Sigma-1 receptor stimulation protects retinal ganglion cells from ischemia-like insult through the activation of extracellular-signal-regulated kinases 1/2

• Published in: Experimental eye research Vol. 128; pp. 156 - 169
• Main Authors: Mueller, Brett H., Park, Yong, Ma, Hai-Ying, Dibas, Adnan, Ellis, Dorette Z., Clark, Abbot F., Yorio, Thomas
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.11.2014
• Subjects: Analgesics, Opioid - pharmacology; Animals; Blotting, Western; Cell Survival; Cells, Cultured; Enzyme Inhibitors - pharmacology; Extracellular signal-regulated kinases 1/2; Fluorescent Antibody Technique, Indirect; Glucose - metabolism; Ischemia - enzymology; Ischemia - prevention & control; Mitogen-Activated Protein Kinase 1 - antagonists & inhibitors; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3 - antagonists & inhibitors; Mitogen-Activated Protein Kinase 3 - metabolism; Neuroprotection; Oxygen - metabolism; Pentazocine - pharmacology; Phosphorylation; Primary retinal ganglion cells; Rats; Rats, Sprague-Dawley; Receptors, sigma - metabolism; Retinal Ganglion Cells - drug effects; Retinal Ganglion Cells - enzymology; Sigma-1 Receptor; Neuroprotection; Primary retinal ganglion cells; Extracellular signal-regulated kinases 1/2; Sigma-1 receptor
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1016/j.exer.2014.10.007

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. •We demonstrated that sigma-1 agonists can protect isolated purified retinal ganglion cells (RGCs) from cell death.•Sigma-1-agonist on RGCs is mediated through sigma-1 receptors as selective antagonists blocked this action.•The mechanism of the neuroprotection involves the phosphorylation of extracellular signal regulated kinase (pERK)1/2.•The results establish a direct relationship between σ-1 receptors and the neuroprotective effects of the ERK1/2 pathway.