Leeuwin R S, Njio K D, Belling G A, van den Hoven S
Arch Int Pharmacodyn Ther. 1983 Dec;266(2):200-7.
The mean cross sectional area of synaptic vesicle profiles of the myoneural junction of rat diaphragm is increased significantly when rats are injected i.p. with single doses of 200 micrograms/kg dexamethasone 1/2 hr to 8 hr previously to a control injection of 0.9% NaCl. A maximum effect is observed at 8 hr after pretreatment with dexamethasone. The treatment of rats with hemicholinium-3 (300 micrograms/kg) induces a significant reduction of the vesicle size. Complete prevention of this decrease in vesicle size is already observed when the animals are pretreated with a single dose of 200 micrograms/kg dexamethasone 1/2 hr before treatment with 300 micrograms/kg hemicholinium-3. Dexamethasone in the same dose causes an optimum increase of the mean cross sectional area when it is given 1 hr before treatment of the animals with hemicholinium-3. It is concluded that glucocorticoids have direct actions in both "normal" motor nerve terminals and in motor nerve terminals with a deficient choline transport system, which may contribute to their proposed beneficial effects in certain cases of muscle weakness.
在对大鼠腹腔注射0.9%氯化钠进行对照注射前1/2小时至8小时，预先给大鼠腹腔注射单剂量200微克/千克地塞米松，大鼠膈神经肌接头处突触小泡轮廓的平均横截面积显著增加。用地塞米松预处理8小时后观察到最大效应。用3 - 甲基-4 - 羟基-6,7 - 二甲氧基喹啉（300微克/千克）处理大鼠会导致小泡大小显著减小。当动物在用300微克/千克3 - 甲基-4 - 羟基-6,7 - 二甲氧基喹啉处理前1/2小时预先用单剂量200微克/千克地塞米松预处理时，已观察到完全防止小泡大小的这种减小。当在动物用3 - 甲基-4 - 羟基-6,7 - 二甲氧基喹啉处理前1小时给予相同剂量的地塞米松时，平均横截面积会出现最佳增加。得出的结论是，糖皮质激素在“正常”运动神经末梢和胆碱转运系统有缺陷的运动神经末梢中都有直接作用，这可能有助于它们在某些肌肉无力病例中所提出的有益作用。
