The Response of Müller Cells in the Early Stages of Ischemia-Reperfusion Injury in the Rat Retina

Abstract

Abstract: : Purpose: To investigate the response of Müller cells in the early stages of ischemia- reperfusion injury. Methods: The intraocular pressure (IOP) was raised to 90-120 mmHg for 60 min, and the animals were sacrificed after 12 h, 24 h and 72 h of reperfusion. Immunocytochemistry using antisera against poliferation cell nuclear antigen (PCNA), clusterin, caspase 3 and 7 or glutamine synthase (GS), a specific marker for Müller cell, was applied, and apoptotic cell death was determined by a modified TUNEL technique and electron microscopy. Western blotting using anti-clusterin antisera and double labeling using antisera against GS and PCNA or clusterin were applied. Results: PCNA immunoreactivity was localized to most Müller cells and clusterin immunoreactivity appeared in a few Müller cells. In addition, double labeling using antisera against PCNA and clusterin demonstrated that these two antigens were not expressed in the same Müller cells. Clusterin labeled Müller cells showed caspases (3 and 7) immunoreactivity and also showed positive staining by TUNEL method. Electron microscopy showed that a few GS labeled Müller cells showed apoptotic cell death patterns. However, PCNA labeled Müller cells did not show any TUNEL positivity. Conclusions: These results suggest that a few Müller cells might die by apoptosis via expression of clusterin, and most Müller cells are resisitant to ischemia-reperfusion injury via expression of PCNA. In addition, caspases 3 and 7 might be involved in apotosis of Müller cells.

Keywords: ischemia • apoptosis/cell death • retinal degenerations: cell biology