Effect of convulsive seizures on protein synthesis in synaptosomal plasma membranes from El mouse brains and the relationship between protein components and seizure-susceptibility.

El小鼠是一种近交突变株，易受向上刺激引起的惊厥发作的影响。将El（+）小鼠大脑皮层突触体质膜的体外蛋白质合成与未刺激惊厥的El(o)小鼠和癫痫不易感的ddY或<C_57> BL小鼠作对照。四组间质膜蛋白合成无显著差异。钾离子和钠离子以及RNase、氯霉素、环己亚胺、嘌呤霉素和瓦巴因的作用在四组小鼠中没有显著差异。除强直性惊厥期外，El（+）小鼠的激前和激后质膜蛋白合成均有所增加，提示El（+）小鼠突触损伤可通过增强蛋白合成得到恢复。SDS-PAGE分析的质膜蛋白谱图显示分子量为15,000、44,000、54,000、67,000和120,000的5个主要带和20 ~ 30个小带。El（+）小鼠的67000蛋白在痫间期低于El(o)、<C_57> BL和ddY小鼠，而El（+）小鼠的120000蛋白在痫间期降低。在四组小鼠中，荧光检测到新合成的蛋白分别为18000、62000和80000，El（+）小鼠的癫痫发作使62000的蛋白含量降低。在多体中合成的蛋白质分别为54,000、62,000、78,000、92,000、104,000和125,000。这些在四组小鼠中都是相同的，而El（+）小鼠的癫痫发作没有观察到显著差异。上述结果提示El小鼠大脑皮层突触体质膜中67,000和120,000蛋白可能与癫痫易感性本身有关。

The El mouse is an inbred mutant strain susceptible to convulsive seizures induced by tossed-up stimulation. Protein synthesis in vitro of the synaptosomal plasma membranes isolated from cerebral cortices of El(+) mice was compared with those of El(o) mice, which have not been stimulated and convulsed after virth, and seizure non-susceptible ddY or <C_57> BL mice as the controls. No significant difference was observed in protein synthesis of plasma membranes among four groups. The effects of potassium and sodium ions, and RNase, chloramphenicol, cycloheximide, puromycin, and ouabain did not significantly differ among four groups of mice. The protein synthesis of plasma membranes in El(+) mice was increased in pre- and post-ictal phases caused by tossed-up stimulation, except to tonic convulsive phase, implying that impairment of synapses in El(+) mice was restored by enhancement of protein synthesis. The pattern of plasma membrane protein analyzed by SDS-PAGE showed 5 major bands containing molecular weights of 15,000, 44,000, 54,000, 67,000 and 120,000, and 20 to 30 minor bands. The protein of 67,000 in El(+) mice during interictal phases was lower than those of El(o), <C_57> BL and ddY mice, while the protein of 120,000 in El(+) mice was decreased by seizures. The newly synthesized protein was detected to be 18,000, 62,000 and 80,000 by fluorography in four groups of mice, and that of 62,000 was decreased by seizures of El(+) mice. The proteins synthesized in polysomes were 54,000, 62,000, 78,000, 92,000, 104,000 and 125,000. These were same in four groups of mice and no remarkable difference was observed by seizures of El(+) mice. The above results suggest that proteins of 67,000 and 120,000 in plasma membranes of synaptosomes of El mouse cerebral cortices might be associated with seizure-susceptibility itself.