title: Sigma-1 receptor stimulation protects retinal ganglion cells from ischemia-like insult through the activation of extracellular-signal-regulated kinases 1/2.
abstract: Sigma-1 receptor (σ-1) activation and mitogen-activated protein kinases (MAPKs) have been shown to protect retinal ganglion cells (RGCs) from cell death. The purpose of this study was to determine if σ-1 receptor stimulation with pentazocine could promote neuroprotection under conditions of an ischemia-like insult (oxygen glucose deprivation (OGD)) through the phosphorylation of extracellular signal regulated kinase (pERK)1/2. Primary RGCs were isolated from P3-P7 Sprague-Dawley rats and purified by sequential immunopanning using Thy1.1 antibodies. RGCs were cultured for 7 days before subjecting the cells to an OGD insult (0.5% oxygen in glucose-free medium) for 6 h. During the OGD, RGCs were treated with pentazocine (σ-1 receptor agonist) with or without BD 1047 (σ-1 receptor antagonist). In other experiments, primary RGCs were treated with pentazocine in the presence or absence of an MEK1/2 inhibitor, PD098059. Cell survival/death was assessed by staining with the calcein-AM/ethidium homodimer reagent. Levels of pERK1/2, total ERK1/2, and beta tubulin expression were determined by immunoblotting and immunofluorescence staining. RGCs subjected to OGD for 6 h induced 50% cell death in primary RGCs (p < 0.001) and inhibited pERK1/2 expression by 65% (p < 0.001). Cell death was attenuated when RGCs were treated with pentazocine under OGD (p < 0.001) and pERK1/2 expression was increased by 1.6 fold (p < 0.05) compared to OGD treated RGCs without pentazocine treatment. The co-treatment of PD098059 (MEK1/2 inhibitor) with pentazocine significantly abolished the protective effects of pentazocine on the RGCs during this OGD insult. Activation of the σ-1 receptor is a neuroprotective target that can protect RGCs from an ischemia-like insult. These results also established a direct relationship between σ-1 receptor stimulation and the neuroprotective effects of the ERK1/2 pathway in purified RGCs subjected to OGD. These findings suggest that activation of the σ-1 receptor may be a therapeutic target for neuroprotection particularly relevant to ocular neurodegenerative diseases that effect RGCs.
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA. Electronic address: bmueller@live.unthsc.edu.
authors.forename: Brett H
authors.initials: BH
authors.lastname: Mueller
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA.
authors.forename: Hai-Ying
authors.initials: HY
authors.lastname: Ma
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA.
authors.forename: Adnan
authors.initials: A
authors.lastname: Dibas
authors.affiliation: College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA.
authors.forename: Dorette Z
authors.initials: DZ
authors.lastname: Ellis
authors.affiliation: Department of Cell Biology and Immunology, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA.
authors.forename: Abbot F
authors.initials: AF
authors.lastname: Clark
authors.affiliation: Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX, USA; North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, USA. Electronic address: Thomas.Yorio@unthsc.edu.
authors.forename: Thomas
authors.initials: T
authors.lastname: Yorio
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D002470:Cell Survival; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019084:Fluorescent Antibody Technique, Indirect; D005947:Glucose / Q000378:metabolism; D007511:Ischemia / Q000201:enzymology / Q000517:prevention & control*; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010423:Pentazocine / Q000494:pharmacology*; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D017480:Receptors, sigma / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000201:enzymology; D000097605:Sigma-1 Receptor
chemical_list: D000701:Analgesics, Opioid; D004791:Enzyme Inhibitors; D005947:Glucose; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D010100:Oxygen; D010423:Pentazocine; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor
keywords: Extracellular signal-regulated kinases 1/2; Neuroprotection; Primary retinal ganglion cells; Sigma-1 receptor