Kozhedub R G, Voronin L L, Kozhechkin S N
Zh Vyssh Nerv Deiat Im I P Pavlova. 1982;32(5):947-53.
Evoked potentials (EPs) of the dorsal hippocampus were recorded in non-immobilized non-anaesthetized rabbits before and after tetanization of the medial septum and the dentate fascia. Changes of acetylcholine (ACh) efficiency were tested during long-lasting potentiation (LLP) and posttetanic depression (PTD). Increase in the amplitude of the EP fast component (population spike) during microiontophoresis of ACh was used as an index of ACh efficiency. In various tests both decrease and enhancement of ACh efficiency after tetanization were observed independent of the LLP or PTD appearance. "Relative" ACh efficiency in most cases decreased during LLP and enhanced during PTD. These changes were nonspecific since they were observed in response to the stimulation of both medial septum (cholinergic input), and dentate fascia (non-cholinergic input). Reactions to the stimulation of the control (non-tetanized) input were mainly depressed with diminution of ACh efficiency. The above experiments do not confirm the hypothesis that LLP and PTD are based on respective changes in the sensitivity of the subsynaptic membrane to the transmitter. The most probable LLP mechanism seems to be the enhancement of synaptic efficiency due to increased release of the transmitter. PTD mechanisms probably include changes at the level of the postsynaptic membrane and call for further analysis.
在对内侧隔区和齿状筋膜进行强直刺激前后，记录未固定、未麻醉家兔背侧海马的诱发电位（EP）。在长时程增强（LLP）和强直后抑制（PTD）期间检测乙酰胆碱（ACh）效能的变化。在ACh微离子导入过程中，EP快速成分（群体峰电位）幅度的增加被用作ACh效能的指标。在各种测试中，强直刺激后观察到ACh效能既有降低也有增强，与LLP或PTD的出现无关。在大多数情况下，“相对”ACh效能在LLP期间降低，在PTD期间增强。这些变化是非特异性的，因为在内侧隔区（胆碱能输入）和齿状筋膜（非胆碱能输入）受到刺激时均观察到了这些变化。对对照（未强直刺激）输入的刺激反应主要受到抑制，同时ACh效能降低。上述实验并未证实LLP和PTD是基于突触后膜对递质敏感性的相应变化这一假说。最可能的LLP机制似乎是由于递质释放增加导致突触效能增强。PTD机制可能包括突触后膜水平的变化，需要进一步分析。
