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: Brett H Mueller 2nd, Yong Park, Hai-Ying Ma, Adnan Dibas, Dorette Z Ellis, Abbot F Clark, Thomas Yorio
• Journal: Experimental eye research (Exp Eye Res) Vol. 128 Pg. 156-69 (Nov 2014) ISSN: 1096-0007 [Electronic] England
• PMID: 25305575 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical References

• Analgesics, Opioid
• Enzyme Inhibitors
• Receptors, sigma
• sigma-1 receptor
• Mitogen-Activated Protein Kinase 1
• Mitogen-Activated Protein Kinase 3
• Glucose
• Pentazocine
• Oxygen

Topics

• Analgesics, Opioid (pharmacology)
• Animals
• Blotting, Western
• Cell Survival
• Cells, Cultured
• Enzyme Inhibitors (pharmacology)
• Fluorescent Antibody Technique, Indirect
• Glucose (metabolism)
• Ischemia (enzymology, prevention & control)
• Mitogen-Activated Protein Kinase 1 (antagonists & inhibitors, metabolism)
• Mitogen-Activated Protein Kinase 3 (antagonists & inhibitors, metabolism)
• Oxygen (metabolism)
• Pentazocine (pharmacology)
• Phosphorylation
• Rats
• Rats, Sprague-Dawley
• Receptors, sigma (metabolism)
• Retinal Ganglion Cells (drug effects, enzymology)