Abstracts

Previously, we revealed that FVB/N showed more sensitive susceptibility to seizure, by electroencephalographic and behavioral observation, compared to C57BL/6 in the kainic acid (KA)-induced amygdalar seizures. Moreover, neuronal cell death in the hippocampal CA3 region was significantly severer in FVB/N than in C57BL/6. In the present study, we investigated the serial changes of GABA and Glutamate concentration in the left hippocampus after KA microinjection into the amygdala in mice with different strains, C57BL/6 and FVB/N., Forty-eight male adult mice with two strains (n=24, respectively) underwent a stereotactic operation using the units for stereotactic coordinates under pentobarbital anesthesia (10 mg / kg i.p.). For microinjection, a stainless steel cannula (outer diameter, 0.6 mm) with an inner needle guide (diameter, 0.3 mm) was inserted into the left amygdala (LA). On the seventh days after surgery , all animals received 0.5 microg of KA into the LA. Two hours (n=12, respectively) or 48 hours (n=12, respectively) after KA injection, animals were decapitated and the ipsilateral hippocampus were removed. Intrahippocampal GABA and glutamate were quantitatively measured using high performance liquid chromatography (HPLC). Data were analyzed statistically between C57BL/6 and FVB/N by using Student[apos]s t-test. In controls (n=12, respectively), PBS was injected into the LA. They likewise were quantitatively measured using HPLC., There was no significant difference concerning Glutamate and GABA concentration between two strains 2 hours after KA injection. Forty-eight hours after KA injection, however, GABA concentration of the C57BL/6 was significantly higher than that of the FVB/N, while there was no significant difference of glutamate concentration between two strains. In control, there was no significant difference between two strains concerning both GABA and Glutamate concentration 2 and 48 hours after PBS injection., The less seizure susceptibilities of the C57BL/6 may be associated with the intrahippocampal higher GABA concentration than that of FVB/N. This result will contribute to reveal the molecular mechanism of both strains, FVB/N and C57BL/6., (Supported by Grant[ndash]in-Aid for Encouragement of Young Scientists from the Ministry of Education, Sciences, and Culture of Japan.)