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Title: Inhibition of neutral sphingomyelinase decreases elevated levels of inducible nitric oxide synthase and apoptotic cell death in ocular hypertensive rats

Endoplasmic reticulum (ER) stress and excessive nitric oxide production via induction of inducible nitric oxide synthase (NOS2) have been implicated in the pathogenesis of neuronal retinal cell death in ocular hypertension. Neutral sphingomyelinase (N-SMase)/ceramide pathway can regulate NOS2 expression, hence this study determined the role of selective neutral sphingomyelinase (N-SMase) inhibition on retinal NOS2 levels, ER stress, apoptosis and visual evoked potentials (VEPs) in a rat model of elevated intraocular pressure (EIOP). NOS2 expression and retinal protein nitration were significantly greater in EIOP and significantly decreased with N-SMase inhibition. A significant increase was observed in retinal ER stress markers pPERK, CHOP and GRP78 in EIOP, which were not significantly altered by N-SMase inhibition. Retinal TUNEL staining showed increased apoptosis in all EIOP groups; however N-SMase inhibition significantly decreased the percent of apoptotic cells in EIOP. Caspase-3, -8 and -9 activities were significantly increased in EIOP and returned to baseline levels following N-SMase inhibition. Latencies of all VEP components were significantly prolonged in EIOP and shortened following N-SMase inhibition. Data confirm the role of nitrative injury in EIOP and highlight the protective effect of N-SMase inhibition in EIOP via down-regulation of NOS2 levels and nitrative stress. - Highlights: • Inhibition ofmore » N-SMase decreases NOS2 levels in ocular hypertension. • Inhibition of N-SMase decreases protein nitration in ocular hypertension. • Inhibition of N-SMase decreases caspase activation in ocular hypertension. • Inhibition of N-SMase decreases apoptosis in ocular hypertension.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [5]
  1. Department of Medical Biochemistry, Akdeniz University Faculty of Medicine, Antalya (Turkey)
  2. Department of Biophysics, Akdeniz University Faculty of Medicine, Antalya (Turkey)
  3. Department of Ophthalmology, Akdeniz University Faculty of Medicine, Antalya (Turkey)
  4. Department of Pathology, Akdeniz University Faculty of Medicine, Antalya (Turkey)
  5. Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario (Canada)
Publication Date:
OSTI Identifier:
22439886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Toxicology and Applied Pharmacology; Journal Volume: 280; Journal Issue: 3; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; APOPTOSIS; ENDOPLASMIC RETICULUM; HYPERTENSION; INHIBITION; INJURIES; NITRATION; NITRIC OXIDE; PATHOGENESIS; PROTEINS; RATS; STRESSES