1 717 152 CALCITONIN GENE-RELATED PEPTIDE REGULATES SPINAL MICROGLIAL ACTIVATION THROUGH THE HISTONE H3 LYSINE 27 TRIMETHYLATION VIA ENHANCER OF ZESTE HOMOLOG-2 IN RATS WITH NEUROPATHIC PAIN. BACKGROUND: CALCITONIN GENE-RELATED PEPTIDE (CGRP) AS A MEDIATOR OF MICROGLIAL ACTIVATION AT THE TRANSCRIPTIONAL LEVEL MAY FACILITATE NOCICEPTIVE SIGNALING. TRIMETHYLATION OF H3 LYSINE 27 (H3K27ME3) BY ENHANCER OF ZESTE HOMOLOG 2 (EZH2) IS AN EPIGENETIC MARK THAT REGULATES INFLAMMATORY-RELATED GENE EXPRESSION AFTER PERIPHERAL NERVE INJURY. IN THIS STUDY, WE EXPLORED THE RELATIONSHIP BETWEEN CGRP AND H3K27ME3 IN MICROGLIAL ACTIVATION AFTER NERVE INJURY, AND ELUCIDATED THE UNDERLYING MECHANISMS IN THE PATHOGENESIS OF CHRONIC NEUROPATHIC PAIN. METHODS: MICROGLIAL CELLS (BV2) WERE TREATED WITH CGRP AND DIFFERENTIALLY ENRICHMENTS OF H3K27ME3 ON GENE PROMOTERS WERE EXAMINED USING CHIP-SEQ. A CHRONIC CONSTRICTION INJURY (CCI) RAT MODEL WAS USED TO EVALUATE THE ROLE OF CGRP ON MICROGLIAL ACTIVATION AND EZH2/H3K27ME3 SIGNALING IN CCI-INDUCED NEUROPATHIC PAIN. RESULTS: OVEREXPRESSIONS OF EZH2 AND H3K27ME3 WERE CONFIRMED IN SPINAL MICROGLIA OF CCI RATS BY IMMUNOFLUORESCENCE. CGRP TREATMENT INDUCED THE INCREASED OF H3K27ME3 EXPRESSION IN THE SPINAL DORSAL HORN AND CULTURED MICROGLIAL CELLS (BV2) THROUGH EZH2. CHIP-SEQ DATA INDICATED THAT CGRP SIGNIFICANTLY ALTERED H3K27ME3 ENRICHMENTS ON GENE PROMOTERS IN MICROGLIA FOLLOWING CGRP TREATMENT, INCLUDING 173 GAINING H3K27ME3 AND 75 LOSING THIS MARK, WHICH MOSTLY ENRICHED IN REGULATION OF CELL GROWTH, PHAGOSOME, AND INFLAMMATION. QRT-PCR VERIFIED EXPRESSIONS OF REPRESENTATIVE CANDIDATE GENES (TRAF3IP2, BCL2L11, ITGAM, DAB2, NLRP12, WNT3, ADAM10) AND REAL-TIME CELL ANALYSIS (RTCA) VERIFIED MICROGLIAL PROLIFERATION. ADDITIONALLY, CGRP TREATMENT AND CCI INCREASED EXPRESSIONS OF ITGAM, ADAM10, MCP-1, AND CX3CR1, KEY MEDIATORS OF MICROGLIAL ACTIVATION IN SPINAL DORSAL HORN AND CULTURED MICROGLIAL CELLS. SUCH INCREASED EFFECTS INDUCED BY CCI WERE SUPPRESSED BY CGRP ANTAGONIST AND EZH2 INHIBITOR, WHICH WERE CONCURRENTLY ASSOCIATED WITH THE ATTENUATED MECHANICAL AND THERMAL HYPERALGESIA IN CCI RATS. CONCLUSION: OUR FINDINGS HIGHLY INDICATE THAT CGRP IS IMPLICATED IN THE GENESIS OF NEUROPATHIC PAIN THROUGH REGULATING MICROGLIAL ACTIVATION VIA EZH2-MEDIATED H3K27ME3 IN THE SPINAL DORSAL HORN. 2021 2 2785 59 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 3 2783 48 EZH2 METHYLTRANSFERASE REGULATES NEUROINFLAMMATION AND NEUROPATHIC PAIN. RECENT STUDIES BY US AND OTHERS HAVE SHOWN THAT ENHANCER OF ZESTE HOMOLOG-2 (EZH2), A HISTONE METHYLTRANSFERASE, IN GLIAL CELLS REGULATES THE GENESIS OF NEUROPATHIC PAIN BY MODULATING THE PRODUCTION OF PROINFLAMMATORY CYTOKINES AND CHEMOKINES. IN THIS REVIEW, WE SUMMARIZE RECENT ADVANCES IN THIS RESEARCH AREA. EZH2 IS A SUBUNIT OF POLYCOMB REPRESSIVE COMPLEX 2 (PRC2), WHICH PRIMARILY SERVES AS A HISTONE METHYLTRANSFERASE TO CATALYZE METHYLATION OF HISTONE 3 ON LYSINE 27 (H3K27), ULTIMATELY RESULTING IN TRANSCRIPTIONAL REPRESSION. ANIMALS WITH NEUROPATHIC PAIN EXHIBIT INCREASED EZH2 ACTIVITY AND NEUROINFLAMMATION OF THE INJURED NERVE, SPINAL CORD, AND ANTERIOR CINGULATE CORTEX. INHIBITION OF EZH2 WITH DZNEP OR GSK-126 AMELIORATES NEUROINFLAMMATION AND NEUROPATHIC PAIN. EZH2 PROTEIN EXPRESSION INCREASES UPON ACTIVATION OF TOLL-LIKE RECEPTOR 4 AND CALCITONIN GENE-RELATED PEPTIDE RECEPTORS, DOWNREGULATION OF MIR-124-3P AND MIR-378 MICRORNAS, OR UPREGULATION OF LNCENC1 AND MALAT1 LONG NONCODING RNAS. GENES SUPPRESSED BY EZH2 INCLUDE SUPPRESSOR OF CYTOKINE SIGNALING 3 (SOCS3), NUCLEAR FACTOR (ERYTHROID-DERIVED 2)-LIKE-2 FACTOR (NRF2), MIR-29B-3P, MIR-146A-5P, AND BRAIN-SPECIFIC ANGIOGENESIS INHIBITOR 1 (BAI1). PRO-INFLAMMATORY MEDIATORS FACILITATE NEURONAL ACTIVATION ALONG PAIN-SIGNALING PATHWAYS BY SENSITIZING NOCICEPTORS IN THE PERIPHERY, AS WELL AS ENHANCING EXCITATORY SYNAPTIC ACTIVITIES AND SUPPRESSING INHIBITORY SYNAPTIC ACTIVITIES IN THE CNS. THESE STUDIES COLLECTIVELY REVEAL THAT EZH2 IS IMPLICATED IN SIGNALING PATHWAYS KNOWN TO BE KEY PLAYERS IN THE PROCESS OF NEUROINFLAMMATION AND GENESIS OF NEUROPATHIC PAIN. THEREFORE, TARGETING THE EZH2 SIGNALING PATHWAY MAY OPEN A NEW AVENUE TO MITIGATE NEUROINFLAMMATION AND NEUROPATHIC PAIN. 2023 4 5851 44 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 5 2470 51 EPIGENETIC TRANSCRIPTIONAL ACTIVATION OF MONOCYTE CHEMOTACTIC PROTEIN 3 CONTRIBUTES TO LONG-LASTING NEUROPATHIC PAIN. A MULTIPLEX ANALYSIS FOR PROFILING THE EXPRESSION OF CANDIDATE GENES ALONG WITH EPIGENETIC MODIFICATION MAY LEAD TO A BETTER UNDERSTANDING OF THE COMPLEX MACHINERY OF NEUROPATHIC PAIN. IN THE PRESENT STUDY, WE FOUND THAT PARTIAL SCIATIC NERVE LIGATION MOST REMARKABLY INCREASED THE EXPRESSION OF MONOCYTE CHEMOTACTIC PROTEIN 3 (MCP-3, KNOWN AS CCL7) A TOTAL OF 33 541 GENES IN THE SPINAL CORD, WHICH LASTED FOR 4 WEEKS. THIS INCREASE IN MCP-3 GENE TRANSCRIPTION WAS ACCOMPANIED BY THE DECREASED TRIMETHYLATION OF HISTONE H3 AT LYS27 AT THE MCP-3 PROMOTER. THE INCREASED MCP-3 EXPRESSION ASSOCIATED WITH ITS EPIGENETIC MODIFICATION OBSERVED IN THE SPINAL CORD WAS ALMOST ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE WITH PARTIAL SCIATIC NERVE LIGATION. CONSISTENT WITH THESE FINDINGS, A SINGLE INTRATHECAL INJECTION OF RECOMBINANT PROTEINS OF INTERLEUKIN 6 SIGNIFICANTLY INCREASED MCP-3 MESSENGER RNA WITH A DECREASE IN THE LEVEL OF LYS27 TRIMETHYLATION OF HISTONE H3 AT THE MCP-3 PROMOTER IN THE SPINAL CORD OF MICE. FURTHERMORE, DELETION OF THE C-C CHEMOKINE RECEPTOR TYPE 2 (CCR2) GENE, WHICH ENCODES A RECEPTOR FOR MCP-3, FAILED TO AFFECT THE ACCELERATION OF MCP-3 EXPRESSION IN THE SPINAL CORD AFTER PARTIAL SCIATIC NERVE LIGATION. A ROBUST INCREASE IN MCP-3 PROTEIN, WHICH LASTED FOR UP TO 2 WEEKS AFTER SURGERY, IN THE DORSAL HORN OF THE SPINAL CORD OF MICE WITH PARTIAL SCIATIC NERVE LIGATION WAS SEEN MOSTLY IN ASTROCYTES, BUT NOT MICROGLIA OR NEURONS. ON THE OTHER HAND, THE INCREASES IN BOTH MICROGLIA AND ASTROCYTES IN THE SPINAL CORD BY PARTIAL SCIATIC NERVE LIGATION WERE MOSTLY ABOLISHED IN INTERLEUKIN 6 KNOCKOUT MICE. MOREOVER, THIS INCREASE IN MICROGLIA WAS ALMOST ABOLISHED BY CCR2 GENE DELETION, WHEREAS THE INCREASE IN ASTROCYTES WAS NOT AFFECTED IN NERVE-LIGATED MICE THAT LACKED THE CCR2 GENE. WE ALSO FOUND THAT EITHER IN VIVO OR IN VITRO TREATMENT WITH MCP-3 CAUSED ROBUST MICROGLIA ACTIVATION. UNDER THESE CONDITIONS, INTRATHECAL ADMINISTRATION OF MCP-3 ANTIBODY SUPPRESSED THE INCREASE IN MICROGLIA WITHIN THE MOUSE SPINAL CORD AND NEUROPATHIC PAIN-LIKE BEHAVIOURS AFTER NERVE INJURY. WITH THE USE OF A FUNCTIONAL MAGNETIC RESONANCE IMAGING ANALYSIS, WE DEMONSTRATED THAT A SINGLE INTRATHECAL INJECTION OF MCP-3 INDUCED DRAMATIC INCREASES IN SIGNAL INTENSITY IN PAIN-RELATED BRAIN REGIONS. THESE FINDINGS SUGGEST THAT INCREASED MCP-3 EXPRESSION ASSOCIATED WITH INTERLEUKIN 6 DEPENDENT EPIGENETIC MODIFICATION AT THE MCP-3 PROMOTER AFTER NERVE INJURY, MOSTLY IN SPINAL ASTROCYTES, MAY SERVE TO FACILITATE ASTROCYTE-MICROGLIA INTERACTION IN THE SPINAL CORD AND COULD PLAY A CRITICAL ROLE IN THE NEUROPATHIC PAIN-LIKE STATE. 2013 6 2253 43 EPIGENETIC MODULATION OF WNT SIGNALING CONTRIBUTES TO NEUROPATHIC PAIN IN RATS. PREVIOUS STUDIES HAVE DEMONSTRATED THAT THE WNT/BETA?CATENIN SIGNALING PATHWAY IS CRITICAL TO THE INDUCTION AND MAINTENANCE OF CHRONIC NEUROPATHIC PAIN CAUSED BY PERIPHERAL INFLAMMATION AND NERVE DAMAGE. EMERGING EVIDENCE FROM RECENT STUDIES SUGGESTS THAT EPIGENETIC MECHANISMS MAY ALSO BE CRITICAL TO THE PATHOGENESIS OF CHRONIC PAIN. THE PRESENT STUDY AIMED TO ELUCIDATE THE EPIGENETIC MECHANISMS UNDERLYING ALTERED WNT SIGNALING AND THEIR INVOLVEMENT IN CCI?INDUCED NEUROPATHIC PAIN IN RAT SCIATIC NERVES. THE RESULTS OF THE PRESENT STUDY DEMONSTRATED A SIGNIFICANT INCREASE IN THE EXPRESSION LEVELS OF WNT3A IN THE DORSAL HORN OF THE RATS WITH CCI. IN ADDITION, A SIGNIFICANT INCREASE IN HISTONE H3 ACETYLATION, AND A SIGNIFICANT DECREASE IN CYTOSINE METHYLATION IN THE PROMOTER REGION OF WNT3A WAS OBSERVED IN THE DORSAL HORN OF THE RATS WITH CCI. INTRATHECAL APPLICATION OF XAV939, WHICH ACTS AS AN INHIBITOR OF WNT SIGNALING, SIGNIFICANTLY DECREASED THE EXPRESSION LEVELS OF ACTIVE BETA?CATENIN, AND ATTENUATED THE RAT BEHAVIORAL RESPONSES TO THERMAL AND MECHANICAL PAIN STIMULI. THESE RESULTS SUGGEST THAT THE EPIGENETIC UPREGULATION OF WNT3A IN THE DORSAL HORN CONTRIBUTES TO THE MAINTENANCE OF PAIN?INDUCED BEHAVIOR IN RATS WITH CCI. 2015 7 1631 50 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 8 5781 46 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 9 6172 45 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 10 3832 43 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 11 3324 50 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 12 3810 44 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 13 3194 39 HDAC INHIBITORS ATTENUATE THE DEVELOPMENT OF HYPERSENSITIVITY IN MODELS OF NEUROPATHIC PAIN. 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. THE AIM OF THIS STUDY WAS TO DETERMINE WHETHER THESE COMPOUNDS COULD ALSO AFFECT NEUROPATHIC PAIN. DIFFERENT CLASS I HDACIS WERE DELIVERED INTRATHECALLY INTO RAT SPINAL CORD IN MODELS OF TRAUMATIC NERVE INJURY AND ANTIRETROVIRAL DRUG-INDUCED PERIPHERAL NEUROPATHY (STAVUDINE, D4T). MECHANICAL AND THERMAL HYPERSENSITIVITY WAS ATTENUATED BY 40% TO 50% AS A RESULT OF HDACI TREATMENT, BUT ONLY IF STARTED BEFORE ANY INSULT. THE DRUGS GLOBALLY INCREASED HISTONE ACETYLATION IN THE SPINAL CORD, BUT APPEARED TO HAVE NO MEASURABLE EFFECTS IN RELEVANT DORSAL ROOT GANGLIA IN THIS TREATMENT PARADIGM, SUGGESTING THAT ANY POTENTIAL MECHANISM SHOULD BE SOUGHT IN THE CENTRAL NERVOUS SYSTEM. MICROARRAY ANALYSIS OF DORSAL CORD RNA REVEALED THE SIGNATURE OF THE SPECIFIC COMPOUND USED (MS-275) AND SUGGESTED THAT ITS MAIN EFFECT WAS MEDIATED THROUGH HDAC1. TAKEN TOGETHER, THESE DATA SUPPORT A ROLE FOR HISTONE ACETYLATION IN THE EMERGENCE OF NEUROPATHIC PAIN. 2013 14 3082 50 GENOME-WIDE REDISTRIBUTION OF MECP2 IN DORSAL ROOT GANGLIA AFTER PERIPHERAL NERVE INJURY. BACKGROUND: METHYL-CPG-BINDING PROTEIN 2 (MECP2), A PROTEIN WITH AFFINITY FOR METHYLATED CYTOSINES, IS CRUCIAL FOR NEURONAL DEVELOPMENT AND FUNCTION. MECP2 REGULATES GENE EXPRESSION THROUGH ACTIVATION, REPRESSION AND CHROMATIN REMODELING. MUTATIONS IN MECP2 CAUSE RETT SYNDROME, AND THESE PATIENTS DISPLAY IMPAIRED NOCICEPTION. WE OBSERVED AN INCREASE IN MECP2 EXPRESSION IN MOUSE DORSAL ROOT GANGLIA (DRG) AFTER PERIPHERAL NERVE INJURY. THE FUNCTIONAL IMPLICATION OF INCREASED MECP2 IS LARGELY UNKNOWN. TO IDENTIFY REGIONS OF THE GENOME BOUND BY MECP2 IN THE DRG AND THE CHANGES INDUCED BY NERVE INJURY, A CHROMATIN IMMUNOPRECIPITATION OF MECP2 FOLLOWED BY SEQUENCING (CHIP-SEQ) WAS PERFORMED 4 WEEKS AFTER SPARED NERVE INJURY (SNI). RESULTS: WHILE THE NUMBER OF BINDING SITES ACROSS THE GENOME REMAINED SIMILAR IN THE SNI MODEL AND SHAM CONTROL, SNI INDUCED THE REDISTRIBUTION OF MECP2 TO TRANSCRIPTIONALLY RELEVANT REGIONS. TO DETERMINE HOW DIFFERENTIAL BINDING OF MECP2 CAN AFFECT GENE EXPRESSION IN THE DRG, WE INVESTIGATED MMU-MIR-126, A MICRORNA LOCUS THAT HAD ENRICHED MECP2 BINDING IN THE SNI MODEL. ENRICHED MECP2 BINDING TO MIR-126 LOCUS AFTER NERVE INJURY REPRESSED MIR-126 EXPRESSION, AND THIS WAS NOT MEDIATED BY ALTERATIONS IN METHYLATION PATTERN AT THE MIR-126 LOCUS. DOWNREGULATION OF MIR-126 RESULTED IN THE UPREGULATION OF ITS TWO TARGET GENES DNMT1 AND VEGFA IN NEURO 2A CELLS AND IN SNI MODEL COMPARED TO CONTROL. THESE TARGET GENES WERE SIGNIFICANTLY DOWNREGULATED IN MECP2-NULL MICE COMPARED TO WILD-TYPE LITTERMATES, INDICATING A REGULATORY ROLE FOR MECP2 IN ACTIVATING DNMT1 AND VEGFA EXPRESSION. INTRATHECAL DELIVERY OF MIR-126 WAS NOT SUFFICIENT TO REVERSE NERVE INJURY-INDUCED MECHANICAL AND THERMAL HYPERSENSITIVITY, BUT DECREASED DNMT1 AND VEGFA EXPRESSION IN THE DRG. CONCLUSIONS: OUR STUDY SHOWS A REGULATORY ROLE FOR MECP2 IN THAT CHANGES IN GLOBAL REDISTRIBUTION CAN RESULT IN DIRECT AND INDIRECT MODULATION OF GENE EXPRESSION IN THE DRG. ALTERATIONS IN GENOME-WIDE BINDING OF MECP2 THEREFORE PROVIDE A MOLECULAR BASIS FOR A BETTER UNDERSTANDING OF EPIGENETIC REGULATION-INDUCED MOLECULAR CHANGES UNDERLYING NERVE INJURY. 2016 15 6461 43 TIME-COURSE PROGRESSION OF WHOLE TRANSCRIPTOME EXPRESSION CHANGES OF TRIGEMINAL GANGLIA COMPARED TO DORSAL ROOT GANGLIA IN RATS EXPOSED TO NERVE INJURY. MECHANISMS UNDERLYING NEUROPATHIC PAIN (NP) ARE COMPLEX WITH MULTIPLE GENES, THEIR INTERACTIONS, ENVIRONMENTAL AND EPIGENETIC FACTORS BEING IMPLICATED. TRANSCRIPTIONAL CHANGES IN THE TRIGEMINAL (TG) AND DORSAL ROOT (DRG) GANGLIA HAVE BEEN IMPLICATED IN THE DEVELOPMENT AND MAINTENANCE OF NP. DESPITE EFFORTS TO UNRAVEL MOLECULAR MECHANISMS OF NP, MANY REMAIN UNKNOWN. ALSO, MOST OF THE STUDIES FOCUSED ON THE SPINAL SYSTEM. ALTHOUGH THE SPINAL AND TRIGEMINAL SYSTEMS SHARE SOME OF THE MOLECULAR MECHANISMS, DIFFERENCES EXIST. WE USED RNA-SEQUENCING TECHNOLOGY TO IDENTIFY DIFFERENTIALLY EXPRESSED GENES (DEGS) IN THE TG AND DRG AT BASELINE AND 3 TIME-POINTS FOLLOWING THE INFRAORBITAL OR SCIATIC NERVE INJURIES, RESPECTIVELY. PATHWAY ANALYSIS AND COMPARISON ANALYSIS WERE PERFORMED TO IDENTIFY DIFFERENTIALLY EXPRESSED PATHWAYS. ADDITIONALLY, UPSTREAM REGULATOR EFFECTS WERE INVESTIGATED IN THE TWO SYSTEMS. DEG (DIFFERENTIALLY EXPRESSED GENES) ANALYSES IDENTIFIED 3,225 GENES TO BE DIFFERENTIALLY EXPRESSED BETWEEN TG AND DRG IN NAIVE ANIMALS, 1,828 GENES FOUR DAYS POST INJURY, 5,644 AT DAY 8 AND 9,777 DEGS AT 21 DAYS POST INJURY. COMPARISON OF TOP ENRICHED CANONICAL PATHWAYS REVEALED THAT A NUMBER OF SIGNALING PATHWAY WAS SIGNIFICANTLY INHIBITED IN THE TG AND ACTIVATED IN THE DRG AT 21 DAYS POST INJURY. FINALLY, CORT UPSTREAM REGULATOR WAS PREDICTED TO BE INHIBITED IN THE TG WHILE EXPRESSION LEVELS OF CSF1 UPSTREAM REGULATOR WERE SIGNIFICANTLY ELEVATED IN THE DRG AT 21 DAYS POST INJURY. THIS STUDY PROVIDES A BASIS FOR FURTHER IN-DEPTH STUDIES INVESTIGATING TRANSCRIPTIONAL CHANGES, PATHWAYS, AND UPSTREAM REGULATION IN TG AND DRG IN RATS EXPOSED TO PERIPHERAL NERVE INJURIES. 2023 16 4906 59 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 17 3141 49 GLOBAL GENE EXPRESSION AND CHROMATIN ACCESSIBILITY OF THE PERIPHERAL NERVOUS SYSTEM IN ANIMAL MODELS OF PERSISTENT PAIN. BACKGROUND: EFFORTS TO UNDERSTAND GENETIC VARIABILITY INVOLVED IN AN INDIVIDUAL'S SUSCEPTIBILITY TO CHRONIC PAIN SUPPORT A ROLE FOR UPSTREAM REGULATION BY EPIGENETIC MECHANISMS. METHODS: TO EXAMINE THE TRANSCRIPTOMIC AND EPIGENETIC BASIS OF CHRONIC PAIN THAT RESIDES IN THE PERIPHERAL NERVOUS SYSTEM, WE USED RNA-SEQ AND ATAC-SEQ OF THE RAT DORSAL ROOT GANGLION (DRG) TO IDENTIFY NOVEL MOLECULAR PATHWAYS ASSOCIATED WITH PAIN HYPERSENSITIVITY IN TWO WELL-STUDIED PERSISTENT PAIN MODELS INDUCED BY CHRONIC CONSTRICTION INJURY (CCI) OF THE SCIATIC NERVE AND INTRA-PLANTAR INJECTION OF COMPLETE FREUND'S ADJUVANT (CFA) IN RATS. RESULTS: OUR RNA-SEQ STUDIES IDENTIFY A VARIETY OF BIOLOGICAL PROCESS RELATED TO SYNAPSE ORGANIZATION, MEMBRANE POTENTIAL, TRANSMEMBRANE TRANSPORT, AND ION BINDING. INTERESTINGLY, GENES THAT ENCODE TRANSCRIPTIONAL REGULATORS WERE DISPROPORTIONATELY DOWNREGULATED IN BOTH MODELS. OUR ATAC-SEQ DATA PROVIDE A COMPREHENSIVE MAP OF CHROMATIN ACCESSIBILITY CHANGES IN THE DRG. A TOTAL OF 1123 REGIONS SHOWED CHANGES IN CHROMATIN ACCESSIBILITY IN ONE OR BOTH MODELS WHEN COMPARED TO THE NAIVE AND 31 SHARED DIFFERENTIALLY ACCESSIBLE REGIONS (DAR)S. FUNCTIONAL ANNOTATION OF THE DARS IDENTIFIED DISPARATE MOLECULAR FUNCTIONS ENRICHED FOR EACH PAIN MODEL WHICH SUGGESTS THAT CHROMATIN STRUCTURE MAY BE ALTERED DIFFERENTLY FOLLOWING SCIATIC NERVE INJURY AND HIND PAW INFLAMMATION. MOTIF ANALYSIS IDENTIFIED 17 DNA SEQUENCES KNOWN TO BIND TRANSCRIPTION FACTORS IN THE CCI DARS AND 33 IN THE CFA DARS. TWO MOTIFS WERE SIGNIFICANTLY ENRICHED IN BOTH MODELS. CONCLUSIONS: OUR IMPROVED UNDERSTANDING OF THE CHANGES IN CHROMATIN ACCESSIBILITY THAT OCCUR IN CHRONIC PAIN STATES MAY IDENTIFY REGULATORY GENOMIC ELEMENTS THAT PLAY ESSENTIAL ROLES IN MODULATING GENE EXPRESSION IN THE DRG. 2021 18 2300 45 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 19 6148 52 THE EXPRESSION OF TRANSCRIPTION FACTORS MECP2 AND CREB IS MODULATED IN INFLAMMATORY PELVIC PAIN. EARLY ACTIVATION OF TRANSCRIPTION FACTORS IS ONE OF THE EPIGENETIC MECHANISMS CONTRIBUTING TO THE INDUCTION AND MAINTENANCE OF CHRONIC PAIN STATES. PREVIOUS STUDIES IDENTIFIED THE CHANGES IN A NUMBER OF NOCICEPTION-RELATED GENES, SUCH AS CALCITONIN GENE-RELATED PEPTIDE (CGRP), SUBSTANCE P (SP), AND BRAIN-DERIVED NEUROTROPIC FACTOR (BDNF) IN THE PELVIC ORGANS AFTER TRANSIENT COLONIC INFLAMMATION. THE GENE AND PROTEIN EXPRESSION OF THESE NEUROPEPTIDES COULD BE MODULATED BY TRANSCRIPTION FACTORS METHYL-CPG-BINDING PROTEIN 2 (MECP2) AND CAMP RESPONSE ELEMENT-BINDING PROTEIN (CREB). IN THIS STUDY, WE AIMED TO EVALUATE TIME-DEPENDENT CHANGES IN THE EXPRESSION LEVELS OF MECP2 AND CREB IN THE LUMBOSACRAL (LS) SPINAL CORD AND SENSORY GANGLIA AFTER INFLAMMATION-INDUCED PELVIC PAIN IN RAT. ADULT SPRAGUE-DAWLEY RATS WERE TREATED WITH 2,4,6-TRINITROBENZENESULFONIC ACID (TNBS) TO INDUCE TRANSIENT COLONIC INFLAMMATION. LS (L6-S2) SPINAL CORD SEGMENTS AND RESPECTIVE DORSAL ROOT GANGLIAS (DRGS) WERE ISOLATED FROM CONTROL AND EXPERIMENTAL ANIMALS AT 1, 2, 6, 24 H AND 3 DAYS POST-TNBS TREATMENT. IMMUNOHISTOCHEMICAL (IHC) LABELING AND WESTERN BLOTTING EXPERIMENTS WERE PERFORMED TO ASSESS THE EXPRESSION OF MECP2, CREB AND THEIR PHOSPHORYLATED FORMS. TOTAL MECP2 EXPRESSION, BUT NOT PHOSPHORYLATED P-MECP2 (PS421MECP2) EXPRESSION WAS DETECTED IN THE CELLS OF THE SPINAL DORSAL HORN UNDER CONTROL CONDITIONS. COLONIC INFLAMMATION TRIGGERED A SIGNIFICANT DECREASE IN THE NUMBER OF MECP2-EXPRESSING NEURONS IN PARALLEL WITH ELEVATED NUMBERS OF PS421MECP2-EXPRESSING CELLS AT 2 H AND 6 H POST-TNBS. THE MAJORITY OF MECP2-POSITIVE CELLS (80 +/- 6%) CO-EXPRESSED CREB. TNBS TREATMENT CAUSED A TRANSIENT UP-REGULATION OF CREB-EXPRESSING CELLS AT 1 H POST-TNBS ONLY. THE NUMBER OF CELLS EXPRESSING PHOSPHORYLATED CREB (PS133CREB) DID NOT CHANGE AT 1 H AND 2 H POST-TNBS, BUT WAS DOWN-REGULATED BY THREE FOLDS AT 6 H POST-TNBS. ANALYSIS OF DRG SECTIONS REVEALED THAT THE NUMBER OF MECP2-POSITIVE NEURONS WAS UP-REGULATED BY TNBS TREATMENT, REACHING THREE-FOLD INCREASE AT 2 H POST-TNBS, AND EIGHT-FOLD INCREASE AT 6 H POST-TNBS (P