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小鼠是一种对由投掷刺激诱导的惊厥性发作敏感的近交突变品系。本文比较了El（+）小鼠、未受刺激和惊厥的El（o）小鼠以及惊厥不敏感的ddY或BL小鼠脑皮质突触体质膜的体外蛋白质合成<C_57>。各组质膜蛋白质合成量无显著差异。钾和钠离子，核糖核酸酶，氯霉素，放线菌酮，嘌呤霉素和哇巴因的影响没有显着差异，四组小鼠。El（+）小鼠在tossed up刺激引起的发作前和发作后，除强直惊厥期外，质膜蛋白质合成均增加，提示El（+）小鼠突触损伤可通过蛋白质合成的增加而恢复。SDS-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析质膜蛋白质的电泳图谱，显示分子量分别为15，000、44，000、54，000、67，000和120，000的5条主带和20 ~ 30条次带。E1（+）小鼠在发作间期的67，000蛋白低于E1（o）、<C_57>BL和ddY小鼠，而E1（+）小鼠的120，000蛋白则因癫痫发作而减少。荧光法测得四组小鼠新合成的蛋白质分别为18，000、62，000和80，000，而62，000的蛋白质则因El（+）小鼠癫痫发作而减少。在多聚核糖体中合成的蛋白质为54，000、62，000、78，000、92，000、104，000和125，000。四组小鼠的癫痫发作情况相同，E1（+）小鼠的癫痫发作无显著差异。上述结果提示，El小鼠大脑皮层突触体质膜上的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.