Ito T, Miura Y, Kadokawa T
Research Laboratories, Dainippon Pharmaceutical Co., Ltd., Osaka, Japan.
Eur J Pharmacol. 1988 Nov 8;156(3):351-9. doi: 10.1016/0014-2999(88)90280-4.
The study dealt with a phenomenon similar to long-term potentiation of hippocampal population spikes that was observed with a high dose of physostigmine given to rats. The population spikes in the dentate granule cells in anesthetized rats were enhanced to 135, 152 and 167% of the control level 60, 120 and 240 min after the administration of physostigmine (0.1 mg/kg i.v.), respectively. The time course of the enhancement was consistent with that of blocked paired pulse inhibition by physostigmine in anesthetized rats. Such a block of paired pulse inhibition was seen at the observation of the long-term potentiation phenomenon to tetanic stimulation (100 Hz, 2 s). Perfusion of physostigmine (10(-5) M) or bicuculline (10(-6) M) elicited second spikes following the population spikes in CA1 pyramidal cells. The second spikes elicited by physostigmine were decreased by scopolamine (10(-6) M) and muscimol (5 x 10(-7) M), while those caused by bicuculline were decreased by muscimol but not by scopolamine. It is suggested that physostigmine induces a long-term potentiation-like phenomenon through a transient, abrupt increase in excitability and the subsequent block of recurrent GABAergic inhibition in the hippocampus.
该研究涉及一种类似于海马体群体峰电位长时程增强的现象，这种现象是在给大鼠注射高剂量毒扁豆碱时观察到的。给麻醉大鼠静脉注射毒扁豆碱（0.1mg/kg）后60、120和240分钟，齿状颗粒细胞中的群体峰电位分别增强至对照水平的135%、152%和167%。增强的时间进程与毒扁豆碱对麻醉大鼠成对脉冲抑制的阻断一致。在观察对强直刺激（100Hz，2s）的长时程增强现象时，可见成对脉冲抑制的这种阻断。用毒扁豆碱（10^(-5)M）或荷包牡丹碱（10^(-6)M）灌注可在CA1锥体细胞的群体峰电位后引发第二个峰电位。毒扁豆碱引发的第二个峰电位被东莨菪碱（10^(-6)M）和蝇蕈醇（5×10^(-7)M）降低，而荷包牡丹碱引发的第二个峰电位被蝇蕈醇降低，但不被东莨菪碱降低。提示毒扁豆碱通过短暂、突然的兴奋性增加以及随后对海马体中反复出现的GABA能抑制的阻断，诱导一种类似长时程增强的现象。
