Abstract
Spontaneously epileptic rats (SER, the double mutants homozygous for zitter and tremor genes), which originated from cross mating between tremor rat strain and zitter rat strain, spontaneously exhibit both absence-like and tonic seizures. In addition, wild jumping or running episodes sometimes occur after the tonic seizures. SER can, therefore, be used as an animal model for human epilepsy. We are going to develop congenic zitter strain (WTC-zi/zi) and new SER (WTC-tm/tm, zi/zi), since genetically defined control strains for SER and ZI (an inbred strain of zitter rats) are not available at present. Then, WTC strain, which derived from TRM (WTC-tm/tm, an inbred strain of tremor rats) will be able to be used as a control strain for the three mutant strains. Development of the absence-like seizure (appearance of 5-7 Hz spike and wave complexes in cortical and hippocampal EEG) and the mode of inheritance were examined in tremor rats and the backcross progeny. The results suggested that the absence-like seizure is semidominantly expressed. Zitter gene has been mapped on the rat chromosome 3 by linkage analysis using biochemical markers, RFLPs and microsatellites. Precise mapping of the epileptic seizurerelated genes should be the first step for gene cloning.
