1 804 133 CENTRAL ENDOTHELIN-1 CONFERS ANALGESIA BY TRIGGERING SPINAL NEURONAL HISTONE DEACETYLASE 5 (HDAC5) NUCLEAR EXCLUSION IN PERIPHERAL NEUROPATHIC PAIN IN MICE. THE RATIONALE OF SPINAL ADMINISTRATION OF ENDOTHELIN-1(ET-1) MEDIATED ANTI-NOCICEPTIVE EFFECT HAS NOT BEEN ELUCIDATED. ET-1 IS REPORTED TO PROMOTE NUCLEAR EFFLUXION OF HISTONE DEACETYLASE 5 (HDAC5) IN MYOCYTES, AND SPINAL HDAC5 IS IMPLICATED IN MODULATION OF PAIN PROCESSING. IN THIS STUDY, WE AIMED TO INVESTIGATE WHETHER CENTRAL ET-1 PLAYS AN ANTI-NOCICEPTIVE ROLE BY FACILITATING SPINAL HDAC5 NUCLEAR SHUTTLING UNDER NEUROPATHIC PAIN. HERE, WE DEMONSTRATE THAT UPREGULATING SPINAL ET-1 ATTENUATED THE NOCICEPTION INDUCED BY PARTIAL SCIATIC NERVE LIGATION SURGERY AND THIS ANALGESIC EFFECT MEDIATED BY ET-1 WAS ATTENUATED BY INTRATHECAL INJECTION OF ENDOTHELIN A RECEPTOR SELECTIVE INHIBITOR (BQ123) OR BY BLOCKING THE EXPORTATION OF NUCLEAR HDAC5 BY ADENO-ASSOCIATED VIRUSES TARGETING NEURONAL HDAC5 (AVV-HDAC5 S259/498A MUTANT). NOTABLY, ET-1 ADMINISTRATION INCREASED SPINAL GLUTAMATE ACID DECARBOXYLASES (GAD65/67) EXPRESSION VIA INITIATING HDAC5 NUCLEAR EXPORTATION AND INCREASED THE ACETYLATION OF HISTONE 3 AT LYSINE 9 (ACETYL-H3K9) IN THE PROMOTOR REGIONS OF SPINAL GAD1 AND GAD2 GENES. THIS WAS REVERSED BY BLOCKING ENDOTHELIN A RECEPTOR FUNCTION OR BY INHIBITING THE SPINAL NEURONAL NUCLEAR EXPORTATION OF HDAC5. THEREFORE, INDUCING SPINAL GABAERGIC NEURONAL HDAC5 NUCLEAR EXPORTATION MAY BE A NOVEL THERAPEUTIC APPROACH FOR MANAGING NEUROPATHIC PAIN. PERSPECTIVE: NEUROPATHIC PAIN IS INTRACTABLE IN A CLINICAL SETTING, AND EPIGENETIC REGULATION IS CONSIDERED TO CONTRIBUTE TO THIS PROCESSING. CHARACTERIZING THE ANTI-NOCICEPTIVE EFFECT OF ET-1 AND INVESTIGATING THE ASSOCIATED EPIGENETIC MECHANISMS IN ANIMAL MODELS MAY LEAD TO THE DEVELOPMENT OF NEW THERAPEUTIC STRATEGIES AND TARGETS FOR TREATING NEUROPATHIC PAIN. 2021 2 2470 47 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 3 4861 31 ORGANIC ANION TRANSPORTER 1 IS AN HDAC4-REGULATED MEDIATOR OF NOCICEPTIVE HYPERSENSITIVITY IN MICE. PERSISTENT PAIN IS SUSTAINED BY MALADAPTIVE CHANGES IN GENE TRANSCRIPTION RESULTING IN ALTERED FUNCTION OF THE RELEVANT CIRCUITS; THERAPIES ARE STILL UNSATISFACTORY. THE EPIGENETIC MECHANISMS AND AFFECTED GENES LINKING NOCICEPTIVE ACTIVITY TO TRANSCRIPTIONAL CHANGES AND PATHOLOGICAL SENSITIVITY ARE UNCLEAR. HERE, WE FOUND THAT, AMONG SEVERAL HISTONE DEACETYLASES (HDACS), SYNAPTIC ACTIVITY SPECIFICALLY AFFECTS HDAC4 IN MURINE SPINAL CORD DORSAL HORN NEURONS. NOXIOUS STIMULI THAT INDUCE LONG-LASTING INFLAMMATORY HYPERSENSITIVITY CAUSE NUCLEAR EXPORT AND INACTIVATION OF HDAC4. THE DEVELOPMENT OF INFLAMMATION-ASSOCIATED MECHANICAL HYPERSENSITIVITY, BUT NEITHER ACUTE NOR BASAL SENSITIVITY, IS IMPAIRED BY THE EXPRESSION OF A CONSTITUTIVELY NUCLEAR LOCALIZED HDAC4 MUTANT. NEXT GENERATION RNA-SEQUENCING REVEALED AN HDAC4-REGULATED GENE PROGRAM COMPRISING MEDIATORS OF SENSITIZATION INCLUDING THE ORGANIC ANION TRANSPORTER OAT1, KNOWN FOR ITS RENAL TRANSPORT FUNCTION. USING PHARMACOLOGICAL AND MOLECULAR TOOLS TO MODULATE OAT1 ACTIVITY OR EXPRESSION, WE CAUSALLY LINK OAT1 TO PERSISTENT INFLAMMATORY HYPERSENSITIVITY IN MICE. THUS, HDAC4 IS A KEY EPIGENETIC REGULATOR THAT TRANSLATES NOCICEPTIVE ACTIVITY INTO SENSITIZATION BY REGULATING OAT1, WHICH IS A POTENTIAL TARGET FOR PAIN-RELIEVING THERAPIES. 2022 4 1689 36 DUAL HDAC/BRD4 INHIBITORS RELIEVES NEUROPATHIC PAIN BY ATTENUATING INFLAMMATORY RESPONSE IN MICROGLIA AFTER SPARED NERVE INJURY. DESPITE THE EFFORT ON DEVELOPING NEW TREATMENTS, THERAPY FOR NEUROPATHIC PAIN IS STILL A CLINICAL CHALLENGE AND COMBINATION THERAPY REGIMES OF TWO OR MORE DRUGS ARE OFTEN NEEDED TO IMPROVE EFFICACY. ACCUMULATING EVIDENCE SHOWS AN ALTERED EXPRESSION AND ACTIVITY OF HISTONE ACETYLATION ENZYMES IN CHRONIC PAIN CONDITIONS AND RESTORATION OF THESE ABERRANT EPIGENETIC MODIFICATIONS PROMOTES PAIN-RELIEVING ACTIVITY. RECENT STUDIES SHOWED A SYNERGISTIC ACTIVITY IN NEUROPATHIC PAIN MODELS BY COMBINATION OF HISTONE DEACETYLASES (HDACS) AND BROMODOMAIN AND EXTRA-TERMINAL DOMAIN (BET) INHIBITORS. ON THESE PREMISES, THE PRESENT STUDY INVESTIGATED THE PHARMACOLOGICAL PROFILE OF NEW DUAL HDAC/BRD4 INHIBITORS, NAMED SUM52 AND SUM35, IN THE SPARED NERVE INJURY (SNI) MODEL IN MICE AS INNOVATIVE STRATEGY TO SIMULTANEOUSLY INHIBIT HDACS AND BETS. INTRANASAL ADMINISTRATION OF SUM52 AND SUM35 ATTENUATED THERMAL AND MECHANICAL HYPERSENSITIVITY IN THE ABSENCE OF LOCOMOTOR SIDE EFFECTS. BOTH DUAL INHIBITORS SHOWED A PREFERENTIAL INTERACTION WITH BRD4-BD2 DOMAIN, AND SUM52 RESULTED THE MOST ACTIVE COMPOUND. SUM52 REDUCED MICROGLIA-MEDIATED SPINAL NEUROINFLAMMATION IN SPINAL CORD SECTIONS OF SNI MICE AS SHOWED BY REDUCTION OF IBA1 IMMUNOSTAINING, INDUCIBLE NITRIC OXIDE SYNTHASE (INOS) EXPRESSION, P65 NUCLEAR FACTOR-KAPPAB (NF-KAPPAB) AND P38 MAPK OVER-PHOSPHORYLATION. A ROBUST DECREASE OF THE SPINAL PROINFLAMMATORY CYTOKINES CONTENT (IL-6, IL-1SS) WAS ALSO OBSERVED AFTER SUM52 TREATMENT. PRESENT RESULTS, SHOWING THE PAIN-RELIEVING ACTIVITY OF HDAC/BRD4 DUAL INHIBITORS, INDICATE THAT THE SIMULTANEOUS MODULATION OF BET AND HDAC ACTIVITY BY A SINGLE MOLECULE ACTING AS MULTI-TARGET AGENT MIGHT REPRESENT A PROMISE FOR NEUROPATHIC PAIN RELIEF. 2022 5 532 28 ASTROCYTIC C-JUN N-TERMINAL KINASE-HISTONE DEACETYLASE-2 CASCADE CONTRIBUTES TO GLUTAMATE TRANSPORTER-1 DECREASE AND MECHANICAL ALLODYNIA FOLLOWING PERIPHERAL NERVE INJURY IN RATS. DECREASE OF GLUTAMATE TRANSPORTER-1 (GLT-1) IN THE SPINAL DORSAL HORN AFTER NERVE INJURY INDUCES ENHANCED EXCITATORY TRANSMISSION AND CAUSES PERSISTENT PAIN. HISTONE DEACETYLASES (HDACS)-CATALYZED DEACETYLATION MIGHT CONTRIBUTE TO THE DECREASE OF GLT-1, WHILE THE DETAILED MECHANISMS HAVE YET TO BE FULLY ELABORATED. SPINAL NERVE LIGATION (SNL) INDUCED SIGNIFICANT INCREASES OF HDAC2 AND DECREASES OF GLT-1 IN SPINAL ASTROCYTES. INTRATHECAL INFUSION OF THE HDAC2 INHIBITORS ATTENUATED THE DECREASE OF GLT-1 AND ENHANCED PHOSPHORYLATION OF GLUTAMATE RECEPTORS. GLT-1 AND PHOSPHORYLATED C-JUN N-TERMINAL KINASE (JNK) WERE HIGHLY COLOCALIZED IN THE SPINAL CORD, AND A LARGE NUMBER OF PJNK POSITIVE CELLS WERE HDAC2 POSITIVE. INTRATHECALLY INFUSION OF THE JNK INHIBITOR SP600125 SIGNIFICANTLY INHIBITED SNL-INDUCED UPREGULATION OF HDAC2. SNL-INDUCED HDAC2 UP-REGULATION COULD BE INHIBITED BY THE NEUTRALIZING ANTI-TUMOR NECROSIS FACTOR-ALPHA (TNF-ALPHA) BINDING PROTEIN ETANERCEPT OR THE MICROGLIAL INHIBITOR MINOCYCLINE. IN CULTURED ASTROCYTES, TNF-ALPHA INDUCED ENHANCED PHOSPHORYLATION OF JNK AND A SIGNIFICANT INCREASE OF HDAC2, AS WELL AS A REMARKABLE DECREASE OF GLT-1, WHICH COULD BE PREVENTED BY SP600125 OR THE HDAC2 SPECIFIC INHIBITOR CAY10683. OUR DATA SUGGEST THAT ASTROCYTIC JNK-HDAC2 CASCADE CONTRIBUTES TO GLT-1 DECREASE AND MECHANICAL ALLODYNIA FOLLOWING PERIPHERAL NERVE INJURY. NEUROIMMUNE ACTIVATION AFTER PERIPHERAL NERVE INJURY COULD INDUCE EPIGENETIC MODIFICATION CHANGES IN ASTROCYTES AND CONTRIBUTE TO CHRONIC PAIN MAINTENANCE. 2021 6 5851 42 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 7 5708 44 SIRT1 ATTENUATES NEUROPATHIC PAIN BY EPIGENETIC REGULATION OF MGLUR1/5 EXPRESSIONS IN TYPE 2 DIABETIC RATS. ACCUMULATING EVIDENCE HAS DEMONSTRATED THAT EPIGENETIC MODIFICATION-MEDIATED CHANGES IN PAIN-RELATED GENE EXPRESSIONS PLAY AN IMPORTANT ROLE IN THE DEVELOPMENT AND MAINTENANCE OF NEUROPATHIC PAIN. SIRTUIN 1 (SIRT1), A NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD)-DEPENDENT DEACETYLASE, IS INVOLVED IN THE DEVELOPMENT OF CHRONIC PAIN. MOREOVER, SIRT1 MAY BE A NOVEL THERAPEUTIC TARGET FOR THE PREVENTION OF TYPE 2 DIABETES MELLITUS (T2DM). BUT THE ROLE OF SIRT1 IN T2DM-INDUCED NEUROPATHIC PAIN REMAINS UNKNOWN. IN THIS STUDY, WE FOUND THAT SPINAL SIRT1 EXPRESSION AND ACTIVITY WERE DOWNREGULATED SIGNIFICANTLY IN HIGH-FAT-FED/LOW-DOSE STREPTOZOTOCIN-INDUCED NEUROPATHIC PAIN RATS. SIRT1 LOCALIZED IN SPINAL NEURONS BUT NOT IN ASTROCYTES OR MICROGLIA. FURTHERMORE, THE EXPRESSIONS OF METABOTROPIC GLUTAMATE RECEPTOR (MGLUR1) AND MGLUR5, WHICH PLAY A KEY ROLE IN CENTRAL SENSITIZATION AND NEUROPATHIC PAIN, AND H3 ACETYLATION LEVELS AT GRM1/5 (ENCODING MGLUR1/5) PROMOTER REGIONS WERE INCREASED IN DIABETIC NEUROPATHIC PAIN RATS. SIRT1 ACTIVATOR SRT1720 REVERSED THERMAL HYPERALGESIA AND MECHANICAL ALLODYNIA AND SPINAL NEURONAL ACTIVATION IN DIABETIC NEUROPATHIC PAIN RATS. CONCURRENTLY, INCREASED EXPRESSIONS OF MGLUR1/5 AND H3 ACETYLATION LEVELS AT GRM1/5 PROMOTER REGIONS WERE REVERSED BY SIRT1 ACTIVATION. IN ADDITION, KNOCKDOWN OF SIRT1 BY AD-SIRT1-SHRNA INDUCED PAIN BEHAVIORS AND SPINAL NEURONAL ACTIVATION IN NORMAL RATS, WHICH WAS ACCOMPANIED BY THE INCREASED EXPRESSIONS OF MGLUR1/5 AND H3 ACETYLATION LEVELS AT GRM1/5 PROMOTER REGIONS. THEREFORE, WE CONCLUDED THAT SIRT1-MEDIATED EPIGENETIC REGULATION OF MGLUR1/5 EXPRESSIONS WAS INVOLVED IN THE DEVELOPMENT OF NEUROPATHIC PAIN IN TYPE 2 DIABETIC RATS. 2017 8 6148 34 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