Author:
JOHNSON MADELEINE A.,VARDI NOGA
Abstract
Mammalian horizontal cells are believed to be GABAergic
because, in most species, they contain both GABA and glutamic
acid decarboxylase (GAD), and their terminals are presynaptic
to GABA receptors. In adult rabbit, however, GABA and GAD
immunoreactivity have not been consistently demonstrated
in horizontal cells, casting doubts on the assumption that
they too are GABAergic. Here we demonstrate that all rabbit
horizontal cell terminals—dendritic terminals of
type A, and both dendritic and axonal terminals of type
B—immunostain for one isoform of GAD, GAD67.
In addition, we show that type A horizontal cell somas
and primary dendrites in the visual streak (identified
by their immunoreactivity to calbindin) are immunoreactive
for the other GAD isoform, GAD65. Double-labeling
experiments for GAD65 and GABA reveal that every
cell that stains for GAD65 also stains for GABA.
The presence of GAD67 in horizontal cell terminals
suggests that rabbit horizontal cells are GABAergic. The
segregation of the two GAD isoforms to different cell compartments
suggests that GABA is released at different sites, possibly
by two different mechanisms.
Publisher
Cambridge University Press (CUP)
Subject
Sensory Systems,Physiology
Cited by
35 articles.
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