Immunohistochemical localization of the glycine receptor in synaptic layers and glial cells of the retina

Glycine has been considered as a neurotransmitter in the inner plexiform layer (IPL) of mammalian retina. In cold-blooded vertebrates both the outer and the inner plexiform layer appear to use glycine as a neurotransmitter. In this work we used monoclonal and polyclonal antibodies to study the localization of the postsynaptic glycine receptor (GlyR) subunits in frog and rat retina. Monoclonal antibodies revealed the presence of GlyR α and β subunits at the inner plexiform layer, whereas immunoreactivity to the polyclonal antibodies was observed, besides the IPL, in the outer plexiform layer and on Muller glial cells. These findings suggest that some isoforms of GlyR are localized in synaptic terminals and glial cells within vertebrate retina.