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BioMed Research International
Volume 2016, Article ID 9020715, 9 pages
http://dx.doi.org/10.1155/2016/9020715
Research Article

Activated Müller Cells Involved in ATP-Induced Upregulation of P2X7 Receptor Expression and Retinal Ganglion Cell Death

Department of Ophthalmology, Affiliated Hospital of Nantong University, Nantong 226001, China

Received 25 May 2016; Revised 10 August 2016; Accepted 28 August 2016

Academic Editor: Michael D. Coleman

Copyright © 2016 Ying Xue et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

P2X7 receptor (P2X7R), an ATP-gated ion channel, plays an important role in glaucomatous retinal ganglion cell (RGC) apoptotic death, in which activated retinal Müller glial cells may be involved by releasing ATP. In the present study, we investigated whether and how activated Müller cells may induce changes in P2X7R expression in RGCs by using immunohistochemistry and Western blot techniques. Intravitreal injection of DHPG, a group I metabotropic glutamate receptor (mGluR I) agonist, induced upregulation of GFAP expression, suggestive of Müller cell activation (gliosis), as we previously reported. Accompanying Müller cell activation, P2X7R protein expression was upregulated, especially in the cells of ganglion cell layer (GCL), which was reversed by coinjection of brilliant blue G (BBG), a P2X7R blocker. In addition, intravitreal injection of ATP also induced upregulation of P2X7R protein expression. Similar results were observed in cultured retinal neurons by ATP treatment. Moreover, both DHPG and ATP intravitreal injection induced a reduction in the number of fluorogold retrogradely labeled RGCs, and the DHPG effect was partially rescued by coinjection of BBG. All these results suggest that activated Müller cells may release ATP and, in turn, induce upregulation of P2X7R expression in the cells of GCL, thus contributing to RGC death.