TIME-DEPENDENT AND REGIONAL EXPRESSION OF GABA TRANSPORTER MESSENGER-RNAS FOLLOWING AMYGDALA-KINDLED SEIZURES IN RATS

To investigate the role played by GABA transporters in epileptic seizu res, we examined time-dependent and regional changes in expression of GAT-1 and GAT-3 GABA transporter mRNA in amygdala-kindled rat brain us ing an in situ hybridization method. GAT-1 mRNA was significantly incr eased bilaterally in the hippocampal dentate gyrus (111-116%) at 1 h a fter kindled generalized seizures. GAT-1 mRNA was also significantly i ncreased bilaterally in the hippocampal subfields (CA1-4 and dentate g yrus [110-117%]) at 4 h after kindled seizures. There were no signific ant changes in GAT-1 mRNA level in the amygdalar nuclei, pyriform cort ex or cerebral cortex either ipsilaterally or contralaterally at any t ime after kindled seizures. In contrast, GAT-3 mRNA was significantly increased bilaterally in the amygdalar nuclei and in the contralateral pyriform cortex and cerebral cortex 1 h after seizures. Since all the se changes returned to control levels by 8 or 24 h after kindled seizu res, the increases in GABA transporter mRNA appeared to be transient r esponses to seizure activity. These findings indicate that GAT-1 subty pe transporter is specifically involved in seizure activity in the hip pocampus, while GAT-3 subtype transporter is mainly involved in seizur e activity in the amygdalar nuclei and pyriform cortex following amygd ala-kindled generalized seizures. (C) 1998 Elsevier Science B.V.