Expression of GABA transaminase immunoreactivity in interneurons of the rat neostriatum

Immunoreactivity for gamma-aminobutyric acid transaminase (GABA-T), a degra dation enzyme for GABA, was localized by immunocytochemistry in the rat neo striatum and the globus pallidus using a monoclonal antibody. Immunoreactiv ity for GABA-T was found primarily in interneurons and in the neuropilar el ements in the neostriatum. Many of GABA-T-immunoreactive neurons were found to display parvalbumin immunoreactivity. This indicates many of the GABA-T -immunoreactive neurons are striatal GABAergic interneurons. Occasionally, GABA-T-immunoreactive glial cells were found. In the globus pallidus, many pallidal neurons also displayed GABA-T immunoreactivity and many of the imm unoreactive neurons were seen to express parvalbumin immunoreactivity. Immu noreactivity for GABA-T was also detected in the neuropil of the globus pal lidus. The present results indicate the GABAergic interneurons in the neost riatum and a subpopulation of pallidal neurons play an important role in me tabolic degradation of GABA in the basal ganglia. (C) 1999 Elsevier Science Ltd. All rights reserved.