1 809 139 CHANGES IN CLASS I AND IIB HDACS BY DELTA-OPIOID IN CHRONIC RAT GLAUCOMA MODEL. PURPOSE: THIS STUDY DETERMINES IF DELTA-OPIOID RECEPTOR AGONIST (I.E. SNC-121)-INDUCED EPIGENETIC CHANGES VIA REGULATION OF HISTONE DEACETYLASES (HDACS) FOR RETINAL GANGLION CELL (RGC) NEUROPROTECTION IN GLAUCOMA MODEL. METHODS: INTRAOCULAR PRESSURE WAS RAISED IN RAT EYES BY INJECTING 2M HYPERTONIC SALINE INTO THE LIMBAL VEINS. SNC-121 (1 MG/KG; I.P.) WAS ADMINISTERED TO THE ANIMALS FOR 7 DAYS. RETINAS WERE COLLECTED AT DAYS 7 AND 42, POST-INJURY FOLLOWED BY MEASUREMENT OF HDAC ACTIVITIES, MRNA, AND PROTEIN EXPRESSION BY ENZYME ASSAY, QUANTITATIVE REAL-TIME PCR (QRT-PCR), WESTERN BLOTTING, AND IMMUNOHISTOCHEMISTRY. RESULTS: THE VISUAL ACUITY, CONTRAST SENSITIVITY, AND PATTERN ELECTRORETINOGRAMS (ERGS) WERE DECLINED IN OCULAR HYPERTENSIVE ANIMALS, WHICH WERE SIGNIFICANTLY IMPROVED BY SNC-121 TREATMENT. CLASS I AND IIB HDACS ACTIVITIES WERE SIGNIFICANTLY INCREASED AT DAYS 7 AND 42 IN OCULAR HYPERTENSIVE ANIMALS. THE MRNA AND PROTEIN EXPRESSION OF HDAC 1 WAS INCREASED BY 1.33 +/- 0.07-FOLD AND 20.2 +/- 2.7%, HDAC 2 BY 1.4 +/- 0.05-FOLD AND 17.0 +/- 2.4%, HDAC 3 BY 1.4 +/- 0.06-FOLD AND 17.4 +/- 3.4%, AND HDAC 6 BY 1.5 +/- 0.09-FOLD AND 15.1 +/- 3.3% AT DAY 7, POST-INJURY. BOTH THE MRNA AND PROTEIN EXPRESSION OF HDACS WERE POTENTIATED FURTHER AT DAY 42 IN OCULAR HYPERTENSIVE ANIMALS. HDAC ACTIVITIES, MRNA, AND PROTEIN EXPRESSION WERE BLOCKED BY SNC-121 TREATMENT AT DAYS 7 AND 42 IN OCULAR HYPERTENSIVE ANIMALS. CONCLUSIONS: DATA SUGGESTS THAT CLASS I AND IIB HDACS ARE ACTIVATED AND UPREGULATED DURING EARLY STAGES OF GLAUCOMA. EARLY INTERVENTION WITH DELTA-OPIOID RECEPTOR ACTIVATION RESULTED IN THE PROLONGED SUPPRESSION OF CLASS I AND IIB HDACS ACTIVITIES AND EXPRESSION, WHICH MAY, IN PART, PLAY A CRUCIAL ROLE IN RGC NEUROPROTECTION. 2020 2 6148 35 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