The immunocytochemical distribution of the three excitatory amino acid
transporter subtypes GLT-1, GLAST-1 and EAAC-1 was studied in the rat
retina using antibodies raised against synthetic peptides correspondi
ng: to the C-terminus of each transporter subtype (Rothstein et al. 19
94). A comparative immunoblot analysis of rat cortex, cerebellum and r
etina membrane proteins suggested the following rank order of glutamat
e transporter subtype expression in retina: GLAST-1 greater than or eq
ual to EAAC-1>GLT-1. GLAST-1 immunoreactivity was seen in Muller cells
and astrocytes. EAAC-1 was found in horizontal cells, in amacrine and
displaced amacrine cells, and in ganglion cells. A minority of bipola
r cells also expressed EAAC-1. GLT-1 was preferentially expressed by d
ifferent types of bipolar cells; however, it was also found in some am
acrine cells. The functional role of this differential distribution of
glutamate transporters in the retina is discussed.