F. Jursky et N. Nelson, DEVELOPMENTAL EXPRESSION OF GABA TRANSPORTERS GAT1 AND GAT4 SUGGESTS INVOLVEMENT IN BRAIN MATURATION, Journal of neurochemistry, 67(2), 1996, pp. 857-867
cDNA clones representing four pharmacologically distinct GABA transpor
ters (GAT1-GAT4) were previously identified in mouse brain. Two of the
se, GAT1 and GAT4, were found to be brain specific. We studied GAT1 an
d GAT4 in the developing rat brain using polyclonal antibodies against
recombinant fusion proteins. Patterns of immunoreactivity were very s
imilar in the embryonic and early postnatal stages for both transporte
rs. However, whereas GAT1 immunoreactivity was detected in distinct pa
tterns in gray matter and growing axons, GAT4 immunoreactivity was fou
nd in a subset of radial glial cell fascicles. These patterns usually
oriented perpendicularly to the axons expressing GAT1. Our results sug
gest a transient relationship between GAT4-expressing radial glial ele
ments and GAT1-expressing axons. The presence of GAT1 in the cortical
marginal zone and the numerous GAT4-positive fascicles observed in the
fetal anterior commissure indicate that both transporters may play a
role in processes of brain maturation. Because the beginning of expres
sion for both GAT1 and GAT4 correlates with the expression of the alph
a 1 subunit of the GABA receptor, the transporters may be connected wi
th the maturation of adult-type GABAergic inhibitory system in the bra
in.