Expression of glycine receptor and transporter on bullfrog retinal Müller cells

The expression of the glycine receptor (GlyR) α1, α2 and β subunits and glycine transporter (GlyT) on Müller cells was studied in bullfrog retina using double immunofluorescence labeling and confocal scanning microscopy. Double labeling of glial fibrillary acidic protein (GFAP), a specific marker for Müller cells, and the GlyR subunits showed that almost all Müller cells moderately expressed GlyR α1 and weakly GlyR β, whereas no immunoreactivity for GlyR α2 was observed. The labeling for GlyR α1 and GlyR β appeared in somata, major processes, endfeet and branchlets of the Müller cells. Müller cells were also GlyT1-labeled. Consistent with previous electrophysiological results, these findings suggest that Müller cells may be involved in modulation of glycinergic transmission by reciprocal interactions with retinal neurons through GlyR and GlyT.