1 2476 126 EPIGENETIC UPREGULATION OF CCL2 AND CCL3 VIA HISTONE MODIFICATIONS IN INFILTRATING MACROPHAGES AFTER PERIPHERAL NERVE INJURY. TO GAIN INSIGHT INTO THE EPIGENETIC REGULATION OF CC-CHEMOKINE LIGAND (CCL) 2 AND CCL3, KEY PLAYERS IN THE PERIPHERAL SENSITIZATION LEADING TO NEUROPATHIC PAIN, WE EXAMINED THE RELATIONSHIP BETWEEN HISTONE H3 MODIFICATION AND THE UPREGULATION OF THESE MOLECULES USING A MOUSE MODEL OF NEUROPATHIC PAIN AFTER PARTIAL SCIATIC NERVE LIGATION (PSL). WE FOUND THAT CIRCUITING BONE MARROW (BM)-DERIVED MACROPHAGES INFILTRATED INTO THE INJURED SCIATIC NERVE (SCN) USING ENHANCED GREEN FLUORESCENT PROTEIN CHIMERIC MICE. THE MRNA LEVELS OF CCL2, CCL3 AND THEIR RECEPTORS (CCR2 AND CCR1/CCR5, RESPECTIVELY) WERE INCREASED IN THE INJURED SCN. CHROMATIN IMMUNOPRECIPITATION ASSAY REVEALED THAT LEVELS OF LYSINE 9-ACETYLATED HISTONE H3 (H3K9AC) AND LYSINE 4-TRIMETHYLATED H3 (H3K4ME(3)) IN THE PROMOTER REGIONS OF THE CCL2 AND CCL3 GENES WERE INCREASED IN THE INJURED SCN AFTER PSL, INDICATING THE ENHANCEMENT OF GENE EXPRESSION. IMMUNOREACTIVITY FOR H3K9AC AND H3K4ME(3) WAS LOCALIZED IN THE NUCLEI OF INFILTRATING BM-DERIVED CELLS AND CCL-EXPRESSING CELLS IN THE INJURED SCN. WE OBSERVED H3K9AC AND H3K4ME(3) MAINLY IN THE NUCLEI OF RECRUITED MACROPHAGES ON DAY 7 AFTER PSL. FURTHERMORE, UPREGULATION OF CCLS AND CCRS WERE SUPPRESSED BY HISTONE ACETYLTRANSFERASE INHIBITOR, ANACARDIC ACID. TAKEN TOGETHER, OUR FINDINGS DEMONSTRATE THAT CCL2 AND CCL3 ARE UPREGULATED IN THE INJURED PERIPHERAL NERVE THROUGH EPIGENETIC HISTONE MODIFICATION IN INFILTRATING IMMUNE CELLS SUCH AS MACROPHAGES. THESE CHEMOKINE CASCADES MAY SUBSEQUENTLY ELICIT CHRONIC NEUROINFLAMMATION FOLLOWING NERVE INJURY. 2013 2 2751 36 EXPRESSION OF ACETYL-HISTONE H3 AND ACETYL-HISTONE H4 IN DORSAL ROOT GANGLION AND SPINAL DORSAL HORN IN RAT CHRONIC PAIN MODELS. AIMS: HISTONE ACETYLATION AND DEACETYLATION ARE TWO HISTONE POSTTRANSLATIONAL MODIFICATIONS THAT ARE USUALLY CONTROLLED BY HISTONE ACETYLTRANSFERASES (HATS) AND HISTONE DEACETYLASES (HDACS). ALTHOUGH HATS OR HDACS INHIBITORS COULD RELIEVE PAIN HYPERSENSITIVITIES IN CHRONIC PAIN ANIMAL MODELS, IT IS NOT CLEAR ON THE EXPRESSION OF GLOBAL HISTONE ACETYLATION IN THE DORSAL ROOT GANGLION (DRG) OR SPINAL DORSAL HORN IN CHRONIC PAIN CONDITIONS. MAIN METHODS: A SPINAL NERVE LIGATION (SNL)-INDUCED NEUROPATHIC PAIN MODEL AND A COMPLETE FREUND'S ADJUVANT (CFA)-INDUCED INFLAMMATORY PAIN MODEL IN RATS WERE USED TO EXAMINE THE EXPRESSION OF TOTAL ACETYL-HISTONE H3 (ACH3) AND TOTAL ACETYL-HISTONE H4 (ACH4) BY IMMUNOFLUORESCENCE OR WESTERN BLOT. KEY FINDINGS: ACH3 AND ACH4 NOT ONLY LOCALIZED IN NEURONAL NUCLEI, BUT ALSO IN NUCLEI OF GLIAL CELLS IN THE DRG. UNILATERAL SNL INDUCED THE INCREASE OF ACH3 AND ACH4 EXPRESSION IN THE INJURED LUMBAR 5 (L5) DRG, BUT NOT IN THE UNINJURED L5 DRG OR THE SPINAL DORSAL HORN, WHILE UNILATERAL INTRAPLANTAR INJECTION OF CFA INCREASED ACH3 AND ACH4 EXPRESSION IN THE IPSILATERAL L4/5 SPINAL DORSAL HORN, BUT NOT IN THE L4/5 DRG. SIGNIFICANCE: THESE RESULTS PROVIDE MORPHOLOGICAL EVIDENCE FOR GLOBAL HISTONE ACETYLATION EXPRESSION IN THE DRG AND SPINAL CORD AND INDICATE THE DIFFERENTIAL EXPRESSION IN THE DRG AND SPINAL DORSAL HORN IN DIFFERENT CHRONIC PAIN MODELS. MORE PRECISE EPIGENETIC MECHANISMS OF HISTONE ACETYLATION ON THE TARGET GENES NEED TO BE REVEALED. 2018 3 1803 14 EFFECT OF PROLONGED EMOTIONAL AND PAIN STRESS ON THE CONTENT OF METHYLCYTOSINE-BINDING PROTEIN MECP2 IN NUCLEI OF HIPPOCAMPAL NEURONS IN RATS WITH DIFFERENT EXCITABILITY OF THE NERVOUS SYSTEM. IN RATS WITH LOW EXCITABILITY THRESHOLD OF THE NERVOUS SYSTEM DEMONSTRATING SIGNIFICANT AND PERSISTENT BEHAVIORAL DISORDERS UNDER STRESS CONDITIONS, THE CONTENT OF METHYLCYTOSINE-BINDING PROTEIN MECP2 IN NEURONAL NUCLEI OF HIPPOCAMPAL FIELD CA3 DECREASED OVER 2 WEEKS AFTER LONG-TERM EMOTIONAL AND PAIN STRESS. IT WAS HYPOTHESIZED THAT PROTEIN MECP2 TRIGGERS EPIGENETIC CHANGES IN DNA THAT UNDERLIE "STRESS MEMORY". 2006 4 2300 42 EPIGENETIC REGULATION OF BDNF EXPRESSION IN THE PRIMARY SENSORY NEURONS AFTER PERIPHERAL NERVE INJURY: IMPLICATIONS IN THE DEVELOPMENT OF NEUROPATHIC PAIN. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) IS KNOWN TO BE UP-REGULATED IN THE DORSAL ROOT GANGLION (DRG) AFTER PERIPHERAL NERVE INJURY, AND TO CONTRIBUTE TO NEUROPATHIC PAIN. HERE, WE FOUND THAT THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA AT DAY 7 POST-INJURY WERE INHIBITED ONLY WHEN ANTI-BDNF ANTIBODY WAS INTRATHECALLY ADMINISTRATED AT DAY 2 POST-INJURY. CONSISTENT WITH BEHAVIORAL RESULTS, WESTERN BLOT ANALYSIS SHOWED THAT THE EXPRESSION LEVELS OF BDNF PROTEIN IN THE SPINAL DORSAL HORN WERE MARKEDLY INDUCED DURING EARLY STAGE POST-INJURY. MOREOVER, THE MAXIMAL INCREASE IN BDNF MRNA EXPRESSION IN THE DRG WAS OBSERVED AT DAY 1 POST-INJURY, AND SIGNIFICANTLY ELEVATED LEVELS WERE SUSTAINED FOR AT LEAST 14 DAYS. FOUR OF FIVE BDNF MRNA TRANSCRIPTS WERE UP-REGULATED AFTER NERVE INJURY, AND THE MOST INDUCIBLE TRANSCRIPT WAS EXON I. USING A CHROMATIN IMMUNOPRECIPITATION (CHIP) ASSAY, WE FOUND THAT NERVE INJURY PROMOTES HISTONE H3 AND H4 ACETYLATION, TRANSCRIPTIONALLY ACTIVE MODIFICATIONS, AT BDNF PROMOTER I AT DAY 1 POST-INJURY, AND THE LEVELS OF HISTONE ACETYLATION REMAIN ELEVATED FOR AT LEAST 7 DAYS. TAKEN TOGETHER, OUR FINDINGS SUGGEST THAT AN INITIAL INCREASE IN BDNF EXON I EXPRESSION CONTROLLED BY EPIGENETIC MECHANISMS MIGHT HAVE A CRUCIAL ROLE IN THE DEVELOPMENT OF NEUROPATHIC PAIN. 2013 5 5749 21 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 6 3331 33 HISTONE DEACETYLASE INHIBITOR SUBERANILOHYDROXAMIC ACID TREATMENT REVERSES HYPOSENSITIVITY TO GAMMA-AMINOBUTYRIC ACID IN THE VENTRAL TEGMENTAL AREA DURING ETHANOL WITHDRAWAL. BACKGROUND: THE VENTRAL TEGMENTAL AREA (VTA) IS IMPORTANT FOR ALCOHOL-RELATED REWARD AND REINFORCEMENT. MOUSE VTA NEURONS ARE HYPOSENSITIVE TO GAMMA-AMINOBUTYRIC ACID (GABA) DURING ETHANOL (ETOH) WITHDRAWAL, AND GABA RESPONSIVENESS IS NORMALIZED BY IN VITRO TREATMENT WITH HISTONE DEACETYLASE INHIBITORS (HDACI). THE PRESENT STUDY EXAMINED THE EFFECT OF A SYSTEMICALLY ADMINISTERED HDACI, SUBERANILOHYDROXAMIC ACID (SAHA) ON GABA SENSITIVITY, AND RELATED MOLECULAR CHANGES IN VTA NEURONS DURING WITHDRAWAL AFTER CHRONIC ETOH INTAKE IN RATS. METHODS: SPRAGUE DAWLEY MALE ADULT RATS WERE FED WITH LIEBER-DECARLI DIET (9% ETOH OR CONTROL DIET) FOR 16 DAYS. EXPERIMENTAL GROUPS INCLUDED CONTROL DIET-FED AND ETOH DIET-FED (0- OR 24-HOUR WITHDRAWAL) RATS TREATED WITH EITHER SAHA OR VEHICLE INJECTION. SINGLE-UNIT RECORDINGS WERE USED TO MEASURE THE RESPONSE OF VTA NEURONS TO GABA. IMMUNOHISTOCHEMISTRY WAS PERFORMED TO EXAMINE LEVELS OF HDAC2, ACETYLATED HISTONE H3 LYSINE 9 (ACH3K9), AND GABA(A) RECEPTOR ALPHA1 AND ALPHA5 SUBUNITS IN THE VTA; QUANTITATIVE POLYMERASE CHAIN REACTION WAS PERFORMED TO EXAMINE THE MRNA LEVELS OF HDAC2 AND GABA(A) RECEPTOR SUBUNITS. RESULTS: VTA NEURONS FROM THE WITHDRAWAL GROUP EXHIBITED GABA HYPOSENSITIVITY. IN VIVO SAHA TREATMENT 2 HOURS BEFORE SACRIFICE NORMALIZED THE SENSITIVITY OF VTA NEURONS TO GABA. ETOH WITHDRAWAL WAS ASSOCIATED WITH INCREASED HDAC2 AND DECREASED ACH3K9 PROTEIN LEVELS; SAHA TREATMENT NORMALIZED ACH3K9 LEVELS. INTERESTINGLY, NO SIGNIFICANT CHANGE WAS OBSERVED IN THE MRNA LEVELS OF HDAC2. THE MRNA LEVELS, BUT NOT PROTEIN LEVELS, OF GABA(A) RECEPTOR ALPHA1 AND ALPHA5 SUBUNITS WERE INCREASED DURING WITHDRAWAL. CONCLUSIONS: WITHDRAWAL FROM CHRONIC ETOH EXPOSURE RESULTS IN A DECREASE IN GABA-MEDIATED INHIBITION, AND THIS GABA HYPOSENSITIVITY IS NORMALIZED BY IN VIVO SAHA TREATMENT. DISRUPTION OF SIGNALING IN THE VTA PRODUCED BY ALTERATION OF GABA NEUROTRANSMISSION COULD BE 1 NEUROADAPTIVE PHYSIOLOGICAL PROCESS LEADING TO CRAVING AND RELAPSE. THESE RESULTS SUGGEST THAT HDACI PHARMACOTHERAPY WITH AGENTS LIKE SAHA MIGHT BE AN EFFECTIVE TREATMENT FOR ALCOHOLISM. 2018 7 5976 28 TET1-DEPENDENT EPIGENETIC MODIFICATION OF BDNF EXPRESSION IN DORSAL HORN NEURONS MEDIATES NEUROPATHIC PAIN IN RATS. TEN-ELEVEN TRANSLOCATION METHYLCYTOSINE DIOXYGENASE 1 (TET1) MEDIATES THE CONVERSION OF 5-METHYLCYTOSINE (5 MC) TO 5-HYDROXYMETHYLCYTOSINE (5 HMC), HENCE PROMOTING DNA DEMETHYLATION. ALTHOUGH RECENT STUDIES HAVE LINKED THE DNA DEMETHYLATION OF SPECIFIC GENES TO PAIN HYPERSENSITIVITY, THE ROLE OF SPINAL TET1-DEPENDENT DNA DEMETHYLATION IN NOCICEPTION HYPERSENSITIVITY DEVELOPMENT REMAINS ELUSIVE. HERE, WE REPORT CORRELATED WITH BEHAVIORAL ALLODYNIA, SPINAL NERVE LIGATION (SNL) UPREGULATED TET1 EXPRESSION IN DORSAL HORN NEURONS THAT HYDROXYLATE 5 MC TO 5 HMC AT CPG DINUCLEOTIDES IN THE BDNF PROMOTER TO PROMOTE SPINAL BDNF EXPRESSION AT DAY 7 AFTER OPERATION. FOCAL KNOCKDOWN OF SPINAL TET1 EXPRESSION DECREASED TET1 BINDING AND 5 HMC ENRICHMENT, FURTHER INCREASED 5 MC ENRICHMENT AT CPG SITES IN THE BDNF PROMOTER AND DECREASED SPINAL BDNF EXPRESSION ACCOMPANIED BY THE ALLEVIATION OF THE DEVELOPED ALLODYNIA. MOREOVER, AT DAY 7 AFTER OPERATION, SNL-ENHANCED TET1 EXPRESSION ALSO INHIBITED THE BINDING OF DNA METHYLTRANSFERASES (DNMTS, I.E., DNMT1, DNMT3A, AND DNMT3B) TO THE BDNF PROMOTER, A REQUIREMENT FOR TRANSCRIPTIONAL SILENCING BY CATALYSING 5-CYTOSINE (5C) TO 5 MC. TOGETHER, THESE DATA SUGGEST AT CPG SITES OF THE BDNF PROMOTER, SNL-ENHANCED TET1 EXPRESSION PROMOTES DNA DEMETHYLATION BOTH BY CONVERTING 5 MC TO 5 HMC AND INHIBITING DNMT BINDING TO REGULATE SPINAL BDNF EXPRESSION, HENCE CONTRIBUTING TO BEHAVIORAL ALLODYNIA DEVELOPMENT. 2016 8 6172 39 THE HDAC1/C-JUN COMPLEX IS ESSENTIAL IN THE PROMOTION OF NERVE INJURY-INDUCED NEUROPATHIC PAIN THROUGH JNK SIGNALING. HISTONE DEACETYLASE INHIBITORS (HDACIS) INTERFERE WITH THE EPIGENETIC PROCESS OF HISTONE ACETYLATION AND ARE KNOWN TO HAVE ANALGESIC PROPERTIES IN MODELS OF CHRONIC INFLAMMATORY PAIN. ADMINISTRATION OF A SELECTIVE HDAC1 INHIBITOR (LG325) IN SNI-SUBJECTED MICE SIGNIFICANTLY ATTENUATED BEHAVIOR RELATED TO INJURY-INDUCED PAIN. UNDERSTANDING THE HDAC1 PATHWAY IN EPIGENETIC REGULATION OF PATHOLOGICAL PAIN IS OF GREAT MEDICAL RELEVANCE. SPARED NERVE INJURY (SNI) MICE SHOWED A SIGNIFICANT INCREASE IN THE HDAC1 PROTEIN LEVELS WITHIN SPINAL CORD IN COINCIDENCE WITH THE NOCICEPTIVE PHENOTYPE AT 1 AND 3 WEEKS AFTER NERVE INJURY. NO VARIATION IN HDAC3, DNMT3A, ACH3, MBD3 AND MECP2 LEVELS WAS DETECTED. INCREASED EXPRESSION OF HDAC1 IS ACCOMPANIED BY ACTIVATION OF THE JNK-C-JUN SIGNALING PATHWAY. A ROBUST SPINAL JNK-1 OVERPHOSPHORYLATION WAS OBSERVED POST NERVE-INJURY ALONG WITH A SELECTIVE JNK-DEPENDENT INCREASE IN P-C-JUN AND HDAC1 PROTEIN LEVELS. CO-IMMUNOPRECIPITATION EXPERIMENTS SHOWED THE PRESENCE OF A HETERODIMERIC COMPLEX BETWEEN HDAC1 AND C-JUN IN SNI MICE INDICATING THAT THESE TRANSCRIPTION FACTORS CAN ACT TOGETHER TO REGULATE TRANSCRIPTION THROUGH HETERODIMERIZATION. STIMULATION OF C-JUN PHOSPHORYLATION WAS PREVENTED BY THE SELECTIVE HDAC1 INHIBITOR LG325. WE FOUND THAT HDAC1 WAS ASSOCIATED WITH C-JUN IN NUCLEI OF SPINAL DORSAL HORN ASTROCYTES EXPRESSING JNK. ON THE OTHER HAND, THE PRESENCE OF HDAC1 AND C-JUN INTERACTION WAS NOT DETECTED IN CONTROL MICE. THESE FINDINGS PROVIDE NEW INSIGHTS INTO THE MECHANISMS UNDERLYING THE ANTI-NOCICEPTIVE ACTIVITY OF HDAC INHIBITORS. TAKEN TOGETHER, THESE DATA SUPPORT A ROLE FOR HISTONE DEACETYLASE IN THE EMERGENCE OF NEUROPATHIC PAIN. 2018 9 5954 38 TBI-INDUCED NOCICEPTIVE SENSITIZATION IS REGULATED BY HISTONE ACETYLATION. CHRONIC PAIN AFTER TRAUMATIC BRAIN INJURY (TBI) IS VERY COMMON, BUT THE MECHANISMS LINKING TBI TO PAIN AND THE PAIN-RELATED INTERACTIONS OF TBI WITH PERIPHERAL INJURIES ARE POORLY UNDERSTOOD. IN THESE STUDIES WE PURSUED THE HYPOTHESIS THAT TBI PAIN SENSITIZATION IS ASSOCIATED WITH HISTONE ACETYLATION IN THE RAT LATERAL FLUID PERCUSSION MODEL. SOME ANIMALS RECEIVED HINDPAW INCISIONS IN ADDITION TO TBI TO MIMIC POLYTRAUMA. NEUROPATHOLOGICAL ANALYSIS OF BRAIN TISSUE FROM SHAM AND TBI ANIMALS REVEALED EVIDENCE OF BLEEDING, BREAKDOWN OF THE BLOOD BRAIN BARRIER, IN THE CORTEX, HIPPOCAMPUS, THALAMUS AND OTHER STRUCTURES RELATED TO PAIN SIGNAL PROCESSING. MECHANICAL ALLODYNIA WAS MEASURED IN THESE ANIMALS FOR UP TO EIGHT WEEKS POST-INJURY. INHIBITORS OF HISTONE ACETYLTRANSFERASE (HAT) AND HISTONE DEACETYLASE (HDAC) WERE USED TO PROBE THE ROLE OF HISTONE ACETYLATION IN SUCH PAIN PROCESSING. WE FOLLOWED SERUM MARKERS INCLUDING GLIAL FIBRILLARY ACIDIC PROTEIN (GFAP), NEURON-SPECIFIC ENOLASE 2 (NSE) MYELIN BASIC PROTEIN (MBP) AND S100BETA TO GAUGE TBI INJURY SEVERITY. OUR RESULTS SHOWED THAT TBI CAUSED MECHANICAL ALLODYNIA IN THE HINDPAWS OF THE RATS LASTING SEVERAL WEEKS. HINDPAWS CONTRALATERAL TO TBI SHOWED MORE RAPID AND PROFOUND SENSITIZATION THAN IPSILATERAL HINDPAWS. THE INHIBITION OF HAT USING CURCUMIN 50 MG/KG S.C REDUCED MECHANICAL SENSITIZATION WHILE THE HDAC INHIBITOR SUBEROYLANILIDE HYDROXAMIC ACID 50 MG/KG I.P. PROLONGED SENSITIZATION IN THE TBI RATS. IMMUNOHISTOCHEMICAL ANALYSES OF SPINAL CORD TISSUE LOCALIZED CHANGES IN THE LEVEL OF ACETYLATION OF THE H3K9 HISTONE MARK TO DORSAL HORN NEURONS. TAKEN TOGETHER, THESE FINDINGS DEMONSTRATE THAT TBI INDUCES SUSTAINED NOCICEPTIVE SENSITIZATION, AND CHANGES IN SPINAL NEURONAL HISTONE PROTEINS MAY PLAY AN IMPORTANT ROLE. 2017 10 6582 30 TRICHOSTATIN A, A HISTONE DEACETYLASE INHIBITOR, ALLEVIATES THE EMOTIONAL ABNORMALITY INDUCED BY MALADAPTATION TO STRESS IN MICE. RECENT REPORTS HAVE IMPLIED THAT ABERRANT BIOCHEMICAL PROCESSES IN THE BRAIN ARE FREQUENTLY ACCOMPANIED BY SUBTLE SHIFTS IN THE CELLULAR EPIGENETIC PROFILE THAT MIGHT UNDERLIE THE PATHOGENIC PROGRESSION OF PSYCHIATRIC DISORDERS. THE AIM OF THE PRESENT STUDY WAS TO EXAMINE THE EFFECT OF TRICHOSTATIN A (TSA), A HISTONE DEACETYLASE (HDAC) INHIBITOR, ON THE EMOTIONAL ABNORMALITY INDUCED BY MALADAPTATION TO STRESS IN MICE. MICE WERE EXPOSED TO REPEATED RESTRAINT STRESS FOR 240 MIN/DAY FOR 14 DAYS. WE APPLIED DOSING SCHEDULES. IN ONE SCHEDULE, FROM THE 3RD DAY OF STRESS EXPOSURE, MICE WERE TREATED WITH TSA (1650 MUM/4 MUL, I.C.V.) IMMEDIATELY AFTER THE DAILY EXPOSURE TO RESTRAINT STRESS. IN THE OTHER SCHEDULE, FROM THE 1ST DAY OF STRESS EXPOSURE, MICE WERE TREATED WITH TSA 2 H BEFORE EXPOSURE TO RESTRAINT STRESS. AFTER THE FINAL EXPOSURE TO RESTRAINT STRESS, THE EMOTIONALITY OF MICE WAS EVALUATED USING THE HOLE-BOARD TEST. MICE THAT WERE EXPOSED TO RESTRAINT STRESS FOR 240 MIN/DAY FOR 14 DAYS SHOWED A DECREASE IN HEAD-DIPPING BEHAVIOR. THIS DECREASED EMOTIONALITY OBSERVED IN STRESS-MALADAPTIVE MICE WAS SIGNIFICANTLY RECOVERED BY CHRONIC TREATMENT WITH TSA 2 H BEFORE DAILY EXPOSURE TO RESTRAINT STRESS, WHICH CONFIRMED THE DEVELOPMENT OF STRESS ADAPTATION. ON THE OTHER HAND, NO SUCH STRESS ADAPTATION WAS OBSERVED UNDER CHRONIC TREATMENT WITH TSA IMMEDIATELY AFTER DAILY STRESS EXPOSURE. A BIOCHEMICAL STUDY SHOWED THAT TRYPTOPHAN HYDROXYLASE, THE RATE-LIMITING ENZYME IN SEROTONIN (5-HT) SYNTHESIS, WAS INCREASED IN MIDBRAIN CONTAINING RAPHE NUCLEI OBTAINED FROM STRESS-ADAPTED MICE THAT WERE CHRONICALLY TREATED WITH TSA 2 H BEFORE DAILY STRESS EXPOSURE. THESE FINDINGS SUGGEST THAT AN HDAC INHIBITOR MAY HAVE A BENEFICIAL EFFECT ON STRESS ADAPTATION BY AFFECTING 5-HT NEURAL FUNCTION IN THE BRAIN AND ALLEVIATE THE EMOTIONAL ABNORMALITY UNDER CONDITIONS OF EXCESSIVE STRESS. 2022 11 808 32 CHANGED HISTONE ACETYLATION PATTERNS IN NORMAL-APPEARING WHITE MATTER AND EARLY MULTIPLE SCLEROSIS LESIONS. THE EPIGENETIC IDENTITY OF OLIGODENDROCYTES IS MODULATED BY POSTTRANSLATIONAL MODIFICATIONS OF HISTONES. ACETYLATION OF HISTONE H3 RESULTS FROM THE BALANCE BETWEEN THE ACTIVITY OF HISTONE ACETYLTRANSFERASES (HATS) AND HISTONE DEACETYLASES AND MODULATES TRANSCRIPTIONAL ACTIVATION. WE HAVE PREVIOUSLY SHOWN THAT, IN RODENTS, HISTONE DEACETYLATION FAVORS OLIGODENDROCYTE DIFFERENTIATION, WHEREAS ACETYLATION IS ASSOCIATED WITH INCREASED LEVELS OF TRANSCRIPTIONAL INHIBITORS OF OLIGODENDROCYTE DIFFERENTIATION. HERE, WE REPORT, IN HUMANS BRAINS, A SHIFT TOWARD HISTONE ACETYLATION IN THE WHITE MATTER OF THE FRONTAL LOBES OF AGED SUBJECTS AND IN PATIENTS WITH CHRONIC MULTIPLE SCLEROSIS (MS). INCREASED IMMUNOREACTIVITY FOR ACETYLATED HISTONE H3 WAS OBSERVED IN THE NUCLEI OF NOGOA+ OLIGODENDROCYTES IN A SUBSET OF MS SAMPLES. THESE CHANGES WERE ASSOCIATED WITH HIGH LEVELS OF TRANSCRIPTIONAL INHIBITORS OF OLIGODENDROCYTE DIFFERENTIATION (I.E., TCF7L2, ID2, AND SOX2) AND HIGHER HAT TRANSCRIPT LEVELS (I.E., CBP, P300) IN FEMALE MS PATIENTS COMPARED WITH NON-NEUROLOGICAL CONTROLS AND CORRELATED WITH DISEASE DURATION. CHROMATIN IMMUNOPRECIPITATION FROM SAMPLES OF MS PATIENTS REVEALED ENRICHMENT OF ACETYL-HISTONE H3 AT THE PROMOTER OF THE INCREASED TARGET GENES (I.E., TCF7L2). THE DATA IN CHRONIC LESIONS CONTRASTED WITH FINDINGS IN EARLY MS LESIONS, WHERE A MARKED OLIGODENDROGLIAL HISTONE DEACETYLATION WAS OBSERVED. TOGETHER, THESE DATA SUGGEST THAT HISTONE DEACETYLATION IS A PROCESS THAT OCCURS AT THE EARLY STAGES OF THE DISEASE AND WHOSE EFFICIENCY DECREASES WITH DISEASE DURATION. 2011 12 5018 32 PERSISTENT INFLAMMATION-INDUCED UP-REGULATION OF BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) PROMOTES SYNAPTIC DELIVERY OF ALPHA-AMINO-3-HYDROXY-5-METHYL-4-ISOXAZOLEPROPIONIC ACID RECEPTOR GLUA1 SUBUNITS IN DESCENDING PAIN MODULATORY CIRCUITS. THE ENHANCED AMPA RECEPTOR PHOSPHORYLATION AT GLUA1 SERINE 831 SITES IN THE CENTRAL PAIN-MODULATING SYSTEM PLAYS A PIVOTAL ROLE IN DESCENDING PAIN FACILITATION AFTER INFLAMMATION, BUT THE UNDERLYING MECHANISMS REMAIN UNCLEAR. WE SHOW HERE THAT, IN THE RAT BRAIN STEM, IN THE NUCLEUS RAPHE MAGNUS, WHICH IS A CRITICAL RELAY IN THE DESCENDING PAIN-MODULATING SYSTEM OF THE BRAIN, PERSISTENT INFLAMMATORY PAIN INDUCED BY COMPLETE FREUND ADJUVANT (CFA) CAN ENHANCE AMPA RECEPTOR-MEDIATED EXCITATORY POSTSYNAPTIC CURRENTS AND THE GLUA2-LACKING AMPA RECEPTOR-MEDIATED RECTIFICATION INDEX. WESTERN BLOT ANALYSIS SHOWED AN INCREASE IN GLUA1 PHOSPHORYLATION AT SER-831 BUT NOT AT SER-845. THIS WAS ACCOMPANIED BY AN INCREASE IN DISTRIBUTION OF THE SYNAPTIC GLUA1 SUBUNIT. IN PARALLEL, THE LEVEL OF HISTONE H3 ACETYLATION AT BDNF GENE PROMOTER REGIONS WAS REDUCED SIGNIFICANTLY 3 DAYS AFTER CFA INJECTION, AS INDICATED BY CHIP ASSAYS. THIS WAS CORRELATED WITH AN INCREASE IN BDNF MRNA LEVELS AND BDNF PROTEIN LEVELS. SEQUESTERING ENDOGENOUS EXTRACELLULAR BDNF WITH TRKB-IGG IN THE NUCLEUS RAPHE MAGNUS DECREASED AMPA RECEPTOR-MEDIATED SYNAPTIC TRANSMISSION AND GLUA1 PHOSPHORYLATION AT SER-831 3 DAYS AFTER CFA INJECTION. UNDER THE SAME CONDITIONS, BLOCKADE OF TRKB RECEPTOR FUNCTIONS, PHOSPHOLIPASE C, OR PKC IMPAIRED GLUA1 PHOSPHORYLATION AT SER-831 AND DECREASED EXCITATORY POSTSYNAPTIC CURRENTS MEDIATED BY GLUA2-LACKING AMPA RECEPTORS. TAKEN TOGETHER, THESE RESULTS SUGGEST THAT EPIGENETIC UP-REGULATION OF BDNF BY PERIPHERAL INFLAMMATION INDUCES GLUR1 PHOSPHORYLATION AT SER-831 SITES THROUGH ACTIVATION OF THE PHOSPHOLIPASE C-PKC SIGNALING CASCADE, LEADING TO THE TRAFFICKING OF GLUA1 TO PAIN-MODULATING NEURONAL SYNAPSES. 2014 13 2750 36 EXPRESSION LEVELS OF THE TYROSINE HYDROXYLASE GENE AND HISTONE MODIFICATIONS AROUND ITS PROMOTER IN THE LOCUS COERULEUS AND VENTRAL TEGMENTAL AREA OF RATS DURING FORCED ABSTINENCE FROM MORPHINE. BACKGROUND: EPIGENETIC MECHANISMS SUCH AS HISTONE MODIFICATIONS MAY BE INVOLVED IN THE STRUCTURAL AND BEHAVIORAL CHANGES ASSOCIATED WITH ADDICTION. WE STUDIED WHETHER MORPHINE-INDUCED CHANGES IN MRNA LEVELS OF THE CATECHOLAMINE BIOSYNTHESIS ENZYME, TYROSINE HYDROXYLASE (TH), ARE ASSOCIATED WITH HISTONE MODIFICATIONS AROUND THE PROMOTER OF THIS GENE IN THE LOCUS COERULEUS (LC) AND VENTRAL TEGMENTAL AREA (VTA) OF RATS. METHODS: DEPENDENCE WAS INDUCED IN RATS BY INTRAPERITONEAL INJECTIONS OF MORPHINE FOR 11 DAYS. THE ANIMALS WERE KILLED 2 H (CHRONIC MORPHINE), 24 H AND 7 DAYS (SPONTANEOUS WITHDRAWAL) AFTER THE LAST INJECTION OF MORPHINE. RESULTS: ANALYSIS OF OUR REAL-TIME QUANTITATIVE REVERSE TRANSCRIPTION PCR RESULTS BY 1-WAY ANOVA SHOWED SIGNIFICANT UPREGULATION (5.13 +/- 0.39 FOLDS) OF LC LEVELS OF THE TH TRANSCRIPT 24 H AFTER THE LAST INJECTION OF MORPHINE TO RATS, WHEN COMPARED WITH 2 H AND 7 DAYS TIME POINTS. CHRONIC MORPHINE AND MORPHINE ABSTINENCE FAILED TO CAUSE ANY SIGNIFICANT CHANGES IN THE LEVELS OF TH MRNA IN THE VTA AFTER CESSATION OF MORPHINE. CONSISTENTLY, CHROMATIN IMMUNOPRECIPITATION REAL-TIME QUANTITATIVE PCR ASSAYS REVEALED THAT 24 H AFTER THE LAST INJECTION OF MORPHINE, LEVELS OF H3 ACETYLATION WERE SIGNIFICANTLY INCREASED (4.12 +/- 0.38 FOLDS) AT THE PROMOTER OF THE TH GENE IN THE LC BUT NOT IN THE VTA. OUR DATA ALSO SHOWED THAT HISTONE H3 TRIMETHYLATION FAILED TO CHANGE AROUND THE TH GENE PROMOTER EITHER IN THE VTA OR IN THE LC AFTER MORPHINE ABSTINENCE. CONCLUSIONS: RESULTS OF THE PRESENT STUDY, FOR THE FIRST TIME, DEMONSTRATE THE INVOLVEMENT OF HISTONE H3 ACETYLATION IN THE REGULATION OF TH GENE EXPRESSION IN THE LC OF RATS DURING FORCED ABSTINENCE FROM MORPHINE. 2018 14 2012 28 EPIGENETIC BASIS OF OPIATE SUPPRESSION OF BDNF GENE EXPRESSION IN THE VENTRAL TEGMENTAL AREA. BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) HAS A CRUCIAL ROLE IN MODULATING NEURAL AND BEHAVIORAL PLASTICITY TO DRUGS OF ABUSE. WE FOUND A PERSISTENT DOWNREGULATION OF EXON-SPECIFIC BDNF EXPRESSION IN THE VENTRAL TEGMENTAL AREA (VTA) IN RESPONSE TO CHRONIC OPIATE EXPOSURE, WHICH WAS MEDIATED BY SPECIFIC EPIGENETIC MODIFICATIONS AT THE CORRESPONDING BDNF GENE PROMOTERS. EXPOSURE TO CHRONIC MORPHINE INCREASED STALLING OF RNA POLYMERASE II AT THESE BDNF PROMOTERS IN VTA AND ALTERED PERMISSIVE AND REPRESSIVE HISTONE MODIFICATIONS AND OCCUPANCY OF THEIR REGULATORY PROTEINS AT THE SPECIFIC PROMOTERS. FURTHERMORE, WE FOUND THAT MORPHINE SUPPRESSED BINDING OF PHOSPHO-CREB (CAMP RESPONSE ELEMENT BINDING PROTEIN) TO BDNF PROMOTERS IN VTA, WHICH RESULTED FROM ENRICHMENT OF TRIMETHYLATED H3K27 AT THE PROMOTERS, AND THAT DECREASED NURR1 (NUCLEAR RECEPTOR RELATED-1) EXPRESSION ALSO CONTRIBUTED TO BDNF REPRESSION AND ASSOCIATED BEHAVIORAL PLASTICITY TO MORPHINE. OUR FINDINGS SUGGEST PREVIOUSLY UNKNOWN EPIGENETIC MECHANISMS OF MORPHINE-INDUCED MOLECULAR AND BEHAVIORAL NEUROADAPTATIONS. 2015 15 5963 29 TEM STUDY OF CHRONIC ALCOHOLISM EFFECTS ON EARLY CARCINOGENESIS BY PROBING THE NANOSCALE STRUCTURAL ALTERATIONS OF CELL NUCLEI. NANOSCALE STRUCTURAL ALTERATION IN THE NUCLEI OF CELLS WITH THE PROGRESSION OF CARCINOGENESIS IS DUE TO THE REARRANGEMENTS OF THE BASIC BUILDING BLOCKS IN THE CELL SUCH AS DNA, RNA, LIPIDS, ETC. ALTHOUGH EPIGENETIC MODIFICATIONS UNDERLIE THE DEVELOPMENT OF CANCER, EXPOSURE TO CARCINOGENIC CHEMICALS SUCH AS ALCOHOL ALSO ENHANCES THE DEVELOPMENT OF CANCER. WE REPORT THE EFFECTS OF CHRONIC ALCOHOLISM ON EARLY-CARCINOGENESIS BASED ON CHANGES IN THE DEGREE OF NANOSCALE STRUCTURAL ALTERATIONS (L (D)) IN NUCLEI. FOR THIS, TRANSMISSION ELECTRON MICROSCOPY (TEM) IMAGING OF THE NUCLEI OF COLONIC CELLS IS PERFORMED FOR THE FOLLOWING FOUR MOUSE MODELS: CONTROL MICE; CHRONIC ALCOHOLIC MICE TREATED WITH ETHANOL (I.E., ETOH MICE); MICE TREATED WITH COLONIC CARCINOGEN AZOXYMETHANE (AOM) AND DEXTRAN SULFATE SODIUM (DSS) THAT INDUCED COLITIS (I.E., AOM + DSS MICE); AND CHRONIC ALCOHOLIC OR ETOH TREATED MICE, TOGETHER WITH AOM AND DSS TREATMENT (I.E., AOM + DSS + ETOH MICE). THE DISORDERED OPTICAL LATTICES ARE CONSTRUCTED FROM THEIR RESPECTIVE TEM IMAGES OF THIN COLONIC CELL NUCLEI AND THE L (D) VALUES ARE CALCULATED USING THE INVERSE PARTICIPATION RATIO (IPR) TECHNIQUE FROM THE SPATIALLY LOCALIZED EIGENFUNCTIONS OF THESE LATTICES. RESULTS SHOW NO SIGNIFICANT DIFFERENCE IN THE AVERAGE L (D) VALUE OF THE COLON CELL NUCLEI OF ALCOHOL TREATED MICE RELATIVE TO ITS CONTROL [I.E., L (D)(C) APPROXIMATELY L (D)(ETOH)]; HOWEVER, AN INCREASE IN THE L (D) VALUE OF ALCOHOL TREATED PRECANCEROUS CELLS [I.E., L (D)(AOM + DSS + ETOH) > L (D)(AOM + DSS)], INDICATING THAT ALCOHOL ACCELERATES THE EARLY CARCINOGENIC PROCESS. 2021 16 4498 33 MORPHINE REGULATES ARGONAUTE 2 AND TH EXPRESSION AND ACTIVITY BUT NOT MIR-133B IN MIDBRAIN DOPAMINERGIC NEURONS. EPIGENETIC CHANGES SUCH AS MICRORNAS (MIRS)/AGO2-INDUCED GENE SILENCING REPRESENT COMPLEX MOLECULAR SIGNATURE THAT REGULATE CELLULAR PLASTICITY. RECENT STUDIES SHOWED INVOLVEMENT OF MIRS AND AGO2 IN DRUG ADDICTION. IN THIS STUDY, WE SHOW THAT CHANGES IN GENE EXPRESSION INDUCED BY MORPHINE AND MORPHINE WITHDRAWAL OCCUR WITH CONCOMITANT EPIGENETIC MODIFICATIONS IN THE MESOLIMBIC DOPAMINERGIC (DA) PATHWAY [VENTRAL TEGMENTAL AREA (VTA)/NUCLEUS ACCUMBENS (NAC) SHELL], WHICH IS CRITICALLY INVOLVED IN DRUG-INDUCED DEPENDENCE. WE FOUND THAT ACUTE OR CHRONIC MORPHINE ADMINISTRATION AS WELL AS MORPHINE WITHDRAWAL DID NOT MODIFY MIR-133B MESSENGER RNA (MRNA) EXPRESSION IN THE VTA, WHEREAS AGO2 PROTEIN LEVELS WERE DECREASED AND INCREASED IN MORPHINE-DEPENDENT RATS AND AFTER MORPHINE WITHDRAWAL, RESPECTIVELY. THESE CHANGES WERE PARALLELED WITH ENHANCED AND DECREASED NAC TYROSINE HYDROXYLASE (TH) PROTEIN (AN EARLY DA MARKER) IN MORPHINE-DEPENDENT RATS AND AFTER WITHDRAWAL, RESPECTIVELY. WE ALSO OBSERVED CHANGES IN TH MRNA EXPRESSION IN THE VTA THAT COULD BE RELATED TO AGO2-INDUCED TRANSLATIONAL REPRESSION OF TH MRNA DURING MORPHINE WITHDRAWAL. HOWEVER, THE VTA NUMBER OF TH-POSITIVE NEURONS SUFFERED NO ALTERATIONS AFTER THE DIFFERENT TREATMENT. ACUTE MORPHINE ADMINISTRATION PRODUCED A MARKED INCREASE IN TH ACTIVITY AND DA TURNOVER IN THE NAC (SHELL). IN CONTRAST, PRECIPITATED MORPHINE WITHDRAWAL DECREASED TH ACTIVATION AND DID NOT CHANGE DA TURNOVER. THESE FINDINGS PROVIDE NEW INFORMATION INTO THE POSSIBLE CORRELATION BETWEEN AGO2/MIRS COMPLEX REGULATION AND DA NEURONS PLASTICITY DURING OPIATE ADDICTION. 2015 17 1320 33 DEMETHYLATION REGULATION OF BDNF GENE EXPRESSION IN DORSAL ROOT GANGLION NEURONS IS IMPLICATED IN OPIOID-INDUCED PAIN HYPERSENSITIVITY IN RATS. REPEATED ADMINISTRATION OF MORPHINE MAY RESULT IN OPIOID-INDUCED HYPERSENSITIVITY (OIH), WHICH INVOLVES ALTERED EXPRESSION OF NUMEROUS GENES, INCLUDING BRAIN-DERIVED NEUROTROPHIC FACTOR (BDNF) IN DORSAL ROOT GANGLION (DRG) NEURONS. YET, IT REMAINS UNCLEAR HOW BDNF EXPRESSION IS INCREASED IN DRG NEURONS AFTER REPEATED MORPHINE TREATMENT. DNA METHYLATION IS AN IMPORTANT MECHANISM OF EPIGENETIC CONTROL OF GENE EXPRESSION. IN THE CURRENT STUDY, WE HYPOTHESIZED THAT THE DEMETHYLATION REGULATION OF CERTAIN BDNF GENE PROMOTERS IN DRG NEURONS MAY CONTRIBUTE TO THE DEVELOPMENT OF OIH. REAL-TIME RT-PCR WAS USED TO ASSESS CHANGES IN THE MRNA TRANSCRIPTION LEVELS OF MAJOR BDNF EXONS INCLUDING EXON I, II, IV, VI, AS WELL AS TOTAL BDNF MRNA IN DRGS FROM RATS AFTER REPEATED MORPHINE ADMINISTRATION. THE LEVELS OF EXON IV AND TOTAL BDNF MRNA WERE SIGNIFICANTLY UPREGULATED BY REPEATED MORPHINE ADMINISTRATION, AS COMPARED TO THAT IN SALINE CONTROL GROUP. FURTHER, ELISA ARRAY AND IMMUNOCYTOCHEMISTRY STUDY REVEALED A ROBUST UPREGULATION OF BDNF PROTEIN EXPRESSION IN DRG NEURONS AFTER REPEATED MORPHINE EXPOSURE. CORRESPONDINGLY, THE METHYLATION LEVELS OF BDNF EXON IV PROMOTER SHOWED A SIGNIFICANT DOWNREGULATION BY MORPHINE TREATMENT. IMPORTANTLY, INTRATHECAL ADMINISTRATION OF A BDNF ANTIBODY, BUT NOT CONTROL IGG, SIGNIFICANTLY INHIBITED MECHANICAL HYPERSENSITIVITY THAT DEVELOPED IN RATS AFTER REPEATED MORPHINE TREATMENT. CONVERSELY, INTRATHECAL ADMINISTRATION OF AN INHIBITOR OF DNA METHYLATION, 5-AZA-2'-DEOXYCYTIDINE (5-AZA-DC) MARKEDLY UPREGULATED THE BDNF PROTEIN EXPRESSION IN DRG NEURONS AND ENHANCED THE MECHANICAL ALLODYNIA AFTER REPEATED MORPHINE EXPOSURE. TOGETHER, OUR FINDINGS SUGGEST THAT DEMETHYLATION REGULATION OF BDNF GENE PROMOTER MAY BE IMPLICATED IN THE DEVELOPMENT OF OIH THROUGH EPIGENETIC CONTROL OF BDNF EXPRESSION IN DRG NEURONS. 2016 18 3832 29 INVOLVEMENT OF SPINAL SIRT1 IN DEVELOPMENT OF CHRONIC CONSTRICTION INJURY INDUCED NEUROPATHIC PAIN IN RATS. IT IS KNOWN THAT THE EPIGENETIC PROCESS OF HISTONE ACETYLATION IS INVOLVED IN THE NEUROPATHIC PAIN. THE AIM OF THIS STUDY WAS TO DETERMINE WHETHER SIRTUIN TYPE 1 (SIRT1), AN NAD(+) DEPENDENT DEACETYLASE, AFFECTED ALLODYNIA AND HYPERALGESIA IN NEUROPATHIC PAIN. THE NEUROPATHIC PAIN MODEL WAS ESTABLISHED BY LIGATURE OF THE RIGHT SCIATIC NERVE TO INDUCE CHRONIC CONSTRICTION INJURY (CCI) IN RATS. HISTONE ACETYLTRANSFERASE (HAT) ACTIVITY WAS INCREASED AND, AND HISTONE DEACETYLASE (HDAC) ACTIVITY WAS DECLINED IN TISSUE OF THE SPINAL DORSA HORN IN CCI RATES BY MEANS OF ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA). THE PERSISTENT HYPERALGESIA AND ALLODYNIA CAUSED BY CCI WERE ASSOCIATED WITH DOWNREGULATION OF SIRT1 AND UPREGULATION OF ACETYLATED-H3 (AC-H3) IN TISSUE OF THE SPINAL CORD BY WESTERN BLOT ASSAY, WHICH WAS REVERSED AFTER INTRATHECAL INJECTION OF SIRT1 AGONIST SRT1720. SRT1720 TREATMENT ACHIEVED ANALGESIC THROUGH INHIBITING THE ACETYLATION OF NUCLEAR FACTOR KAPPA B (NF-KAPPAB) AND BLOCKING THE RELEASES OF THE INFLAMMATORY FACTORS INCLUDING TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA) AND INTERLEUKIN (IL)-6 BY MEANS OF WESTERN BLOT AND REAL-TIME QUANTITATIVE PCR (RT-PCR), RESPECTIVELY. TAKEN TOGETHER, THESE DATA SUGGEST THAT SIRT1 IN THE SPINAL CORD PLAYS AN IMPORTANT ROLE IN THE NEUROPATHIC PAIN IN THE RAT MODEL. 2018 19 6039 50 THE CHEMOKINE RECEPTOR CXCR2 SUPPORTS NOCICEPTIVE SENSITIZATION AFTER TRAUMATIC BRAIN INJURY. CHRONIC PAIN AFTER TRAUMATIC BRAIN INJURY (TBI) IS VERY COMMON, BUT THE MECHANISMS LINKING TBI TO PAIN AND THE PAIN-RELATED INTERACTIONS OF TBI WITH PERIPHERAL INJURIES ARE POORLY UNDERSTOOD. CHEMOKINE RECEPTORS PLAY AN IMPORTANT ROLE IN BOTH PAIN AND BRAIN INJURY. IN THE CURRENT WORK, WE PURSUED THE HYPOTHESIS THAT THE EPIGENETICALLY REGULATED CXC CHEMOKINE RECEPTOR 2 (CXCR2) IS A CRUCIAL MODULATOR OF NOCICEPTIVE SENSITIZATION INDUCED BY TBI. FOR THESE STUDIES, WE USED THE RAT LATERAL FLUID PERCUSSION MODEL OF TBI. HISTONE ACTYLTRANSFERASE ACTIVITY WAS BLOCKED USING ANACARDIC ACID BEGINNING IMMEDIATELY FOLLOWING INJURY, OR DELAYED FOR SEVEN DAYS PRIOR TO ADMINISTRATION. THE SELECTIVE CXCR2 ANTAGONIST SCH527123 ADMINISTERED SYSTEMICALLY OR INTRATHECALLY WAS USED TO PROBE THE ROLE OF CHEMOKINE SIGNALING ON MECHANICAL HINDPAW SENSITIZATION AFTER TBI. THE EXPRESSION OF THE CXCR2 RECEPTOR WAS ACCOMPLISHED USING REAL-TIME PCR, IMMUNOHISTOCHEMISTRY, AND WESTERN BLOTTING, WHILE EPIGENETIC REGULATION WAS ASSESSED USING CHROMATIN IMMUNOPRECIPITATION ASSAY. THE SPINAL LEVELS OF SEVERAL PAIN-RELATED MEDIATORS INCLUDING CXCL1, AN ENDOGENOUS LIGAND FOR CXCR2, AS WELL AS BRAIN-DERIVED NEUROTROPHIC FACTOR AND PRODYNORPHIN WERE MEASURED BY ENZYME-LINKED IMMUNOSORBENT ASSAY. WE OBSERVED THAT ANACARDIC ACID POTENTLY BLOCKED AND REVERSED MECHANICAL HINDPAW SENSITIZATION AFTER TBI. THE SAME DRUG WAS ABLE TO PREVENT THE UPREGULATION OF CXCR2 AFTER TBI, BUT DID NOT AFFECT THE SPINAL EXPRESSION OF OTHER PAIN MEDIATORS. ON THE OTHER HAND, BOTH SYSTEMICALLY AND INTRATHECALLY ADMINISTERED SCH527123 REVERSED HINDPAW ALLODYNIA AFTER TBI. MOST OF THE SPINAL CXCR2 APPEARED TO BE EXPRESSED BY SPINAL CORD NEURONS. CHROMATIN IMMUNOPRECIPITATION EXPERIMENTS DEMONSTRATED TBI-ENHANCED ASSOCIATION OF THE CXCR2 PROMOTER WITH ACETYLATED-H3K9 HISTONE PROTEIN THAT WAS ALSO REVERSIBLE USING ANACARDIC ACID. TAKEN TOGETHER, OUR FINDINGS SUGGESTED THAT TBI CAUSES THE UPREGULATION OF SPINAL CXCR2 THROUGH AN EPIGENETIC MECHANISM ULTIMATELY SUPPORTING NOCICEPTIVE SENSITIZATION. THE USE OF CXCR2 ANTAGONISTS MAY, THEREFORE, BE USEFUL IN PAIN RESULTING FROM TBI. 2017 20 2785 38 EZH2 REGULATES SPINAL NEUROINFLAMMATION IN RATS WITH NEUROPATHIC PAIN. ALTERATION IN GENE EXPRESSION ALONG THE PAIN SIGNALING PATHWAY IS A KEY MECHANISM CONTRIBUTING TO THE GENESIS OF NEUROPATHIC PAIN. ACCUMULATING STUDIES HAVE SHOWN THAT EPIGENETIC REGULATION PLAYS A CRUCIAL ROLE IN NOCICEPTIVE PROCESS IN THE SPINAL DORSAL HORN. IN THIS PRESENT STUDY, WE INVESTIGATED THE ROLE OF ENHANCER OF ZESTE HOMOLOG-2 (EZH2), A SUBUNIT OF THE POLYCOMB REPRESSIVE COMPLEX 2, IN THE SPINAL DORSAL HORN IN THE GENESIS OF NEUROPATHIC PAIN IN RATS INDUCED BY PARTIAL SCIATIC NERVE LIGATION. EZH2 IS A HISTONE METHYLTRANSFERASE, WHICH CATALYZES THE METHYLATION OF HISTONE H3 ON K27 (H3K27), RESULTING IN GENE SILENCING. WE FOUND THAT LEVELS OF EZH2 AND TRI-METHYLATED H3K27 (H3K27TM) IN THE SPINAL DORSAL HORN WERE INCREASED IN RATS WITH NEUROPATHIC PAIN ON DAY 3 AND DAY 10 POST NERVE INJURIES. EZH2 WAS PREDOMINANTLY EXPRESSED IN NEURONS IN THE SPINAL DORSAL HORN UNDER NORMAL CONDITIONS. THE NUMBER OF NEURONS WITH EZH2 EXPRESSION WAS INCREASED AFTER NERVE INJURY. MORE STRIKINGLY, NERVE INJURY DRASTICALLY INCREASED THE NUMBER OF MICROGLIA WITH EZH2 EXPRESSION BY MORE THAN SEVENFOLD. INTRATHECAL INJECTION OF THE EZH2 INHIBITOR ATTENUATED THE DEVELOPMENT AND MAINTENANCE OF MECHANICAL AND THERMAL HYPERALGESIA IN RATS WITH NERVE INJURY. SUCH ANALGESIC EFFECTS WERE CONCURRENTLY ASSOCIATED WITH THE REDUCED LEVELS OF EZH2, H3K27TM, IBA1, GFAP, TNF-ALPHA, IL-1BETA, AND MCP-1 IN THE SPINAL DORSAL HORN IN RATS WITH NERVE INJURY. OUR RESULTS HIGHLY SUGGEST THAT TARGETING THE EZH2 SIGNALING PATHWAY COULD BE AN EFFECTIVE APPROACH FOR THE MANAGEMENT OF NEUROPATHIC PAIN. 2017