1 2680 108 EVALUATION OF EPIGENETIC (HDAC, DNMT) AND PAIN (GAD65, TGF) FACTORS FOLLOWING PHOTOBIOMODULATION THERAPY IN A NEUROPATHIC PAIN MODEL. PHOTOBIOMODULATION THERAPY (PBMT) IS CONVERTED TO THE MOST COMMON ANALGESIC TREATMENT BEFORE THE WHOLE MECHANISM IS YET TO BE DISCOVERED. THIS STUDY FOR THE FIRST TIME WAS DESIGNED TO INVESTIGATE ALTERNATIONS OF EPIGENETIC FACTORS AFTER PAIN AND PBMT. THE CCI MODEL WAS CHOSEN TO INDUCE PAIN. PAIN EVALUATION TESTS INCLUDING PLANTAR, ACETONE, VON FREY, AND PINCH WERE DONE WEEKLY. THEN SPINAL CORD TISSUE WAS ISOLATED FOR EVALUATING MRNA EXPRESSION OF DNMT3A, HDAC1, AND NRSF USING RT-QPCR METHOD, AND PROTEIN EXPRESSION FACTORS OF HDAC2 AND DNMT3A USING WESTERN BLOTTING. GAD65 AND TGF-BETA PROTEINS WERE ASSESSED BY THE IHC METHOD. PBMT INCREASED THE PAIN THRESHOLD UP TO THE POINT WHERE IT ROUGHLY MET THE PAIN THRESHOLD OF THE CONTROL GROUP. AFTER THREE WEEKS OF TREATMENT, BOTH PBMT PROTOCOLS DEMONSTRATED A REDUCTION IN ALLODYNIA AND HYPERALGESIA. WHILE SOME MOLECULES, SUCH AS TGF-BETA AND GAD65, INCREASED FOLLOWING PBMT, WE OBSERVED NO INHIBITION OF NRSF, HDAC1, AND DNMT3A EXPRESSION DESPITE IMPLEMENTING TWO DIFFERENT PROTOCOLS. 2023 2 6148 36 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