Expression of c–Jun in NMDA–induced Apoptosis Pathway in the Rat Retina

Abstract

Abstract: : Purpose: c–Jun, a member of the activation protein 1 (AP–1) family of transcription factors, has been implicated in regulation of many biological processes including neuronal cell death. The purpose of this study is to investigate whether c–Jun is activated during NMDA–induced apoptosis in the rat retina. Methods: Eight–week–male Wistar rats were used as subjects. The rats were received a single 2 µl injection of 10 mM (total amount of 20 nmol) NMDA into one eye, the same amount of PBS was administrated into the other eye, as a control. The eyes were enucleated at 6, 12, 24 and 168 hours after intravitreal injection. The expression of phosphorylated c–Jun (p–c–Jun) was examined by western blot analysis. Localization of p–c–Jun was studied by fluorescent double–labeling. Double–labeling with TUNEL staining and p–c–Jun was performed to examine the relation between apoptotic cells and c–Jun activity. Results: Western blot analysis showed that the increase of p–c–Jun appeared at 6 and 12 hours after intravitreal injection of NMDA. p–c–Jun immunoreactivities were especially localized in the retinal ganglion cell layer (RGCL). Double–labeling studies showed the co–localization of p–c–Jun and Thy–1, a marker for retinal ganglion cells (RGCs), in the RGCL. Furthermore, co–localization of TUNEL positive cells with p–c–Jun was observed in the RGCL. Conclusions: Phosphorylation of c–Jun in the retina was increased in early phase after NMDA injection. Activated c–Jun was observed in RGCs and TUNEL positive cells. These findings suggested that p–c–Jun might participate in NMDA–induced retinal apoptosis.

Keywords: apoptosis/cell death • retina • ganglion cells