Abstracts

Previously, we investigated seizures following microinjection of the kainic acid (KA) into the left amygdala (LA) in mice with different strains, C57BL/6 (B6) and FVB/N (FVB). We reported that mice of the FVB strain show more seizure susceptibility than those of the B6 in the KA-induced amygdalar seizures. However, the details of the genes responsible for such difference remain obscure. In the present study, we crossed male B6 with female FVB to produce an F1 generation, and made seizure models of the F1., Male B6 were crossed with female FVB to produce an F1 generation. The F1 (n=6) underwent implantation of electrodes in the LA and the left sensorimotor cortex (LCx). Stainless cannula was also inserted into the LA for KA injection. All animals received KA injection into the LA (0.5 microg) to induce seizures, Electroencephalographic and behavioral observation was made for 48 hours, and the voltages of the spike were statically analized. Mice then were decapitated and histologic studies including analysis of the neuronal density of the CA3 in the hippocampus were carried out., On electoroencephalograms (EEGs), multiple spike discharges initially appeared in the LA within 10-20 min after KA injection and mouth and facial movement were behaviorally observed. At 20-60 min after KA injection, the seizure discharge propagated to the LCx. Within 60-90 min after KA injection the amplitude of the multiple spike discharges increased. Behaviorally, the animals demonstrated seizure motor manifestation such as head nodding, forelimb clonus, rearing and falling. During ictal EEG change, all mice showed only immobilization, lasting 1-2 min and recurring every 10-20 min. At 48 hours after KA injection multiple spike discharges were disappeared. Neuronal damage in the CA3 region was moderated., In the KA-induced amygdalar seizures, it is likely that mice of the F1 show resistant to seizure susceptibility similar to B6. Further examination related to genetic factor will be needed., (Supported by Grant-in-Aid for Encouragement of Young Scientists from the Ministry of Education, Sciences, and Culture of Japan.)