GABA transporter-1 (GAT-1) immunoreactivity in the cat periaqueductal gray matter

Using light- and electron-microscopic immunocytochemistry, we investigated the regional distribution and the ultrastructural localization of GAT-1, a prominent GABA transporter, in the cat FAG. Light microscopic observations indicate that GAT-1-immunoreactive elements are particularly dense in PAG-DL and form a pair of longitudinal columns extending in the intermediate region of this structure. At electron-microscopic level, GAT-1 immunoreactivity was present in axon terminals forming symmetric synapses and in the distal processes of astroglial cells. These data further confirm the existence of longitudinal columns within FAG. They also indicate that GAT-1 could influence the action of GABA on its receptors, probably regulating the magnitude and duration of GABA's synaptic action on FAG neurons, and suggest that astrocytes may play an important role in this process. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.