Expression of clusterin in muller cells of the rat retina after pressure-induced ischemia

We have investigated the expression and cellular localization of clusterin in the rat retina following ischemia induced by transiently increasing the intraocular pressure. In the normal retina, weak clusterin immunoreactivity was visible in Muller cell profiles located in the inner nuclear layer. Following ischemia and reperfusion, strong immunoreactivity appeared in Muller cell somata and processes up to 3 days postlesion. Quantitative evaluation by immunoblotting confirmed that clusterin expression continuously increased and showed a peak value at 3 days after ischemic injury (to 1300% of control levels), and then decreased again to 400% of controls at 4 weeks postlesion. Immunocytochemistry using antisera against clusterin or glutamine synthase combined with the TUNEL method or immunocytochemistry using antisera activated caspase 3 and electron microscopy revealed that some clusterin-labeled Muller cells underwent apoptotic cell death. Our findings demonstrate that some Muller cells die by apoptosis, and suggest that clusterin produced and released by Muller cell may play an important role in the pathogenesis of ischemic injury in the rat retina. (C) 2004 Wiley-Liss, Inc.