Erythropoietin exerts a neuroprotective function against glutamate neurotoxicity in experimental diabetic retina

Limin Gu, Hua Xu, Fang Wang, Guoxu Xu, Debasish Sinha, Juan Wang, Jing Ying Xu, Haibin Tian, Furong Gao, Weiye Li, Lixia Lu, Jingfa Zhang, Guo Tong Xu

Research output: Contribution to journalArticle

Abstract

PURPOSE. Retinal neuronal cell dysfunction and even cell death are associated with increased excitotoxic glutamate (Glu) level in the retina. Our aim was to study a causative mechanism of Glu on retinal cell death and explore the neuroprotective role of erythropoietin (EPO) against Glu neurotoxicity in the diabetic retina.

RESULTS. In 2-week diabetic rat retinas, Glu concentration was approximately 1.21-fold that in normal control. TUNEL staining demonstrated that retinal cell death was increased. Retinal GS and GLAST expressions were decreased, while the iGluRs, for example, KA1 and NR1, and PAR polymer expression was increased. In R28 cells, 24 hours after Glu (10 mM) treatment, the cell viability was decreased by 52.7%; KA1, NR1, PAR polymer, and nuclear AIF all increased in expression. The above conditions could be largely reversed by EPO both in vivo and in vitro. The protective effect of EPO was abolished by sEPOR.

METHODS. Male Sprague-Dawley (SD) rats and R28 cell line were employed in this study. Diabetes was induced with intraperitoneal injection of streptozotocin (STZ) in SD rats. Two weeks after diabetes onset, the intravitreal injection was performed; 4 days later, the retinas were harvested for testing. R28 cells were treated with Glu, GluþEPO, or GluþEPOþsoluble EPO receptor (sEPOR), respectively, for 24 hours, and then the cells were collected for the following studies. Glutamate level in the retina was measured with a glutamate assay kit. Cell death was determined with TUNEL staining. The changes in glutamine synthetase (GS), glutamate–aspartate transporter (GLAST), ionotropic glutamate receptors (iGluRs), apoptosisinducing factor (AIF), and poly(ADP-ribose) (PAR) polymer were studied with RT-PCR, Western blot, and immunofluorescence.

CONCLUSIONS. Erythropoietin showed a neuroprotective function against Glu-mediated neurotoxicity both in diabetic rat retina and in Glu-treated R28 cells. The neuroprotective mechanisms were largely through maintaining the normal expression of glutamate–glutamine cycle-related proteins and inhibiting AIF translocation and PAR polymer formation.

Original languageEnglish (US)
Pages (from-to)8208-8222
Number of pages15
JournalInvestigative Ophthalmology and Visual Science
Volume55
Issue number12
DOIs
StatePublished - Dec 15 2014

Keywords

  • Cell death
  • Diabetic retina
  • Erythropoietin
  • Glutamate

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Fingerprint Dive into the research topics of 'Erythropoietin exerts a neuroprotective function against glutamate neurotoxicity in experimental diabetic retina'. Together they form a unique fingerprint.

  • Cite this

    Gu, L., Xu, H., Wang, F., Xu, G., Sinha, D., Wang, J., Xu, J. Y., Tian, H., Gao, F., Li, W., Lu, L., Zhang, J., & Xu, G. T. (2014). Erythropoietin exerts a neuroprotective function against glutamate neurotoxicity in experimental diabetic retina. Investigative Ophthalmology and Visual Science, 55(12), 8208-8222. https://doi.org/10.1167/iovs.14-14435