The changes of AP-1 DNA binding activity and components in hippocampus of seizure-sensitive rat induced by kainate

Seizure-sensitive Fisher 344 rats were prepared 7 d after seizure episodes induced by a single subcutaneous administration of convulsive dose (7.5 mg/kg) of kainic acid. The activator protein-1 (AP-1) DNA binding activity and its components in the hippocampus of such rats were examined by Gel shift, Super-shift and Western blot assay. Gel shift assay showed that the basal level of AP-1 DNA binding activity was significantly higher than that of control rat hippocampus. Super-shift showed that only Fra and Jun D antibodies could super-shift AP-1 complex to a higher position. It suggested that the AP-1 complex was composed of Fra and Jun D in hippocampus of the seizure-sensitive rats. Western blot analysis further confirmed that Jun D proteins contained components of 43, 39 and 28 kDa. When secondary seizure stimulations were given to seizure-sensitive rats, the AP-1 DNA binding activity was attenuated and the components of AP-1 proteins changed transiently. In light of our results and those of literature, it appears that all the mentioned changes may play an important role in induction of long-lasting enhancement in seizure susceptibility.