Immunocytochemical localization of the GABA transporter in rat brain

Abstract

Polyclonal antibodies were raised against the GABA transporter (GABA-Tp) purified from rat brain tissue (Radian et al., 1986) and used for immunocytochemical localization of the antigen in several rat brain areas, including the cerebellum, hippocampus, substantia nigra, and cerebral cortex. Light microscopic studies with the peroxidase-antiperoxidase and biotin-avidin-peroxidase techniques suggested that GABA-Tp is localized in the same types of axons and terminals that contain endogenous GABA, as judged by comparison with parallel sections incubated with antibodies against glutaraldehyde-conjugated GABA. However, as expected from biochemical results, different neurons differed in their relative contents of GABA-Tp and GABA; thus, GABA-Tp was relatively low in striatonigral and Purkinje axon terminals and relatively high in nerve plexus around the bases of cerebellar Purkinje cells and hippocampal pyramidal and granule cells. The GABA-Tp antiserum did not produce detectable labeling of nerve cell bodies. Electron microscopic studies supported the light microscopic observations and provided direct evidence of cellular co-localization of GABA-Tp and GABA (as visualized by the peroxidase-antiperoxidase technique and postembedding immunogold labeling, respectively). The ultrastructural studies indicated the presence of GABA-Tp also in glial processes but not in glial cell bodies. The relative intensity of the neuronal and glial staining varied among regions: glial staining predominated over neuronal staining in the substantia nigra, whereas the converse was true in the cerebellum and hippocampus. The present immunocytochemical data demonstrate directly what has previously been inferred from biochemical and autoradiographic evidence: that the mechanisms for high-affinity GABA uptake is selectively and differentially localized in GABAergic neurons and in glial cells.

The Family of Na+/Cl− Neurotransmitter Transporters

“…The GABA uptake was not sensitive to /3-alanine, and it was concluded that GAT1 is the neuronal GABA transporter (Kanner et al, 1989). This conclusion was endorsed by immunocytochemical localization of GAT1 in rat brain sections using an antibody that was raised against the purified protein (Radian et al, 1990). However, some of the results indicated that GATI may also be present in glial cells.…”

Expression of GAT1 in Male Reproductive System and its Effects on Reproduction in Mice

“…Synaptic transmission is mainly terminated by reuptake of the GABA transport protein (GAT). GAT1 is the primary neuron transport protein in rodent brain among the four GATs (GAT1-GAT4) [Radian et al 1990;Pietrini et al 1994]. Besides the CNS, the GABA system is present in many peripheral tissues [Erdö and Wolff 1990], but its function is still not clearly understood.…”

Reduced Anxiety and Depression-Like Behaviors in Mice Lacking GABA Transporter Subtype 1

“…Through reuptake of released GABA, GATs control the duration and intensity of GABAergic activity at the synapse (Borden, 1996;Radian et al, 1990). Molecular cloning studies have identified multiple GABA transporter subtypes, including GAT1, GAT2, GAT3, and GAT4.…”