Koroleva V I, Oitzl M S, Bures J
Electroencephalogr Clin Neurophysiol. 1985 Jan;60(1):55-64. doi: 10.1016/0013-4694(85)90951-4.
The role played by synaptic phenomena in the initiation of Leão's spreading depression (SD) was examined in 30 rats anaesthetized with pentobarbital. SD was elicited by a train of 8 electrical pulses (0.1-0.3 msec, 10 Hz) applied through bipolar electrodes to the exposed cortical surface. The slow potential waves of SD were recorded from the stimulated site and from a remote cortical area. Threshold stimulus intensity (40 V) was increased above 80 V when low frequency stimulation (0.3 Hz, 10 V) was applied through the same electrodes. SD penetration into the stimulated area was blocked with higher stimulus rates (3-10 Hz) and intensities (20 V). Systemic application of the pyrrolopyrimidine drug BE 58-271 decreased SD threshold from 40 V to 7 V and reduced also the intensity and frequency of stimulation inducing the SD blockade. Similar effects were obtained with local application of 2 microliters of 10(-3) M 4-amino-pyridine to the stimulated cortex. The SD threshold was reduced from 40 V to 5 V, probably by prolonged depolarization of axon terminals and increased output of transmitters. Estimation of SD threshold revealed a biphasic effect of locally applied penicillin: an initial threshold decrease which gradually changed with the development of regular interictal discharge into a threshold increase and eventual SD blockade. It is concluded that sudden synaptic activation of cerebral cortex elicits SD whereas prolonged continuous stimulation decreases SD susceptibility, probably by enhancing the K+ clearance.
在30只戊巴比妥麻醉的大鼠中，研究了突触现象在莱昂扩散性抑制（SD）起始过程中所起的作用。通过双极电极向暴露的皮质表面施加一串8个电脉冲（0.1 - 0.3毫秒，10赫兹）来诱发SD。从刺激部位和远处皮质区域记录SD的慢电位波。当通过同一电极施加低频刺激（0.3赫兹，10伏）时，阈值刺激强度（40伏）升高至80伏以上。较高的刺激频率（3 - 10赫兹）和强度（20伏）可阻断SD向刺激区域的渗透。全身应用吡咯并嘧啶药物BE 58 - 271可使SD阈值从40伏降至7伏，同时也降低了诱发SD阻断的刺激强度和频率。向受刺激皮质局部应用2微升10⁻³ M 4 - 氨基吡啶也获得了类似效果。SD阈值从40伏降至5伏，可能是由于轴突终末的去极化延长和递质释放增加所致。SD阈值的估计显示局部应用青霉素有双相作用：最初阈值降低，随着规则的发作间期放电的发展逐渐转变为阈值升高并最终导致SD阻断。结论是大脑皮质的突然突触激活引发SD，而长时间持续刺激会降低SD易感性，可能是通过增强钾离子清除来实现的。
