Baclofen Protects Primary Rat Retinal Ganglion Cells from Chemical Hypoxia-Induced Apoptosis Through the Akt and PERK Pathways

• Published in: Frontiers in cellular neuroscience Vol. 10; p. 255
• Main Authors: Fu, Pingping, Wu, Qiang, Hu, Jianyan, Li, Tingting, Gao, Fengjuan
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Research Foundation 04.11.2016; Frontiers Media S.A
• Subjects: AKT protein; Apoptosis; Baclofen; Bcl-2 protein; Caspase; Caspase-3; Cell viability; Cobalt; Diabetes; Diabetic retinopathy; er stress; FDA approval; Flow cytometry; GABAB receptor; Gene expression; Hypoxia; Kinases; Laboratory animals; Neurons; Neuroscience; Neurosciences; Nitric oxide; Phosphorylation; Polymerase chain reaction; Proteins; Retina; Retinal Ganglion Cells; RNA-mediated interference; Western blotting; γ-Aminobutyric acid B receptors; United States > US; China; Grand Island New York; GABAB receptor; ER stress; apoptosis; cobalt; retinal ganglion cells; baclofen; retinal hypoxia disease
• ISSN: 1662-5102; 1662-5102
• DOI: 10.3389/fncel.2016.00255

Retinal ganglion cells (RGCs) consume large quantities of energy to convert light information into a neuronal signal, which makes them highly susceptible to hypoxic injury. This study aimed to investigate the potential protection by baclofen, a GABA receptor agonist of RGCs against hypoxia-induced apoptosis. Cobalt chloride (CoCl ) was applied to mimic hypoxia. Primary rat RGCs were subjected to CoCl with or without baclofen treatment, and RNA interference techniques were used to knock down the GABA 2 gene in the primary RGCs. The viability and apoptosis of RGCs were assessed using cell viability and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assays, Hoechst staining, and flow cytometry. The expression of cleaved caspase-3, bcl-2, bax, Akt, phospho-Akt, protein kinase RNA (PKR)-like ER kinase (PERK), phospho-PERK, eIF2α, phospho-eIF2α, ATF-4 and CCAAT/enhancer-binding protein homologous protein (CHOP) were measured using western blotting. GABA 2 mRNA expression was determined using quantitative real-time polymerase chain reaction (qRT-PCR) analysis. Our study revealed that CoCl significantly induced RGC apoptosis and that baclofen reversed these effects. CoCl -induced reduction of Akt activity was also reversed by baclofen. Baclofen prevented the activation of the PERK pathway and the increase in CHOP expression induced by CoCl . Knockdown of GABA 2 and the inactivation of the Akt pathway by inhibitors reduced the protective effect of baclofen on CoCl -treated RGCs. Taken together, these results demonstrate that baclofen protects RGCs from CoCl -induced apoptosis by increasing Akt activity and by suppressing the PERK pathway and CHOP activation.