DIFFERENTIAL DISTRIBUTION OF BETA-DYSTROGLYCAN IN RABBIT AND RAT RETINA

The distribution of the dystrophin-associated glycoprotein complex was investigated in rabbit and rat retina by using the monoclonal antibod y 43DAG/8D5, which specifically recognizes beta-dystroglycan, a centra l component of the complex, In cryostat sections of retinae from both species, the authors observed staining of blood vessels, continuous la beling around the vitreal border, and strong immunoreactivity in the o uter plexiform layer (OPL), Electron microscopy showed that the immuno reactivity associated with the vitreal border of the retina was the re sult of a subcellular concentration of beta-dystroglycan in the endfee t of Muller glial cells, A similar concentration was observed in endfe et of perivascular astrocytes in the region of contact with the capill ary basal lamina, In the OPL, beta-dystroglycan was associated with th e terminals of both rods and cones, The label was almost exclusively f ound outside the synaptic area and was particularly strong in the exte nsions of the photoreceptor terminals protruding into the OPL, In the OPL of the rabbit retina, the authors found additional immunoreactivit y associated with the tips of postsynaptic horizontal and bipolar cell processes. These results show that the dystrophin-associated glycopro tein complex is subcellularly concentrated in photoreceptor terminals and glial cell endfeet, and that the rabbit retina differs from the ra t retina by the additional expression of this complex in bipolar and h orizontal cells, (C) 1998 Wiley-Liss, Inc.