Localization of neuronal and glial glutamate transporters.

ABSTRACT

The cellular and subcellular distributions of the glutamate transporter subtypes EAAC1, GLT-1, and GLAST in the rat CNS were demonstrated using anti-peptide antibodies that recognize the C-terminal domains of each transporter. On immunoblots, the antibodies specifically recognize proteins of 65-73 kDa in total brain homogenates. Immunocytochemistry shows that glutamate transporter subtypes are distributed differentially within neurons and astroglia. EAAC1 is specific for certain neurons, such as large pyramidal cortical neurons and Purkinje cells, but does not appear to be selective for glutamatergic neurons. GLT-1 is localized only to astroglia. GLAST is found in both neurons and astroglia. The regional localizations are unique to each transporter subtype. EAAC1 is highly enriched in the cortex, hippocampus, and caudate-putamen and is confined to pre- and postsynaptic elements. GLT-1 is distributed in astrocytes throughout the brain and spinal cord. GLAST is most abundant in Bergmann glia in the cerebellar molecular layer brain, but is also present in the cortex, hippocampus, and deep cerebellar nuclei.