASED, WHILE SSRI INCREASED H3K9AC IMMUNOSIGNAL, UNLIKE IN THE DEPRIVED MICE, WHERE THE OPPOSITE EFFECT WAS DETECTED. FOSB IN STRESS WAS STIMULATED BY FLUOXETINE IN THE PFC, WHILE IT WAS INHIBITED IN THE HIPPOCAMPUS. THE FOSB IMMUNOREACTIVITY WAS ALMOST COMPLETELY ABOLISHED IN THE HIPPOCAMPUS OF THE DEPRIVED MICE. THIS STUDY SHOWED THAT FOSB AND H3K9AC WERE MODULATED IN A TERRITORY-SPECIFIC MANNER BY EARLY LIFE ADVERSITIES AND LATER LIFE STRESS INTERACTING WITH THE EFFECT OF FLUOXETINE THERAPY SUPPORTING THE RELIABILITY OF OUR MODEL. 2022 3 1003 36 CHRONIC TREATMENT WITH FLUOXETINE INDUCES SEX-DEPENDENT ANALGESIC EFFECTS AND MODULATES HDAC2 AND MGLU2 EXPRESSION IN FEMALE MICE. GENDER AND SEX DIFFERENCES IN PAIN RECOGNITION AND DRUG RESPONSES HAVE BEEN REPORTED IN CLINICAL TRIALS AND EXPERIMENTAL MODELS OF PAIN. AMONG ANTIDEPRESSANTS, CONTRADICTORY RESULTS HAVE BEEN OBSERVED IN PATIENTS TREATED WITH SELECTIVE SEROTONIN REUPTAKE INHIBITORS (SSRIS). THIS STUDY EVALUATED SEX DIFFERENCES IN RESPONSE TO THE SSRI FLUOXETINE AFTER CHRONIC ADMINISTRATION IN THE MOUSE FORMALIN TEST. ADULT MALE AND FEMALE CD1 MICE WERE INTRAPERITONEALLY INJECTED WITH FLUOXETINE (10 MG/KG) FOR 21 DAYS AND SUBJECTED TO PAIN ASSESSMENT. FLUOXETINE TREATMENT REDUCED THE SECOND PHASE OF THE FORMALIN TEST ONLY IN FEMALE MICE WITHOUT PRODUCING BEHAVIORAL CHANGES IN MALES. WE ALSO OBSERVED THAT FLUOXETINE WAS ABLE TO SPECIFICALLY INCREASE THE EXPRESSION OF METABOTROPIC GLUTAMATE RECEPTOR TYPE-2 (MGLU2) IN FEMALES. ALSO A REDUCED EXPRESSION OF THE EPIGENETIC MODIFYING ENZYME, HISTONE DEACETYLASE 2 (HDAC2), IN DORSAL ROOT GANGLIA (DRG) AND DORSAL HORN (DH) TOGETHER WITH AN INCREASE HISTONE 3 ACETYLATION (H3) LEVEL WAS OBSERVED IN FEMALES BUT NOT IN MALES. WITH THIS STUDY WE PROVIDE EVIDENCE THAT FLUOXETINE INDUCES SEX SPECIFIC CHANGES IN HDAC2 AND MGLU2 EXPRESSION IN THE DH OF THE SPINAL CORD AND IN DRGS AND SUGGESTS A MOLECULAR EXPLANATION FOR THE ANALGESIC EFFECTS IN FEMALE MICE. 2017 4 2826 36 FLUOXETINE EPIGENETICALLY ALTERS THE CAMKIIALPHA PROMOTER IN NUCLEUS ACCUMBENS TO REGULATE DELTAFOSB BINDING AND ANTIDEPRESSANT EFFECTS. CHRONIC SOCIAL DEFEAT STRESS IN MICE PRODUCES A SUSCEPTIBLE PHENOTYPE CHARACTERIZED BY SEVERAL BEHAVIORAL ABNORMALITIES CONSISTENT WITH HUMAN DEPRESSION THAT ARE REVERSED BY CHRONIC BUT NOT ACUTE EXPOSURE TO ANTIDEPRESSANT MEDICATIONS. RECENT WORK IN ADDICTION MODELS DEMONSTRATES THAT THE TRANSCRIPTION FACTOR DELTAFOSB AND PROTEIN KINASE CALMODULIN-DEPENDENT PROTEIN KINASE II (CAMKII) ARE CO-REGULATED IN NUCLEUS ACCUMBENS (NAC), A BRAIN REWARD REGION IMPLICATED IN BOTH ADDICTION AND DEPRESSION MODELS INCLUDING SOCIAL DEFEAT. PREVIOUS WORK HAS ALSO DEMONSTRATED THAT DELTAFOSB IS INDUCED IN NAC AFTER CHRONIC SOCIAL DEFEAT STRESS OR AFTER CHRONIC ANTIDEPRESSANT TREATMENT, WHEREIN IT MEDIATES A PRO-RESILIENCE OR ANTIDEPRESSANT-LIKE PHENOTYPE. HERE, USING CHROMATIN IMMUNOPRECIPITATION ASSAYS, WE FOUND THAT DELTAFOSB BINDS THE CAMKIIALPHA GENE PROMOTER IN NAC AND THAT THIS BINDING INCREASES AFTER MICE ARE EXPOSED TO CHRONIC SOCIAL DEFEAT STRESS. PARADOXICALLY, CHRONIC EXPOSURE TO THE ANTIDEPRESSANT FLUOXETINE REDUCES BINDING OF DELTAFOSB TO THE CAMKIIALPHA PROMOTER AND REDUCES CAMKII EXPRESSION IN NAC, DESPITE THE FACT THAT DELTAFOSB IS INDUCED UNDER THESE CONDITIONS. THESE DATA SUGGEST A NOVEL EPIGENETIC MECHANISM OF ANTIDEPRESSANT ACTION, WHEREBY FLUOXETINE INDUCES SOME CHROMATIN CHANGE AT THE CAMKIIALPHA PROMOTER, WHICH BLOCKS THE DELTAFOSB BINDING. INDEED, CHRONIC FLUOXETINE REDUCES ACETYLATION AND INCREASES LYSINE-9 DIMETHYLATION OF HISTONE H3 AT THE CAMKIIALPHA PROMOTER IN NAC, EFFECTS ALSO SEEN IN DEPRESSED HUMANS EXPOSED TO ANTIDEPRESSANTS. OVEREXPRESSION OF CAMKII IN NAC BLOCKS FLUOXETINE'S ANTIDEPRESSANT EFFECTS IN THE CHRONIC SOCIAL DEFEAT PARADIGM, WHEREAS INHIBITION OF CAMKII ACTIVITY IN NAC MIMICS FLUOXETINE EXPOSURE. THESE FINDINGS SUGGEST THAT EPIGENETIC SUPPRESSION OF CAMKIIALPHA EXPRESSION IN NAC IS BEHAVIORALLY RELEVANT AND OFFER A NOVEL PATHWAY FOR POSSIBLE THERAPEUTIC INTERVENTION IN DEPRESSION AND RELATED SYNDROMES. 2014 5 3177 37 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 6 6388 32 THE ROLE OF SIRT1 IN THE BASOLATERAL AMYGDALA IN DEPRESSION-LIKE BEHAVIORS IN MICE. PREVIOUS INVESTIGATIONS HAVE IMPLICATED THE BASOLATERAL AMYGDALA (BLA) EPIGENETIC MECHANISMS IN THE PATHOPHYSIOLOGY OF DEPRESSION. SIRT1 IS A NAD+-DEPENDENT CLASS III HISTONE DEACETYLASE, WIDELY EXPRESSES IN BLA. HOWEVER, EPIGENETIC MECHANISMS IN THE BLA UNDER THE REGULATION OF SIRT1 IN THE DEPRESSION ARE LARGELY UNCHARACTERIZED. UNDER THE CHRONIC UNPREDICTABLE CHRONIC MILD STRESS (CUMS) MOUSE MODEL, WE USED ADENO-ASSOCIATED VIRAL VECTORS (AAV) THAT ENCODED SIRT1-SHRNA OR SIRT1 TO SPECIFICALLY KNOCKDOWN OR OVEREXPRESS SIRT1 IN BLA NEURONS, RESPECTIVELY. CUMS PROCEDURE INDUCED SIGNIFICANT DEPRESSION SYMPTOMS INCLUDING THE DECREASED SUCROSE PREFERENCE, THE LESS BODYWEIGHT GAINED, THE DECREASED IMMOBILE LATENCY AND THE INCREASED IMMOBILE TIME BOTH IN FORCED SWIM TEST (FST) AND TAIL SUSPENSION TEST (TST). KNOCKDOWN OF SIRT1 IN BLA GLUTAMATERGIC NEURONS REVERSED THESE DEPRESSION-LIKE BEHAVIORS AND RESTORED THE SYNAPTIC ABNORMALITIES. OVEREXPRESSION OF SIRT1 IN BLA GLUTAMATERGIC NEURONS INDUCED DEPRESSION-LIKE BEHAVIORS IN NON-STRESSED CONTROL MICE. THE RESULT OF PROTEIN EXPRESSIONS AND ULTRASTRUCTURAL CHANGES WERE CONSISTENT WITH THE BEHAVIORAL RESULTS. OUR STUDY SUGGESTED THAT DOWNREGULATION OF SIRT1 IN BLA HAS CERTAIN BENEFICIAL EFFECT ON CUMS-INDUCED DEPRESSION-LIKE BEHAVIORS SUCH AS ANOREXIA, ANHEDONIA, HOPELESSNESS AND DESPAIR. IN ADDITION, THE INCREASED EXPRESSION OF SIRT1 MAY BE THE IMMEDIATE CAUSE OF DEPRESSIVE-LIKE SYMPTOMS. THE ABNORMAL EXPRESSION OF SIRT1 MAY AFFECT THE TRANSCRIPTIONAL REGULATION MECHANISM AND SIGNALING PROTEIN ACETYLATION, AFFECTING NEUROPLASTICITY AND ULTIMATELY CONTRIBUTE TO MDD. IN THE STRESS-SUSCEPTIBLE MICE, THESE TWO MECHANISMS MAY CO-EXIST, BUT THE SPECIFIC MECHANISM NEEDS FURTHER RESEARCH. 2021 7 6108 39 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 8 2828 28 FLUOXETINE TREATMENT SUPPORTS PREDICTIVE VALIDITY OF THE THREE HIT MODEL OF DEPRESSION IN MALE PACAP HETEROZYGOUS MICE AND UNDERPINS THE IMPACT OF EARLY LIFE ADVERSITY ON THERAPEUTIC EFFICACY. ACCORDING TO THE THREE HIT CONCEPT OF DEPRESSION, INTERACTION OF GENETIC PREDISPOSITION ALTERED EPIGENETIC PROGRAMMING AND ENVIRONMENTAL STRESS FACTORS CONTRIBUTE TO THE DISEASE. EARLIER WE DEMONSTRATED THE CONSTRUCT AND FACE VALIDITY OF OUR THREE HIT CONCEPT-BASED MOUSE MODEL. IN THE PRESENT WORK, WE AIMED TO EXAMINE THE PREDICTIVE VALIDITY OF OUR MODEL, THE THIRD WILLNERIAN CRITERION. FLUOXETINE TREATMENT WAS APPLIED IN CHRONIC VARIABLE MILD STRESS (CVMS)-EXPOSED (ENVIRONMENTAL HIT) CD1 MICE CARRYING ONE MUTATED ALLELE OF PITUITARY ADENYLATE CYCLASE-ACTIVATING POLYPEPTIDE GENE (GENETIC HIT) THAT WERE PREVIOUSLY EXPOSED TO MATERNAL DEPRIVATION (EPIGENETIC HIT) VS. CONTROLS. FLUOXETINE REDUCED THE ANXIETY LEVEL IN CVMS-EXPOSED MICE IN MARBLE BURYING TEST, AND DECREASED THE DEPRESSION LEVEL IN TAIL SUSPENSION TEST IF MICE WERE NOT DEPRIVED MATERNALLY. HISTORY OF MATERNAL DEPRIVATION CAUSED FUNDAMENTAL FUNCTIONAL-MORPHOLOGICAL CHANGES IN RESPONSE TO CVMS AND FLUOXETINE TREATMENT IN THE CORTICOTROPIN-RELEASING HORMONE-PRODUCING CELLS OF THE BED NUCLEUS OF THE STRIA TERMINALIS AND CENTRAL AMYGDALA, IN TYROSINE-HYDROXYLASE CONTENT OF VENTRAL TEGMENTAL AREA, IN UROCORTIN 1-EXPRESSING CELLS OF THE CENTRALLY PROJECTING EDINGER-WESTPHAL NUCLEUS, AND SEROTONERGIC CELLS OF THE DORSAL RAPHE NUCLEUS. THE EPIGENETIC BACKGROUND OF ALTERATIONS WAS APPROVED BY ALTERED ACETYLATION OF HISTONE H3. OUR FINDINGS FURTHER SUPPORT THE VALIDITY OF BOTH THE THREE HIT CONCEPT AND THAT OF OUR ANIMAL MODEL. REVERSAL OF BEHAVIORAL AND FUNCTIONAL-MORPHOLOGICAL ANOMALIES BY FLUOXETINE TREATMENT SUPPORTS THE PREDICTIVE VALIDITY OF THE MODEL. THIS STUDY HIGHLIGHTS THAT EARLY LIFE STRESS DOES NOT ONLY INTERACT WITH THE GENETIC AND ENVIRONMENTAL FACTORS, BUT HAS STRONG INFLUENCE ALSO ON THERAPEUTIC EFFICACY. 2022 9 3971 36 LONG-LASTING NEUROTOXIC EFFECTS OF EXPOSURE TO METHYLMERCURY DURING DEVELOPMENT. AMONGST ENVIRONMENTAL CHEMICAL CONTAMINANTS, METHYLMERCURY (MEHG) REMAINS A MAJOR CONCERN BECAUSE OF ITS DETRIMENTAL EFFECTS ON DEVELOPING ORGANISMS, WHICH APPEAR TO BE PARTICULARLY SUSCEPTIBLE TO ITS TOXICITY. HERE, WE INVESTIGATED THE EFFECTS OF LOW MEHG LEVELS ON THE DEVELOPMENT OF THE NERVOUS SYSTEM USING BOTH IN VITRO AND IN VIVO EXPERIMENTAL MODELS. IN NEURAL STEM CELLS (NSCS), MEHG DECREASED PROLIFERATION AND NEURONAL DIFFERENTIATION AND INDUCED CELLULAR SENESCENCE ASSOCIATED WITH IMPAIRMENT IN MITOCHONDRIAL FUNCTION AND A CONCOMITANT DECREASE IN GLOBAL DNA METHYLATION. INTERESTINGLY, THE EFFECTS WERE HERITABLE AND COULD BE OBSERVED IN DAUGHTER NSCS NEVER DIRECTLY EXPOSED TO MEHG. BY CHRONICALLY EXPOSING PREGNANT/LACTATING MICE TO MEHG, WE FOUND PERSISTENT BEHAVIOURAL CHANGES IN THE MALE OFFSPRING, WHICH EXHIBITED DEPRESSION-LIKE BEHAVIOUR THAT COULD BE REVERSED BY CHRONIC TREATMENT WITH THE ANTIDEPRESSANT FLUOXETINE. THE BEHAVIOURAL ALTERATIONS WERE ASSOCIATED WITH A DECREASED NUMBER OF PROLIFERATING CELLS AND LOWER EXPRESSION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA IN THE HIPPOCAMPAL DENTATE GYRUS. MEHG EXPOSURE ALSO INDUCED LONG-LASTING DNA HYPERMETHYLATION, INCREASED HISTONE H3-K27 TRI-METHYLATION AND DECREASED H3 ACETYLATION AT THE BDNF PROMOTER IV, INDICATING THAT EPIGENETIC MECHANISMS PLAY A CRITICAL ROLE IN MEDIATING THE LONG-LASTING EFFECTS OF PERINATAL EXPOSURE TO MEHG. FLUOXETINE TREATMENT RESTORED THE BDNF MRNA EXPRESSION LEVELS, AS WELL AS THE NUMBER OF PROLIFERATING CELLS IN THE GRANULE CELL LAYER OF THE DENTATE GYRUS, WHICH FURTHER SUPPORTS THE HYPOTHESIS THAT LINKS DEPRESSION TO IMPAIRED NEUROGENESIS. ALTOGETHER, OUR FINDINGS HAVE SHOWN THAT LOW CONCENTRATIONS OF MEHG INDUCE LONG-LASTING EFFECTS IN NSCS THAT CAN POTENTIALLY PREDISPOSE INDIVIDUALS TO DEPRESSION, WHICH WE HAVE REPORTED EARLIER TO OCCUR IN EXPERIMENTAL ANIMALS EXPOSED TO MEHG DURING PRENATAL AND EARLY POSTNATAL DEVELOPMENT. 2013 10 869 33 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 11 6170 37 THE HDAC INHIBITOR SAHA IMPROVES DEPRESSIVE-LIKE BEHAVIOR OF CRTC1-DEFICIENT MICE: POSSIBLE RELEVANCE FOR TREATMENT-RESISTANT DEPRESSION. MAJOR DEPRESSION IS A HIGHLY COMPLEX DISABLING PSYCHIATRIC DISORDER AFFECTING MILLIONS OF PEOPLE WORLDWIDE. DESPITE THE AVAILABILITY OF SEVERAL CLASSES OF ANTIDEPRESSANTS, A SUBSTANTIAL PERCENTAGE OF PATIENTS ARE UNRESPONSIVE TO THESE MEDICATIONS. A BETTER UNDERSTANDING OF THE NEUROBIOLOGY OF DEPRESSION AND THE MECHANISMS UNDERLYING ANTIDEPRESSANT RESPONSE IS THUS CRITICALLY NEEDED. WE PREVIOUSLY REPORTED THAT MICE LACKING CREB-REGULATED TRANSCRIPTION COACTIVATOR 1 (CRTC1) EXHIBIT A DEPRESSIVE-LIKE PHENOTYPE AND A BLUNTED ANTIDEPRESSANT RESPONSE TO THE SELECTIVE SEROTONIN REUPTAKE INHIBITOR FLUOXETINE. IN THIS STUDY, WE SIMILARLY SHOW THAT CRTC1(-/-) MICE ARE RESISTANT TO THE ANTIDEPRESSANT EFFECT OF CHRONIC DESIPRAMINE IN A BEHAVIORAL DESPAIR PARADIGM. SUPPORTING THE BLUNTED RESPONSE TO THIS TRICYCLIC ANTIDEPRESSANT, WE FOUND THAT DESIPRAMINE DOES NOT SIGNIFICANTLY INCREASE THE EXPRESSION OF BDNF AND NR4A1-3 IN THE HIPPOCAMPUS AND PREFRONTAL CORTEX OF CRTC1(-/-) MICE. EPIGENETIC REGULATION OF NEUROPLASTICITY GENE EXPRESSION HAS BEEN ASSOCIATED WITH DEPRESSION AND ANTIDEPRESSANT RESPONSE, AND HISTONE DEACETYLASE (HDAC) INHIBITORS HAVE BEEN SHOWN TO HAVE ANTIDEPRESSANT-LIKE PROPERTIES. HERE, WE SHOW THAT UNLIKE CONVENTIONAL ANTIDEPRESSANTS, CHRONIC SYSTEMIC ADMINISTRATION OF THE HDAC INHIBITOR SAHA PARTIALLY RESCUES THE DEPRESSIVE-LIKE BEHAVIOR OF CRTC1(-/-) MICE. THIS BEHAVIORAL EFFECT IS ACCOMPANIED BY AN INCREASED EXPRESSION OF BDNF, BUT NOT NR4A1-3, IN THE PREFRONTAL CORTEX OF THESE MICE, SUGGESTING THAT THIS EPIGENETIC INTERVENTION RESTORES THE EXPRESSION OF A SUBSET OF GENES BY ACTING DOWNSTREAM OF CRTC1. THESE FINDINGS SUGGEST THAT CRTC1 ALTERATIONS MAY BE ASSOCIATED WITH TREATMENT-RESISTANT DEPRESSION, AND SUPPORT THE INTERESTING POSSIBILITY THAT TARGETING HDACS MAY BE A USEFUL THERAPEUTIC STRATEGY IN ANTIDEPRESSANT DEVELOPMENT. 2016 12 1848 44 EFFECTS OF VENLAFAXINE ON THE EXPRESSION LEVEL AND METHYLATION STATUS OF GENES INVOLVED IN OXIDATIVE STRESS IN RATS EXPOSED TO A CHRONIC MILD STRESS. RECENT HUMAN AND ANIMAL STUDIES INDICATE THAT OXIDATIVE AND NITROSATIVE STRESS MAY PLAY A ROLE IN THE AETIOLOGY AND PATHOGENESIS OF DEPRESSION. THIS STUDY INVESTIGATES THE EFFECT OF CHRONIC ADMINISTRATION OF THE SEROTONIN-NOREPINEPHRINE REUPTAKE INHIBITOR, VENLAFAXINE, ON THE EXPRESSION AND METHYLATION STATUS OF SOD1, SOD2, GPX1, GPX4, CAT, NOS1 AND NOS2 IN THE BRAIN AND BLOOD OF RATS EXPOSED TO A CHRONIC MILD STRESS (CMS) MODEL OF DEPRESSION. SEPARATE GROUPS OF ANIMALS WERE EXPOSED TO CMS FOR 2 OR 7 WEEKS; THE SECOND GROUP RECEIVED SALINE OR VENLAFAXINE (10 MG/KG/D, IP) FOR 5 WEEKS. AFTER COMPLETION OF BOTH STRESS CONDITIONS AND DRUG ADMINISTRATION, THE MRNA AND PROTEIN EXPRESSION OF SELECTED GENES AND THE METHYLATION STATUS OF THEIR PROMOTERS WERE MEASURED IN PERIPHERAL MONONUCLEAR BLOOD CELLS (PBMCS) AND IN BRAIN STRUCTURES (HIPPOCAMPUS, AMYGDALA, HYPOTHALAMUS, MIDBRAIN, CORTEX, BASAL GANGLIA) WITH THE USE OF TAQMAN GENE EXPRESSION ASSAY, WESTERN BLOT AND METHYLATION-SENSITIVE HIGH-RESOLUTION MELTING TECHNIQUES. CMS CAUSED A DECREASE IN SUCROSE CONSUMPTION, AND THIS EFFECT WAS NORMALIZED BY FLUOXETINE. IN PBMCS, SOD1, SOD2 AND NOS2 MRNA EXPRESSION CHANGED ONLY AFTER VENLAFAXINE ADMINISTRATION. IN BRAIN, CAT, GPX1, GPX4 AND NOS1 GENE EXPRESSION CHANGED FOLLOWING CMS OR VENLAFAXINE EXPOSURE, MOST PROMINENTLY IN THE HIPPOCAMPUS, MIDBRAIN AND BASAL GANGLIA. CMS INCREASED THE METHYLATION OF THE GPX1 PROMOTER IN PBMCS, THE SECOND GPX4 PROMOTER IN MIDBRAIN AND BASAL GANGLIA, AND SOD1 AND SOD2 IN HIPPOCAMPUS. THE CMS ANIMALS TREATED WITH VENLAFAXINE DISPLAYED A SIGNIFICANTLY HIGHER CAT LEVEL IN MIDBRAIN AND CEREBRAL CORTEX. CMS CAUSED AN ELEVATION OF GPX4 IN THE HIPPOCAMPUS, WHICH WAS LOWERED IN CEREBRAL CORTEX BY VENLAFAXINE. THE RESULTS INDICATE THAT CMS AND VENLAFAXINE ADMINISTRATION AFFECT THE METHYLATION OF PROMOTERS OF GENES INVOLVED IN OXIDATIVE AND NITROSATIVE STRESS. THEY ALSO INDICATE THAT PERIPHERAL AND CENTRAL TISSUE DIFFER IN THEIR RESPONSE TO STRESS OR ANTIDEPRESSANT TREATMENTS. IT IS POSSIBLE THAT THAT APART FROM DNA METHYLATION, A CRUCIAL ROLE OF EXPRESSION LEVEL OF GENES MAY BE PLAYED BY OTHER FORMS OF EPIGENETIC REGULATION, SUCH AS HISTONE MODIFICATION OR MICRORNA INTERFERENCE. THESE FINDINGS PROVIDE STRONG EVIDENCE FOR THESIS THAT ANALYSIS OF THE LEVEL OF MRNA AND PROTEIN EXPRESSION AS WELL AS THE STATUS OF PROMOTER METHYLATION CAN HELP IN UNDERSTANDING THE PATHOMECHANISMS OF MENTAL DISEASES, INCLUDING DEPRESSION, AND THE MECHANISMS OF ACTION OF DRUGS EFFECTIVE IN THEIR THERAPY. 2020 13 5749 27 SOCIAL DEFEAT INDUCES CHANGES IN HISTONE ACETYLATION AND EXPRESSION OF HISTONE MODIFYING ENZYMES IN THE VENTRAL HIPPOCAMPUS, PREFRONTAL CORTEX, AND DORSAL RAPHE NUCLEUS. CHRONIC EXPOSURE TO STRESS IS ASSOCIATED WITH A NUMBER OF PSYCHIATRIC DISORDERS, BUT LITTLE IS KNOWN ABOUT THE EPIGENETIC MECHANISMS THAT UNDERLIE THE STRESS RESPONSE OR RESILIENCE TO CHRONIC STRESS. WE INVESTIGATED HISTONE ACETYLATION IN SEVEN DIFFERENT BRAIN REGIONS OF RATS EXPOSED TO CHRONIC SOCIAL DEFEAT STRESS: THE DORSAL HIPPOCAMPUS (DHPC), VENTRAL HIPPOCAMPUS (VHPC), MEDIAL PREFRONTAL CORTEX (MPFC), BASOLATERAL AMYGDALA (BLA), LOCUS COERULEUS (LC), PARAVENTRICULAR THALAMUS (PVT), AND DORSAL RAPHE (DR) NUCLEUS. THIS STRESS PARADIGM WAS UNIQUE IN THAT IT ALLOWED RATS TO DISPLAY RESILIENCE IN THE FORM OF AN ACTIVE COPING MECHANISM. WE FOUND THAT THERE WAS AN INCREASE IN ACETYLATION OF H3K9/14 (H3K9/14AC) AND BULK ACETYLATION OF H4K5,8,12,16 (H4K5,8,12,16AC) IN THE DR NUCLEUS OF RATS THAT WERE LESS RESILIENT. LESS RESILIENT RATS ALSO DISPLAYED INCREASED LEVELS OF H3K18 ACETYLATION (H3K18AC) IN THE MPFC WHEN COMPARED TO NON-STRESSED CONTROLS. IN THE VHPC, THERE WAS AN INCREASE IN H3K18AC AND H4K12 (H4K12AC) IN RATS THAT WERE LESS RESILIENT WHEN COMPARED TO NON-STRESSED CONTROL RATS. IN ADDITION, THERE WAS A DECREASE IN LEVELS OF H4K8 ACETYLATION (H4K8AC) IN BOTH RESILIENT AND NON-RESILIENT RATS AS COMPARED TO CONTROLS. WE ASSESSED EXPRESSION OF HISTONE MODIFYING ENZYMES IN THE VHPC AND THE MPFC USING QUANTITATIVE REAL-TIME POLYMERASE CHAIN REACTION (PCR) AND FOUND CHANGES IN EXPRESSION OF A NUMBER OF TARGETS. THESE INCLUDED CHANGES IN SIRT1 AND SIRT2 IN THE VHPC AND CHANGES IN KAT5 IN THE MPFC. OVERALL, THESE RESULTS SUGGEST THAT CHANGES IN HISTONE ACETYLATION AND EXPRESSION OF HISTONE MODIFYING ENZYMES IN THESE REGIONS CORRELATE WITH THE BEHAVIORAL RESPONSE TO STRESS IN SOCIALLY DEFEATED RATS. 2014 14 1753 34 EARLY LIFE STRESS TRIGGERS SUSTAINED CHANGES IN HISTONE DEACETYLASE EXPRESSION AND HISTONE H4 MODIFICATIONS THAT ALTER RESPONSIVENESS TO ADOLESCENT ANTIDEPRESSANT TREATMENT. EARLY LIFE STRESS CAN ELICIT LONG-LASTING CHANGES IN GENE EXPRESSION AND BEHAVIOR. RECENT STUDIES ON RODENTS SUGGEST THAT THESE LASTING EFFECTS DEPEND ON THE GENETIC BACKGROUND. WHETHER EPIGENETIC FACTORS ALSO PLAY A ROLE REMAINS TO BE INVESTIGATED. HERE WE EXPOSED THE STRESS-SUSCEPTIBLE MOUSE STRAIN BALB/C AND THE MORE RESILIENT STRAIN C57BL/6 TO A POWERFUL EARLY LIFE STRESS PARADIGM, INFANT MATERNAL SEPARATION. IN BALB/C MICE, INFANT MATERNAL SEPARATION LED TO DECREASED EXPRESSION OF MRNA ENCODING THE HISTONE DEACETYLASES (HDACS) 1, 3, 7, 8, AND 10 IN THE FOREBRAIN NEOCORTEX IN ADULTHOOD, AN EFFECT ACCOMPANIED BY INCREASED EXPRESSION OF ACETYLATED HISTONE H4 PROTEINS, ESPECIALLY ACETYLATED H4K12 PROTEIN. THESE CHANGES IN HDAC EXPRESSION AND HISTONE MODIFICATIONS WERE NOT DETECTED IN C57BL/6 MICE EXPOSED TO EARLY LIFE STRESS. MOREOVER, A REVERSAL OF THE H4K12 HYPERACETYLATION DETECTED IN INFANT MATERNALLY SEPARATED BALB/C MICE (ACHIEVED WITH CHRONIC ADOLESCENT TREATMENT WITH A LOW DOSE OF THEOPHYLLINE THAT ONLY ACTIVATES HDACS) WORSENED THE ABNORMAL EMOTIONAL PHENOTYPE RESULTING FROM THIS EARLY LIFE STRESS EXPOSURE. IN CONTRAST, FLUOXETINE, A DRUG WITH POTENT ANTIDEPRESSANT EFFICACY IN INFANT MATERNALLY SEPARATED BALB/C MICE, POTENTIATED ALL HISTONE MODIFICATIONS TRIGGERED BY EARLY LIFE STRESS. MOREOVER, IN NON-STRESSED BALB/C MICE, CO-ADMINISTRATION OF AN HDAC INHIBITOR AND FLUOXETINE, BUT NOT FLUOXETINE ALONE, ELICITED ANTIDEPRESSANT EFFECTS AND ALSO TRIGGERED CHANGES IN HISTONE H4 EXPRESSION THAT WERE SIMILAR TO THOSE PROVOKED BY FLUOXETINE TREATMENT OF MICE EXPOSED TO EARLY LIFE STRESS. THESE RESULTS SUGGEST THAT BALB/C MICE DEVELOP EPIGENETIC MODIFICATIONS AFTER EARLY LIFE STRESS EXPOSURE THAT, IN TERMS OF THE EMOTIVE PHENOTYPE, ARE OF ADAPTIVE NATURE, AND THAT ENHANCE THE EFFICACY OF ANTIDEPRESSANT DRUGS. 2012 15 5158 29 PRE-REPRODUCTIVE STRESS AND FLUOXETINE TREATMENT IN RATS AFFECT OFFSPRING A-TO-I RNA EDITING, GENE EXPRESSION AND SOCIAL BEHAVIOR. ADENOSINE TO INOSINE RNA EDITING IS AN EPIGENETIC PROCESS THAT ENTAILS SITE-SPECIFIC MODIFICATIONS IN DOUBLE-STRANDED RNA MOLECULES, CATALYZED BY ADENOSINE DEAMINASES ACTING ON RNA (ADARS). USING THE MULTIPLEX MICROFLUIDIC PCR AND DEEP SEQUENCING TECHNIQUE, WE RECENTLY SHOWED THAT EXPOSING ADOLESCENT FEMALE RATS TO CHRONIC UNPREDICTABLE STRESS BEFORE REPRODUCTION AFFECTS EDITING IN THE PREFRONTAL CORTEX AND AMYGDALA OF THEIR NEWBORN OFFSPRING, PARTICULARLY AT THE SEROTONIN RECEPTOR 5-HT2C (ENCODED BY HTR2C). HERE, WE USED THE SAME TECHNIQUE TO DETERMINE WHETHER POST-STRESS, PRE-REPRODUCTIVE MATERNAL TREATMENT WITH FLUOXETINE (5 MG/KG, 7 DAYS) REVERSES THE EFFECTS OF STRESS ON EDITING. WE ALSO EXAMINED THE MRNA EXPRESSION OF ADAR ENZYMES IN THESE REGIONS, AND ASKED WHETHER SOCIAL BEHAVIOR IN ADULT OFFSPRING WOULD BE ALTERED BY MATERNAL EXPOSURE TO STRESS AND/OR FLUOXETINE. MATERNAL TREATMENT WITH FLUOXETINE ALTERED HTR2C EDITING IN OFFSPRING AMYGDALA AT BIRTH, ENHANCED THE EXPRESSION OF HTR2C MRNA AND RNA EDITING ENZYMES IN THE PREFRONTAL CORTEX, AND REVERSED THE EFFECTS OF PRE-REPRODUCTIVE STRESS ON HTR2C EDITING IN THIS REGION. FURTHERMORE, MATERNAL FLUOXETINE TREATMENT ENHANCED DIFFERENCES IN EDITING OF GLUTAMATE RECEPTORS BETWEEN OFFSPRING OF CONTROL AND STRESS-EXPOSED RATS, AND LED TO ENHANCED SOCIAL PREFERENCE IN ADULT OFFSPRING. OUR FINDINGS INDICATE THAT PRE-GESTATIONAL FLUOXETINE TREATMENT AFFECTS PATTERNS OF RNA EDITING AND EDITING ENZYME EXPRESSION IN NEONATAL OFFSPRING BRAIN IN A REGION-SPECIFIC MANNER, IN INTERACTION WITH PRE-REPRODUCTIVE STRESS. OVERALL, THESE FINDINGS IMPLY THAT FLUOXETINE TREATMENT AFFECTS SEROTONERGIC SIGNALING IN OFFSPRING BRAIN EVEN WHEN TREATMENT IS DISCONTINUED BEFORE GESTATION, AND ITS EFFECTS MAY DEPEND UPON PRIOR EXPOSURE TO STRESS. 2018 16 4397 38 MODULATION OF DNA METHYLATION AND GENE EXPRESSION IN RODENT CORTICAL NEUROPLASTICITY PATHWAYS EXERTS RAPID ANTIDEPRESSANT-LIKE EFFECTS. BACKGROUND: STRESS INCREASES DNA METHYLATION, PRIMARILY A SUPPRESSIVE EPIGENETIC MECHANISM CATALYZED BY DNA METHYLTRANSFERASES (DNMT), AND DECREASES THE EXPRESSION OF GENES INVOLVED IN NEURONAL PLASTICITY AND MOOD REGULATION. DESPITE CHRONIC ANTIDEPRESSANT TREATMENT DECREASES STRESS-INDUCED DNA METHYLATION, IT IS NOT KNOWN WHETHER INHIBITION OF DNMT WOULD CONVEY RAPID ANTIDEPRESSANT-LIKE EFFECTS. AIM: THIS WORK TESTED SUCH A HYPOTHESIS AND EVALUATED WHETHER A BEHAVIORAL EFFECT INDUCED BY DNMT INHIBITORS (DNMTI) CORRESPONDS WITH CHANGES IN DNA METHYLATION AND TRANSCRIPT LEVELS IN GENES CONSISTENTLY ASSOCIATED WITH THE NEUROBIOLOGY OF DEPRESSION AND SYNAPTIC PLASTICITY (BDNF, TRKB, 5-HT(1A), NMDA, AND AMPA). METHODS: MALE WISTAR RATS RECEIVED INTRAPERITONEAL (I.P.) INJECTION OF TWO PHARMACOLOGICALLY DIFFERENT DNMTI (5-AZAD 0.2 AND 0.6 MG/KG OR RG108 0.6 MG/KG) OR VEHICLE (1 ML/KG), 1 H OR 7 DAYS BEFORE THE LEARNED HELPLESSNESS TEST (LH). DNA METHYLATION IN TARGET GENES AND THE CORRESPONDENT TRANSCRIPT LEVELS WERE MEASURED IN THE HIPPOCAMPUS (HPC) AND PREFRONTAL CORTEX (PFC) USING MEDIP-QPCR. IN PARALLEL SEPARATE GROUPS, THE ANTIDEPRESSANT-LIKE EFFECT OF 5-AZAD AND RG108 WAS INVESTIGATED IN THE FORCED SWIMMING TEST (FST). THE INVOLVEMENT OF CORTICAL BDNF-TRKB-MTOR PATHWAYS WAS ASSESSED BY INTRA-VENTRAL MEDIAL PFC (VMPFC) INJECTIONS OF RAPAMYCIN (MTOR INHIBITOR), K252A (TRKB RECEPTOR ANTAGONIST), OR VEHICLE (0.2 MUL/SIDE). RESULTS: WE FOUND THAT BOTH 5-AZAD AND RG108 ACUTELY AND 7 DAYS BEFORE THE TEST DECREASED ESCAPE FAILURES IN THE LH. LH STRESS INCREASED DNA METHYLATION AND DECREASED TRANSCRIPT LEVELS OF BDNF IV AND TRKB IN THE PFC, EFFECTS THAT WERE NOT SIGNIFICANTLY ATTENUATED BY RG108 TREATMENT. THE SYSTEMIC ADMINISTRATION OF 5-AZAD (0.2 MG/KG) AND RG108 (0.2 MG/KG) INDUCED AN ANTIDEPRESSANT-LIKE EFFECT IN FST, WHICH WAS, HOWEVER, ATTENUATED BY TRKB AND MTOR INHIBITION INTO THE VMPFC. CONCLUSION: THESE FINDINGS SUGGEST THAT ACUTE INHIBITION OF STRESS-INDUCED DNA METHYLATION PROMOTES RAPID AND SUSTAINED ANTIDEPRESSANT EFFECTS ASSOCIATED WITH INCREASED BDNF-TRKB-MTOR SIGNALING IN THE PFC. 2021 17 3969 35 LONG-LASTING DEPRESSION-LIKE BEHAVIOR AND EPIGENETIC CHANGES OF BDNF GENE EXPRESSION INDUCED BY PERINATAL EXPOSURE TO METHYLMERCURY. SUBSTANTIAL EVIDENCE INDICATES THAT PREDISPOSITION TO DISEASES CAN BE ACQUIRED DURING EARLY STAGES OF DEVELOPMENT AND INTERACTIONS BETWEEN ENVIRONMENTAL AND GENETIC FACTORS MAY BE IMPLICATED IN THE ONSET OF MANY PATHOLOGICAL CONDITIONS. DATA COLLECTED OVER SEVERAL DECADES HAVE SHOWN THAT CHEMICALS ARE AMONG THE RELEVANT FACTORS THAT CAN ENDANGER CNS. WE PREVIOUSLY SHOWED THAT PERINATAL EXPOSURE TO METHYLMERCURY (MEHG) CAUSES PERSISTENT CHANGES IN LEARNING AND MOTIVATIONAL BEHAVIOR IN MICE. IN THIS STUDY, WE REPORT THAT THE DEPRESSION-LIKE BEHAVIOR IN MEHG-EXPOSED MALE MICE IS REVERSED BY CHRONIC TREATMENT WITH THE ANTIDEPRESSANT FLUOXETINE. BEHAVIORAL ALTERATIONS ARE ASSOCIATED WITH A DECREASE IN BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) MRNA IN THE HIPPOCAMPAL DENTATE GYRUS AND FLUOXETINE TREATMENT RESTORES BDNF MRNA EXPRESSION. WE ALSO SHOW THAT MEHG-EXPOSURE INDUCES LONG-LASTING REPRESSIVE STATE OF THE CHROMATIN STRUCTURE AT THE BDNF PROMOTER REGION, IN PARTICULAR DNA HYPERMETHYLATION, AN INCREASE IN HISTONE H3-K27 TRI-METHYLATION AND A DECREASE IN H3 ACETYLATION AT THE PROMOTER IV. WHILE FLUOXETINE TREATMENT DOES NOT ALTER HYPERMETHYLATION OF H3-K27, IT SIGNIFICANTLY UP-REGULATES H3 ACETYLATION AT THE BDNF PROMOTER IV IN MEHG-EXPOSED MICE. OUR STUDY SHOWS THAT DEVELOPMENTAL EXPOSURE TO LOW LEVELS OF MEHG PREDISPOSES MICE TO DEPRESSION AND INDUCES EPIGENETIC SUPPRESSION OF BDNF GENE EXPRESSION IN THE HIPPOCAMPUS. 2008 18 1332 38 DEPRESSIVE-LIKE PHENOTYPE INDUCED BY PRENATAL DEXAMETHASONE IN MICE IS REVERSED BY DESIPRAMINE. EXPOSURE TO PRENATAL INSULTS HAS BEEN ASSOCIATED WITH AN INCREASED RISK FOR NEUROPSYCHIATRIC DISORDERS, INCLUDING DEPRESSION, BUT THE MECHANISMS ARE STILL POORLY UNDERSTOOD. PERSISTENT ALTERATIONS OF THE HPA AXIS FEEDBACK MECHANISM AS WELL AS ADULT IMPAIRED NEUROGENESIS ARE BELIEVED TO PLAY A RELEVANT ROLE IN THE ETIOLOGY OF DEPRESSION. IN ADDITION, GROWING EVIDENCE POINTS AT EPIGENETIC REPROGRAMMING AS A KEY FACTOR. WE HAVE PREVIOUSLY SHOWN THAT PRENATAL EXPOSURE TO THE SYNTHETIC GLUCOCORTICOID DEXAMETHASONE (DEX) IMPAIRS NEUROGENESIS AND LEADS TO LATE ONSET OF DEPRESSION-LIKE BEHAVIOR THAT DOES NOT RESPOND TO THE SSRI ANTIDEPRESSANT FLUOXETINE (FLX). THE AIMS OF THIS STUDY WERE TO ASSESS THE EFFECT OF DEX PRENATAL EXPOSURE ON THE MORPHOLOGY OF HIPPOCAMPAL GRANULE NEURONS AND ON THE EXPRESSION OF GENES RELATED TO PLASTICITY; AND TO TEST WHETHER THE SNRI ANTIDEPRESSANT DESIPRAMINE (DMI), UNLIKE FLX, COULD COUNTERACT THE EFFECT OF PRENATAL-DEX. C57BL/6 MICE WERE EXPOSED TO DEX (0.05 MG/KG/DAY) IN UTERO AND RECEIVED INTRA-HIPPOCAMPAL INJECTION OF GFP EXPRESSING RETROVIRAL VECTOR FOR LABELING OF NEWBORN GRANULE CELLS AT ELEVEN MONTHS. BY TWELVE MONTHS, DEX MICE SHOWED DEPRESSION-LIKE BEHAVIOR ASSOCIATED WITH DECREASED NEUROGENESIS AND MORPHOLOGICAL ALTERATIONS OF THE NEWBORN GRANULE CELLS IN THE DENTATE GYRUS (DG). FURTHERMORE DEX MICE DISPLAYED ALTERED EXPRESSION OF GENES CONTROLLING NEUROGENESIS AND NEURONAL MORPHOLOGY, SUCH AS CDKN1C, P16, TRKB, DISC1 AND REELIN. CHRONIC TREATMENT WITH DMI LED TO A SIGNIFICANT DECREASE IN IMMOBILITY TIME IN THE FORCED SWIM TEST. IN ADDITION, DMI RESTORED NEUROGENESIS, NEURONAL MORPHOLOGY IN THE DG, AS WELL AS THE EXPRESSION OF ALL RELATED GENES. OUR RESULTS SUGGEST THAT (1) PRENATAL DEX INDUCES EARLY AND PERSISTENT REPROGRAMMING EFFECTS RESULTING IN ALTERED NEUROGENESIS AND NEURONAL MORPHOLOGY; AND (2) DMI TREATMENT REVERSES DEX-INDUCED DEPRESSION BY RESTORING THE EXPRESSION OF GENES RELEVANT TO NEURONAL PLASTICITY. 2017 19 431 38 ANTIDEPRESSANT ADMINISTRATION MODULATES STRESS-INDUCED DNA METHYLATION AND DNA METHYLTRANSFERASE EXPRESSION IN RAT PREFRONTAL CORTEX AND HIPPOCAMPUS. STRESS AND ANTIDEPRESSANT TREATMENT CAN MODULATE DNA METHYLATION IN PROMOTER REGION OF GENES RELATED TO NEUROPLASTICITY AND MOOD REGULATION, THUS IMPLICATING THIS EPIGENETIC MECHANISM IN DEPRESSION NEUROBIOLOGY AND TREATMENT. ACCORDINGLY, SYSTEMIC ADMINISTRATION OF DNA METHYLTRANSFERASE (DNMT) INHIBITORS INDUCES ANTIDEPRESSANT-LIKE EFFECTS IN RODENTS. DNA METHYLATION IS CONVEYED BY DNMT 1, 3A AND 3B ISOFORMS, WHICH ARE DIFFERENTIALLY EXPRESSED IN THE BRAIN. IN ORDER TO INVESTIGATE IF THE BEHAVIORAL EFFECTS OF ANTIDEPRESSANTS COULD BE ASSOCIATED WITH CHANGES IN DNA METHYLATION AND DNMT EXPRESSION, WE INVESTIGATED THE EFFECTS INDUCED BY ACUTE AND REPEATED ANTIDEPRESSANT TREATMENT ON DNA METHYLATION AND DNMT EXPRESSION (1, 3A AND 3B ISOFORMS) IN DIFFERENT BRAIN REGIONS OF RATS EXPOSED TO A STRESS MODEL OF DEPRESSION, THE LEARNED HELPLESSNESS (LH). THEREFORE, RATS WERE EXPOSED TO PRETEST AND TREATED WITH ONE OR SEVEN INJECTIONS OF VEHICLE OR IMIPRAMINE (15 MG KG(-1)), WITH TEST SESSION PERFORMED ONE HOUR AFTER THE LAST INJECTION. CHRONIC, BUT NOT ACUTE, IMIPRAMINE ADMINISTRATION ATTENUATED ESCAPE FAILURES DURING THE TEST, A WELL DESCRIBED ANTIDEPRESSANT-LIKE EFFECT IN THIS MODEL. DNA METHYLATION AND DNMT (1, 3A AND 3B) LEVELS WERE MEASURED IN THE DORSAL AND VENTRAL HIPPOCAMPUS (DHPC, VHPC) AND IN THE PREFRONTAL CORTEX (PFC) OF RATS EXPOSED TO STRESS AND TREATMENT. STRESS INCREASED DNA METHYLATION, DNMT3A AND DNMT3B EXPRESSION IN THE DHPC AND PFC. CHRONIC, BUT NOT ACUTE, IMIPRAMINE ADMINISTRATION ATTENUATED STRESS EFFECTS ONLY IN THE PFC. THESE RESULTS SUGGEST THE REGULATION OF DNA METHYLATION IN THE PFC MAY BE AN IMPORTANT MECHANISM FOR ANTIDEPRESSANT-LIKE EFFECTS IN THE LH MODEL. 2018 20 1783 37 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