1 5865 120 SUPPRESSION OF HDAC2 IN SPINAL CORD ALLEVIATES MECHANICAL HYPERALGESIA AND RESTORES KCC2 EXPRESSION IN A RAT MODEL OF BONE CANCER PAIN. EPIGENETIC MODULATION PARTICIPATES IN THE MECHANISM OF MULTIPLE TYPES OF PATHOLOGICAL PAIN, SO TARGETING THE INVOLVED REGULATORS MAY BE A PROMISING STRATEGY FOR PAIN TREATMENT. OUR PREVIOUS RESEARCH IDENTIFIED THE ANALGESIC EFFECT OF THE HISTONE DEACETYLASE (HDAC) INHIBITOR TRICHOSTATIN A (TSA) ON MECHANICAL HYPERALGESIA IN A RAT MODEL OF BONE CANCER PAIN (BCP) VIA RESTORATION OF MU-OPIOID RECEPTOR (MOR) EXPRESSION. HOWEVER, THE SPECIFIC TYPES OF HDACS CONTRIBUTING TO BCP HAVE NOT BEEN EXPLORED. THE PRESENT STUDY INVESTIGATED THE EXPRESSION PATTERN OF SOME COMMON HDACS AND FOUND THAT HDAC2 WAS UP-REGULATED IN A TIME-DEPENDENT MANNER IN THE LUMBAR SPINAL CORD OF BCP RATS. TSA APPLICATION SUPPRESSED HDAC2 EXPRESSION IN CULTURED PC12 CELLS AND REVERSED THE AUGMENTED HDAC2 IN BCP RATS. AN RNA-INTERFERING STRATEGY CONFIRMED THE ESSENTIAL ROLE OF HDAC2 IN THE MODULATION OF MECHANICAL HYPERALGESIA FOLLOWING TUMOR CELL INOCULATION, AND WE FURTHER EXAMINED ITS POSSIBLE DOWNSTREAM TARGETS. NOTABLY, HDAC2 KNOCK-DOWN DID NOT RESTORE MOR EXPRESSION, BUT IT ROBUSTLY REVERSED THE DOWN-REGULATION OF POTASSIUM-CHLORIDE COTRANSPORTER 2 (KCC2). THE IMPAIRED KCC2 EXPRESSION IS A VITAL MECHANISM OF MANY TYPES OF PATHOLOGICAL PAIN. THEREFORE, OUR RESULTS DEMONSTRATED THAT HDAC2 IN SPINAL CORD CONTRIBUTED TO THE MECHANICAL HYPERALGESIA IN BCP RATS, AND THIS EFFECT MAY BE ASSOCIATED WITH KCC2 MODULATION. 2018 2 4160 34 MECP2 EPIGENETIC SILENCING OF OPRM1 GENE IN PRIMARY SENSORY NEURONS UNDER NEUROPATHIC PAIN CONDITIONS. OPIOIDS ARE THE LAST OPTION FOR THE PHARMACOLOGICAL TREATMENT OF NEUROPATHIC PAIN, BUT THEIR ANTINOCICEPTIVE EFFECTS ARE LIMITED. DECREASED MU OPIOID RECEPTOR (MOR) EXPRESSION IN THE PERIPHERAL NERVOUS SYSTEM MAY CONTRIBUTE TO THIS. HERE, WE SHOWED THAT NERVE INJURY INDUCED HYPERMETHYLATION OF THE OPRM1 GENE PROMOTER AND AN INCREASED EXPRESSION OF METHYL-CPG BINDING PROTEIN 2 (MECP2) IN INJURED DORSAL ROOT GANGLION (DRG). THE DOWNREGULATION OF MOR IN THE DRG IS CLOSELY RELATED TO THE AUGMENTATION OF MECP2, AN EPIGENETIC REPRESSOR, WHICH COULD RECRUIT HDAC1 AND BIND TO THE METHYLATED REGIONS OF THE OPRM1 GENE PROMOTER. MECP2 KNOCKDOWN RESTORED THE EXPRESSION OF MOR IN INJURED DRG AND ENHANCED THE ANALGESIC EFFECT OF MORPHINE, WHILE THE MIMICKING OF THIS INCREASE VIA THE INTRATHECAL INFUSION OF VIRAL VECTOR-MEDIATED MECP2 WAS SUFFICIENT TO REDUCE MOR IN THE DRG. MOREOVER, HDAC1 INHIBITION WITH SUBEROYLANILIDE HYDROXAMIC ACID, AN HDAC INHIBITOR, ALSO PREVENTED MOR REDUCTION IN THE DRG OF NEUROPATHIC PAIN MICE, CONTRIBUTING TO THE AUGMENTATION OF MORPHINE ANALGESIA EFFECTS. MECHANISTICALLY, UPREGULATED MECP2 PROMOTES THE BINDING OF A HIGH LEVEL OF HDCA1 TO HYPERMETHYLATED REGIONS OF THE OPRM1 GENE PROMOTER, REDUCES THE ACETYLATION OF HISTONE H3 (ACH3) LEVELS OF THE OPRM1 GENE PROMOTER, AND ATTENUATES OPRM1 TRANSCRIPTION IN INJURED DRG. THUS, UPREGULATED MECP2 AND HDAC1 IN OPRM1 GENE PROMOTER SITES, NEGATIVELY REGULATES MOR EXPRESSION IN INJURED DRG, MITIGATING THE ANALGESIC EFFECT OF THE OPIOIDS. TARGETING MECP2/HDAC1 MAY THUS PROVIDE A NEW SOLUTION FOR IMPROVING THE THERAPEUTIC EFFECT OF OPIOIDS IN A CLINICAL SETTING. 2021 3 3832 32 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 4 2452 43 EPIGENETIC SUPPRESSION OF POTASSIUM-CHLORIDE CO-TRANSPORTER 2 EXPRESSION IN INFLAMMATORY PAIN INDUCED BY COMPLETE FREUND'S ADJUVANT (CFA). BACKGROUND: MULTIPLE MECHANISMS CONTRIBUTE TO THE STIMULUS-EVOKED PAIN HYPERSENSITIVITY THAT MAY BE EXPERIENCED AFTER PERIPHERAL INFLAMMATION. PERSISTENT PATHOLOGICAL STIMULI IN MANY PAIN CONDITIONS AFFECT THE EXPRESSION OF CERTAIN GENES THROUGH EPIGENETIC ALTERNATIONS. THE MAIN PURPOSE OF OUR STUDY WAS TO INVESTIGATE THE ROLE OF EPIGENETIC MODIFICATION ON POTASSIUM-CHLORIDE CO-TRANSPORTER 2 (KCC2) GENE EXPRESSION IN THE PERSISTENCE OF INFLAMMATORY PAIN. METHODS: PERSISTENT INFLAMMATORY PAIN WAS INDUCED THROUGH THE INJECTION OF COMPLETE FREUND'S ADJUVANT (CFA) IN THE LEFT HIND PAW OF RATS. ACETYL-HISTONE H3 AND H4 LEVEL WAS DETERMINED BY CHROMATIN IMMUNOPRECIPITATION IN THE SPINAL DORSAL HORN. PAIN BEHAVIOUR AND INHIBITORY SYNAPTIC FUNCTION OF SPINAL CORD WERE DETERMINED BEFORE AND AFTER CFA INJECTION. KCC2 EXPRESSION WAS DETERMINED BY REAL TIME RT-PCR AND WESTERN BLOT. INTRATHECAL KCC2 SIRNA (2 MUG PER 10 MUL PER RAT) OR HDAC INHIBITOR (10 MUG PER 10 MUL PER RAT) WAS INJECTED ONCE DAILY FOR 3 DAYS BEFORE CFA INJECTION. RESULTS: PERSISTENT INFLAMMATORY PAIN EPIGENETICALLY SUPPRESSED KCC2 EXPRESSION THROUGH HISTONE DEACETYLASE (HDAC)-MEDIATED HISTONE HYPOACETYLATION, RESULTING IN DECREASED INHIBITORY SIGNALLING EFFICACY. KCC2 KNOCK-DOWN CAUSED BY INTRATHECAL ADMINISTRATION OF KCC2 SIRNA IN NAIVE RATS REDUCED KCC2 EXPRESSION IN THE SPINAL CORD, LEADING TO SENSITIZED PAIN BEHAVIOURS AND IMPAIRED INHIBITORY SYNAPTIC TRANSMISSION IN THEIR SPINAL CORDS. MOREOVER, INTRATHECAL HDAC INHIBITOR INJECTION IN CFA RATS INCREASED KCC2 EXPRESSION, PARTIALLY RESTORING THE SPINAL INHIBITORY SYNAPTIC TRANSMISSION AND RELIEVING THE SENSITIZED PAIN BEHAVIOUR. CONCLUSION: THESE FINDINGS SUGGEST THAT THE TRANSCRIPTION OF SPINAL KCC2 IS REGULATED BY HISTONE ACETYLATION EPIGENETICALLY FOLLOWING CFA. SIGNIFICANCE: PERSISTENT PAIN SUPPRESSES KCC2 EXPRESSION THROUGH HDAC-MEDIATED HISTONE HYPOACETYLATION AND CONSEQUENTLY IMPAIRS THE INHIBITORY FUNCTION OF INHIBITORY INTERNEURONS. DRUGS SUCH AS HDAC INHIBITORS THAT SUPPRESS THE INFLUENCES OF PERSISTENT PAIN ON THE EXPRESSION OF KCC2 MAY SERVE AS A NOVEL ANALGESIC. 2017 5 5851 45 SUBEROYLANILIDE HYDROXAMIC ACID TRIGGERS AUTOPHAGY BY INFLUENCING THE MTOR PATHWAY IN THE SPINAL DORSAL HORN IN A RAT NEUROPATHIC PAIN MODEL. HISTONE ACETYLATION LEVELS CAN BE UPREGULATED BY TREATING CELLS WITH HISTONE DEACETYLASE INHIBITORS (HDACIS), WHICH CAN INDUCE AUTOPHAGY. AUTOPHAGY FLUX IN THE SPINAL CORD OF RATS FOLLOWING THE LEFT FIFTH LUMBER SPINAL NERVE LIGATION (SNL) IS INVOLVED IN THE PROGRESSION OF NEUROPATHIC PAIN. SUBEROYLANILIDE HYDROXAMIC ACID (SAHA), ONE OF THE HDACIS CAN INTERFERE WITH THE EPIGENETIC PROCESS OF HISTONE ACETYLATION, WHICH HAS BEEN SHOWN TO EASE NEUROPATHIC PAIN. RECENT RESEARCH SUGGEST THAT SAHA CAN STIMULATE AUTOPHAGY VIA THE MAMMALIAN TARGET OF RAPAMYCIN (MTOR) PATHWAY IN SOME TYPES OF CANCER CELLS. HOWEVER, LITTLE IS KNOWN ABOUT THE ROLE OF SAHA AND AUTOPHAGY IN NEUROPATHIC PAIN AFTER NERVE INJURY. IN THE PRESENT STUDY, WE AIM TO INVESTIGATE AUTOPHAGY FLUX AND THE ROLE OF THE MTOR PATHWAY ON SPINAL CELLS AUTOPHAGY ACTIVATION IN NEUROPATHIC PAIN INDUCED BY SNL IN RATS THAT RECEIVED SAHA TREATMENT. AUTOPHAGY-RELATED PROTEINS AND MTOR OR ITS ACTIVE FORM WERE ASSESSED BY USING WESTERN BLOT, IMMUNOHISTOCHEMISTRY, DOUBLE IMMUNOFLUORESCENCE STAINING AND TRANSMISSION ELECTRON MICROSCOPY (TEM). WE FOUND THAT SAHA DECREASED THE PAW MECHANICAL WITHDRAWAL THRESHOLD (PMWT) OF THE LOWER COMPARED WITH SNL. AUTOPHAGY FLUX WAS MAINLY DISRUPTED IN THE ASTROCYTES AND NEURONAL CELLS OF THE SPINAL CORD DORSAL HORN ON POSTSURGICAL DAY 28 AND WAS REVERSED BY DAILY INTRATHECAL INJECTION OF SAHA (N = 100 NMOL/DAY OR N = 200 NMOL/DAY). SAHA ALSO DECREASED MTOR AND PHOSPHORYLATED MTOR (P-MTOR) EXPRESSION, ESPECIALLY P-MTOR EXPRESSION IN ASTROCYTES AND NEURONAL CELLS OF THE SPINAL DORSAL HORN. THESE RESULTS SUGGEST THAT SAHA ATTENUATES NEUROPATHIC PAIN AND CONTRIBUTES TO AUTOPHAGY FLUX IN ASTROCYTES AND NEURONAL CELLS OF THE SPINAL DORSAL HORN VIA THE MTOR SIGNALING PATHWAY. 2019 6 6172 32 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 7 2300 31 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 8 4906 45 P300 EXERTS AN EPIGENETIC ROLE IN CHRONIC NEUROPATHIC PAIN THROUGH ITS ACETYLTRANSFERASE ACTIVITY IN RATS FOLLOWING CHRONIC CONSTRICTION INJURY (CCI). BACKGROUND: NEUROPATHIC PAIN IS DETRIMENTAL TO HUMAN HEALTH; HOWEVER, ITS PATHOGENESIS STILL REMAINS LARGELY UNKNOWN. OVEREXPRESSION OF PAIN-ASSOCIATED GENES AND INCREASED NOCICEPTIVE SOMATO-SENSITIVITY ARE WELL OBSERVED IN NEUROPATHIC PAIN. THE IMPORTANCE OF EPIGENETIC MECHANISMS IN REGULATING THE EXPRESSION OF PRO- OR ANTI-NOCICEPTIVE GENES HAS BEEN REVEALED BY STUDIES RECENTLY, AND WE HYPOTHESIZE THAT THE TRANSCRIPTIONAL COACTIVATOR AND THE HISTONE ACETYLTRANSFERASE E1A BINDING PROTEIN P300 (P300), AS A PART OF THE EPIGENETIC MECHANISMS OF GENE REGULATION, MAY BE INVOLVED IN THE PATHOGENESIS OF NEUROPATHIC PAIN INDUCED BY CHRONIC CONSTRICTION INJURY (CCI). TO TEST THIS HYPOTHESIS, TWO DIFFERENT APPROACHES WERE USED IN THIS STUDY: (I) DOWN-REGULATING P300 WITH SPECIFIC SMALL HAIRPIN RNA (SHRNA) AND (II) CHEMICAL INHIBITION OF P300 ACETYLTRANSFERASE ACTIVITY BY A SMALL MOLECULE INHIBITOR, C646. RESULTS: USING THE CCI RAT MODEL, WE FOUND THAT THE P300 EXPRESSION WAS INCREASED IN THE LUMBAR SPINAL CORD ON DAY 14 AFTER CCI. THE TREATMENT WITH INTRATHECAL P300 SHRNA REVERSED CCI-INDUCED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA, AND SUPPRESSED THE EXPRESSION OF CYCLOOXYGENASE-2 (COX-2), A NEUROPATHIC PAIN-ASSOCIATED FACTOR. FURTHERMORE, C646, AN INHIBITOR OF P300 ACETYLTRANSFERASE, ALSO ATTENUATED MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA, ACCOMPANIED BY A SUPPRESSED COX-2 EXPRESSION, IN THE SPINAL CORD. CONCLUSIONS: THE RESULTS SUGGEST THAT, THROUGH ITS ACETYLTRANSFERASE ACTIVITY IN THE SPINAL CORD AFTER CCI, P300 EPIGENETICALLY PLAYS AN IMPORTANT ROLE IN NEUROPATHIC PAIN. INHIBITING P300, USING INTERFERING RNA OR C646, MAY BE A PROMISING APPROACH TO THE DEVELOPMENT OF NEW NEUROPATHIC PAIN THERAPIES. 2012 9 3721 45 INHIBITION OF CLASS II HISTONE DEACETYLASES IN THE SPINAL CORD ATTENUATES INFLAMMATORY HYPERALGESIA. BACKGROUND: SEVERAL CLASSES OF HISTONE DEACETYLASES (HDACS) ARE EXPRESSED IN THE SPINAL CORD THAT IS A CRITICAL STRUCTURE OF THE NOCICEPTIVE PATHWAY. HDAC-REGULATED HISTONE ACETYLATION IS AN IMPORTANT COMPONENT OF CHROMATIN REMODELING LEADING TO EPIGENETIC REGULATION OF GENE TRANSCRIPTION. TO UNDERSTAND THE ROLE OF HISTONE ACETYLATION IN EPIGENETIC REGULATION OF PATHOLOGICAL PAIN, WE HAVE STUDIED THE IMPACT OF DIFFERENT CLASSES OF HDACS IN THE SPINAL CORD ON INFLAMMATORY HYPERALGESIA INDUCED BY COMPLETE FREUND'S ADJUVANT (CFA). RESULTS: WE INTRATHECALLY APPLIED INHIBITORS SPECIFIC TO DIFFERENT CLASSES OF HDACS AND EVALUATED THEIR IMPACT ON INFLAMMATORY HYPERALGESIA. PRE-INJECTED INHIBITORS TARGETING CLASS I AS WELL AS II (SAHA, TSA, LAQ824) OR IIA (VPA, 4-PB) HDACS SIGNIFICANTLY DELAYED THE THERMAL HYPERALGESIA INDUCED BY UNILATERAL CFA INJECTION IN THE HINDPAW. EXISTING HYPERALGESIA INDUCED BY CFA WAS ALSO ATTENUATED BY THE HDAC INHIBITORS (HDACIS). IN CONTRAST, THESE INHIBITORS DID NOT INTERFERE WITH THE THERMAL RESPONSE EITHER IN NAIVE ANIMALS, OR ON THE CONTRALATERAL SIDE OF INFLAMED ANIMALS. INTERESTINGLY, MS-275 THAT SPECIFICALLY INHIBITS CLASS I HDACS FAILED TO ALTER THE HYPERALGESIA ALTHOUGH IT INCREASED HISTONE 3 ACETYLATION IN THE SPINAL CORD AS SAHA DID. USING IMMUNOBLOT ANALYSIS, WE FURTHER FOUND THAT THE LEVELS OF CLASS IIA HDAC MEMBERS (HDAC4, 5, 7, 9) IN THE SPINAL DORSAL HORN WERE UPREGULATED FOLLOWING CFA INJECTION WHILE THOSE OF CLASS I HDAC MEMBERS (HDAC1, 2, 3) REMAINED STABLE OR WERE SLIGHTLY REDUCED. CONCLUSIONS: OUR DATA SUGGEST THAT ACTIVITY OF CLASS II HDACS IN THE SPINAL CORD IS CRITICAL TO THE INDUCTION AND MAINTENANCE OF INFLAMMATORY HYPERALGESIA INDUCED BY CFA, WHILE ACTIVITY OF CLASS I HDACS MAY BE UNNECESSARY. COMPARISON OF THE EFFECTS OF HDACIS SPECIFIC TO CLASS II AND IIA AS WELL AS THE EXPRESSION PATTERN OF DIFFERENT HDACS IN THE SPINAL CORD IN RESPONSE TO CFA SUGGESTS THAT THE MEMBERS OF CLASS IIA HDACS MAY BE POTENTIAL TARGETS FOR ATTENUATING PERSISTENT INFLAMMATORY PAIN. 2010 10 4615 40 NERVE INJURY DIMINISHES OPIOID ANALGESIA THROUGH LYSINE METHYLTRANSFERASE-MEDIATED TRANSCRIPTIONAL REPRESSION OF MU-OPIOID RECEPTORS IN PRIMARY SENSORY NEURONS. THE MU-OPIOID RECEPTOR (MOR, ENCODED BY OPRM1) AGONISTS ARE THE MAINSTAY ANALGESICS FOR TREATING MODERATE TO SEVERE PAIN. NERVE INJURY CAUSES DOWN-REGULATION OF MORS IN THE DORSAL ROOT GANGLION (DRG) AND DIMINISHES THE OPIOID EFFECT ON NEUROPATHIC PAIN. HOWEVER, THE EPIGENETIC MECHANISMS UNDERLYING THE DIMINISHED MOR EXPRESSION CAUSED BY NERVE INJURY ARE NOT CLEAR. G9A (ENCODED BY EHMT2), A HISTONE 3 AT LYSINE 9 METHYLTRANSFERASE, IS A KEY CHROMATIN REGULATOR RESPONSIBLE FOR GENE SILENCING. IN THIS STUDY, WE DETERMINED THE ROLE OF G9A IN DIMINISHED MOR EXPRESSION AND OPIOID ANALGESIC EFFECTS IN ANIMAL MODELS OF NEUROPATHIC PAIN. WE FOUND THAT NERVE INJURY IN RATS INDUCED A LONG-LASTING REDUCTION IN THE EXPRESSION LEVEL OF MORS IN THE DRG BUT NOT IN THE SPINAL CORD. NERVE INJURY CONSISTENTLY INCREASED THE ENRICHMENT OF THE G9A PRODUCT HISTONE 3 AT LYSINE 9 DIMETHYLATION IN THE PROMOTER OF OPRM1 IN THE DRG. G9A INHIBITION OR SIRNA KNOCKDOWN FULLY REVERSED MOR EXPRESSION IN THE INJURED DRG AND POTENTIATED THE MORPHINE EFFECT ON PAIN HYPERSENSITIVITY INDUCED BY NERVE INJURY. IN MICE LACKING EHMT2 IN DRG NEURONS, NERVE INJURY FAILED TO REDUCE THE EXPRESSION LEVEL OF MORS AND THE MORPHINE EFFECT. IN ADDITION, G9A INHIBITION OR EHMT2 KNOCKOUT IN DRG NEURONS NORMALIZED NERVE INJURY-INDUCED REDUCTION IN THE INHIBITORY EFFECT OF THE OPIOID ON SYNAPTIC GLUTAMATE RELEASE FROM PRIMARY AFFERENT NERVES. OUR FINDINGS INDICATE THAT G9A CONTRIBUTES CRITICALLY TO TRANSCRIPTIONAL REPRESSION OF MORS IN PRIMARY SENSORY NEURONS IN NEUROPATHIC PAIN. G9A INHIBITORS MAY BE USED TO ENHANCE THE OPIOID ANALGESIC EFFECT IN THE TREATMENT OF CHRONIC NEUROPATHIC PAIN. 2016 11 1631 44 DNMT3A METHYLATION IN NEUROPATHIC PAIN. BACKGROUND: MU OPIOID RECEPTOR (MOR) PLAYS A CRUCIAL ROLE IN MEDIATING ANALGESIC EFFECTS OF OPIOIDS AND IS CLOSELY ASSOCIATED WITH THE PATHOLOGIES OF NEUROPATHIC PAIN. PREVIOUS STUDIES HAVE REPORTED THAT PERIPHERAL NERVE INJURY DOWNREGULATES MOR EXPRESSION, BUT THE EPIGENETIC MECHANISMS REMAIN UNKNOWN. OBJECTIVE: THEREFORE, WE INVESTIGATED DNA METHYLTRANSFERASE3A (DNMT3A) EXPRESSION OR METHYLATION CHANGES WITHIN MOR PROMOTER IN THE SPINAL CORD IN A NEUROPATHIC PAIN INDUCED BY A CHRONIC CONSTRICTION INJURY (CCI) MOUSE MODEL AND FURTHER DETERMINED WHETHER THESE INJURY-ASSOCIATED CHANGES ARE REVERSIBLE BY PHARMACOLOGICAL INTERVENTIONS. METHODS: A CCI MOUSE MODEL WAS ESTABLISHED AND TISSUE SPECIMENS OF LUMBAR SPINAL CORDS WERE COLLECTED. THE NOCICEPTION THRESHOLD WAS EVALUATED BY A MODEL HEATED 400 BASE. DNMT3A AND MOR MRNA AND PROTEIN LEVEL WERE DETECTED BY REAL-TIME-POLYMERASE CHAIN REACTION AND WESTERN BLOT, RESPECTIVELY. METHYLATION OF DNMT3A GENE WAS MEASURED BY METHYLATION-SPECIFIC PCR. RESULTS: OUR DATA SHOWED THAT CHRONIC NERVE INJURY LED TO A SIGNIFICANT UPREGULATION OF DNMT3A EXPRESSION THAT WAS ASSOCIATED WITH INCREASED METHYLATION OF MOR GENE PROMOTER AND DECREASED MOR PROTEIN EXPRESSION IN THE SPINAL CORD. INHIBITION OF DNMT3A CATALYTIC ACTIVITY WITH DNMT INHIBITOR RG108 SIGNIFICANTLY BLOCKED THE INCREASE IN METHYLATION OF THE MOR PROMOTER, AND THEN UPREGULATED MOR EXPRESSION AND ATTENUATED THERMAL HYPERALGESIA IN NEUROPATHIC PAIN MICE. CONCLUSION: THIS STUDY DEMONSTRATES THAT AN INCREASE OF DNMT3A EXPRESSION AND MOR METHYLATION EPIGENETICALLY PLAY AN IMPORTANT ROLE IN NEUROPATHIC PAIN. TARGETING DNMT3A TO THE PROMOTER OF MOR GENE BY DNMT INHIBITOR MAY BE A PROMISING APPROACH TO THE DEVELOPMENT OF NEW NEUROPATHIC PAIN THERAPY. 2017 12 2785 39 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 13 1105 40 COMBINED INHIBITION OF HISTONE DEACETYLASES AND BET FAMILY PROTEINS AS EPIGENETIC THERAPY FOR NERVE INJURY-INDUCED NEUROPATHIC PAIN. CURRENT TREATMENTS FOR NEUROPATHIC PAIN HAVE OFTEN MODERATE EFFICACY AND PRESENT UNWANTED EFFECTS SHOWING THE NEED TO DEVELOP EFFECTIVE THERAPIES. ACCUMULATING EVIDENCE SUGGESTS THAT HISTONE ACETYLATION PLAYS ESSENTIAL ROLES IN CHRONIC PAIN AND THE ANALGESIC ACTIVITY OF HISTONE DEACETYLASES (HDACS) INHIBITORS IS DOCUMENTED. BROMODOMAIN AND EXTRA-TERMINAL DOMAIN (BET) PROTEINS ARE EPIGENETIC READERS THAT INTERACT WITH ACETYLATED LYSINE RESIDUES ON HISTONES, BUT LITTLE IS KNOWN ABOUT THEIR IMPLICATION IN NEUROPATHIC PAIN. THUS, THE CURRENT STUDY WAS AIMED TO INVESTIGATE THE EFFECT OF THE COMBINATION OF HDAC AND BET INHIBITORS IN THE SPARED NERVE INJURY (SNI) MODEL IN MICE. INTRANASAL ADMINISTRATION OF I-BET762 (BET INHIBITOR) OR SAHA (HDAC INHIBITOR) ATTENUATED THERMAL AND MECHANICAL HYPERSENSITIVITY AND THIS ANTIALLODYNIC ACTIVITY WAS IMPROVED BY CO-ADMINISTRATION OF BOTH DRUGS. SPINAL CORD SECTIONS OF SNI MICE SHOWED AN INCREASED EXPRESSION OF HDAC1 AND BRD4 PROTEINS AND COMBINATION PRODUCED A STRONGER REDUCTION COMPARED TO EACH EPIGENETIC AGENT ALONE. SAHA AND I-BET762, ADMINISTERED ALONE OR IN COMBINATION, COUNTERACTED THE SNI-INDUCED MICROGLIA ACTIVATION BY INHIBITING THE EXPRESSION OF IBA1, CD11B, INDUCIBLE NITRIC OXIDE SYNTHASE (INOS), THE ACTIVATION OF NUCLEAR FACTOR-KAPPAB (NF-KAPPAB) AND SIGNAL TRANSDUCER AND ACTIVATOR OF TRANSCRIPTION-1 (STAT1) WITH COMPARABLE EFFICACY. CONVERSELY, THE EPIGENETIC INHIBITORS SHOWED A MODEST EFFECT ON SPINAL PROINFLAMMATORY CYTOKINES CONTENT THAT WAS SIGNIFICANTLY POTENTIATED BY THEIR COMBINATION. PRESENT RESULTS INDICATE A KEY ROLE OF ACETYLATED HISTONES AND THEIR RECRUITMENT BY BET PROTEINS ON MICROGLIA-MEDIATED SPINAL NEUROINFLAMMATION. TARGETING NEUROPATHIC PAIN WITH THE COMBINATION OF HDAC AND BET INHIBITORS MAY REPRESENT A PROMISING NEW THERAPEUTIC OPTION. 2021 14 2353 29 EPIGENETIC REGULATION OF OPIOID-INDUCED HYPERALGESIA, DEPENDENCE, AND TOLERANCE IN MICE. REPEATED ADMINISTRATION OF OPIOIDS SUCH AS MORPHINE INDUCES PERSISTENT BEHAVIORAL CHANGES INCLUDING OPIOID-INDUCED HYPERALGESIA (OIH), TOLERANCE, AND PHYSICAL DEPENDENCE. IN THE CURRENT WORK WE EXPLORED HOW THE BALANCE OF HISTONE ACETYLTRANSFERASE (HAT) VERSUS HISTONE DEACETYLASE (HDAC) MIGHT REGULATE THESE MORPHINE-INDUCED CHANGES. NOCICEPTIVE THRESHOLDS, ANALGESIA, AND PHYSICAL DEPENDENCE WERE ASSESSED DURING AND FOR A PERIOD OF SEVERAL WEEKS AFTER MORPHINE EXPOSURE. TO PROBE THE ROLES OF HISTONE ACETYLATION, THE HAT INHIBITOR CURCUMIN OR A SELECTIVE HDAC INHIBITOR SUBEROYLANILIDE HYDROXAMIC ACID (SAHA) WAS ADMINISTERED DAILY TO GROUPS OF ANIMALS. HISTONE ACETYLATION IN SPINAL CORD WAS ASSESSED BY WESTERN BLOT AND IMMUNOHISTOCHEMISTRY. CONCURRENT ADMINISTRATION OF CURCUMIN WITH MORPHINE FOR 4 DAYS SIGNIFICANTLY REDUCED DEVELOPMENT OF OPIOID-INDUCED MECHANICAL ALLODYNIA, THERMAL HYPERALGESIA, TOLERANCE, AND PHYSICAL DEPENDENCE. CONVERSELY, THE HDAC INHIBITOR SAHA ENHANCED THESE RESPONSES. INTERESTINGLY, SAHA TREATMENT AFTER THE TERMINATION OF OPIOID ADMINISTRATION SUSTAINED THESE BEHAVIORAL CHANGES FOR AT LEAST 4 WEEKS. HISTONE H3 ACETYLATION IN THE DORSAL HORN OF THE SPINAL CORD WAS INCREASED AFTER CHRONIC MORPHINE TREATMENT, BUT H4 ACETYLATION WAS UNCHANGED. MOREOVER, WE OBSERVED A DECREASE IN HDAC ACTIVITY IN THE SPINAL CORDS OF MORPHINE-TREATED MICE WHILE OVERALL HAT ACTIVITY WAS UNCHANGED, SUGGESTING A SHIFT TOWARD A STATE OF ENHANCED HISTONE ACETYLATION. PERSPECTIVE: THE CURRENT STUDY INDICATES THAT EPIGENETIC MECHANISMS PLAY A CRUCIAL ROLE IN OPIOID-INDUCED LONG-LASTING NEUROPLASTICITY. THESE RESULTS PROVIDE NEW SIGHT INTO UNDERSTANDING THE MECHANISMS OF OPIOID-INDUCED NEUROPLASTICITY AND SUGGEST NEW STRATEGIES TO LIMIT OPIOID ABUSE POTENTIAL AND INCREASE THE VALUE OF THESE DRUGS AS ANALGESICS. 2013 15 1800 31 EFFECT OF HISTONE DEACETYLASE INHIBITOR ON ETHANOL WITHDRAWAL-INDUCED HYPERALGESIA IN RATS. BACKGROUND: INCREASED PAIN SENSITIVITY IS OBSERVED FOLLOWING ALCOHOL WITHDRAWAL, AND ATTEMPTS TO ALLEVIATE THIS HYPERALGESIA CAN CONTRIBUTE TO THE CYCLE OF ADDICTION. THE AIM OF THIS STUDY WAS TO DETERMINE IF ALCOHOL WITHDRAWAL-INDUCED HYPERALGESIA WAS OBSERVED IN A CHRONIC ETHANOL EXPOSURE MODEL AND IF THIS PAIN WAS AFFECTED BY HISTONE DEACETYLASE INHIBITORS, THUS REVEALING AN EPIGENETIC MECHANISM. METHODS: ADULT MALE SPRAGUE DAWLEY RATS RECEIVED LIEBER-DECARLI LIQUID CONTROL OR ETHANOL (9% V/V) DIET FOR 15 DAYS. MECHANICAL SENSITIVITY WAS MEASURED WITH VON FREY HAIR STIMULATION OF THE HINDPAW DURING ETHANOL ADMINISTRATION AND 24- AND 72-HOUR WITHDRAWAL. RESULTS: ETHANOL WITHDRAWAL PRODUCED SEVERE AND SUSTAINED MECHANICAL HYPERALGESIA, AN EFFECT NOT OBSERVED IN THE CONTROL OR ETHANOL-MAINTAINED GROUPS. FURTHERMORE, THIS HYPERALGESIA WAS ATTENUATED BY THE HISTONE DEACETYLASE INHIBITOR, SUBEROYLANILIDE HYDROXAMIC ACID TREATMENT. CONCLUSIONS: HEIGHTENED PAIN SENSITIVITY WAS OBSERVED FOLLOWING WITHDRAWAL FROM CHRONIC ETHANOL EXPOSURE, AND HISTONE DEACETYLASE INHIBITORS COULD BE NOVEL TREATMENTS FOR THIS ALCOHOL WITHDRAWAL-INDUCED HYPERALGESIA. 2019 16 2365 32 EPIGENETIC REGULATION OF SPINAL CXCR2 SIGNALING IN INCISIONAL HYPERSENSITIVITY IN MICE. BACKGROUND: THE REGULATION OF GENE EXPRESSION IN NOCICEPTIVE PATHWAYS CONTRIBUTES TO THE INDUCTION AND MAINTENANCE OF PAIN SENSITIZATION. HISTONE ACETYLATION IS A KEY EPIGENETIC MECHANISM CONTROLLING CHROMATIN STRUCTURE AND GENE EXPRESSION. CHEMOKINE CC MOTIF RECEPTOR 2 (CXCR2) IS A PROINFLAMMATORY RECEPTOR IMPLICATED IN NEUROPATHIC AND INFLAMMATORY PAIN AND IS KNOWN TO BE REGULATED BY HISTONE ACETYLATION IN SOME SETTINGS. THE AUTHORS SOUGHT TO INVESTIGATE THE ROLE OF HISTONE ACETYLATION ON SPINAL CXCR2 SIGNALING AFTER INCISION. METHODS: GROUPS OF 5-8 MICE UNDERWENT HIND PAW INCISION. SUBEROYLANILIDE HYDROXAMIC ACID AND ANACARDIC ACID WERE USED TO INHIBIT HISTONE DEACETYLASE AND HISTONE ACETYLTRANSFERASE, RESPECTIVELY. BEHAVIORAL MEASURES OF THERMAL AND MECHANICAL SENSITIZATION AS WELL AS HYPERALGESIC PRIMING WERE USED. BOTH MESSAGE RNA QUANTIFICATION AND CHROMATIN IMMUNOPRECIPITATION ANALYSIS WERE USED TO STUDY THE REGULATION OF CXCR2 AND LIGAND EXPRESSION. FINALLY, THE SELECTIVE CXCR2 ANTAGONIST SB225002 WAS ADMINISTERED INTRATHECALLY TO REVEAL THE FUNCTION OF SPINAL CXCR2 RECEPTORS AFTER HIND PAW INCISION. RESULTS: SUBEROYLANILIDE HYDROXAMIC ACID SIGNIFICANTLY EXACERBATED MECHANICAL SENSITIZATION AFTER INCISION. CONVERSELY, ANACARDIC ACID REDUCED INCISIONAL SENSITIZATION AND ALSO ATTENUATED INCISION-INDUCED HYPERALGESIC PRIMING. OVERALL, ACETYLATED HISTONE H3 AT LYSINE 9 WAS INCREASED IN SPINAL CORD TISSUES AFTER INCISION, AND ENHANCED ASSOCIATION OF ACETYLATED HISTONE H3 AT LYSINE 9 WITH THE PROMOTER REGIONS OF CXCR2 AND KERATINOCYTE-DERIVED CHEMOKINE (CXCL1) WAS OBSERVED AS WELL. BLOCKING CXCR2 REVERSED MECHANICAL HYPERSENSITIVITY AFTER HIND PAW INCISION. CONCLUSIONS: HISTONE MODIFICATION IS AN IMPORTANT EPIGENETIC MECHANISM REGULATING INCISION-INDUCED NOCICEPTIVE SENSITIZATION. THE SPINAL CXCR2 SIGNALING PATHWAY IS ONE EPIGENETICALLY REGULATED PATHWAY CONTROLLING EARLY AND LATENT SENSITIZATION AFTER INCISION. 2013 17 3324 43 HISTONE DEACETYLASE 2 IS INVOLVED IN MICRO?OPIOID RECEPTOR SUPPRESSION IN THE SPINAL DORSAL HORN IN A RAT MODEL OF CHRONIC PANCREATITIS PAIN. CHRONIC PAIN OCCURS IN ~85-90% OF CHRONIC PANCREATITIS (CP) PATIENTS. HOWEVER, AS THE PATHOGENESIS OF CP PAIN REMAINS TO BE FULLY UNDERSTOOD, THE CURRENT THERAPIES FOR CP PAIN REMAIN INADEQUATE. EMERGING EVIDENCE HAS SUGGESTED THAT THE EPIGENETIC MODULATIONS OF GENES ARE INVOLVED IN CHRONIC PAIN. IN THE PRESENT STUDY, INTRAPANCREATIC TRINITROBENZENE SULFONIC ACID INFUSIONS WERE USED TO ESTABLISH A CP MODEL IN RATS. MECHANICAL ALLODYNIA WAS MEASURED WITH VON FREY FILAMENTS. IMMUNOFLUORESCENT STAINING ANALYSIS WAS USED TO OBSERVE THE EXPRESSION CHANGES OF HISTONE DEACETYLASE 2 (HDAC2) AND MICRO?OPIOID RECEPTOR (MOR), AND INTRATHECAL ADMINISTRATION OF THE SELECTIVE HDAC2 INHIBITOR AR?42 WAS USED TO ASSESS THE UNDERLYING MECHANISMS. THE EXPRESSION LEVELS OF C?JUN N?TERMINAL KINASE (JNK) IN THE THORACIC SPINAL CORD WERE DETECTED BY WESTERN BLOTTING, AND THE MRNA EXPRESSION LEVELS OF INTERLEUKIN (IL)1?BETA, IL?6 AND TUMOR NECROSIS FACTOR (TNF)?ALPHA WERE DETECTED BY REVERSE TRANSCRIPTION?QUANTITATIVE POLYMERASE CHAIN REACTION. THE RESULTS DEMONSTRATED THAT HDAC2 EXPRESSION WAS UPREGULATED DURING THE COURSE OF CP INDUCTION, WHILE MOR ACTIVITY IN THE THORACIC SPINAL DORSAL HORN WAS SIGNIFICANTLY SUPPRESSED. INTRATHECAL INFUSION OF AR?42 SIGNIFICANTLY ATTENUATED CP?INDUCED MECHANICAL ALLODYNIA, WITH RESCUED MOR ACTIVITY. ADDITIONALLY, HDAC2 FACILITATED THE RELEASE OF INFLAMMATORY CYTOKINES, INCLUDING IL?1BETA, IL?6 AND TNF?ALPHA. THESE RESULTS SUGGESTED THAT THE UNDERLYING MECHANISMS OF HDAC2 REGULATING MOR ACTIVITY UNDER CP INDUCTION MAY OCCUR VIA PROMOTING THE RELEASE OF INFLAMMATORY CYTOKINES, THUS ACTIVATING THE JNK SIGNALING PATHWAY. THE PRESENT STUDY SUGGESTED THAT THE EPIGENETIC?REGULATED DISTURBANCE OF MOR IS DEPENDENT ON THE ENDOGENOUS ANALGESIA SYSTEM IN CP, WHICH MAY A PROVIDE NOVEL THERAPEUTIC STRATEGY FOR TREATING PAIN IN CP. 2018 18 3810 31 INTRATHECAL 5-AZACYTIDINE INHIBITS GLOBAL DNA METHYLATION AND METHYL- CPG-BINDING PROTEIN 2 EXPRESSION AND ALLEVIATES NEUROPATHIC PAIN IN RATS FOLLOWING CHRONIC CONSTRICTION INJURY. THE PATHOGENESIS OF NEUROPATHIC PAIN REMAINS LARGELY UNKNOWN. EPIGENETIC MECHANISMS MAY PLAY A MAJOR ROLE IN REGULATING EXPRESSION OF PRO- OR ANTINOCICEPTIVE GENES. DNA METHYLATION IS A MAJOR EPIGENETIC MECHANISM IN VERTEBRATES, AND METHYL- CPG-BINDING PROTEIN 2 (MECP2) IS DIRECTLY INVOLVED IN METHYLATION-MEDIATED GENE SILENCING. TO DETERMINE HOW CHANGES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION OCCUR FOLLOWING CHRONIC CONSTRICTION INJURY (CCI) AND HOW REPRESSION OF DNA METHYLATION AFFECTS THESE CHANGES AND ATTENUATES NEUROPATHIC PAIN, WE USED INTRATHECAL 5-AZACYTIDINE, A DNA METHYLTRANSFERASE INHIBITOR, IN CCI RATS. RATS RECEIVED 0.9% SALINE OR 5-AZACYTIDINE (10MUMOL.D(-1)) VIA SPINAL INJECTION ONCE DAILY FROM DAY 3 TO DAY 14 AFTER CCI SURGERY. GLOBAL DNA METHYLATION AND MECP2 EXPRESSION INCREASED IN THE SPINAL CORD IN CCI RATS ON DAY 14 AFTER CCI SURGERY. MECHANICAL ALLODYNIA AND THERMAL HYPERALGESIA INDUCED BY CCI WERE ATTENUATED BY INTRATHECAL 5-AZACYTIDINE FROM DAY 5 TO DAY 14 AFTER CCI SURGERY. THE INCREASES IN GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD IN CCI RATS WERE ALSO SIGNIFICANTLY INHIBITED BY INTRATHECAL 5-AZACYTIDINE. THESE RESULTS DEMONSTRATE THAT INCREASED GLOBAL DNA METHYLATION AND MECP2 EXPRESSION IN THE SPINAL CORD AFTER NERVE DAMAGE MAY PLAY AN IMPORTANT ROLE IN NEUROPATHIC PAIN. 5-AZACYTIDINE SHOWS POTENTIAL FOR TREATING NEUROPATHIC PAIN. 2011 19 2120 26 EPIGENETIC HISTONE MODIFICATIONS IN A CLINICALLY RELEVANT RAT MODEL OF CHRONIC ETHANOL-BINGE-MEDIATED LIVER INJURY. PURPOSE: ETHANOL BINGE AUGMENTS LIVER INJURY AFTER CHRONIC ETHANOL CONSUMPTION IN HUMANS, BUT THE MECHANISM BEHIND THE ENHANCED LIVER INJURY BY ETHANOL BINGE IS NOT KNOWN. IN THIS STUDY WE USED A CLINICALLY RELEVANT RAT MODEL IN WHICH LIVER INJURY IS AMPLIFIED BY BINGE AFTER CHRONIC ETHANOL TREATMENT AND INVESTIGATED THE IMPORTANCE OF HISTONE MODIFICATIONS. METHODS: EIGHT-WEEK-OLD SPRAGUE-DAWLEY RATS WERE FED ETHANOL IN A LIQUID DIET FOR 4 WEEKS. CONTROL RATS WERE FED AN ISOCALORIC LIQUID DIET. THIS WAS FOLLOWED BY THREE BINGE ADMINISTRATIONS OF ETHANOL (INTRAGASTRIC 5 G/KG BODY WEIGHT, 12 H APART). IN THE CONTROL, ETHANOL WAS REPLACED BY WATER. FOUR HOURS AFTER THE LAST BINGE ADMINISTRATION, LIVER SAMPLES WERE ANALYZED FOR HISTONE MODIFICATIONS AND PARAMETERS OF LIVER INJURY. RESULTS: CHRONIC ETHANOL ADMINISTRATION ALONE CAUSED AN INCREASE IN HISTONE H3 SER10 AND SER28 (H3S10 OR S28) PHOSPHORYLATION, AND BINGE ETHANOL REDUCED THEIR LEVELS. LEVELS OF DUALLY MODIFIED PHOSPHOACETYLATED HISTONE H3 (H3ACK9/PS10) INCREASED AFTER ACUTE BINGE ETHANOL AND REMAINED SAME AFTER CHRONIC ETHANOL BINGE. IN CONTRAST, HISTONE H3 LYSINE-9 ACETYLATION (H3ACK9) WAS NOT INCREASED AFTER CHRONIC ETHANOL BUT INCREASED SIGNIFICANTLY AFTER ACUTE BINGE AND CHRONIC ETHANOL BINGE. INCREASE IN HISTONE ACETYLATION WAS ACCOMPANIED BY INCREASED PHOSPHO-ERK1/2 IN THE NUCLEAR EXTRACTS. INCREASED ACETYLATION AFTER CHRONIC ETHANOL BINGE WAS ALSO ACCOMPANIED BY INCREASED PROTEIN LEVELS OF GCN5 HISTONE ACETYL TRANSFERASE AND A MODEST INCREASE IN HDAC3 IN THE NUCLEUS. HISTONE LYSINE-9 DIMETHYLATION WAS SIGNIFICANTLY INCREASED AFTER CHRONIC ETHANOL BINGE. CHRONIC ETHANOL BINGE ALSO RESULTED IN A DECREASE IN THE SAM:SAH RATIO WITH A RELATIVE DECREASE OF SAM LEVELS AND A CORRESPONDING INCREASE IN SAH LEVELS. CONCLUSIONS: ETHANOL BINGE AFTER CHRONIC ETHANOL ALTERED THE PROFILE OF SITE-SPECIFIC HISTONE MODIFICATIONS AND MAY UNDERLIE THE MECHANISM OF AUGMENTED LIVER INJURY BY CHRONIC-ETHANOL-BINGE-TREATED RATS. 2014 20 5781 44 SPINAL SIRT1 ACTIVATION ATTENUATES NEUROPATHIC PAIN IN MICE. ABNORMAL HISTONE ACETYLATION OCCURS DURING NEUROPATHIC PAIN THROUGH AN EPIGENETIC MECHANISM. SILENT INFORMATION REGULATOR 1 (SIR2 OR SIRT1), A NAD-DEPENDENT DEACETYLASE, PLAYS COMPLEX SYSTEMIC ROLES IN A VARIETY OF PROCESSES THROUGH DEACETYLATING ACETYLATED HISTONE AND OTHER SPECIFIC SUBSTRATES. BUT THE ROLE OF SIRT1 IN NEUROPATHIC PAIN IS NOT WELL ESTABLISHED YET. THE PRESENT STUDY WAS INTENDED TO DETECT SIRT1 CONTENT AND ACTIVITY, NICOTINAMIDE (NAM) AND NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD) IN THE SPINAL CORD USING IMMUNOBLOTTING OR MASS SPECTROSCOPY OVER TIME IN MICE FOLLOWING CHRONIC CONSTRICTION INJURY (CCI) OR SHAM SURGERY. IN ADDITION, THE EFFECT OF INTRATHECAL INJECTION OF NAD OR RESVERATROL ON THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA WAS EVALUATED IN CCI MICE. FINALLY, WE INVESTIGATED WHETHER SIRT1 INHIBITOR EX-527 COULD REVERSE THE ANTI-NOCICEPTIVE EFFECT OF NAD OR RESVERATROL. IT WAS FOUND THAT SPINAL SIRT1 EXPRESSION, DEACETYLASE ACTIVITY AND NAD/NAM DECREASED SIGNIFICANTLY 1, 3, 7, 14 AND 21 DAYS AFTER CCI SURGERY AS COMPARED WITH SHAM GROUP. IN ADDITION, DAILY INTRATHECAL INJECTION OF 5 MICROL 800 MM NAD 1 H BEFORE AND 1 DAY AFTER CCI SURGERY OR SINGLE INTRATHECAL INJECTION OF 5 MICROL 90 MM RESVERATROL 1 H BEFORE CCI SURGERY PRODUCED A TRANSIENT INHIBITORY EFFECT ON THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA IN CCI MICE. FINALLY, AN INTRATHECAL INJECTION OF 5 MICROL 1.2 MM EX-527 1 H BEFORE NAD OR RESVERATROL ADMINISTRATION REVERSED THE ANTI-NOCICEPTIVE EFFECT OF NAD OR RESVERATROL. THESE DATA INDICATE THAT THE REDUCTION IN SIRT1 DEACETYLASE ACTIVITY MAY BE A FACTOR CONTRIBUTING TO THE DEVELOPMENT OF NEUROPATHIC PAIN IN CCI MICE. OUR FINDINGS SUGGEST THAT THE ENHANCEMENT OF SPINAL NAD/NAM AND/OR SIRT1 ACTIVITY MAY BE A POTENTIALLY PROMISING STRATEGY FOR THE PREVENTION OR TREATMENT OF NEUROPATHIC PAIN. 2014