てんかん焦点内興奮性アミノ酸の変動と痙攣発作

Sequential Changes in Content of Excitatory Amino Acids in the Epileptic focus During Seizure

　てんかん準備性およびけいれん発現機序における興奮性アミノ酸の関与が注目されている。今回我々は，猫扁桃核Kindlingモデルに脳微小透析法を用いて，てんかん準備状態およびけいれん発作前後のてんかん焦点内組織間質液中のグルタミン酸（Glu）とアスパラギン酸（Asp）の経時的変化について検討した。

　雑種成猫15匹を電極刺入のみ行ったsham operation群（Sh群），部分けいれん群（P群），全身けいれん群（C群）の各5匹3群に分類し，probeを刺激側扁桃核に刺入し，電気刺激（けいれん発作）前15分から刺激後30分まで5分間2μl／minで灌流し，透析液に回収されたGluとAspをHPLCにより測定した。Sh群とP群・C群の刺激前値とは有意な差はなかった。P群のGluは，刺激後有意に上昇し，5分後には基礎値にもどる一過性上昇を示した。Aspも一過性に上昇するが有意ではなかった。C群では刺激後，AspおよびGluがともに有意に上昇し，5分後には基礎値にもどった。以上より，てんかん準備状態ではGlu\Aspの放出に変化なく，けいれん発作発現時に，部分けいれんではGluの，全身けいれんではAspおよびGluの放出が促進されることから，興奮性アミノ酸はけいれん発作に深く関与していることが示唆された。

Recently much attention has been paid to ex-citatory amino acids in seizure susceptibility and induction. In order to examine the relationship between epilepsy, especially seizure induction, and excitatory amino acids, we examined sequential change in content of excitatory amino acids in the epileptic focus by microdialysis system in a cat amygdaloid kindling model.

Fifteen crossbred adult cats divided into three groups: a sham operation group (Sh) as the con-trol, just after stage 4 group (S4), and just after stage 6 seizure group (S6) . Under halotane anesthe-sia, Microdialysis probe was inserted to the kindled focus, the right amygdala, and glutamate and aspar-tate contents of extracellular fluid were measured from 15 minutes prior to 30 minutes after seizure by high performance liquid chromatography (HPLC). The probe was perfused with artificial cerebrospinal fluid at a flow rate of 2μl/min for 5 minutes.

Before seizure, glutamate and aspartate concen-tration showed no significant changes in the S4 and S6 group compared with the Sh group. But after seizure, glutamate concentration was significantly higher in the S4 and S6 group temporally, while aspartate concentration was higher only in the S6 group temporally.

Based on the results that the release of glutamate and aspartate do not change in seizure susceptibil-ity, that glutamate is released in partial seizure, and that glutamate and aspartate are released in gener-alized seizure from the epileptic focus, excitatory amino acids are involved in seizure induction in a cat amygdaloid kindling.